Nanocasting and Direct Synthesis Strategies for Mesoporous Carbons

Subscriber access provided by Kaohsiung Medical University

Review

Nanocasting and Direct Synthesis Strategies for Mesoporous Carbons as Supercapacitor Electrodes Min Zhang, Liu He, Tuo Shi, and Ruhua Zha Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.8b03345 • Publication Date (Web): 19 Oct 2018 Downloaded from http://pubs.acs.org on October 19, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemistry of Materials

Nanocasting and Direct Synthesis Strategies for Mesoporous Carbons as Supercapacitor Electrodes Min Zhang,a Liu He,b Tuo Shi,c Ruhua Zhaa* College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, P. R. China. Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, Virginia, USA c Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, P. R. China. a

b

ABSTRACT: The flexible construction of electrode materials performs important functions in significant enhancing the electrochemical properties of both energy storage and conversion device. There is an increasing demand, not only for current but also the near-future energy field, where both high energy and power densities are necessary for the fabricated electrode materials. Carbon based nanoporous electrode materials demonstrate diverse superiority with respect to their application in electrochemical capacitors (i.e. supercapacitors) industry. The striking characteristics of mesoporous carbons include abundance in raw materials, sustainability, good conductivity, excellent heat and chemical resistance, good workability and lightweight nanostructure. Recently, various mesoporous carbons have increasingly been applied in energy storage filed because of their intrinsic open pore structure as well as high surface areas. However, the relationship between the synthesis strategies-the product structure, the structure-the supercapacitive properties of mesoporous carbons has not been comprehensively reviewed in the literature. Here, we focus on the progress made towards the construction of mesoporous carbons, with special emphasis on the state-of-the-art developments that has been able to achieve better management of pore networks and porosity, in addition to the better filter of low cost and readily available carbon precursors and catalysts. The synthesis strategies used to produce the mesoporous carbon materials are summarized and the necessary synthesis condition, the structure features of resulting mesoporous carbons and the supercapacitive properties are presented using a series of examples. Besides, some foreseeable challenges are presented for the better exploitation of diverse mesoporous carbon materials with tunable pore networks and the expansion of supercapacitor markets. This review provides guidelines for those who work on mesoporous carbon materials about the control their structure and morphology and those who focus on energy storage device about the enhancement of the energy and power densities.

INTRODUCTION Owing to the growing resource depletion and energy shortage issue throughout the world, there is in urgent need of making breakthroughs in the energy filed. Inexpensive, highly-efficient and green energy storage systems have all the time been widely regarded as a common goal for the academics and industry researchers. Recently, novel energy storage devices with high power density as well as high energy density were born as the flourish of all kinds of portable electronics and electric vehicles. Because of the strengths of being inexpensive, pro-environment and high-performance, supercapacitors win a place in the energy revolution. Fundamentally, supercapacitors possess particular advantages: (i) higher power density (up to 400 kW kg-1), (ii) ultrafast charge/discharge reaction, (iii) high cycling stability (specific capacitances have no apparent decrease after up to 4000 cycles) and (iv) higher coulombic efficiencies.6-10 In many cases, supercapacitors can be used along with rechargeable batteries to provide the additional power required in various cases, for example, the electrical vehicles and hybrid electric vehicles for gathering energy and supplying acceleration power upon regenerative braking. This can protect rechargeable batteries from high-frequency rapid discharge/charge processes. At present, supercapacitors are utilized in many fields, such as the solar energy systems, wind turbine system, military and aerospace, new energy vehicles and electric vehicles, etc.11-13 The proper utilization of the electrode materials has great potential in increasing

corresponding electrochemical properties because the energy and power density of a supercapacitor device are directly affected by the specific capacitance of the electrode materials as well as the overall cell voltage.14-19 Different electrode materials demonstrate different charge/discharge rate. Carbon-based materials have the advantage of abundance in raw material, high chemical and thermal stability, ease of processing and modification. Thus, they exhibit great potential in many energy-related applications and arise considerable attention from both the academic research and practical applications.20-24 As a huge family of porous materials, mesoporous carbons stand out from the competition owing to their environmental friendliness, broad pore size distribution (PSD), large accessible pore networks, high specific surface area, controllable porosity, as well as the relatively low density and various mesostructures in favor of necessary conditions for advanced applications.25-27 As such, they have gained global concern over recent decades.28-30 Discovering and creating novel mesoporous carbon materials with tailored architectures present a chance to improve the performance with both high power and energy density. There are several physical forms for mesoporous carbons, including nanoparticles31-33, nanosheets34-36, nanotubes37, nanofibers38, etc, which can meet all kinds of needs for industrial applications. Additionally, the porosity distribution of mesoporous carbons is relatively broad. There are micropores, mesopores and macropores in the nanostructures of mesoporous carbons. The pore size control is of significant importance for their supercapacitor application. Although previous reviews with regards to the

ACS Paragon Plus Environment

Chemistry of Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

construction of mesoporous carbons already existed, most of them just emphasized on the microstructure of the fabrications. Generally, there is still a lack of clear explanations the structure-property relationship of mesoporous carbons. As a matter of fact, the relationship between the synthesis strategies-the product structure, the structure-the supercapacitive properties of mesoporous carbons allows them to obtain deeper application in supercapacitors, thus, their structure-function relevance is expected to be drawn. The current review will describe the design and synthesis of the mesoporous carbons, with emphasis on the state-of-the-art that has been able to achieve better management of pore networks and porosity, in addition to the better filter of low cost and readily available carbon precursors and catalysts. The synthesis strategies used to produce the mesoporous carbon materials are summarized and the necessary synthesis condition, the structure features of resulting mesoporous carbons and the supercapacitive properties are presented using a series of examples. In particular, this work will investigate recent progress in EDLC, pseudocapacitors and hybrid supercapacitors, which give a deep description of the detailed charge storage mechanism for carbons in supercapacitors, and the respective strategies associated with different mesostructural properties of electrode materials for improving energy and power density. The synthesis strategies, the mesostructural properties and their supercapacitive properties of the recently reported mesoporous carbon based electrodes are highlighted in different examples. 2. Synthesis strategies of mesoporous carbons Different assembly routes may generate mesoporous carbon materials with different particle structure (as seen in Fig. 1), which all have individual strengths and weaknesses.39 These methods can be mainly divided into nanocasting strategies and direct synthesis strategies. The interaction between the used templates, the special carbon precursors and the activation condition plays vital effects on the generation of target products.

Page 2 of 24

Nanocasting technique has all the time been considered to be one of the most straightforward ways for fabricating uniformly distributed mesopores in carbon materials based on the introduction of highly ordered inorganic mesoporous solid materials as suitable templates. The applied diverse mesoporous inorganic substances can replicate their internal frameworks into the nanoporous carbon structure with well distributed mesoporosity. Hard and soft templating methods are two mature techniques in the nanocasting strategies for the production of mesoporous carbons. Generally, the nanocasting method is rather a conventional templating process. Despite that the assembled mesoporous carbons have unique physical and chemical properties, it is still difficult for the large scale production of the target product. What makes nanocasting technique special is its targeting assembly ability of target mesoporous carbons. Nevertheless, the results from laboratory and industrial trials indicate that the traditional assembly routes of generating target products with desired nanostructures via nanocasting technique have disadvantages of being complicated and high-cost. Recently, various mesoporous carbons with different textural properties have been obtained through a direct synthesis strategy by the self-assembly of organic–organic precursors (as seen in Fig. 2), which affords much lower cost and more scalable manufacturing approach.40

Fig. 2 Two typical strategies for the fabrication of mesoporous carbons. Reproduced with permission from ref. 40. Copyright 2013 Royal Society of Chemistry.

Fig. 1 The assembly of mesoporous carbons with diverse structures through different reaction routes. Reproduced with permission from ref. 39. Copyright 2016 Springer Nature.

There are several reviews reporting the progress of different mesoporous carbon materials, covering their origin, production methods, and the formation mechanism.40,41 However, in the present section, the state-of-the-art developments in the synthesis methods for diverse mesoporous carbons have been systematically expatiated, which can provide direction and instructions for future research. A wealth of examples has been present so as to offer methodologies and technologies to assemble carbon materials with desired mesoporous structures. The dominating construction methodologies and technologies aiming to build unique pore networks are deeply described and discussed in the following. 2.1 Nanocasting strategies A tailored mold with nanoscale size is required in the nanocasting strategies. Suitable templates with tailored properties are filled in the mold to initiate the reaction process. And the initial mold is eliminated after the reaction. As a flexible pathway, nanocasting strategy can create mesostructured materials which are harder to obtain by conventional processes. The great progress made in nanocasting strategy with hard and soft templates provide


Page 3 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


insightful guidance for the assembly of new types of mesoporous carbons with novel framework and compositions, leading to its extended functions and prospect. Rational use of templates in the nanocasting strategy can contribute to the generation of products with desired pore networks. Controlling the property of used templates plays significant role in determining the structure, composition and morphology of the final carbons. The commonly assembled mesostructured materials includes single crystals,42 monoliths,43 fibers,43 nanospheres,44 and vesicles45, etc. Generally, hard templates and soft templates are involved for the synthesis of the true solids in nanocasting strategy. 2.1.1 Hard templates Basically, the hard-template pathway is versatile enough to assemble the desired pore networks, and great advance has been made during the past decades. Based on the feasible control of the structural characteristics for the host template, various pore morphologies and porosity can be well controlled by the hard-template method. There are mainly four stages with regards to the hard-template pathway46: (a) the assembly of a tailored silica matrix with controlled shape and morphology to generate the mesopores; (b) adding special carbon precursor into the mesopores involved reaction system; (c) combination of organic–inorganic hybrid and pyrolyzation or carbonization under appropriate temperature; and (d) eliminating initial mould through the means of chemical etching under acid or alkaline solution. On the occasion, the host hard template in the solution rapidly entered into the gradually formed cavities. After carbonization under high temperature, the porosity of the final product is produced. In addition, the morphology of consequent carbon is the same as that of the mesoporous silica, that is, a replica of the mold. Among all hard-template routes, mesoporous silicas are the most commonly used hard template to assemble diverse mesostructured carbons. The mesoporous silica with cubic conformation (denoted as MCM-48) was firstly applied as the hard template to produce mesoporous carbons.47 That is, the mixed solutions of a carbon source and the hard template (mesoporous silica) were stirred and heated for a while. Then the resulting solution was carbonized at around 800 °C. Finally, silica mold is eliminated by means of etching with hydrofluoric acid or sodium hydroxide solution, leading to the desired mesoporous carbons. Besides, many other mesoporous silicas, such as hexagonal mesoporous silicas48 are also explored as hard templates. The hard template is the core for the preparation of mesoporous carbons. There are three ways to obtain the desired hard templates: (i) commercially available, such as clays or zeolites, (ii) produced from soft-template synthesis, (iii) generated from sol–gel routes. Nevertheless, the hard-template method still has its intrinsic disadvantages: the toxic hydrofluoric acid in the treatment of hard templates and the costly production cost (the sacrificial use of the hard templates). Hence, it is impractical for the mass production of target carbons with desired pore networks via the route of hard templates. 2.1.2 Soft templates Various carbon materials with tunable mesostructures have been fabricated on the basis of the soft-template method. The soft-template route has the following advantages: low-cost, ease of operation and largescale yield, relative to the hard-template method above. The rational cooperative construction of amphiphilic surfactant components and special precursor moieties plays an important role with respect to the

ordered mesoporous framework structure in the soft-templating process. In this case, mesoporosity can be formed upon getting rid of the surfactants by the high-temperature calcination. What’s more, as a result of the continuous framework structure, the as-synthesized mesoporous carbon materials are mechanically stable and their microstructure can be more accurately adjusted. Based on the soft-template route, a soft template is gradually formed via the self-assembly of amphiphilic surfactant molecules, in which block copolymers are served as the carbon precursors.49 In a word, the soft-template method is proved to be a highly efficient and economical way to produce the desired targets with tunable mesostrutures. Briefly, 3D ordered mesostructures can be obtained by the assembly of phenolic resin and block copolymer surfactant. Then the mesoporous polymer materials are produced by the removal of the surfactant. Finally, mesoporous carbons are generated after the carbonization of the mesoporous polymer materials. Generally, the driving force for the assembly of phenolic resin and soft template in the soft-template route depends on the hydrogen-bonding interactions taking place in the block copolymer surfactant and the polymer precursors.50,51 Suitable calcination process can effectively remove the used template agent. An inert gas or an extraction method is needed for the elimination of soft templates, which is determined by the chemical and thermal stability of the block copolymers. However, the as-synthesized mesoporous carbon materials in the soft-template method frequently present a minimal pore size of 3 nm. In this case, several other templates, such as inorganic nanofibers,52 AAO,53 and silica inverse opal,54 were introduced into the soft templates to generate diverse hierarchical microstructures. With regards to the post-processing of the carbon precursors, there are mainly four steps during the calcination process of carbon precursors: (a) generation of supramolecules; (b) polymerization under thermal treatment to form highly cross-linked networks; (c) extraction of templating agent; and (d) carbonization.55-57 Besides, the thermal stability, antioxidant power and mechanical stability of mesoporous carbons are in the leading position in this field because of stable pore walls and interpenetrating pore networks. The involved four steps in the soft template route are easier in operation and the reaction condition is more liable to be controlled, as compared to the hard-template route. The above routes are the dominating strategies for the preparation of mesoporous carbons. Each preparation strategy has individual strengths and weaknesses. Essentially, it has been found that the nanocasting strategy has the main limitations in assembly the mesoporous carbons with low porosity. Although the experimental process in the nanocasting pathway is easy to implement and operate as a result of the precise structure of the mother templates, the PSD value of the target product is often higher than that of the mother template because of the dependent processing conditions and the treatment temperature. Besides, the heavy consumption of soft templates (such as silica) as the reactive sacrificial agent and surfactants in the nanocasting pathway increases the production cost. In particular, the unavoidable preparation process is a waste of time and energy owing to multiple synthesis procedures. Therefore ， the choose of suitable pathway has great potential in adjusting the nanostructure characteristic of the final carbons and should evaluate the actual requirements. The quest for a convenient, green and capable of mass production method is highly



desired and still urgent. 2.2 Direct synthesis Direct strategy offers a fresh way to the generation of mesoporous carbons. Direct synthesis from organic polymer frameworks (amphiphilic block copolymers) by the rational manipulation of monomer polymerization can form highly ordered mesostructures. The fabrication of mesoporous carbons with diverse mesostructures through direct synthesis strategies is based on an assembly process of thermal-stable macromolecules precursors. Compared with the nanocasting pathway, the experimental operations in the direct synthesis method have many outstanding merits. Basically, the preparation process for mesoporous carbons with desired pore networks can be summarized as follows: (i) assembly of macromolecules and surfactants into 3D mesostructures; (ii) the removal of surfactants and the residual polymers can serve as the pore-forming agent; (iii) the calcination of the mesoporous macromolecules, leading to the final mesoporous carbons. The size and molecule network of the supramolecular aggregates play an essential effect on the dimension and shape of the final carbons. Generally, rational controlling the reaction temperature, reaction solvent and ionic strength can obtain the desired products with suitable pore structure and surface properties.58-60 The following will introduce the direct synthesized mesoporous carbon materials based on the summary of the recent and worldwide reports, which will provide insightful instructions for both academics and industry. The main effective factors, including the synthesis mechanism taking place in the reaction, the rational use of the precursors and suitable catalyst are discussed in following. 2.2.1 Reaction mechanism The direct calcination of self-assembled block copolymers cannot generate the mesoporous carbon materials as a result of the fairly low carbon residue during the pyrolytic reaction. It must be noted that the used block copolymer precursors must have high thermal stability and great production yield of carbon residue with regard to the soft-template route.51 If the self-assembled block copolymers are directly pyrolyzed under heating, mesoporous carbons cannot be generated as a result of the weak thermal and chemical stability of the linearly structured copolymers. Thus, it is necessary to introduce polymer precursors with high crosslinking density and high thermal stability to the reactive system, for example, the block copolymers. The self-assembly process of multicomponent polymers is finished under enough driving force, including hydrogen-bonding interactions, coulombic effects and the van der Waals forces taking place in the template agents and the polymer precursors. The structure adjustment and controlling of the synthesized mesoporous carbons largely depends on the used thermostable copolymers and decomposable surfactants. Among various thermosetting polymers, resorcinol, formaldehyde as well as triethyl orthoacetate have become the most frequently applied carbon precursors. Among the existing and cheap surfactant, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO–PPO–PEO) were the commonly used block copolymer in direct synthesis of carbon targets with mesostructures. The driving force taking place in the direct synthesis strategy for the assembly of target carbons with desired nanostructured pore networks has been proved to be ascribed to the hydrogen-bonding interaction between removable parent templates and thermal stable polymer precursors.61 As

Page 4 of 24

illustrated in Fig. 3, the block-copolymers and organic precursors are strongly linked by the hydrogen-bonding interactions in the reaction system of direct synthesis strategy, leading to the final formation of the carbon products. Ikkala et al. found that there was strong chemical driving, namely hydrogen-bonding interaction existed in PhOH and poly(4-vinylpyridine)–polystyrene (P4VP–PS), which could be utilized as the driving force for the synthesis of mesostructured carbons.62 In addition, the morphology and structure of the self-assembled target molecules was adjustable, ranging from nanosheet to cylinder and sphere, depending on the controlling of the block lengths of involved polymer precursors.

Fig. 3 The driving force of hydrogen-bonding interaction existed in diverse assembly system for the generation of mesoporous carbons. Reproduced with permission from ref. 61. Copyright 2008 American Chemical Society.

In a word, besides the parent template of block-copolymer surfactant, the characteristic of polymer precursors plays essential role throughout the whole reaction in the direct synthesis strategy. In view of the aspects of economy and green production, the future research development trend will focus on: (1) reduce the use of carbon co-precursors to cut the production cost; (2) use environmentally friendly precursors, and avoid the use of toxic gas precursors. In general, the block copolymers liked carbon precursors, such as PEO–PPO–PEO, are the mostly employed parent templates, and the reactionary power triggering the assembly of all reaction components is primarily controlled by the hydrogen-bonding interaction. Nevertheless, other types of reaction initiators such as coulombic and van der Waals forces have also great potential in the assembly of monomers. In this way, a series of surfactant templates, including cationic quaternary ammonium and nonionic alkyl PEO oligomer have the ability to serve independently as the carbon precursors. Besides, they can be used together with block copolymers in the synthesis process, resulting in smaller or even more multi-scaled mesoporosity for the synthesized mesoporous carbons in the direct strategy. 2.2.2 Precursor Diverse three-dimensional (3D) carbonaceous frameworks with large porosity can be created under the driving force of the organic-organic monomers self-assembly with direct synthesis technique. The key point in determining the assembly of mesoporous carbons rests on the reasonable choose of suitable precursor. The used precursor must have the potential of generating a stable 3D thermosetting network and strong interaction with templates to maintain firmly mesostructures. What’s more, the ordered mesostructures should be intact even after the removal of templates with respect to the production of mesostructured precursors with


Page 5 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


high carbon yield and their corresponding mesoporous carbons. Zhao’s research team has devoted a great deal of efforts to the fabrication of diverse carbon materials with tunable pore networks via the approach of organic–organic self-assembly.39 The typical polymer precursor PEO-PPO-PEO with ordered mesostructures as well as various symmetries has been used in the preparation of mesoporous carbons. The pH value is of great importance for the self-assembly of organic monomers with direct synthesis technique. For example, the preparation of polymer precursors with resol-type phenolic resin as the carbon source was under basic conditions (pH ≈ 9). On the other hand, acidic condition is favor of the reaction of phloroglucinol, resorcinol or phenol and formaldehyde, as well as the further acidic polymerization of the reaction products, in which the hydrated formaldehyde can be protonated and the electrophilic aromatic substitution reactions of phenols can be implemented. Jaroniec’s research team systematically investigated the preparation of diverse novel carbons with controllable mesostructures via the organosilane-assisted soft-templating route under acidic condition.63 As illustrated in Fig. 4, resorcinol and formaldehyde as well as the organosilanes such as tetraethyl orthosilicate and tris(3-trimethoxysilylpropyl)isocyanurate were used in the synthetic reaction. The typical triblock copolymer of PEO-PPO-PEO (namely Pluronic F127), was used as a removable soft template for the construction of desired mesostructured carbons. Based on heat polymerization and further heating process, the self-assembly of the reaction system leaded to the generation of mesoporous carbons with uniform mesostructures and well defined mesoporosity. It was found that the acidic polymerization condition affected the TEOS incorporation into the mesoporous carbon structure.

Fig. 4 Self-assembly strategy for diverse mesoporous carbons. Reprinted with permission from ref. 63. Copyright 2010 American Chemical Society.

Novolac is also one of the most important thermoplastic phenolic resin in the plastic industry. Nevertheless, novolac is not suitable as the precursor for the construction of desired carbons with tunable pore networks. Novolac is a type of thermoplastic polymer with unstable linear molecular chain, which is easy to be decomposed in the carbonization process, leading to the destruction of resulting carbon structure. Researchers have made great efforts in the preparation of mesostructured thermosetting polymers based on the novolac resin precursors.64,65 Adding suitable curing agent to the polymerization system is an effective approach and a feasible idea to realize the goal. Zhao and coworkers reported the

fabrication of 3D and 2D ordered mesoporous carbons through the evaporation-induced self-assembly (EISA) strategy with a linear polymer as the precursor.66 The key factor for obtaining the idea carbon materials with mesostructures and tunable pore frameworks was the addition of hexamethyltetramine (HMTA) to the acidic reaction system of crosslinked novolac precursors. The key components in the reaction consisted of the mixtures of the curing agent HMTA, polymer precursor novolac as well as the amphiphilic triblock copolymer PEO-PBO-PEO. The resulting mesoporous carbons had the configurations of 3D body-centered cubic and 2D hexagonal arrangements, and exhibited large surface areas (690 m2g-1) and high pore volumes (0.49 cm3g-1) and narrow PSD (3.3–3.8 nm). Higher temperature condition can promote the release of the methylene gas from HMTA, leading to the generation of a thermosetting polymeric network. The use of suitable polymer based precursors can flexibly control the morphology, composition and pore nanostructure of the generated mesoporous carbons.67-69 Dai’s research team described an attractive “silica-assisted” route for the construction of mesoporous carbons with tunable pore networks. Detailedly, diverse phenolic resols were applied as the main precursor, silicate oligomers as an inorganic precursor, and hexadecyl trimethylammoniumchloride as a surfactant template.70 The assembled products include mesoporous carbon with diverse morphologies, including nanospheres, hollow nanospheres, and yolk-shell nanospheres. All these carbon nanospheres present excellent charging/discharging rate in supercapacitors. The template-directed synthesis has the drawbacks of being time-consuming and costly, which hinders the facile and large volume production. Hence, exploring an efficient method without the use of any templates for the construction of desired mesostructured carbons is in urgent need. Antonietti’s research group realized an efficient template-free route to prepare the mesostructured carbon materials with graphitic phase behavior, in which ionic liquid typed monomers and corresponding polymers were employed as carbon precursors.71 Consequently, the optimum carbonization temperature was at 900-1000 °C, resulting in large pore volume, high specific surface area as well as low resistance. Besides, right acid etching process facilitates the removal of the remainder of the primary catalyst, and contributes to the formation of pure mesoporous carbons with uniform graphitic structure. Because of the advantages of being template-free, this method is simple and has the potential of mass production, contributing to the extended prospect of mesoporous carbons in the fundamental research and practical applications. 2.2.3 Catalyst Rational use of catalysts can reduce the activation energy of the chemical reaction, leading to high reaction efficiency. With regards to the fabrication of mesoporous carbon materials, the catalyst such as HCl,72,73 HNO3,74 or NaOH,75 is often used to catalyze the polymerization reaction of phloroglucinol or resorcinol precursors with formaldehyde. The basic system was often applied in the synthesis of precursors of resols with low molecular weight through the polymerization of phenol and formaldehyde. As the strong acid and alkali catalysts, NaOH and HCl are not advisable because of its corrosiveness to the equipment and the environment. Therefore, it is in urgent need for seeking alternatives for these commonly used catalysts. Lu and coworkers found that the amino acid was an effective catalyst to prepare porous materials. Employing glutamic acid



as a powerful catalyst, highly ordered mesostructured carbons with tunable pore sizes, high specific surface areas (720 m2 g-1) as well as typical hexagonal mesophase were obtained through the aqueous solution self-assembly of resorcinol/formaldehyde precursor and F127 surfactant.76 Particularly, the function of the glutamic acid catalyst in self-assembly of uniform mesostructures frameworks includes: 1) speed up the polymerization reaction of resorcinol with formaldehyde; 2) trigger the driving force (hydrogen-bonding interaction) taking place in carbon precursors and the surfactant. Consequently, the concentration of glutamic acid in the polymerization system was of great significance in determining the feature of mesostructured carbons. Particularly, there were no inorganic compounds involved in the synthesis route, contributing to mesoporous carbons with high purity. Soon afterwards, Lu et al. used the amino acids as the catalyst for the fabrication of mesostructures (Fig. 5). The organic base lysine was employed in the polymerization reaction, in which lysine was served as the polymerization catalyst as well as the assembly promoter to control the final pore frameworks.77 On one hand, lysine molecules could promote the generation of intra-molecule salts in the polymerization reaction. Thus, the hydrogen bonds could be generated between the deprotonated -COOH and the protonated NH3+ with the –OH contained in resorcinol. Hence, the chain segment in lysine skeleton could rapidly promote the assembly of F127 and phenolic resins. Highly crosslinked F127/phenolic resins via the hydrogen-bonding interaction can promote the architecture of resulting rigid pore networks with mesostructured distribution. On the other hand, the polymerization reaction between resorcinol with formaldehyde can be promoted by the basic condition offered by lysine molecules.

Fig. 5 Lysine-catalyzed rapid fabrication of desired carbons with meso-structures. Reproduced with permission from ref. 77. Copyright 2011 Elsevier.

Using a template as the catalyst, Zhao et al. demonstrated an effectual way to prepare N-doped uniform carbons with tunable mesostructure, adjustable pore size and high N content, involving in situ polymerization and co-assembly means.78 As illustrated in Fig. 6, in this synthesis route, besides as the polymer precursors, ureaformaldehyde (UF) was also utilized as a good N source, while the block copolymer polystyrene-block-poly(acrylic acid) (PS-b-PAA) was utilized as a catalyst and meanwhile offered acidic reaction condition as well as target structure-directing agent.

Page 6 of 24

The driving force in the catalysis of acidic PAA segments for the formation of uniform mesoporous carbon was ascribed to the hydrogen bonding and electrostatic interaction. Through the high temperature (600 °C) calcination process under N2 atmosphere, the resultant N-doped target molecules can obtain high N content (＞ 19 wt%), high PSD value (9.5–17.2 nm) and specific surface area (458–476 m2 g-1). As a result of the above particular merits, the obtained N-doped nanoporous carbon electrode constructions exhibited superhigh specific capacitance (239–252 F g-1) for supercapacitor application.

Fig. 6 In situ polymerization and co-assembly means for the assembly of high N-doped nanoporous carbons with mesostructures. Reproduced with permission from ref. 78. Copyright 2018 Royal Society of Chemistry.

3 Reaction conditions Flexible controlling the required reaction condition has direct impact on the properties of resulting mesoporous carbons. The required conditions for the fabrication of mesostructured carbons refer to the choice of carbon precursors, activation methods, activation agents, reaction temperature control, etc. There are mainly three constituents in hard templates or soft templates involved reaction system. The structure, morphology, composition as well as pore size of mesostructured carbons to a great extent depend on the used carbon precursors and templates.79-81 The property of thermosetting precursors and removable surfactants play a vital role in governing the structure, morphology, composition as well as pore size of target carbons. Phenolic resins, acting as typical thermosetting resins, are the main carbon precursors which are used to synthesize the ordered carbons. The key point for using phenolic resins as carbon precursors is that abundant PhOH can generate hydrogen bonds with the molecule networks of surfactants, which soon afterwards generate active micelles. It is certainly of great significance in formation of mesoporosity in the final mesoporous carbons. It has been reported that polybenzoxazines can also be used as the carbon precursors.82-84 Zhang and coworkers synthesized novel nanoporous N self-doped carbon aerogels based on the concentrated HCl catalyzed polymerization of trifunctional benzoxazine and further carbonization under high temperature. The facile approach can endow the products with ultralight density and good yield (shown in Fig. 7).85 Compared with other conventional electrode materials, biomass derived mesoporous carbons sparked extensive academic and commercial research. They have the advantages of being inexpensive, sustainable, availability hugely, and green. They are one of the most promising carbon electrodes for supercapacitors86-91 In particular, natural biomass-derived


Page 7 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


carbon precursors can endow the resulting carbon electrodes with all types of microstructures. So far, numerous natural biomass materials have been applied so as to produce large-scale carbonaceous electrodes for energy storage devices. The mostly used biomass materials include lignin92-95, watermelon96-98, willow catkin99-102, wood fiber103,104, crab shells105, silk proteins106, fish scale107,108, white clover109, chicken feather110, banana peel111, waste rubber112,113, etc. Even walnut or Fungi biomass was adopted as the carbon precursors.114,115 In particular, three types of herb plants were also used as the carbon precursors (shown in Fig. 8) to fabricate diverse nanoporous carbons. The results indicated that the spores-based carbon nano-architectures present superhigh specific surface area (＞ 3053 m2 g-1) and tunable pore networks, which to a great extent benefit for the enhancement of the resulting specific capacitance.116

Fig. 7 Preparation route for mesoporous carbons via the polymerization of trifunctional benzoxazine monomer in the catalysis of concentrated HCl and further carbonization treatment. Reprinted with permission from ref. 85. Copyright 2018 Royal Society of Chemistry.

To sum up, there are several routes to the architecture of mesoporous carbon. Acidic or basic catalysts are essential in the soft-template method. In particular, the interactions taking place in the template and the polymer precursor, for example, hydrogen bonding and Van der Waals force are sometimes important in soft-template method. For example, a stable resol precursor can make sure the co-assembly of multiple components, which benefit the formation of desired mesoporous carbons and can reduce the aggregation of reactive reagents. Generally speaking, the versatility of the synthetic routes gives a pretty concise procedure to produce diverse mesoporous carbons possessing tunable pore networks and mesoporous carbon based composites.

Fig. 8 Synthesis process of hierarchically porous structured hollow microspheres using three types of herb plants as carbon precursors. Reprinted with permission from ref. 116. Copyright 2016 Royal Society of Chemistry.

4 Activation methods The advantages of the approachable and reliable manufacture processes for the mesoporous carbons make them to be essential carbon based electrode materials in energy industry. Suitable activation process is an essential part for the fabrication of the mesoporous carbons. It is because that suitable activation process can lead to enhanced porosity, high purity as well as stable structural framework for the resulting mesoporous carbons. Physical activation and chemical activation are the commonly used strategies for the structure optimization of the resulting mesoporous carbon materials.117-122 Different activation processes can lead to diverse porosity, wettability, electrical conductivity and microstructures. With regards to the physical activation method, various oxidizing gases, such as air, O2, CO2, steam or their mixtures are usually used. There are mainly two stages in the physical activation process. The first stage is the pyrolysis of the precursor, which occurs at approximately 400–900°C under inert atmosphere. The second stage is the further pyrolysis under oxidizing gas at approximately 350– 1000°C, which can promote the formation of diverse porosity. Generally, typical chemical activation undergoes a one-step process, in which suitable activation agents such as KOH, NaOH, H3PO4 or ZnCl2 are usually added before the pyrolysis at 450-900°C into the carbon precursor involved reaction system. In the practical production process, the physical and chemical processes are often combined to obtain the optimal activation effect. 4.1. Physical activation Precise control of the activation temperature is of great significance in determining the microstructure, composition and pore networks of the resulting carbon materials in physical activation process.123,124 Yang’s research team applied the raw material chitosan in the fabrication of carbon aerogels with graphene phase and nanoporous networks, which was assembled via the route of aerogel construction, high temperature carbonization and physical activation.125 It was found that the amorphous carbon in the nanostructure of final carbons would be removed when the activation temperature increased (700→800→900°C), leading to the generation of a stable graphene portion in the target carbon framework. In particular, a large proportion of volatile matter existed in the bulk of the carbon precursors can be effectively eliminated during the gasification effect under shielded inert gas at the temperature range of 400-900 °C, resulting in the generation of a large number of hierarchically pore walls. The reactive areas in the main skeleton of carbon component are apt to be burn away by the oxidizing agent, in which huge amounts of



CO and CO2 are released. Afterwards, a large number of microporous frameworks come into being instantaneously. It was found that the activation temperature in the physical activation process determined the existence forms of the resulting carbon products. Kin Liao et al. investigated that the low temperature hydrothermal treatment cannot fully convert the winter melon to carbon.73 Only under calcination at high temperature can obtain the ideal mesoporous carbons. It has been reported that compared with CO2, more extensive micropores can be fabricated through the activation of steam. In addition, steam activation can lead to more ordered mesoporosity, lower micropore volumes, as well as relatively high pore volumes (＞0.9 cm3 g-1).126 4.2. Chemical activation High temperature activation process by suitable chemical agents can optimize the nanostructure of final mesoporous carbons. The most commonly used chemical agents in chemical activation process include ZnCl2, MgCl2, AlCl3, KOH, KHCO3, NaOH, H3PO4, etc. Compared with commonly applied physical activation, typical chemical activation process has the following advantages: (a) just need a simple step, (b) relatively low activation temperature, (c) achieve larger carbon yield, (d) generate mesoporous carbons with superhigh specific surface area and (e) endow the target carbons with precisely controlled microporosity.127-130 The heat-treatment process in the chemical activation methods is always conducted in the 450-900 °C range. The mesoporous carbons generated by the chemical activation methods exhibit attractive features, such as high specific surface areas, suitable microporosity, which can match well with the size of the electrolyte ions in supercapacitors. The activation temperature has a significant impact on PSD value of the final carbon frameworks. Activation treatment can further improve the pore size distribution, porosity and total pore volumes of the fabricated carbons so as to extend their practical application fields.131-135 In order to try out a proven and effective method to optimize the mesostructures and pore networks of target carbons, Zhao et al. found that chemical activation behavior using CuO as the activation agent could dramatically increase the mesoporosity and simultaneously preserve its mesostructure (Fig. 9). The experiment results indicated that after CuO activation, the mesopore size of the mesoporous carbons was raised from 3.2 to 5.5 nm, the total pore volume from 0.48 to 1.06 cm3 g-1 and the specific surface area from 827 to 1084 m2 g-1. When used as the carbon electrode for an EDLC, the tested CV curves displayed typical rectangle. What’s more, high specific capacitance (7.2 mF cm-2) could be realized in polypropylene carbonate electrolyte.133

Page 8 of 24

Fig. 9 CuO activation route for the fabrication of mesostructured carbons with large pore size. Reproduced with permission from ref. 133. Copyright 2012 Royal Society of Chemistry.

Using KHCO3 activation means, Zhang et al. synthesized diverse micro/mesoporous carbon sheets, in which waste watermelon peels were employed as the carbon precursor.96 Systematical measurements indicated that, compared with the carbon product MMC, the MMC-A sample with KHCO3 activation had the optimal pore networks, in which the specific surface area could achieve 2360 m2 g-1 and the pore volume could achieve 1.31 cm3 g-1. After KHCO3 activation, the specific surface area was increased. Besides, along with the rise in activation temperature, the specific surface area as well as total pore volume for the target carbons was further improved. It was because that higher temperature could promote the activation reaction. During specific activation process, chain reactions rapidly occurred just as shown in eqns (1)–(5). At about 200 °C, as seen in eqn (1), KHCO3 would be decomposed. The released CO2 gas can promote the formation of numerous micropores and mesopores. Besides, the chain reactions in eqns (2)–(5) would occur when the temperature exceeded to 400 °C. Moreover, the decomposition rate could be speeded up after the increase of activation temperature, leading to the expansion of the pore size for the target carbon materials.

2 KHCO3  K 2CO3  CO2  H 2O.......(1)

K 2CO3  K 2O  CO2 .........................(2) K 2CO3  2C  2 K  3CO..................(3) K 2O  C  2 K  CO..........................(4) CO2  C  2CO.................................(5) 5 Application of mesoporous carbons in supercapacitors Nanostructured carbons with desired pore networks are the most extensively employed electrode materials in supercapacitor industry in virtue of their easy in operation, flexibility in condition control and high chemical stability.136,137 The summary of the synthesis strategies, mesostructural properties and their supercapacitive properties of the recently reported mesoporous carbon based electrodes was listed in Table 1. Carbon based electrode materials with large specific surface areas, such as active carbon,138 mesoporous carbon,139 CNT,140 and graphene.141,142 have great potential in the advancement of the supercapacitors. Because that there is no chemical reaction taking place at the electrode surface during the charge/discharge behavior, EDLCs can generate excellent ability of capturing and storing energy and good charge/discharge cycling property. Nevertheless, the energy density obtained in EDLCs is always at relatively low level. The energy storage occurs at the electrode/electrolyte interfaces, depending on charge separation in EDLCs. The narrowed charge separation distance limited in pore networks can endow the porous carbon electrodes with better capability of storing much larger amounts of energy than conventional capacitors. Compared with the conventional batteries, the electrostatic effects taking place in the storing process contributes to higher power densities by offering the device with additional power. Pseudocapacitors are known as another kind of peculiar supercapacitors-based energy storage device.143-146 The energy storage capacity in pseudocapacitors in most cases is superior to that in EDLCs. However, the charge/discharge cycling performance and power density are usually at a lower level, compared with that in EDLCs. The


Page 9 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


fascinating thing is that rational filter of high capacitance materials has great potential in the fabrication of such devices with high energy density. The porosity of mesoporous carbons plays an important role in its practical applications. Until now, considerable efforts have been made in the configuration of carbon-based electrode materials to sustainably enhance the energy density of such devices without sacrificing their power capability. Following this eternal goal, various types of mesostructured carbons, involving mesoporous carbons, activated carbons, nanoporous carbon spheres, etc. with rationally designed structure and tailored PSD have been extensively investigated to optimize electrochemical energy storage. The incorporation of electroactive species into carbonaceous electrodes on the premise that the basic structural features of the electrodes can be preserved is also received comprehensive concern. This idea is proved to be an effective way to further promote the electrochemical energy storage. 5.1 Electrical double layer capacitors (EDLCs) From the perspective of charge storage mechanism, EDLCs are similar to a traditional capacitor. The mechanism of charge storage taking place in EDLCs is fundamentally derived from the reversible electrostatic accumulation of ions, which is the adsorption and desorption of electrolyte ions taking place at the interface of active electrode materials.137,147 There are two non-reactive porous plates in EDLCs. The flooded plates in an electrolyte function as a good carrier for the applied voltage. As shown in Fig. 10, the applied voltage on the cathode can attract plentiful of e- coming from the electrolyte while the applied voltage on the anode attracts the positive charge in the surrounding electrolyte. The two layers in EDLCs are in favor for electrostatic charges storage.

Fig. 10. Principal charge storage mechanism of supercapacitor (Pseudocapacitors and EDLCs are involved). Reprinted with permission from ref. 137. Copyright 2016 Royal Society of Chemistry.

The whole structure configuration of electrochemical capacitors is similar to that of a battery, in which two independent electrodes are flooded in an electrolyte with certain concentration. The ion separators lies between two independent electrodes.148 Each electrode-electrolyte interface in the electrochemical capacitors is equal to two capacitors (Fig. 11C). The typical feature of each electrode in the configuration of a supercapacitor, including the specific surface area, pore volume, pore wall composition and electric conductivity, etc, determines the entire electrochemical performance of an electrochemical capacitor. The typical

equivalent circuits of the EDLC are present in Fig. 11A, where Rs denotes equivalent series resistance (ESR), RF is referred to a Faradaic resistance. An equivalent circuit of double-layer charging behavior is just like charging a pseudocapacitance (Cq) by means of a Faradaic leakage resistance (RF) and Faradaic resistance (RD). As revealed in Fig. 11B, this combination includes Faradaic impedance (Cq, RF and RD) in parallel with EDL capacitance (Cdl). Based on the above analysis, it comes to a conclusion that the entire electrochemical capacitor performance primarily relies on both electrodes in given electrolytes.

Fig. 11 (A) Equivalent circuit diagram illustrating the charging behavior of a single electrochemical capacitor. (B) Equivalent circuit for EDLCs at an electrode solution interface. (C) Equivalent circuit for an electrode interface. Reprinted with permission from ref. 148. Copyright 2011 Royal Society of Chemistry.

Note that, the charge separation process in an EDLC at both electrodes can produce two electric double layers, and each layer corresponds to a traditional capacitor, leading to enhanced energy density.149-153 Nevertheless, the specific capacitance of an EDLC is much larger. It is because that the charge separation taking place in the EDLC relates to the ions movement on the surface, which goes through a much smaller distance as a result of the intrinsic configuration of two electric double layers. Thus, the specific capacitance in an EDLC is determined according to the peculiar feature of accessible surface/interface structure as well as the PSD value of the electrode materials. Different PSD value leads to diverse supercapacitor performance. Consequently, the specific capacitance of the EDLC to a great extent rests with the pore volume as well as the specific surface area of the used carbonaceous electrodes. Mesoporous carbon is one of the most momentous electrode materials and is extensively utilized in commercial EDLCs as a result of its superhigh specific surface area, high pore volume, good electrical conductivity, high chemical stability and availability. The above inherent feature of mesoporous carbon can promote the accumulation and transport of huge amount of charges, fast ionic transport and efficient electrolyte wetting. What’s more, arising from distinct dimensions of electrolyte molecules and ions, movement capacities of different charges can be reasonably improved owing to tunable pore sizes and PSD value of mesoporous carbons. Besides, great charge storage ability as well as outstanding rate capability can be realized because of the regularly interconnected mesopores ( ＞ 2 nm) for the



mesoporous carbon materials. In particular, powder mesoporous carbons are widely used in most of their commercial supercapacitors, deriving from the coconut shells. In order to obtain higher supercapacitors performance, some companies synthesizes special carbon precursors by further activation with KOH. So far, despite that diverse nanostructured carbonaceous materials have been served as the electrode materials for supercapacitors, mesoporous carbons with tunable pore networks are still dominating in energy field. Mesoporous carbons are generally produced based on the template of mesoporous silica. Thus, 2D hexagonal and 3D cubic mesoporous silica can generate 2D or 3D ordered mesoporous carbons, respectively. There is a complicated relationship between the microstructure of the mesoporous carbons and the capacitance of the supercapacitor device. Considerable efforts have been made so as to increase the pore volume in mesoporous carbons through the optimization of the activation process.154,155 For the organic electrolytes, due to their larger sizes ( ＞ 1 nm) ， the pores in the nanostructured carbon networks with diameter ＜ 1 nm are not large enough for the movement of the solvated ions. In the case of the hydrated ions, the pores larger than 0.5 nm also required to ensure their normal transportation. If a pore size distribution is ranged from 2 to 5 nm, which exceeds the diameter of two solvated ions, it would be beneficial for the enhancement of the energy density as a result of the extended voltage.156,157 In the case of the partially desolvated ions, the pores smaller than 2 nm was preferred to their migration and transport. High capacitance can be realized depending on a great quantity of small micropores and uniform distributed pore walls contained in the pore frameworks of utilized mesoporous carbons with different nanoscaled pores, suggesting that a partial ion desolvation could contribute to sharp enhancement of specific capacitance.158 Intensive efforts have been devoted to illustrate the mutual relation between the microstructure of mesoporous carbons with tunable pore networks with their charging and discharging behavior taking place in different electrolytes. Until now, there is no explicit answer to quantitatively describe the relationship between the surface area, pore size, pore volume and specific capacitance. This confusion is affected by several factors: (1) The pore size of the existed small pores are too small to solvate the electrolyte ions. (2) Diverse micropores with different pore size show different electrochemical adsorption behavior. (3) The accompanying pseudocapacitance effects would impact the final specific capacitance of carbon electrode. All these issues will become the important directions for the near-future research and urgently need to be settled. 5.2 Pseudocapacitors There is quite a big difference in the charging and discharging behavior taking place in pseudocapacitor and the general supercapacitors (Fig. 10). The electrochemical reaction in pseudocapacitance is based on two ways, one is the reversible faradaic charge transfer process, and the other is chemical redox reactions on the surface or near surface of electrodes. The peculiar charging and discharging behavior can provide a green channel for obtaining superhigh energy density at high charging/discharging rates. The chemical reactions taking place in a pseudocapacitor are more like a lithium ion battery. The primary difference is that the lithium ion battery is subject to cation diffusion taking place in the pore networks of carbon electrodes, while pseudocapacitor is tend to not affected by the cation diffusion. The kinetic

Page 10 of 24

difference between the pseudocapacitor and the battery can be identified by Cyclic voltammetry (CV) analysis. In theory, the voltage change measured on a certain electrode material with the increase of sweep rates can be determined as follows: 159,160 i=avb (6) where the current (i) measured in CV test at a fixed potential conforms to a power law relationship with the potential sweep rate (v). Because the charging storage taking place in pseudocapacitor is not diffusion-controlled, and the electrode potential of the carbon electrodes shows a continuous logarithmic function with the increase of sorption capacity, the current (i) in CV test demonstrates obvious linear relationship with the changed sweep rate (b=1), which can be determined as follows:159,160 i=CdAv (7) where Cd refers to the capacitance and A refers to the surface area of the electrode material. That is to say, the stored charges in the electrode materials are linearly dependent with the charging potential applied on the electrode. Particularly, the charging behavior of the stored charges is not dependent on the ions accumulation in two electrodes, but complies with electron-transfer mechanisms. Transitional metal oxides, such as MnO2,161 NiO,162 and conducting polymers, e.g., polyaniline,163 polypyrrole,164 and deravatives165 are the two most investigated electrode materials. The incorporation of pseudocapacitive materials can significantly enhance the specific energy of the used electrodes. This case becomes more obvious when the pseudocapacitance behavior is arisen from the reversible redox reactions taking place at the surface of an electrode. Thus, the electrochemical device belongs to a carbon-based capacitor. The difference is that significantly higher capacitances can be achieved for the electrochemical device. It is well considered that pseudocapacitance is an important source for the generation of some extra functions for the used electrodes.165-166 Lee and coworkers fabricated novel mesostructured WO3-x/C nanocomposites (Fig. 12). When applied as a pseudocapacitor electrode, the WO3-x/C nanocomposites possessed high capacitance (169 F g-1) and fast rate performance. The excellent supercapacitive performance of these WO3-x/C-s nanocomposites was derived from the high specific surface area due to its particular pore networks and composition, as well as the low internal resistance.166


Page 11 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemistry of Materials reach 390 F g-1. In addition, the device display good cycling stability, that is 7% capacitance loss after 10 000 cycles. The key point for high performance energy storage system is to a great extent due to the enhanced specific surface area and optimized PSD value. Furthermore, the high N content retention of the precursor plays also vital role in the enhanced electrochemical performance.

Fig. 12 (a) Fabrication route of mesostructured WO3-x/C nanocomposites and its high capacitance and fast rate performance (b, c). Reprinted with permission from ref. 166. Copyright 2013 John Wiley and Sons.

Fig. 13 (A) Schematic illustration of the protein derived N-rich mesoporous carbons and (B, C) their excellent electrochemical performance arising from their peculiar mesostructures. Reprinted with permission from ref. 167. Copyright 2013 Royal Society of Chemistry.

Besides, the heteroatom-rich carbon electrodes can lead to the pseudocapacitance behavior. The introduction of heteroatoms can be achieved by using the biomass hybrids as the carbon precursors, or through chemical doping. The pseudocapacitance effects mainly occur in the used mesoporous carbon electrodes with oxygen-containing functionalities in the surface of the material. In this case, the specific capacitance in an EDLC can be enhanced, leading to the increase of specific energy. It is known that nitrogen is a good electron donor. Thus, suitable nitrogen doping into the electrode contributes to the increase of the specific capacitance based on faradaic reaction and the optimized wettability. Chen and coworkers synthesized N self-doped well defined nanoporous carbons with tunable pore networks by means of an ordinary approach, including the high temperature carbonization process and further KOH activation process (Fig. 12). Thanks to high specific surface area (1775.7 m2 g-1) and high pore volume (0.85 cm3 g-1) of the electrode material, the carbon electrode demonstrated excellent charging and discharging ability. The gravimetric capacitance can reach 292 F g-1 when measured at 1 A g-1. In particular, the carbon electrode retains good rate capability retention (83.5%) at 10 A g-1 (Fig. 12). All these examples demonstrate that the modification of heteroatomic doping is undoubtedly advisable to improve the surface wettability and the improvement of the sorption of oxygen-containing moieties. The construction of carbons with large specific surface area, good mechanical stability, proper pore size, stable pore walls as well as high N content could endow the mesoporous carbons with superior electrochemical properties.167 Detailedly, N-rich mesostructured carbons containing partially graphitized carbons were fabricated by employing egg white as carbon precursor (Fig. 13A). The fabrication route endows the target products with a surface area of 805.7 m2 g-1. The pore wall thickness is approximately 4 nm, and the pore diameter is about 20-30 nm. Besides, the N content in the target carbons is 10.1 wt%. As shown in Fig. 13B, C, when employing in supercapacitor, the electrode demonstrated great energy storage ability. The corresponding specific capacitance can

Stable discharge process often results in the backward reaction. And a pseudocapacitance effect is generated during the redox reaction of the material.168-171 Besides, oxygen groups contained in the mesoporous carbons can affect directly the electrochemical performance of the supercapacitor. On one hand, the oxygen functional groups, which are inert to electrochemical performance, are often sensitive to the wettability. The increased wettability of the electrode can raise the corresponding specific capacitance as a result of the ameliorative access to internal pores and enhanced surface use ratio.172 On the other hand, several oxygen groups with high polarity, for example, carboxyl, anhydride and lactone, etc. are bad for the charging and discharging process of the carbon based electrodes. These oxygen groups may increase the resistance of the electrode, resulting in decreased specific capacitance at high current densities.173-176 5.3 Hybrid supercapacitors In our quest to realize high energy densities, hybrid capacitors have been extensively explored for the past few years. Soon, both the aqueous system and the nonaqueous redox materials are rapidly developed.177-179 As illustrated in Fig. 14, hybrid supercapacitors combine the metal oxide anodes with the carbon-based cathodes in its configuration. Among them, metal oxide anodes (HTO) are the same as that in lithium-ion batteries (LIBs), while carbon-based cathodes (AC) are the same as that in supercapacitors.180-183 Hybrid supercapacitors are a type of supercapacitors based on various electrode materials, one of which is the EDLC electrode (carbon material).184 The generation of hybrid supercapacitors can satisfy the practical applications for both high power density as well as high energy density by means of fusing the advantages of supercapacitor and LIBs. It is clear that the charge storage capacity of a metal oxide electrode is several times higher than that of carbon electrode. Consequently, hybrid supercapacitors can generate much higher energy densities than supercapacitors. With regards to the charge storage mechanism in hybrid



supercapacitors, the electrochemical reaction taking place in two electrodes is totally different, in which the positive electrode is based on an anion adsorption-desorption process, while the negative electrode is based on a faradaic charge-transfer process in Li+ containing solution.185,186 As a result of both high power density as well as high energy density, hybrid supercapacitors have already been applied in the daily electric vehicles, in which the supercapacitors offer peak power for rapid acceleration or hill climbing while LIBs offer electric power for general driving.

Page 12 of 24

the electrolyte ions and there is no empty pore volume left in the pore, high specific capacitance would be achieved for this carbon electrode. Thus, it is of great importance to control the pore size and meanwhile improve the specific surface area by providing the electroactive materials with more holes. In this case, the improvement of efficient specific surface area accessible to the electrolytes can be obtained. It is essential to prepare the electrode materials with proper microstructures that make for the increase of the specific surface area as well as porosity, leading to the optimization of supercapacitor performance.

Fig. 14 Schematic illustration of the structure of hybrid supercapacitors. Reprinted with permission from ref. 177. Copyright 2012 Royal Society of Chemistry.

Substituting other carbon based electrode materials with high specific capacitance for the conventional used activated carbon electrode materials is an effect means to raise the energy density of hybrid supercapacitors. It is worth noting that mesoporous carbon has great potential in both devices as suitable electrode material. The performance of these devices can be further improved by using a tailored mesoporous carbon. Considering the vast difference between the performance characteristics of the two electrodes, the mass balance of two electrode mass in both devices is very important to guarantee the highly effective use of each electrode and retain the best cycling stability. 6. Relationship between structure and supercapacitive properties of mesoporous carbons The nanostructure has great potential in enhancing the electrochemical properties of corresponding mesoporous carbons. The average pore diameters of mesoporous carbons are at the level of intermediate size, which are ranged from 2 to 50 nm. The electrochemical properties of mesoporous carbons to a great extent arise from the average pore size, specific surface area, total pore volume of pore networks as well as any heteroatom introduction.187-193 With regards to the supercapacitive performance, the pore size control of the fabricated carbons with tunable pore frameworks is critical for determining the electrochemical reaction within vast pores.25 As the increase of pore size and pore volume of mesoporous carbon electrode, the accessible pores or pore surface would be decreased, consequently leading to a decreased capacitance (as shown in Fig. 15). Smaller mesopores have the following advantages in the electrochemical reaction of mesoporous carbons: (1) The narrow distance between internal pore walls makes electrolyte ions to easily pass the pores; (2) Stable contact with the pore walls can be ensured for the electrolyte ions. Frequent ions exchanging occurs between the adsorbed ions and the non-adsorbed ions in an accessible pore. Besides, the competition between anions and the adsorbed electrolyte ions endows the generation of the double layer. The pore size must meet the following requirements to maximize the use of the pore space. First, the pore must be big enough for the pass of the vast majority of electrolyte ions. Second, the pore must be small enough to promote the generation of the double layer inside the pore walls. Furthermore, the pores must guarantee that the interspace existed in the pores would not be covered by electrolyte ions. When all pores can be efficiently filled by

Fig. 15 Influence of pore size control on the movement of the electrolyte ions, as well as the capacitance of the supercapacitors. Reprinted with permission from ref. 25. Copyright 2011 Royal Society of Chemistry.

As shown in Fig. 16, even in the case of flow supercapacitor, the pore size control of electrode materials is vital to determine the charging/discharging process of the supercapacitor device. For the sake of obtaining the high power density and energy density, intense efforts are currently devoted to the design of porous and nanosized electrode materials to effectively improve the supercapacitors performance and extend the utilization range of such devices.

Fig. 16 Schematic illustration of the charging/discharging process taking place in the flow supercapacitor. Reprinted with permission from ref. 1. Copyright 2017 Royal Society of Chemistry.

With regards to the EDLCs, the energy storage depends on the physical surface adsorption and accumulation on the carbon based electrodes (Fig. 17a). But unlike the case in EDLCs, the electrical energy in pseudocapacitors can be generated through a chain of Faradaic reactions (Fig. 17b). As a whole, the microstructures of the used mesoporous carbons play decisive effects on the performance of both types of supercapacitor. High capacitance can only be generated at a moderate rate of charge and discharge process on account of relatively slow transport of electrolyte ions in the micropores. Fast charge and discharge rate does not mean high capacitance. In fact, only moderate rate of charge and


Page 13 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


discharge may contribute to relatively high capacitance because that the desolvation of ion-shells and the transport process of electrolyte ions often occur at relatively slow rate. Ordered mesopore channels in mesoporous carbons can offer express entry for the transport and movement of electrolyte ions into other space of the carbon networks. Therefore, mesoporous carbons have the ability of achieving a high capacitance and excellent energy and power characteristics (Fig. 17c,d).194-196

Fig. 17 Schematic illustrations for the mesoporous materials based EDLCs (a) and pseudocapacitor (b). Reproduced with permission from ref. 195. Copyright 2011 John Wiley and Sons. Specific capacitance retention (c) and ragone plot (d) of carbon based electrodes with diverse nanostructures. Reproduced with permission from ref. 194. Copyright 2010 American Chemical Society. Reproduced with permission from ref. 195. Copyright 2011 John Wiley and Sons. Reproduced with permission from ref. 196. Copyright 2013 John Wiley and Sons.

Carbon-based electrode can endow the supercapacitor device with high electrical power. Nevertheless, the responding energy density still cannot compete with that of batteries.197-199 In this case, fabricating a supercapacitor that can store as much energy as a battery while retain rapid charging and recharging ability would undoubtedly be deemed as a technological revolution in energy industry. Rational structural design has become a hot topic and an effective way in solving the coordination of energy densities and power densities. In the case of carbon-based EDLC, researchers have been working on constructing functional carbon electrodes with refined pore frameworks, tunable PSD, as well as superhigh specific surface area.200-205 Fundamentally, different pore size distributions of the supercapacitor electrode materials played different roles in the electrochemical reaction of the supercapacitor. As a result of the status of a bulk buffering reservoir, the macropores (＞ 50 nm) can minimize the diffusion distances to speed up the movement of the electrolyte ions. The mesopores (2-50 nm) are in favor of the movement and transport of electrolyte ions and charge storage because of its large accessible surface area. While the micropores ( ＜ 2 nm) can sequentially promote charge accommodation.116 Nevertheless, a great deal of macroand mesopores can result in low electrode density, as a result the volumetric energy density and volumetric capacitance are

discounted back to a mediocre level. In addition, the cavities of the macro- and mesopores are filled with the electrolyte, leading to the increase of the device weight. Hence, the increase of the macro- and mesopores contributes a little to capacitance.206 Decrease the surplus cavities inside the macropores as well as the mesopores is proved to be an effective way to enhance the volumetric energy density. To this end, mechanical pressure was applied to successfully compress the macropores, while the mesopores was little changed.207,208 Consequently, the rational control of pore size distribution of electrodes is of significant importance to further increase the density of carbon electrodes and the energy densities of EDLC. The key point in realizing this goal is to balance high surface area and effective ion accessibility during electrochemistry. Based on collapsing the carbon nanocages through capillarity, Hu et al. realized the optimization of the porous structure and further obtained superhigh power density and good cycling stability. The correlation between volumetric energy density and porous structure was illuminated on the basis of a series of carbons, which have the feature of diminishing mesopore sizes and macropore sizes. The results demonstrate that the volumetric energy density can be effectively enhanced (reaching 73 Wh L-1) while retain high power density and cycling stability by means of curtailing the surplus space in macropores and especially in mesopores.206 Besides, fabricating carbonaceous material electrodes with two-dimensional (2D) nanosheets nanostructures is also proved to be a fascinating means to enhance the energy density of corresponding supercapacitor.209 As a result of the particular anisotropic structure, 2D nanosheets have more advantages in various applications than other types of nanostructures. The shorter diffusion path in 2D nanosheets can speed up the diffusion of electrons and ions so as to achieve an optimized overall electrochemical performance. Huang et al. found that introducing defects into the mesoporous structure of the electrode can endow the supercapacitor with excellent energy storage capacity.210 A nitrogen-doped few-layered mesoporous carbon was fabricated (Fig. 18), demonstrating a bimodal PSD, high specific surface area (1580 m2 g-1) and large pore volume (2.20 cm3 g-1). Consequently, the formed electrode possessed a capacitance of 855 F g-1 measured in 0.5 M H2SO4 (pH=0) aqueous electrolyte. Besides, the corresponding supercapacitor demonstrates an energy density of 23.0 Wh kg-1 and a power density of 18.5 kW kg-1, while measured in 2 M H2SO4 aqueous solution, the energy density and power density are 38.5 Wh kg-1 and 22.5 kW kg-1, respectively. All the progress is ascribed to the N-doping mesostructures involved robust redox reactions.

Fig. 18 (a) Assembly of ordered mesoporous few-layer carbons. (b)



Page 14 of 24

Possible distribution of N atom in the fabricated carbon framework. (c) Pore size distributions and (d) specific capacitance retention of the fabricated carbons. Reproduced with permission from ref. 210. Copyright 2015 Science.

Fig. 19 (a) Hydrothermal synthesis of mesoporous carbons; (b) specific capacitance retention and (c) cycling stability of the as-synthesized carbon based electrode. Reproduced with permission from ref. 211. Copyright 2014 Royal Society of Chemistry.

Zhao and coworkers fabricated a highly ordered mesoporous carbons based supercapacitor electrode (as illustrated in Fig. 19). These mesoporous carbon materials had the characteristic of 2D hexagonal p6mm symmetry conformation. Owing to these unique features, these mesoporous carbons based electrochemical capacitor electrode showed outstanding specific capacitance, rate capabilities as well as cycling stability.211 They further demonstrated that the particular characteristic of the obtained carbon materials, including the tunable carbon networks, large pore volumes ( ＞ 2.3 cm3 g-1), large specific surface areas ( ＞ 750 m2 g-1) and high degree of graphitization could make huge contributions to the enhancement of the supercapacitor performance without the introduction of any conductive additives into supercapacitor device.212

Suitable adjustment of the porosity in the assembly procedure of mesocarbon monoliths while retaining their large specific surface area is critical for the improvement of supercapacitor performance.213-216 Based on the analysis of electrochemical impedance spectroscopy, Jaroniec et al. revealed that decrease the pore size and control the monodispersity of as-synthesized mesoporous graphene spheres could lower the mass transport and charge transfer resistances, which enhanced the performance of EDLCs (Fig. 20).217 In detail, the resulting mesoporous graphene spheres had a graphitic structure, in which approximately 7 layers graphene existed in each unit. A relatively rectangular shape was obtained in the current–voltage curves for these mesoporous graphene spheres, even at high voltage scan rates. In addition, the assembled supercapacitor device can realize a high percentage of capacitance retention (＞ 10,000 cycles).

Fig. 20 (a) Fabrication process of mesoporous graphene spheres (MGS) for supercapacitors; (b) SEM image and (c) CV curves of MGS; and (d) cycle stability of the MGS-based supercapacitor. Reproduced with permission from ref. 217. Copyright 2015 Springer Nature.

Table 1 Summary of the synthesis strategies, mesostructural properties and their supercapacitive properties of the recently reported mesoporous carbon based electrodes Pore volume (cm3 g-1)

Pore size (nm)

Specific capacity (F g-1)

Ref.

Carbon

Synthesis strategies

BET (m2 g-1)

Activated carbons

Direct synthesis

2450

1.30

1.5

361

17

Carbon aerogels

Direct synthesis

2410

3.61

___

170

31

Nitrogen self-doped carbon aerogels

Direct synthesis

2435

1.09

___

197

125

Nitrogen self-doped carbon aerogels

Direct synthesis

862

1.03

3.5

199

85

Porous tubular carbons

Direct synthesis

2925

___

3.0

200

101

Activated carbon xerogels

Direct synthesis

1010

0.80

3.5

210

25

Honeycomb-like porous carbons

Direct synthesis

1971

0.98

3.68

227

181

Porous carbon microtubes

Direct synthesis

1775

0.85

___

292

99


Page 15 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemistry of Materials Nitrogen-doped porous carbons

Direct synthesis

999

0.79

3.2

293

35

Porous carbon spheres

Direct synthesis

1811

0.91

2.0

296

98

Mesoporous carbon nanofiber arrays

Hard-template

1266

4.30

11

152

105

Lamellar porous carbons

Hard-template

2273

2.74

4.5

168

107

Mesoporous carbons

Hard-template

2023

___

2.9

178

153

Hollow Carbon Spheres in Carbonaceous nanotubes

Hard-template

318

0.78

9.23

235

215

Ordered mesoporous carbons

Hard-template

1650

1.83

3.9

260

48

Nitrogen-doped mesoporous carbons

Hard-template

1580

2.20

2.2

855

210

Porous carbons

Soft-template

1560

1.50

5.1

120

60

Ordered mesoporous carbons

Soft-template

781

0.41

4.5

157

211

Porous microspheres

Soft-template

3053

1.43

___

308

116

7. Summary and outlook Two mainstream methods, nanocasting and direct synthesis strategies have been developed for the assembly of mesoporous carbons as supercapacitor electrodes. A wide breadth of research findings in mesoporous carbon architectures, ranging from the relationship between the synthesis strategies-the product structure, the structure-the supercapacitive properties of mesoporous carbons to theory to supercapacitor application are expounded in present review. Significant progress in current literature demonstrates that mesoporous carbon materials have great potential in enhancing the energy density as well as power density of electrochemical energy storage device because that the readily available synthesis strategies for mesoporous carbons allows for the tailoring and accurately controlling their particle size, surface area, electronic conductivity, phase structure, and crystalline for high supercapacitive performance and stability. Different assembly routes may generate mesoporous carbon materials with different particle structure, and all have individual strengths and weaknesses. Nanocasting technique is the most straightforward ways for fabricating uniformly distributed mesopores in carbon materials based on the introduction of highly ordered inorganic mesoporous solid materials as suitable templates. The interaction between the used templates, the special carbon precursors and the activation condition plays vital effects on the generation of target products. Nevertheless, the heavy consumption of soft templates as the reactive sacrificial agent and surfactants in the nanocasting pathway increases the production cost. In particular, the unavoidable preparation process is a waste of time and energy owing to multiple step synthesis procedures. It is still difficult for the large scale production of the target as a result of being time-consuming and costly, which hinders its expanded production. Direct synthesis strategy can solve this problem. Diverse carbonaceous frameworks with large porosity can be created on the basis of the assembly of

organic-organic monomers via direct synthesis technique. The vital point in determining the mesostructure feature of desired carbon assemblies is the reasonable choose of carbon precursors in the direct synthesis technique. Through suitable precursors filter and further activation treatment, mesoporous carbon materials featuring superhigh specific surface area (ca. 4000 m2 g-1) and controllable mesostructures with the forms of powder, fiber, and 3D monolithic structure are proposed for various applications. High surface area generated through this approach is generally at the cost of precious control over pore size distribution, which leads to diminished performances in supercapacitor applications. Hence, exploring a suitable approach without using any template is in urgent need, not only for nanocasting technique but also the direct synthesis strategy, or any other synthesis approaches. Besides, green and cost-effective carbon or polymer precursors such as biomass should be widely utilized in the production of carbon materials with tunable mesostructures, which would play a critical role in future commercialization. What’s more, the greatest challenge for any mesoporous carbon materials is still to achieve a large-scale yield with high purity. Much more effort should be made to realize massive production to meet the industry requirements. With regards to the supercapacitor application, the electrochemical properties of mesoporous carbons to a great extent hinge on the specific surface area, porosity and PSD value of target carbons. In addition, the modification of heteroatomic doping is undoubtedly advisable to improve the surface wettability and the pseudocapacitance behavior. It is of great importance to control the pore size and improve the specific surface area by providing the electroactive materials with more holes. The pore must be big enough for the pass of the vast majority of electrolyte ions and must be small enough to promote the generation of the double layer inside the pore walls. In this case, the improvement of efficient specific surface area accessible to the electrolytes can be obtained. It is



essential to prepare the electrode materials with proper microstructures that make for the increase of the specific surface area as well as porosity, leading to the optimization of supercapacitor performance. The incorporation of electroactive species into carbonaceous electrodes on the premise that the basic structural features of the electrodes are reserved can enhance the comprehensive performance of the supercapacitors. As illustrated in Fig. 21, to truly boost ambient temperature storage capacities, a chemical modification approach can be introduced to decorate the porous carbon surface with metal nanoparticles, etc, which endows the electrode with higher charging stability even at a high voltage, longer discharge cycles, as well as higher conductivity. Last but not least, the expansion of commercialization in supercapacitor applications of mesoporous materials is still of great importance in the future research, which completely depends not only on materials innovation, but also on service life and production cost. Hence, the theory research, production control and technoeconomic means are desired to realize the perfect integration of desired mesoporous carbons with tunable nanostructures to a sustainable and green energy system to develop the field of practical supercapacitors. The overall goals point the direction for the improvement of both the mesoporous carbon materials and the supercapacitor markets.

Fig. 21 The future outlook for mesoporous carbon-based

electrodes in supercapacitor markets.

ASSOCIATED CONTENT AUTHOR INFORMATION Corresponding Author *

Author to whom correspondence should be addressed. Tel: +86-376-6390232; Fax: +86-376-6390232; E-mail: [email protected]

Author Contributions The manuscript was written through contributions of all authors.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT We acknowledge the funding support from the Natural Science Foundation of Henan province (182300410285) ， the Henan Key Scientific Research Project (16A430026 and 17A150048) and the Nanhu Scholar Program for Young Scholars of XYNU.

Page 16 of 24

1. Wang, F.; Wu, X.; Yuan, X.; Liu, Z.;

Zhang, Y.; Fu, L.; Zhu, Y.; Zhou, Q.; Wu, Y.; Huang, W. Latest advances in supercapacitors: from new electrode materials to novel device designs. Chem. Soc. Rev. 2017, 46, 6816-6854.

2. Peng, X.; Peng, L.; Wu, C.; Xie, Y. Two dimensional nanomaterials for flexible supercapacitors. Chem. Soc. Rev. 2014, 43, 3303-3323. 3. Zhang, D.; Miao, M.; Niu, H.; Wei, Z. Core-spun carbon nanotube yarn supercapacitors for wearable electronic textiles. ACS Nano 2014, 8, 4571-4579. 4. Chee, W. K.; Lim, H. N.; Zainal, Z.; Huang, N. M.; Harrison, I.; Andou, Y. Flexible graphene-based supercapacitors: a review. J. Phys. Chem. C. 2016, 120, 4153-4172. 5. Chen, C.; Cao, J.; Lu, Q.; Wang, X.; Song, Li.; Niu, Z.; Chen, J. Foldable all-solid-state supercapacitors integrated with photodetectors. Adv. Funct. Mater. 2017, 27, 1604639-1604646. 6. Mai, L.; Tian, X.; Xu, X.; Chang, L.; Xu, L. Nanowire electrodes for electrochemical energy storage devices. Chem. Rev. 2014, 114, 11828-11862. 7. Chen, X.; Lin, H.; Deng, J.; Zhang, Y.; Sun, X.; Chen, P.; Fang, X.; Zhang, Z.; Guan, G.; Peng, H. Electrochromic fiber-shaped supercapacitors. Adv. Mater. 2014, 26, 8126-8132. 8. Chen, T.; Hao, R.; Peng, H.; Dai, L. High-performance, stretchable, wire-shaped supercapacitors. Angew. Chem. Int. Ed. 2015, 54, 618-622. 9. Béguin, F.; Presser, V.; Balducci, A.; Frackowiak, E. Carbons and electrolytes for advanced supercapacitors. Adv. Mater. 2014, 26, 2219-2251. 10. Chen, X.; Lin, H.; Chen, P.; Guan, G.; Deng, J.; Peng, H. Smart, stretchable supercapacitors. Adv. Mater. 2014, 26, 4444-4449. 11. Huang, Y.; Liang, J.; Chen, Y. An overview of the applications of graphene-based materials in supercapacitors. Small 2012, 8, 1805-1834. 12. Li, C.; Balamurugan, J.; Kim, N. H.; Lee, J. H. Hierarchical Zn–Co–S nanowires as advanced electrodes for all solid state asymmetric supercapacitors. Adv. Energy. Mater. 2018, 8, 1702014-1702021. 13. Over, H. Surface chemistry of ruthenium dioxide in heterogeneous catalysis and electrocatalysis: from fundamental to applied research. Chem. Rev. 2012, 112, 3356-3426. 14. Wang, X.; Yan, C.; Sumboja, A.; Yan, J.; Lee, P. S. Achieving high rate performance in layered hydroxide supercapacitor electrodes. Adv. Energy. Mater. 2014, 4, 1301240-1301246. 15. Niu, Z.; Liu, L.; Zhang, L.; Zhou, W.; Chen, X.; Xie, S. Programmable nanocarbon-based architectures for flexible supercapacitors. Adv. Energy. Mater. 2015, 5, 1500677-1500696. 16. Yang, M. H.; Choi, B. G.; Jung, S. C.; Han, Y. K.; Huh, Y. S.; Lee, S. B. Polyoxometalate-coupled graphene via polymeric ionic liquid linker for supercapacitors. Adv. Funct. Mater. 2014, 24, 7301-7309. 17. Genovese, M.; Lian, K. Polyoxometalate modified pine cone biochar carbon for supercapacitor electrodes. J. Mater. Chem. A 2017, 5, 3939-3947.

REFERENCES ACS Paragon Plus Environment

Page 17 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


18. Wang, P.; Wang, R.; Lang, J.; Zhang, X.; Chen, Z.; Yan, X. Porous niobium nitride as a capacitive anode material for advanced Li-ion hybrid capacitors with superior cycling stability. J. Mater. Chem. A 2016, 4, 9760-9766. 19. Su, Y.; Zhitomirsky, I. Pulse electrosynthesis of MnO2 electrodes for supercapacitors. Adv. Eng. Mater. 2014, 16, 760-766. 20. Wang, D. W.; Li, F.; Liu, M.; Lu, G. Q.; Cheng, H. M. 3D aperiodic hierarchical porous graphitic carbon material for high‐rate electrochemical capacitive energy storage. Angew. Chem. Int. Edit. 2008, 120, 379-382. 21. Wang, J.; Xu, Y.; Ding, B.; Chang, Z.; Zhang, X.; Yamauchi, Y. ; Wu, K. C. W. Confined self-assembly in two-dimensional interlayer space: monolayered mesoporous carbon nanosheets with in-Plane orderly arranged mesopores and a highly graphitized framework. Angew. Chem. Int. Edit. 2018, 57, 2894-2898. 22. Meng, Q.; Wu, H.; Meng, Y.; Xie, K.; Wei, Z.; Guo. Z. High-performance all-carbon yarn micro-supercapacitor for an integrated energy system. Adv. Mater. 2014, 26, 4100-4106. 23. Sun, H.; Mei, L.; Liang, J.; Zhao, Z.; Lee, C.; Fei, H.; Ding, M.; Lau, J.; Li, M.; Wang, C.; Xu, X.; Hao, G.; Papandrea, B.; Shakir, I.; Dunn, B.; Huang, Y.; Duan, X. Ultrafine jagged platinum nanowires enable ultrahigh mass activity for the oxygen reduction reaction. Science 2017, 356,599-604. 24. Jiang, H.; Ma, J.; Li, C. Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes. Adv. Mater. 2012, 24, 4197-4202. 25. Sillars, F. B.; Fletcher, S. I.; Mirzaeian, M.; Hall, P. J. Effect of activated carbon xerogel pore size on the capacitance performance of ionic liquid electrolytes. Energy Environ. Sci. 2011, 4, 695-706. 26. Qiang, Z.; Xia, Y.; Xia, X.; Vogt, B. D. Generalized synthesis of a family of highly heteroatom-doped ordered mesoporous carbons. Chem. Mater. 2017, 29, 10178-10186. 27. Zhang, J.; Song, Y.; Kopeć, M.; Lee, J.; Wang, Z.; Liu, S.; Yan, J.; Yuan, R.; Kowalewski, T.; Bockstaller, M. R.; Matyjaszewski, K. Facile aqueous route to nitrogen-doped mesoporous carbons. J. Am. Chem. Soc. 2017, 139, 12931-12934. 28. Sevilla, M.; Ferrero, G. A.; Fuertes, A. B. Beyond KOH activation for the synthesis of superactivated carbons from hydrochar. Carbon 2017, 114, 50-58. 29. Wang, Y. G.; Li, H. Q.; Xia, Y. Y. Ordered whisker like polyaniline grown on the surface of mesoporous carbon and its electrochemical capacitance performance. Adv. Mater. 2006, 18, 2619-2623. 30. Antink, W. H.; Choi, Y.; Seong, K.; Kim, J. M.; Piao, Y. Recent progress in porous graphene and reduced graphene oxide‐based nanomaterials for electrochemical energy storage devices. Adv. Mater. Interfaces. 2018, 5, 1701212-1701230. 31. Oschatz, M.; Boukhalfa, S.; Nickel, W.; Hofmann, J. P.; Fischer, C.; Yushin G.; Kaskel, S. Carbide-derived carbon aerogels with tunable pore structure as versatile electrode material in high power supercapacitors. Carbon 2017, 113, 283-291. 32. Górka, J.; Jaroniec, M. Tailoring adsorption and framework properties of mesoporous polymeric composites and carbons by

33.

34.

35.

36.

37.

38.

39.

40. 41. 42.

43.

44.

45.

46.

47.

addition of organosilanes during soft-templating synthesis. J. Phys. Chem. C. 2010, 114, 6298-6303. Lee, H. I.; Stucky, G. D.; Kim, J. H.; Pak, C.; Chang H.; Kim, J. M. Spontaneous phase separation mediated synthesis of 3D mesoporous carbon with controllable cage and window size. Adv. Mater. 2011, 23, 2357-2361. Wang, J.; Xu, Y.; Ding, B.; Chang, Z.; Zhang, X.; Yamauchi, Y.; Wu, K. C. W. Titelbild: confined self-assembly in two-dimensional interlayer space: monolayered mesoporous carbon nanosheets with in-plane orderly arranged mesopores and a highly graphitized framework. Angew. Chem. Int. Edit. 2018, 130, 2777-2777. Li, X.; Hao, C.; Tang, B.; Wang, Y.; Liu, M.; Wang, Y.; Zhu, Y.; Lu, C.; Tang, Z. Supercapacitor electrode materials with hierarchically structured pores from carbonization of MWCNTs and ZIF-8 composites. Nanoscale 2017, 9, 2178-2187. Ding, J.; Wang, H.; Li, Z.; Kohandehghan, A.; Cui, K.; Xu, Z.; Zahiri, B.; Tan, X.; Lotfabad, E. M.; Olsen, B. C.; Mitlin, D. Carbon nanosheet frameworks derived from peat moss as high performance sodium ion battery anodes. ACS Nano 2013, 7, 11004–11015. Guo, B.; Wang, X.; Fulvio, P. F.; Chi, M.; Mahurin, S. M.; Sun, X. G.; Dai, S. Soft-templated mesoporous carbon-carbon nanotube composites for high performance lithium-ion batteries. Adv. Mater. 2011, 23, 4661-4666. Wu, Z. Y.; Xu, X. X.; Hu, B. C.; Liang, H. W.; Lin, Y.; Chen, Li. F.; Yu, S. H. Iron carbide nanoparticles encapsulated in mesoporous Fe-N-doped carbon nanofibers for efficient electrocatalysis. Angew. Chem. Int. Edit. 2015, 127, 8297-8301. Li, W.; Liu, J.; Zhao, D. Y. Mesoporous materials for energy conversion and storage devices. Nat. Rev. Mater. 2016, 1, 16023-16039. Ma, T. Y.; Liu, L.; Yuan, Z. Y. Direct synthesis of ordered mesoporous carbons. Chem. Soc. Rev. 2013, 42, 3977-4003. Slater, A. G.; Cooper, A. I. Function-led design of new porous materials. Science 2015, 348, 8075-8084. Joo, S. H.; Choi, S. J.; Oh, I.; Kwak, J.; Liu, Z.; Terasaki, O.; Ryoo, R. Ordered nanoporous arrays of carbon supporting high dispersions of platinum nanoparticles. Nature 2001, 412, 169-172. Jun, S.; Joo, S. H.; Ryoo, R.; Kruk, M.; Jaroniec, M.; Liu, Z.; Ohsuna T.; Terasaki, O. Synthesis of new, nanoporous carbon with hexagonally ordered mesostructure. J. Am. Chem. Soc. 2000, 122, 10712-10713. Li, F.; Song, J. X.; Shan, C. S.; Gao, D. M.; Xu, X. Y.; Niu, L. Electrochemical determination of morphine at ordered mesoporous carbon modified glassy carbon electrode. Biosens. Bioelectron 2010, 25, 1408-1413. Li, J.; Guo, S. J.; Zhai, Y. M.; Wang, E. K. High-sensitivity determination of lead and cadmium based on the nafion-graphene composite film. Anal. Chim. Acta. 2009, 649, 196-201. Hsieh, C. T.; Teng, H. Influence of oxygen treatment on electric double-layer capacitance of activated carbon fabrics. Carbon 2002, 40, 667-674. Ryoo, R.; Joo S. H.; Jun, S. Synthesis of highly ordered carbon molecular sieves via template-mediated structural transformation. J. Phys. Chem. B 1999, 103, 7743-7746.



48. Banham, D.; Feng, F.; Burt, J.; Alsrayheen, E.; Birss, V. Bimodal, templated mesoporous carbons for capacitor applications. Carbon 2010, 48, 1056-1063. 49. Huang, C.; Doong, R.; Gu, D.; Zhao, D. Dual-template synthesis of magnetically-separable hierarchically-ordered porous carbons by catalytic graphitization. Carbon 2011, 49, 3055-3064. 50. Zhao, D.; Huo, Q.; Feng, J.; Chmelka, B. F.; Stucky, G. D. Tri-, tetra-, and octablock copolymer and nonionic surfactant syntheses of highly ordered, hydrothermally stable, mesoporous silica structures. J. Am. Chem. Soc. 1998, 120, 6024-6036. 51. Benzigar, M. R.; Talapaneni, S. N.; Joseph, S.; Ramadass, K.; Singh, G.; Scaranto, J.; Ravon, U.; Al-Bahily, K.; Vinu, A. Recent advances in functionalized micro and mesoporous carbon materials: synthesis and applications. Chem. Soc. Rev. 2018, 478, 2680-2721. 52. Hulicova-Jurcakova, D.; Kodama, M.; Shiraishi, S.; Hatori, H.; Zhu, Z. H.; Lu, G. Q. Nitrogen-enriched nonporous carbon electrodes with extraordinary supercapacitance. Adv. Funct. Mater. 2009, 19, 1800-1809. 53. Hulicova, D.; Kodama, M.; Hatori, H. Electrochemical performance of nitrogen-enriched carbons in aqueous and non-aqueous supercapacitors. Chem. Mater. 2006, 18, 2318-2326. 54. Hulicova, D.; Yamashita, J.; Soneda, Y.; Hatori, H. Supercapacitors prepared from melamine-based carbon. Chem. Mater. 2005, 17, 1241-1247. 55. Sun, L. B.; Liu, X. Q.; Zhou. H. C. Design and fabrication of mesoporous heterogeneous basic catalysts. Chem. Soc. Rev. 2015, 44, 5092-5147. 56. Joo, J. B.; Zhang, Q.; Lee, I.; Dahl, M.; Zaera, F.; Yin, Y. Mesoporous anatase titania hollow nanostructures though silica-protected calcination. Adv. Funct. Mater. 2012, 22, 166-174. 57. Li, X.; Forouzandeh, F.; Fürstenhaupt, T.; Banham, D.; Feng, F.; Ye, S.; Kwok, D. Y.; Birss, V. New insights into the surface properties of hard-templated ordered mesoporous carbons. Carbon. 2018, 127, 707-717. 58. Petkovich N. D.; Stein, A. Controlling macro-and mesostructures with hierarchical porosity through combined hard and soft templating. Chem. Soc. Rev. 2013,42, 3721-3739. 59. Kong, Q.; Zhang, L.; Wang, M.; Li, M.; Yao, H.; Shi, J. Soft-to-hard templating to well-dispersed N-doped mesoporous carbon nanospheres via one-pot carbon/silica source copolymerization. Sci. Bull. 2016, 61,1195-1201. 60. Zhou, Y.; Candelaria, S. L.; Liu, Q.; Uchaker E.; Cao, G.; Porous carbon with high capacitance and graphitization through controlled addition and removal of sulfur-containing compounds. Nano Energy, 2015, 12, 567-577. 61. Wan, Y.; Shi Y.; Zhao, D. Supramolecular aggregates as templates: ordered mesoporous polymers and carbons. Chem. Mater. 2008 , 20, 932-945. 62. Valkama, S.; Nykänen, A.; Kosonen, H.; Ramani, R.; Tuomisto, F.; Engelhardt, P.; ten Brinke, G.; Ikkala, O.; Ruokolainen, J. Hierarchical porosity in self-assembled polymers: post-modification of block copolymer–phenolic resin complexes by pyrolysis allows the control of micro-and mesoporosity. Adv. Funct. Mater. 2007, 17, 183-190.

Page 18 of 24

63. Górka, J.; Jaroniec, M. Tailoring adsorption and framework properties of mesoporous polymeric composites and carbons by addition of organosilanes during soft-templating synthesis. J. Phys. Chem. C. 2010, 114, 6298-6303. 64. Chuenchom, L.; Kraehnert, R.; Smarsly, B. M. Recent progress in soft-templating of porous carbon materials. Soft Matter 2012, 8, 10801-10812. 65. Zhou, J.; Fang, L.; Wang, J.; Sun, J.; Jin, K.; Fang, Q. Post-functionalization of novolac resins by introducing thermo-crosslinkable–OCF [double bond, length as m-dash] CF2 groups as the side chains: a new strategy for production of thermosetting polymers without releasing volatiles. Polym. Chem. 2016, 7, 4313-4316. 66. Huang, Y.; Yang, J.; Cai, H.; Zhai, Y.; Feng, D.; Deng, Y.; Tu, B.; Zhao, D. A curing agent method to synthesize ordered mesoporous carbons from linear novolac phenolic resin polymers. J. Mater. Chem. 2009, 19, 6536-6541. 67. Sopronyi, M.; Sima, F.; Vaulot, C.; Delmotte, L.; Bahouka, A.; Ghimbeu, C. M. Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations. Sci. Rep. 2016, 6, 39617-39629. 68. Liu, J.; Yang, T.; Wang, D.W.; Lu, G. Q. M.; Zhao, D.; Qiao, S. Z. A facile soft-template synthesis of mesoporous polymeric and carbonaceous nanospheres. Nat. Commun. 2013, 4, 2798-2804. 69. Braghiroli, F. L.; Fierro, V.; Parmentier, J.; Pasc, A.; Celzard, A. Easy and eco-friendly synthesis of ordered mesoporous carbons by self-assembly of tannin with a block copolymer. Green Chem 2016,18, 3265-3271. 70. Qiao, Z. A.; Guo, B.; Binder, A. J.; Chen, J.; Veith, G. M.; Dai, S. Controlled synthesis of mesoporous carbon nanostructures via a “silica-assisted” strategy. Nano Lett 2012, 13, 207-212. 71. Yuan, J.; Giordano, C.; Antonietti, M. Ionic liquid monomers and polymers as precursors of highly conductive, mesoporous, graphitic carbon nanostructures. Chem. Mater. 2010, 22, 5003-5012. 72. Li, Z.; Del Cul, G. D.; Yan, W.; Liang, C.; Dai, S.; Fluorinated carbon with ordered mesoporous structure. J. Am. Chem. Soc., 2004, 126, 12782-12783. 73. Liu, L.; Wang, F. Y.; Shao, G. S.; Yuan, Z. Y. A low-temperature autoclaving route to synthesize monolithic carbon materials with an ordered mesostructure. Carbon 2010, 48, 2089-2099. 74. Liu, L.; Deng, Q. F.; Liu, Y. P.; Ren, T. Z.; Yuan, Z. Y. HNO3-activated mesoporous carbon catalyst for direct dehydrogenation of propane to propylene. Catal. Commun. 2011, 16, 81-85. 75. Liu, C.; Li, L.; Song, H.; Chen, X. Facile synthesis of ordered mesoporous carbons from F108/resorcinol–formaldehyde composites obtained in basic media. Chem. Commun. 2007, 7, 757-759. 76. Lu, A. H.; Spliethoff, B.; Schüth, F. Aqueous synthesis of ordered mesoporous carbon via self-assembly catalyzed by amino acid. Chem. Mater. 2008, 20, 5314-5319. 77. Hao, G. P.; Li, W. C.; Wang, S.; Wang, G. H.; Qi, L.; Lu, A. H. Lysine-assisted rapid synthesis of crack-free hierarchical carbon monoliths with a hexagonal array of mesopores. Carbon 2011, 49, 3762-3772.


Page 19 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


78. Liu, Y.; Wang, Z.; Teng, W.; Zhu, H.; Wang, J.; Elzatahry, A. A.; Al-Dahyan, D.; Li, W.; Deng, Y.; Zhao, D. A template-catalyzed in situ polymerization and co-assembly strategy for rich nitrogen-doped mesoporous carbon. J. Mater. Chem. A 2018, 6, 3162-3170. 79. Yang, X. Y.; Chen, L. H.; Li, Y.; Rooke, J. C.; Sanchez, C.; Su, B. L. Hierarchically porous materials: synthesis strategies and structure design. Chem. Soc. Rev. 2017, 46, 481-558. 80. Gu, D.; Schüth. F. Synthesis of non-siliceous mesoporous oxides. Chem. Soc. Rev. 2014, 43, 313-344. 81. Wang, T.; Tang, J.; Fan, X.; Zhou, J.; Xue, H.; Guo, H.; He, J. The oriented growth of tungsten oxide in ordered mesoporous carbon and their electrochemical performance. Nanoscale 2014, 6, 5359-5371. 82. Mahadik-Khanolkar, S.; Donthula, S.; Sotiriou-Leventis, C.; Leventis, N. Polybenzoxazine aerogels. 1. high-yield room-temperature acid-catalyzed synthesis of robust monoliths, oxidative aromatization, and conversion to microporous carbons. Chem. Mater. 2014, 26, 1303-1317. 83. Ye, Y. S.; Huang, Y. J.; Chang, F. C.; Xue, Z. G.; Xie, X. L. Synthesis and characterization of thermally cured polytriazole polymers incorporating main or side chain benzoxazine crosslinking moieties. Polym. Chem. 2014, 5, 2863-2871. 84. Barwe, S.; Andronescu, C.; Masa, J.; Ventosa, E.; Klink, S.; Genc, A.; Arbiol, J.; Schuhmann, W. Polybenzoxazine-derived N-doped carbon as matrix for powder-based electrocatalysts. ChemSusChem 2017, 10, 2653-2659. 85. Zhang, M.; Chen, M.; Reddeppa, N.; Xu, D.; Jing, Q.; Zha, R. Nitrogen self-doped carbon aerogels derived from trifunctional benzoxazine monomers as ultralight supercapacitor electrodes. Nanoscale 2018, 10, 6549-6557. 86. White, R. J.; Budarin, V.; Luque, R.; Clark, J. H.; Macquarrie, D. J. Tuneable porous carbonaceous materials from renewable resources. Chem. Soc. Rev. 2009, 38, 3401-3418. 87. Zeinu, K. M.; Hou, H.; Liu, B.; Yuan, X.; Huang, L.; Zhu, X.; Hu, J.; Yang, J.; Liang, S.; Wu, X. A novel hollow sphere bismuth oxide doped mesoporous carbon nanocomposite material derived from sustainable biomass for picomolar electrochemical detection of lead and cadmium. J. Mater. Chem. A 2016, 4, 13967-13979. 88. Zhang, Y.; Meng, Y.; Chen, L.; Guo, Y.; Xiao, D. High lithium and sodium anodic performance of nitrogen-rich ordered mesoporous carbon derived from alfalfa leaves by a ball-milling assisted template method. J. Mater. Chem. A 2016, 4, 17491-17502. 89. Deng, J.; Li, M.; Wang, Y.; Biomass-derived carbon: synthesis and applications in energy storage and conversion.Green Chem., 2016, 18, 4824-4854. 90. Hu, X.; Xiong, W.; Wang, W.; Qin, S.; Cheng, H.; Zeng, Y.; Wang, B.; Zhu, Z. Hierarchical manganese dioxide/poly (3, 4-ethylenedioxythiophene) core–shell nanoflakes on ramie-derived carbon fiber for high-performance flexible all-solid-state supercapacitor. ACS Sustainable Chem. Eng. 2016, 4, 1201-1211. 91. Titirici, M. M.; White, R. J.; Falco, C.; Sevilla, M. Black perspectives for a green future: hydrothermal carbons

for environment protection and energy storage. Energy Environ. Sci. 2012, 5, 6796-6822. 92. Senthil, T.; Weng, Z.; Wu, L. Interlaminar microstructure and mechanical response of 3D robust glass fabric-polyester composites modified with carbon nanofibers. Carbon 2017, 112, 17-26. 93. Paripovic, D.; Klok, H. A. Polymer brush guided formation of thin gold and palladium/gold bimetallic films. ACS Appl. Mater. Interfaces 2011, 3, 910-917. 94. Tenhaeff, W. E.; Rios, O.; More, K.; McGuire, Michael. A. Highly robust lithium ion battery anodes from lignin: an abundant, renewable, and low-cost material. Adv. Funct. Mater. 2014, 24, 86-94. 95. Morris, E. A.; Weisenberger, M. C.; Abdallah, M. G.; Vautard, F.; Grappe, H.; Ozcan, S.; Paulauskas, F. L.; Eberle, C.; Jackson, D.; Mecham S. J.; Naskar, K. A. High performance carbon fibers from very high molecular weight polyacrylonitrile precursors. Carbon 2016, 101, 245-252. 96. El-Deen, A. G.; Boom, R. M.; Kim, H. Y.; Duan, H.; Chan-Park, M. B.; Choi, J. H. Flexible 3D nanoporous graphene for desalination and bio-decontamination of brackish water via asymmetric capacitive deionization. ACS Appl. Mater. Interfaces 2016, 8 , 25313-25325. 97. Li, Y.; Samad, Y. A.; Polychronopoulou, K.; Alhassan, S. M.; Liao, K. From biomass to high performance solar–thermal and electric–thermal energy conversion and storage materials. J. Mater. Chem. A 2014, 2, 7759-7765. 98. Hao, Z. Q.; Cao, J. P.; Wu, Y.; Zhao, X. Y.; Zhuang, Q. Q.; Wang, X. Y.; Wei, X. Y. Preparation of porous carbon sphere from waste sugar solution for electric double-layer capacitor. J. Power Sources 2017, 361, 249-258. 99. Xie, L.; Sun, G.; Su, F.; Guo, X.; Kong, Q.; Li, X.; Huang, X.; Wan, L.; Song, W.; Li, K.; Lv, C.; Chen, C. M. Hierarchical porous carbon microtubes derived from willow catkins for supercapacitor applications. J. Mater. Chem. A 2016,4, 1637-1646. 100. Wang, B.; Xu, L.; Liu, G.; Zhang, P.; Zhu, W.; Xia, J.; Li, H. Biomass willow catkin-derived Co3O4/N-doped hollow hierarchical porous carbon microtubes as an effective tri-functional electrocatalyst. J. Mater. Chem. A 2017, 5, 20170-20179. 101. Chen, L.; Ji, T.; Brisbin, L.; Zhu, J. Hierarchical porous and high surface area tubular carbon as dye adsorbent and capacitor electrode. ACS Appl. Mater. Interfaces 2015, 7, 12230-12237. 102. Tan, H.; Wang, X.; Jia, D.; Hao, P.; Sang, Y.; Liu, H. Structure-dependent electrode properties of hollow carbon micro-fibers derived from platanus fruit and willow catkins for high-performance supercapacitors. J. Mater. Chem. A 2017, 5, 2580-2591. 103. Dutta, S.; Kim, J.; Ide, Y.; Kim, J. H.; Hossain, M. S. A.; Bando, Y.; Yamauchi, Y.; Wu, Kevin C. W. 3D network of cellulose-based energy storage devices and related emerging applications. Mater. Horiz. 2017, 4, 522-545. 104. Moon, R. J.; Martini, A.; Nairn, J.; Simonsen, J.; Youngblood, J. Cellulose nanomaterials review: structure, properties and nanocomposites. Chem. Soc. Rev. 2011, 40, 3941-3994. 105. Liu, H. J.; Wang, X. M.; Cui, W. J.; Dou, Y. Q.; Zhao, D. Y.; Xia, Y. Y. Highly ordered mesoporous carbon nanofiber arrays



106.

107.

108.

109.

110.

111.

112.

113.

114.

115.

116.

117. 118.

119.

120.

from a crab shell biological template and its application in supercapacitors and fuel cells. J. Mater. Chem. 2010, 20, 4223-4230. Fu, C.; Shao, Z.; Fritz, V. Animal silks: their structures, properties and artificial production. Chem. Commun. 2009, 43, 6515-6529. Chen, W.; Zhang, H.; Huang, Y.; Wang, W. A fish scale based hierarchical lamellar porous carbon material obtained using a natural template for high performance electrochemical capacitors. J. Mater. Chem. 2010, 20, 4773-4775. Zhao, S.; Li, C.; Wang, W.; Zhang, H.; Gao, M.; Xiong, X.; Wang, A.; Yuan, K.; Huang, Y.; Wang, F. A novel porous nanocomposite of sulfur/carbon obtained from fish scales for lithium–sulfur batteries. J. Mater. Chem. A 2013, 1, 3334-3339. Zhu, Y.; Cui, H.; Meng, X.; Zheng, J.; Yang, P.; Li, L.; Wang, Z.; S. Jia.; Zhu, Z. Chlorine-induced in situ regulation to synthesize graphene frameworks with large specific area for excellent supercapacitor performance. ACS Appl. Mater. Interfaces 2016, 8 , 6481-6487. Deng, Y.; Xie, Y.; Zou, K.; Ji, X. Review on recent advances in nitrogen-doped carbons: preparations and applications in supercapacitors. J. Mater. Chem. A 2016,4, 1144-1173. Li, M.; Jiao, C.; Yang, X.; Wang, C.; Wu, Q.; Wang, Z. Solid phase extraction of carbamate pesticides with banana peel derived hierarchical porous carbon prior to high performance liquid chromatography. Anal. Methods 2017, 9, 593-599. Wu, Z. Y.; Ma, C.; Bai, Y. L.; Liu, Y. S.; Wang, S. F.; Wei, X.; Wang, K. X.; Chen, J. S. Rubber-based carbon electrode materials derived from dumped tires for efficient sodium-ion storage. Dalton Trans 2018, 47, 4885-4892. Yu, B. C.; Jung, J. W.; Park, K.; Goodenough, J. B. A new approach for recycling waste rubber products in Li-S batteries. Energy Environ. Sci. 2017, 10, 86-90. Qiu, X.; Wang, L.; Zhu, H.; Guan, Y.; Zhang, Q. Lightweight and efficient microwave absorbing materials based on walnut shell-derived nano-porous carbon. Nanoscale 2017, 9, 7408-7418. Zhu, H.; Wang, X.; Yang, F.; Yang, X. Promising carbons for supercapacitors derived from fungi. Adv. Mater. 2011, 23, 2745-2748. Jin, Y.; Tian, K.; Wei, L.; Guo, X. Hierarchical porous microspheres of activated carbon with a high surface area from spores for electrochemical double-layer capacitors. J. Mater. Chem. A 2016, 4, 15968-15979. Joos, F. Global warming: Growing feedback from ocean carbon to climate. Nature 2015, 522, 295-296. Zapata-Benabithe, Z.; Vicente, J. de.; Carrasco-Marín, F.; Moreno-Castilla, C. Importance of the rheological properties of resorcinol–formaldehyde sols in the preparation of Cu-doped organic and carbon xerogel microspheres. Carbon 2013, 53, 402-405. Maciá-Agulló, J. A.; Moore, B. C.; Cazorla-Amorós, D.; Linares-Solano, A. Activation of coal tar pitch carbon fibres: physical activation vs. chemical activation. Carbon 2004, 42, 1367-1370. Sevilla, M.; Fuertes, A. B. A green approach to high-performance supercapacitor electrodes: the chemical

121.

122.

123.

124.

125.

126.

127.

128.

129.

130.

131.

132.

133.

134.

135.

Page 20 of 24

activation of hydrochar with potassium bicarbonate. ChemSusChem 2016, 9, 1880-1888. Oschatz, M.; Borchardt, L.; Thommes, M.; Cychosz, K. A.; Senkovska, I.; Klein, N.; Frind, R.; Leistner, M.; Presser, V.; Gogotsi, Y.; Kaskel, S. Aus carbiden abgeleitete kohlenstoffmonolithe mit hierarchischer porenarchitektur. Angew. Chem. Int. Edit. 2012, 124, 7695-7698. Yun, C. H.; Park, Y. H.; Park, C. R. Effects of pre-carbonization on porosity development of activated carbons from rice straw. Carbon 2001, 39, 559-567. Rodrı́guez-Reinoso, F.; Pastor, A. C.; Marsh, H.; Martı́nez, M. A. Preparation of activated carbon cloths from viscous rayon. part II: physical activation processes. Carbon 2000, 38, 379-395. Vázquez-Santos, M. B.; Suárez-García, F.; Martínez-Alonso, A.; Tascón, J. M. D. Activated carbon fibers with a high heteroatom content by chemical activation of PBO with phosphoric acid. Langmuir 2012, 28, 5850-5860. Hao, P.; Zhao, Z.; Leng, Y.; Tian, J.; Sang, Y.; Boughton, R. I.; Wong, C. P.; Liu, H.; Yang, B. Graphene-based nitrogen self-doped hierarchical porous carbon aerogels derived from chitosan for high performance supercapacitors. Nano Energy 2015, 15, 9-23. Salvador, F.; Sánchez-Montero, M. J.; Montero, J.; Izquierdo, C. Activated carbon fibers prepared from a phenolic fiber by supercritical water and steam activation. J. Phys. Chem. C 2008, 112, 20057-20064. Guo, Y.; Rockstraw, D. A. Physical and chemical properties of carbons synthesized from xylan, cellulose, and kraft lignin by H3PO4 activation. Carbon 2006, 44, 1464-1475. Xing, Z.; Qi, Y.; Tian, Z.; Xu, J.; Yuan, Y.; Bommier, C.; Lu, J.; Tong, W.; Jiang, D.; Ji, X. Identify the removable substructure in carbon activation. Chem. Mater. 2017, 29, 7288-7295. Sevilla, M.; Alam, N.; Mokaya, R. Enhancement of hydrogen storage capacity of zeolite-templated carbons by chemical activation. J. Phys. Chem. C 2010, 114, 11314-11319. Smith, M. R.; Bittner, E. W.; Shi, W.; Johnson, J. K.; Bockrath, B. C. Chemical activation of single-walled carbon nanotubes for hydrogen adsorption. J. Phys. Chem. B 2003, 107, 3752-3760. Zhou, Y.; Jin, P.; Zhou, Y.; Zhu, Y. Carbon nanospheres hanging on carbon nanotubes: a hierarchical three-dimensional carbon nanostructure for high-performance supercapacitors. J. Mater. Chem. A 2017 , 5 , 16595-16599. Zhu, S.; Li, L.; Liu, J.; Wang, H.; Wang, T.; Zhang, Y.; Zhang, L.; Ruoff, R. S.; Dong, F. Structural directed growth of ultrathin parallel birnessite on β-MnO2 for high-performance asymmetric supercapacitors. ACS Nano 2018, 12 , 1033-1042. Xue, C.; Lv, Y.; Zhang, F.; Wu, L.; Zhao, D. Copper oxide activation of soft-templated mesoporous carbons and their electrochemical properties for capacitors. J. Mater. Chem. 2012, 22, 1547-1555 . Blankenship, T. S.; Balahmar, N.; Mokaya, R. Oxygen-rich microporous carbons with exceptional hydrogen storage capacity. Nat. Commun. 2017, 8, 1545-1549. Asaka, K.; Saito, Y. Spontaneous graphenization of amorphous


Page 21 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

136.

137.

138.

139.

Chemistry of Materials carbon on clean surfaces of nanometer-sized nickel particles at room temperature. Carbon 2016, 103, 352-355. Borenstein, A.; Hanna, O.; Attias, R.; Luski, S., Brousse, T.; Aurbach, D. Carbon-based composite materials for supercapacitor electrodes: a review. J. Mater. Chem. A 2017, 5, 12653-12672. Wang, Y.; Song, Y.; Xia, Y. Electrochemical capacitors: mechanism, materials, systems, characterization and applications. Chem. Soc. Rev. 2016, 45, 5925-5950. Jurewicz, K.; Pietrzak, R.; Nowicki, P.; Wachowsk, H. Capacitance behaviour of brown coal based active carbon modified through chemical reaction with urea. Electrochim. Acta 2008, 53, 5469-5475. Schuster, J.; He, G.; Mandlmeier, B.; Yim, Taeeun.; Lee, K. T.; Bein,T.; Nazar, L. F. Spherical ordered mesoporous carbon nanoparticles with high porosity for lithium–sulfur batteries. Angew. Chem. Int. Edit. 2012, 51, 3591-3595.

140. Yu, D.; Dai, L. Self-assembled graphene/carbon nanotube hybrid films for supercapacitors. J. Phys. Chem. Lett. 2009, 1, 467-470. 141. Zhu, Y. W.; Murali, S.; Stoller, M. D.; Ganesh, K. J.; Cai, W. W.; Ferreira, P. J.; Pirkle, A.; Wallace, R. M.; Cychosz, K. A.; Thommes, M.; Su, D.; Stach, E. A.; Ruoff, R. S. Carbon-based supercapacitors produced by activation of graphene. Science 2011, 332,1537-1541. 142. Wang, Y.; Shi, Z. Q.; Huang, Y.; Ma, Y. F.; Wang, C. Y.; Chen, M. M.; Chen, Y. S. Supercapacitor devices based on graphene materials. J. Phys. Chem. C 2009, 113, 13103-13107. 143. Deng, T.; Zhang, W.; Arcelus, O.; Kim, J. G.; Carrasco, J.; Yoo, S. J.; Zheng, W.; Wang, J.; Tian, H.; Zhang, H.; Cui, X.; Rojo, T. Atomic-level energy storage mechanism of cobalt hydroxide electrode for pseudocapacitors. Nat. Commun. 2017, 8, 15194-15202. 144. Bryan, A. M.; Santino, L. M.; Lu, Y.; Acharya, S.; D’Arcy, J. M. Conducting polymers for pseudocapacitive energy storage. Chem. Mater. 2016, 28, 5989-5998. 145. F, Yu.; Chang, Z.; Yuan, X.; Wang, F.; Zhu, Y.; Fu, L.; Chen, Y.; Wang, H.; Wu, Y.; Lie, W. Ultrathin NiCo2S4@ graphene with a core–shell structure as a high performance positive electrode for hybrid supercapacitors. J. Mater. Chem. A 2018, 6 , 5856-5861. 146. Dubal, D. P.; Chodankar, N. R.; Kim, D. H.; Romero, P. G. Towards flexible solid-state supercapacitors for smart and wearable electronics. Chem. Soc. Rev. 2018, 47, 2065-2129. 147. Simon, P.; Gogotsi, Y. Materials for electrochemical capacitors. Nat. Mater. 2008, 7, 845-854. 148. Yuan, C. Z.; Gao, B.; Shen, L. F.; Yang, S. D.; Hao, L.; Lu, X. J.; Zhang, F.; Zhang, L. J.; Zhang, X. G. Hierarchically structured carbon-based composites: design, synthesis and their application in electrochemical capacitors. Nanoscale 2011, 3, 529-545. 149. Jiang, D.; Wu, J. Microscopic insights into the electrochemical behavior of nonaqueous electrolytes in electric double-layer capacitors. J. Phys. Chem. Lett. 2013, 4, 1260-1267. 150. Evanko, B.; Boettcher, S. W.; Yoo, S. J.; Stucky, G. D. Redox-enhanced electrochemical capacitors: status, opportunity, and best practices for performance evaluation. ACS Energy Lett. 2017, 2 , 2581-2590.

151. Wang, H.; Köster, T. K. J.; Trease, N. M.; Ségalini, J.; Taberna, P. L.; Simon, P.; Gogotsi, Y.; Grey, C. P. Real-time NMR studies of electrochemical double-layer capacitors. J. Am. Chem. Soc. 2011, 133, 19270-19273. 152. Ray, P.; Dohm, S.; Husch, T.; Schütter, C.; Schütter, C.; Persson, K. A.; Balducci, A.; Kirchner, B.; Korth, M. Insights into bulk electrolyte effects on the operative voltage of electrochemical double-layer capacitors. J. Phys. Chem. C. 2016, 120, 12325-12336. 153. Vu, A.; Li, X.; Phillips, J.; Han, A.; Smyrl, W. H.; Bühlmann, P.; Stein, A. Three-dimensionally ordered mesoporous (3DOm) carbon materials as electrodes for electrochemical double-layer capacitors with ionic liquid electrolytes. Chem. Mater. 2013, 25 , 4137-4148. 154. Chmiola, J.; Yushin, G.; Gogotsi, Y.; Portet, C.; Simon, P.; Taberna, P. L. Anomalous increase in carbon capacitance at pore sizes less than 1 nanometer. Science 2006, 313, 1760-1763. 155. Simon, P.; Gogotsi, Y. Materials for electrochemical capacitors. Nat. Mater. 2008, 7, 845-854. 156. Eliad, L.; Salitra, G.; Soffer, A.; Aurbach, D. On the mechanism of selective electroadsorption of protons in the pores of carbon molecular sieves. Langmuir 2005, 21,3198-3202. 157. Fischer, A. E.; Pettigrew, K. A.; Rolison, D. R.; Stroud, R. M.; Long, J. W. Incorporation of homogeneous, nanoscale MnO2 within ultraporous carbon structures via self-limiting electroless deposition: implications for electrochemical capacitors. Nano Lett 2007, 7, 281-286. 158. Futaba, D. N.; Hata, K.; Yamada, T.; Hiraoka, T.; Hayamizu, Y.; Kakudate, Y.; Tanaike, O.; Hatori, H.; Yumura, M.; Iijima, S. Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes. Nat. Mater 2006, 5, 987-994. 159. Brezesinski, T.; Wang, J.; Tolbert, S. H.; Dunn, B. Ordered mesoporous α-MoO3 with iso-oriented nanocrystalline walls for thin-film pseudocapacitors. Nat. Mater 2010, 9, 146-151. 160. Bard, A. J.; Faulkner, L. R. Electrochemical methods fundamentals and applications, John Wiley, Inc., New York, 2nd edn, 2001, ch. 6, pp. 233, 235. 161. Wei, W. F.; Cui, X. W.; Chen, W. X.; Ivey, D. G. Manganese oxide-based materials as electrochemical supercapacitor electrodes. Chem. Soc. Rev. 2011, 40, 1697-1721. 162. Nam, K. W.; Kim, K. B. A study of the preparation of NiOx electrode via electrochemical route for supercapacitor applications and their charge storage mechanism. J. Electrochem. Soc. 2002, 149, A346- A354. 163. Snook, G. A.; Kao, P.; Best, A. S. Conducting-polymer-based supercapacitor devices and electrodes. conducting-polymer-based supercapacitor devices and electrodes. J. Power Sources 2011, 196,1-12. 164. Sharma, R. K.; Rastogi, A. C.; Desu, S. B. Pulse polymerized polypyrrole electrodes for high energy density electrochemical supercapacitor. Electrochem. Commun. 2008, 10, 268-272. 165. Augustyn, V.; Simon, P.; Dunn, B. Pseudocapacitive oxide materials for high-rate electrochemical energy storage. Energy Environ. Sci. 2014, 7, 1597-1614.



166. Jo, C.; Hwang, J.; Dao, A. H.; Kim, Y. T.; Lee, S. H.; Hong, S. W.; Yoon,S.; Lee, J. Block-Copolymer-Assisted One-Pot Synthesis of Ordered Mesoporous WO3-x/Carbon Nanocomposites as High-Rate-Performance Electrodes for Pseudocapacitors. Adv. Funct. Mater. 2013, 16, 3747-3754. 167. Li, Z.; Xu, Z.; Tan, X.; Wang, H.; Holt, C. M. B.; Stephenson, T.; Olsen, B. C.; Mitlin, D. Mesoporous nitrogen-rich carbons derived from protein for ultra-high capacity battery anodes and supercapacitor. Energy Environ. Sci. 2013, 6, 871-878. 168. Augustyn, V.; Come, J.; Lowe, M. A.; Kim, J. W.; Taberna, P. L.; Tolbert, S. H.; Abruña, H. D.; Simon, P.; Dunn, B. High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance. Nature Mater 2013, 12, 518-522. 169. Chen, C.; Wen, Y.; Hu, X.; Ji, X.; Yan, M.; Mai, L.; Hu, P.; Shan, B.; Huang, Y. Na+ intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling. Nat. Commun. 2015, 6, 6929-6936. 170. Wang, X.; Kajiyama, S.; Iinuma, H.; Hosono, E.; Oro, S.; Moriguchi, I.; Okubo, M.; Yamada, A. Pseudocapacitance of mxene nanosheets for high-power sodium-ion hybrid capacitors. Nat. Commun. 2015, 6, 6544-6549. 171. Rakhi, R. B.; Chen, W.; Cha, D.; Alshareef, H. N. Substrate dependent self-organization of mesoporous cobalt oxide nanowires with remarkable pseudocapacitance. Nano Lett 2012, 12, 2559-2567. 172. Qu, D. Studies of the activated carbons used in double-layer supercapacitors. J Power Sources 2002, 109, 403-411. 173. Nian, Y. R.; Teng, H. Influence of surface oxides on the impedance behavior of carbon-based electrochemical capacitors. J. Electroanal. Chem 2003, 540, 119-127. 174. Zhou, H.; Peng, Y.; Wu, H. B.; Sun, F.; Yu, H.; Liu, F.; Xu, Q.; Lu, Y. Fluorine-rich nanoporous carbon with enhanced surface affinity in organic electrolyte for high-performance supercapacitors. Nano Energy 2016, 21, 80-89. 175. Wang, J. A.; Lu, Y. T.; Lin, S. C.; Wang, Y. S.; Ma, C. C. M.; Hu, C. C. Designing a novel polymer electrolyte for improving the electrode/electrolyte interface in flexible all-solid-state electrical double-layer capacitors. ACS Appl. Mater. Interfaces 2018, 10, 17871-17882. 176. Sheberla, D.; Bachman, J. C.; Elias, J. S.; Sun, C. J.; Horn, Y. S.; Dincă, M. Conductive MOF electrodes for stable supercapacitors with high areal capacitance. Nature Mater 2017, 16, 220-224. 177. Naoi, K.; Ishimoto, S.; Miyamoto, J.; Naoi, W. Second generation 'nanohybrid supercapacitor': evolution of capacitive energy storage devices. Energy Environ. Sci. 2012, 5, 9363-9373. 178. Stoller, M. D.; Murali, S.; Quarles, N.; Zhu, Y.; Potts, J. R.; Zhu, X.; Ha, H. W.; Ruoff, R. S. Activated graphene as a cathode material for Li-ion hybrid supercapacitors. Phys. Chem. Chem. Phys. 2012,14, 3388-3391. 179. Dubal, D. P.; Chodankar, N. R.; Kim, D. H.; Gomez-Romero, P. Towards flexible solid-state supercapacitors for smart and wearable electronics. Chem. Soc. Rev. 2018, 47, 2065-2129.

Page 22 of 24

180. Zhang, F.; Zhang, T.; Yang, X.; Zhang, L.; Leng, K.; Huang, Y.; Chen, Y. A high-performance supercapacitor-battery hybrid energy storage device based on graphene-enhanced electrode materials with ultrahigh energy density. Energy Environ. Sci. 2013, 6, 1623-1632. 181. Veerasubramani, G. K.; Chandrasekhar, A.; P, S. M. S.; Mok, Y. S.; Kim, S. J. Liquid electrolyte mediated flexible pouch-type hybrid supercapacitor based on binderless core– shell nanostructures assembled with honeycomb-like porous carbon. J. Mater. Chem. A 2017, 5, 11100-11113. 182. Raju, G. S. R.; Pavitra, E.; Nagaraju, G.; Sekhar, S. C.; Ghoreishian, S. M.; Kwak, C. H.; Yu, J. S.; Huh, Y. S.; Han, Y. K. Rational design of forest-like nickel sulfide hierarchical architectures with ultrahigh areal capacity as a binder-free cathode material for hybrid supercapacitors. J. Mater. Chem. A 2018, 6, 13178-13190. 183. Wang, R.; Yan, X.; Lang, J.; Zheng, Z.; Zhang, P. A hybrid supercapacitor based on flower-like Co(OH)2 and urchin-like VN electrode materials. J. Mater. Chem. A 2014, 2, 12724-12732. 184. Zhu, M.; Huang, Y.; Meng, W.; Gong, Q.; Li, G.; Zhi, C. An electrochromic supercapacitor and its hybrid derivatives: quantifiably determining their electrical energy storage by an optical measurement. J. Mater. Chem. A 2015, 3, 21321-21327. 185. Wang, Q.; Wen, Z. H.; Li, J. H. A hybrid supercapacitor fabricated with a carbon nanotube cathode and a TiO2–B nanowire anode. Adv. Funct. Mater. 2006, 16, 2141-2146. 186. Zhao, X.; Johnston, C.; Grant, P. S. A novel hybrid supercapacitor with a carbon nanotube cathode and an iron oxide/carbon nanotube composite anode. J. Mater. Chem. 2009, 19, 8755-8760. 187. Koh, K.; Meng, Y.; Huang, X.; Zou, X.; Chhowalla, M.; Asefa, T. N-and O-doped mesoporous carbons derived from rice grains: efficient metal-free electrocatalysts for hydrazine oxidation. Chem. Commun. 2016, 52, 13588-13591. 188. Liu, D.; Zeng, C.; Qu, D.; Tang, H.; Li, Y.; Su, B. L.; Qu, D. Highly efficient synthesis of ordered nitrogen-doped mesoporous carbons with tunable properties and its application in high performance supercapacitors. J. Power Sources 2016, 321, 143-154. 189. Shi, Q.; Zhang, R.; Lv, Y.; Deng, Y.; Elzatahrya, A. A.; Zhao, D. Nitrogen-doped ordered mesoporous carbons based on cyanamide as the dopant for supercapacitor. Carbon 2015, 84, 335-346. 190. Zhang, J.; Qiao, Z. A.; Mahurin, S. M.; Jiang, X.; Chai, S. H.; Lu, H.; Nelson, K.; Dai, S. Hypercrosslinked phenolic polymers with well-developed mesoporous frameworks. Angew. Chem. Int. Edit. 2015, 54, 4582-4586. 191. Zhao, X.; Li, S.; Cheng, H.; Schmidt, J.; Thomas, A. Ionic liquid-assisted synthesis of mesoporous carbons with surface-enriched nitrogen for the hydrogen evolution reaction. ACS Appl. Mater. Interfaces 2018, 10, 3912-3920. 192. Ma, W.; Wang, N.; Tong, T.; Zhang, L.; Lin, K. Y. A.; Han, X.; Du, Y. Nitrogen, phosphorus, and sulfur tri-doped hollow carbon shells derived from ZIF-67@ poly (cyclotriphosphazene-co-4,4′-sulfonyldiphenol) as a robust catalyst of peroxymonosulfate activation for degradation of bisphenol A. Carbon 2018, 137, 291-303.


Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


193. Kowalczyk, P.; Gauden, P. A .; Furmaniak, S.; Terzyk, A. P.; Wiśniewski, M.; IInicka, A.; Łukaszewicz, J.; Burian, A.; Włoch, J.; Neimark, V. A. Morphologically disordered pore model for characterization of micro-mesoporous carbons. Carbon 2017, 111, 358-370. 194. Korenblit, Y.; Rose, M.; Kockrick, E.; Borchardt, L.; Kvit, A.; Kaskel, S.; Yushin, G. High-rate electrochemical capacitors based on ordered mesoporous silicon carbide-derived carbon. ACS Nano 2010, 4, 1337-1344. 195. Liu, H. J.; Wang, J.; Wang, C. X. Ordered hierarchical mesoporous/microporous carbon derived from mesoporous titanium-carbide/carbon composites and its electrochemical performance in supercapacitor. Adv. Energy. Mater. 2011, 1, 1101-1108. 196. Oschatz, M.; Borchardt, L.; Pinkert, K.; Thieme, S.; Lohe, M. R.; Hoffmann, C.; Benusch, M.; Wisser, F. M.; Ziegler, C.; Giebeler, L.; Rümmeli, M. H.; Eckert, J.; Eychmüller, A.; Kaskel, S. Hierarchical carbide-derived carbon foams with advanced mesostructure as a versatile electrochemical energy-storage material. Adv. Energy. Mater. 2014, 4, 1300645-1300653. 197. Ma, Z.; Yuan, X.; Li, L.; Ma, Z. F.; Wilkinson, D. P.; Zhang, L.; Zhang, J. A review of cathode materials and structures for rechargeable lithium–air batteries. Energy Environ. Sci. 2015, 8, 2144-2198. 198. Sun, B.; Kretschmer, K.; Xie, X.; Munroe, P.; Peng, Z.; Wang, G. Hierarchical porous carbon spheres for high-performance Na–O2 batteries. Adv. Mater. 2017, 29, 1606816-1606823. 199. Xie, Y.; Chen, Y.; Liu, L.; Tao, P.; Fan, M.; Xu, N.; Shen, X.; Yan, C. Ultra-high pyridinic n-doped porous carbon monolith enabling high-capacity k-ion battery anodes for both half-cell and full-cell applications. Adv. Mater. 2017, 29,1702268-1702276. 200. Yang, Z.; Ren, J.; Zhang, Z.; Chen, X.; Guan, G.; Qiu, L.; Zhang,Ye.; Peng, H. Recent advancement of nanostructured carbon for energy applications. Chem. Rev. 2015, 115,

207.

208.

209.

210.

211.

212.

213.

214.

215.

5159-5223.

201. Li, Z.; Liu, Z.; Sun, H.; Gao, C. Superstructured assembly of nanocarbons: fullerenes, nanotubes, and graphene. Chem. Rev. 2015, 115, 7046-7117. 202. Sevilla, M.; Mokaya, R.; Fuertes, A. B. Ultrahigh surface area polypyrrole-based carbons with superior performance for hydrogen storage. Energy Environ. Sci. 2011, 4, 2930-2936. 203. Xie, K.; Qin, X.; Wang, X.; Wang, Y.; Tao, H.; Wu, Q.; Yang, L. J.; Hu, Z. Carbon nanocages as supercapacitor electrode materials. Adv. Mater. 2012, 24, 347-352. 204. Zhai,Y.; Dou, Y.; Zhao, D.; Fulvio, P. F.; Mayes. R. T.; Dai, S. Carbon materials for chemical capacitive energy storage. Adv. Mater. 2011, 23, 4828-4850. 205. Zhu,Y.; Murali, S.; Stoller, M. D.; Ganesh, K. J.; Cai, W.; Ferreira1, P. J.; Pirkle, A.; Wallace, R. M.; Cychosz, K. A.; Thommes, M.; Su, D.; Stach, E. A.; Ruoff, R. S. Carbon-based supercapacitors produced by activation of graphene. Science 2011, 332, 1537-1541. 206. Bu, Y.; Sun, T.; Cai, Y.; Du, L.; Zhuo, O.; Yang, L.; Wu, Q.; Wang, X.; Hu, Z. Compressing carbon nanocages by capillarity for optimizing porous structures toward

216.

217.

ultrahigh‐volumetric‐performance supercapacitors. Adv. Mater. 2017, 29, 1700470-1700476. Xu, Y.; Lin, Z.; Zhong, X.; Huang, X.; Weiss, N. O.; Huang, Y.; Duan, X. Holey graphene frameworks for highly efficient capacitive energy storage. Nat. Commun. 2014, 5, 4554-4562. Wang, Z.; Tammela, P.; Zhang, P.; Strømme, M.; Nyholm, L. High areal and volumetric capacity sustainable all-polymer paper-based supercapacitors. J. Mater. Chem. A 2014, 2, 16761-16769. Sahoo, R.; Pal, A.; Pal, T. 2D materials for renewable energy storage devices: outlook and challenges. Chem. Commun. 2016, 52, 13528-13542. Lin, T.; Chen, I. W.; Liu, F.; Yang, C.; Bi, H.; Xu, F.; Huang, F. Nitrogen-doped mesoporous carbon of extraordinary capacitance for electrochemical energy storage. Science 2015, 350, 1508-1513. Feng, S.; Li, W.; Wang, J.; Song, Y.; Elzatahry, A. A.; Xia, Y.; Zhao, D. Hydrothermal synthesis of ordered mesoporous carbons from a biomass-derived precursor for electrochemical capacitors. Nanoscale 2014, 6, 14657-14662. Wu, Z.; Li, W.; Xia, Y.; Webley, P.; Zhao, D. Ordered mesoporous graphitized pyrolytic carbon materials: synthesis, graphitization, and electrochemical properties. J. Mater. Chem. 2012, 22, 8835-8845 . Jeon, J. W.; Zhang, L.; Lutkenhaus, J. L.; Laskar, D. D.; Lemmon, J. P.; Choi, D.; Nandasiri, M. I.; Hashmi, A.; Xu, J.; Motkuri, R. K.; Fernandez, C. A.; Liu, J.; Tucker, M. P.; McGrail, P. B.; Yang, B.; Nune, S. K. Controlling porosity in lignin-derived nanoporous carbon for supercapacitor applications. ChemSusChem 2015, 8, 428-432. Zhang, Y.; Liu, S.; Zheng, X.; Wang, X.; Xu, Y.; Tang, H.; Kang, F.; Yang, Q. H.; Luo, J. Biomass organs control the porosity of their pyrolyzed carbon. Adv. Funct. Mater. 2017, 27, 1604687-1604694. Chen, Z.; Ye, S.; Evans, S. D.; Ge, Y.; Zhu, Z.; Tu, Y.; Yang, X. Confined assembly of hollow carbon spheres in carbonaceous nanotube: a spheres-in-tube carbon nanostructure with hierarchical porosity for high-performance supercapacitor. Small 2018, 14, 1704015-1704022. Saha, D.; Li, Y.; Bi, Z.; Chen, J.; Keum, J. K.; Hensley, D. K.; Grappe, H. A.; Meyer, H. M.; Dai, S.; Paranthaman, M. P.; Naskar, A. K. Studies on supercapacitor electrode material from activated lignin-derived mesoporous carbon. Langmuir 2014, 30, 900-910. Liu, J.; Wickramaratne, N. P.; Qiao, S. Z.; Jaroniec, M. Molecular-based design and emerging applications of nanoporous carbon spheres. Nature Mater 2015, 14, 763-774.



Fabrication Strategies of Mesoporous Carbons with High Specific Surface Areas, High Pore Volumes and Tunable Pore Networks for Advanced Supercapacitors


Page 24 of 24

Nanocasting and Direct Synthesis Strategies for Mesoporous Carbons

Recommend Documents