Hierarchical Porous Carbon Derived from Coal Tar Pitch Containing

Subscriber access provided by UNIV AUTONOMA DE COAHUILA UADEC

Article

Hierarchical Porous Carbon Derived from Coal Tar Pitch Containing Discrete Co-Nx-C Active Sites for Efficient Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries Fang Dong, Cong Liu, Mingjie Wu, Jianing Guo, Kaixi Li, and Jinli Qiao ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.9b00373 • Publication Date (Web): 03 Apr 2019 Downloaded from http://pubs.acs.org on April 3, 2019

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 34 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

ACS Sustainable Chemistry & Engineering

Hierarchical Porous Carbon Derived from Coal Tar Pitch Containing Discrete Co-Nx-C Active Sites for Efficient Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries Fang Donga, Cong Liua, Mingjie Wua,d, Guo, Jianinga, Kaixi Lic, Jinli Qiaoa,b* a

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of

Environmental Science and Engineering, Donghua University, 2999 Ren’min North Road, Shanghai 201620, China b

c

Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China

Institute of Coal Chemistry, Chinese Academy of Sciences, 27 Taoyuan South Road, Taiyuan,

Shanxi 030001, China d

Institut National de la Recherche Scientifique-Énergie Matériaux et Télécommunications,

Varennes, Quebec J3X 1S2, Canada *Corresponding author. Tel: +86-21-67792379. Fax: +86-21-67792159. E-mail: [email protected] (JLQ) KEYWORDS: Coal tar pitch, high specific surface area, oxygen reduction reaction, Co-Nx-C active site, rechargeable zinc-air battery. 1 ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 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

ABSTRACT. Coal tar pitch (CTP), as a by-product of the rich, low-cost, high-carbon yield coal industry, is expected to achieve high value-added and comprehensive utilization. The oxygen reduction reaction is the cornerstone of both fuel cells and zinc-air batteries (ZABs). Herein, as a proof-of-concept application, the activated CTP (ACTP) firstly used as carbon source through cobalt/nitrogen reengineering is demonstrated to be an effective and, straightforward strategy for fabrication of high-performing hierarchical porous carbons (Co/N-HPCs). The as-prepared Co/N-HPC150/800 with a large specific surface area of 2076.58 m2 g-1 exhibits superior electrocatalytic properties for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in terms of a half-wave potential of 0.85 V (vs. RHE) for ORR and an onset potential of 1.42 V (vs. RHE) for OER, respectively, in 0.1M KOH, superior to commercial Pt/C catalyst. Notably, we have experimentally shown that Co/N-HPC150/800 as the air electrode for zinc-air battery demonstrates a high discharge peak power density achieving 425 mW cm-2, a current density of 291 mA cm-2 at a voltage of 1 V, and a long cycling stability beyond 250 hours at 10 mA cm−2. Moreover, the obtained rechargeable Zn-air battery exhibits a low dischargecharge voltage gap and long cycle life (2100 cycles with 10 min per cycle). The outstanding electrocatalytic properties are attributed to the unique hierarchical pore structures as well as coupling effects originated from cobalt doping and trace nitrogen-containing active sites from aqueous ammonia, which largely facilitates the charge transfer and enhances the stability of rechargeable ZABs. It opens a new and viable way for realizing the high value-added utilization of CTP.

2 ACS Paragon Plus Environment

Page 2 of 34

Page 3 of 34 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


INTRODUCTION

The developments of clean and renewable energy have attracted tremendous interest in response to the rapid consumption of non-renewable fossil fuels, which has caused significant environmental and social problems on a global scale.1-2 Fuel cells and metal-air batteries have attracted a lot of scientific appeal due to their low operating temperatures, high energy density and energy efficiency, environmentally-friendly nature, quick start-up and long life.3-9 However, the inefficient performance of the oxygen electrocatalysts that can catalyze oxygen reduction reaction (ORR) at the air electrodes seriously limit the development of fuel cells and znic-air batteries (ZABs).3 The oxygen reduction reaction is an indispensable cathodic reaction in these renewable energy devices,10-11 which is more challenging than anode fuel or metal oxidation reactions because it dominates in terms of power density and durability.12-15 Platinum (Pt) has been commonly used for ORR, unavoidably, it suffers from high cost, low natural abundance, suspicious stability, easy deactivation by methanol poisoning and crossover effect, which inevitably hinder the scalable implementation of fuel cells and ZABs.16-18 In this context, Pt alloys, non-noble metal-based catalysts and even metal-free carbonaceous materials have emerged as promising oxygen electrocatalysts to replace the expensive and rare noble-metal catalysts and meet the scalable requirements.7-20 Unfortunately, Pt alloys are still expensive, and non-noble metal based catalysts generally have complex manufacturing, low electrical conductivity, and deleterious environmental effects caused by catalyst residues. The most important thing is that none of these catalyst groups has reached the level of Pt based catalysts in terms of catalytic activity, durability and chemical/electrochemical stability. Therefore, economically feasible and innovative high-performance catalysts are constantly being explored to find the replacement for Pt catalyst.21-23 3 ACS Paragon Plus Environment


Carbon materials such as carbon nanotubes (CNTs) and graphene hold great potential as promising candidates as ORR electrocatalysts for energy conversion applications due to their fundamental properties of high specific surface area, controlled microstructures, excellent corrosion resistance, sufficient electronic conductivity and stability.24-28 However, carbon materials only serve as supporting materials rather than join more active electrocatalytic materials unless modified or doped.24 Recently, through engineering heteroatoms chemistry including N, S, P, B, Cl, I, Se (especially for N)9, 29 has been proved to be an effective way to tune the physicochemical properties and to improve the catalytic performance of the carbon materials. Compared with the undoped carbon, for example, the ORR performance is improved by destroying the electrical neutrality of the carbon materials, since these heteroatoms have strong electron affinity and relatively high positive charge density on adjacent carbon atoms, thus improving the conductivity of the support and enhancing the bond between the metal and the support.30-33 Thereinto, nitrogen has been considered to be the most common and effective doping heteroatom. In this regard, nitrogen source precursors including both macrocyclic compounds (thalocyanine, tetramethoxyphenyl porphyrin) and non-macrocyclic nitrogen compounds (monocyanamide, dicyandiamide, ethylenediamine, pyridine), and even ammonia gas have been extensively studied.34-40 Additionally, transition metals, especially for Fe, Co and Ni engineered M-N/C catalysts have attracted a lot of attention due to their reasonable activity and remarkable selectivity and durability, and their active sites are considered to be involved surface nitrogen coordinated with metal.41-43 When nitrogen and transition metals are combined and introduced into the carbon lattice, the improvement in ORR activity can be attributed to the M-Nx active site consisting of metal atoms coordinated to the surrounding nitrogen moiety, or nitrogen-doped graphitic carbon on the underlying metal/metal carbide.2, 44-45 Nevertheless, most 4 ACS Paragon Plus Environment

Page 4 of 34

Page 5 of 34 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


of these reported catalysts still suffer from high overpotential and low durability in application to rechargeable ZABs system. After all, bifunctional catalysts for both ORR and OER are highly necessary in rechargeable Zn–air battery applications. However, OER is traditionally carried out with metal oxides (such as RuO2 and MnO2) as catalysts.3-4 Although metal-based bifunctional catalysts has recently attracted considerable attention, the use of carbon materials as catalysts used for rechargeable ZABs has rarely been reported.46-47 Evenly, some catalysts have reduced competitiveness because they are expensive or cumbersome to prepare.

Coal tar pitch (CTP), as a significant by-product in the processing of coal tar with high carbon yield and thermoplasticity, wide sources and low prices, are attentively used for staple commodity including paving, building waterproofing, advanced asphalt paint, and others.48-51 However, it is highly desired to achieve high value-added and comprehensive utilization of CTP through deep processing. The incorporation of nitrogen into pitch has revealed to enhance the electrochemical performance in supercapacitors and lithium-ion batteries.1, 48-49, 52-54 This may give us a clue that through effective doping engineering of the chemical composition, the CTP could provide both-way rich active sites and improved electronic conductivity, which could result in enhanced charge transfer with the generation of O defects or vacancies. Surprisingly, to the best of our knowledge, the exploration of CTP as carbon materials used for the ORR electrocatalysts is rarely concerned,55 and no truly CTP and related nanomaterials as bifunctional ORR and OER catalysts used for rechargeable ZABs has been discussed to date.

In this work, we develop a unique facile coupling approach to firstly fabricate highperforming hierarchical porous carbons (Co/N-HPCs) derived from CTP, aqueous ammonia and cobalt, which are chosen as carbon sources, nitrogen sources and doped transition metals. 5 ACS Paragon Plus Environment


Through a simple ammonia-Co enhanced hydrothermal approach and post-treatment, the resulted Co/N-HPCs produce excellent activity and durability for both ORR and OER. Prototypes of the Zn-air battery with CTP derived Co/N-HPCs as cathodic electrode catalyst display a remarkable current density and an excellent long cycling operation, a low discharge-charge voltage gap and long cycle life, which shows promising potential application for rechargeable ZABs. Furthermore, it is worth noting that natural abundance and cheap prices of CTP makes it very promising as an ORR catalyst for large-scale production.

RESULT AND DISCUSSION Synthesis and characterization of Co/N-HPCs The strategy of two two-steps is adopted to accomplish the final Co/N-HPCs derived from raw material CTP. First, activated coal tar pitch (ACTP) is obtained by activating and calcining CTP (supporting information). Next, ammonia-Co co-engineering approach was conducted by a hydrothermal method and carbonization to prepare porous high specific surface area catalysts Co/N-HPCs that is applied to ZABs (Figure 1). The transmission electron microscopy (TEM) image (Figure 2a and Figure S1) and scanning electron microscopy (SEM) image (Figure 2b and Figure S2) show that the catalysts have a large number of hierarchical porous structure and huge specific surface area to expose the active sites, which are consistent with the BET results (Figure 3a and Figure S3b). Scanning unit electron microscopy-Energy Dispersive Spectroscopy (STEM-EDS) element mapping (Figure 2c and Figure S3a) and X-ray diffraction (XRD) (Figure 3b) of Co/N-HPCs further proves that cobalt and nitrogen have been successfully doped into and combined with the catalyst. Just as X-ray photoelectron spectroscopy (XPS) demonstrated (Figure 3c-f and Figure S3c), the carbonization temperature of 800 oC is more conducive to the occurrence of oxygen reduction caused by cobalt-nitrogen 6 ACS Paragon Plus Environment

Page 6 of 34

Page 7 of 34 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


active sites. The prior ammonolysis process and the later carbonization induced unprecedented Co- and N-atomic engineered ACTP in the nanoparticles and tunable pore structure network, which successfully completed conversion from raw material CTP to novel Co/N-HPCs. Considering that particle morphology and particle size strongly influence the performance of the catalyst, TEM was used to characterize the morphology of ACTP and Co/N-HPC150/800. Under low magnifications (Figure S1a and c), the sharp contrast shows that ACTP exhibits a lot of bright micropores due to the homogeneous graphite sheet stacking layer by layer. In contrast, Co/N-HPC150/800 is unevenly agglomerated and has a large number of large holes. It looks like a cracked and crumpled bark, which is closely related to the incorporation of metal particles into carbon. The images shown in Figure S1b and Figure 2a present the edges of the catalyst, and the high magnified TEM images further show that ACTP and Co/N-HPC150/800 exhibit a wormlike microporous/mesoporous structure of typical carbon materials. It is worth noting that we did not clearly observed Co nanoparticles in the porous carbon, which may be encapsulated by the agglomeration of coal tar pitch. For understanding the overall morphology and microstructure of the Co/N-HPCs and, the effect of temperature and acid leaching on the catalysts, SEM measurements were performed. ACTP, as an undoped catalyst, is cultivated together like micron-sized hard pebbles in lowmagnification SEM images. However, it can be observed that there is an irregular small circular particle with few surface pores to form a strong structure in high-magnification SEM image (Figure S2a-c). To investigate the effects of temperature on the modified catalyst, we compared Co/N-HPC150/700, Co/N-HPC150/800 and Co/N-HPC150/900 (Figure S2d-o). The SEM images of Co/N-HPC150/700 at low magnification shows relatively uniform small particles stacked together to form a surface with a lot of obvious nanoscale macropores. The magnified SEM image shows 7 ACS Paragon Plus Environment


that the crushed biscuits with a size of about 100 nm to 2 μm on the surface with bumps and cracks, which are stacked together to produce mesoporous and macroporous structures of different sizes. Larger magnifications show that smaller particles are stacked together with a large number of mesopores (Figure S2d-f). For Co/N-HPC150/800 with the best electrochemical performance as will be discussed below, its surface has a large number of large pores and mesoporous coarse wrinkles. The SEM images with larger magnifications appear to be gradually extending the stacked sheet structure, forming a large number of macropores and mesopores. The unique layered structure favors a larger specific surface area to provide a wider area of active sites, and improve the exchange and transport of gases and electrons on the catalyst surface (Figure 2b and Figure S2g-i). For Co/N-HPC150/900 (Figure S2j-l), however, it no longer has the extended thin layer structure of Co/N-HPC150/800. The pore collapse occurs for calcination at high temperature of 900 oC, and the surface area exposed to the outside decreases accordingly due to the decreased number of pores. During the heat treatment (600-1000 °C), suitable high temperature promotes modification of the catalyst structure, increasing the concentration of available ORR active sites and improving catalyst stability, which is considered to be a significant breakthrough for the ORR performance.44-45 As for acid leaching, Co/N-HPC150/800LH has small particles like antennae anchored on the surface, which is quite different from Co/N-HPC150/800 that has a recessed cavity structure (Figure S2m-o). This is likely to be a special structure that selectively removes acid-soluble substances due to acid leaching. STEM-EDS element mapping of Co/N-HPC150/800 were performed to illustrate a homogeneous distribution of C, O, N and Co atoms (Figure 2c). As indicated by Figure S3a, C, O and N heteroatoms on Co/N-HPC150/800-LH are also obviously detected and dispersed uniformly in the whole matrix. The elemental mappings verify that heteroatoms are effectively 8 ACS Paragon Plus Environment

Page 8 of 34

Page 9 of 34 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


incorporated and homogeneously distributed throughout Co/N-HPC150/800 and Co/N-HPC150/800LH at the nanoscale. However, the content of N and Co of Co/N-HPC150/800 is obviously more than that of Co/N-HPC150/800-LH. The porosity of the ACTP and Co/N-HPC150/800 was studied by a nitrogen adsorption technique, whereby the specific surface area and the pore diameter of the catalyst can be calculated (Figure S3b and Figure 3a). According to the International Union of Pure and Applied Chemistry (IUPAC) nomenclature, the shape of the N2 sorption-desorption isotherms of both catalysts belongs to the type IV isotherm, which is usually associated with capillary condensation occurring in the mesopores.56 In the middle pressure and high pressure areas, it can be classified as H3 hysteresis loop characteristics (P/P0 = 0.4-1), which is a sign of plate-like particle aggregation, indicating that a narrow pore size distribution is formed. Except for the slit parallel plate mesoporous structures, the capillary condensation occurs at P/P0 = 0.4-0.5. The curves for the two catalysts show a sharply increasing adsorption at low relative pressures, indicating the presence of a distinct microporous structure (< 2 nm). The dramatic increase in adsorption at high relative pressure regions indicates the presence of a large proportion of macroporous structures (50-100 nm). This phenomenon is more pronounced with the catalyst Co/N-HPC150/800, which may originate from pyrolysis and gas evolution during high temperature carbonization. In contrast, the slope of the adsorption branch of ACTP is significantly lower compared to Co/N-HPC150/800 (Figure S3b), suggesting that Co/N-HPC150/800 has a more uniform pore structure than ACTP. The Brunauere-Emmette-Teller (BET) specific surface area of the catalyst before and after the modification was measured to be 2516.31 m2 g-1 and 2076.58 m2 g-1, respectively. The BET result of Co/N-HPC150/800 is smaller than that of based on ACTP. This may be due to the higher degree of graphitization of the catalyst that can result from the heat 9 ACS Paragon Plus Environment


treatment and the fact that the catalyst nanosheets may agglomerate with each other, causing the specific surface area of the sample to be decreased. Specifically, the addition of cobalt may increase the formation of closed-end carbon structures, which can lead to pore plugging and thus a decrease in BET surface area. In connection with the analysis by SEM, doping of cobalt and nitrogen tailored structure of ACTP becoming a three-dimensional structure of the stack. The pore size distribution (Figure S3b and Figure 3a) showed dense peaks in the range of 0-60 nm, indicating that the catalysts have the hierarchical porous architectonics. According to calculations using the Barrett-Joyer-Halenda (BJH) method, both ACTP and Co/N-HPC150/800 have a large number of micropores and mesopores, but for Co/N-HPC150/800, more micropores and ultramicropores appear. The number of mesopores correspondingly decreases, instead, the number of macropores increases at this stage. The hierarchically micro-, meso- and macroporous carbon featured with a decent specific surface area and abundant dopant species have a great influence on ORR performance.57 As demonstrated in the next section, Co/N-HPC150/800, having a smaller BET value than ACTP, shows a better electrocatalytic performance, suggesting that a catalyst with a large surface area does not necessarily owning a large surface availability, instead, the effective surface utilization depends largely on the porous structure of the material. Because only the reactants pass through the easily accessible surface of the porous structure, the active site on the catalyst’ surface can be activated. The hierarchical porous structure not only provides an excellent structural stability and a convenient path for the active site but also enhances the properties of transporting ORR-related substances. Actually, the active sites are mainly formed in micropores and mesopores, while macropores serve as a reservoir of reactive molecules that enable rapid mass transfer to take advantage of the high surface area and large pores of


Page 10 of 34

Page 11 of 34 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


microscopic and mesoporous structures, thus shortening the diffusion path into and out of the micropores and the mesopores.12 Figure 3b shows the XRD pattern of Co/N-HPCs doping different amounts of cobalt. The three directivity peaks located at 2θ = 44.22°, 51.52°, 75.85° exhibit strong intensity, which matched well with the XRD pattern of Co (111), (200), and (220) (PDF#15-0806). Further verifying the effect of temperature on the formation of active site on the surface of catalyst, the XPS spectra of Co/N-HPC150/700, Co/NHPC150/800 and Co/N-HPC150/900 were measured, respectively. The emission of four XPS peaks from C 1s, O 1s, N 1s, and Co 2p core levels was observed (Figure S3c). From Figure 3c, the C 1s of Co/NHPC150/800 is at a peak of 284.6 ± 0.1 eV, which is attributed to the C sp2 structure that can be assigned to the graphite domain. In addition to the C-C (284.6 eV), the high-resolution C 1s spectrum of the Co/N-HPC150/800 further confirmed the existence of C-N (285.2 eV) and O-rich groups such as C−O (286.6 eV), C=O (288.3 eV) bonds, which is close to the increased oxygen content (Table S1). From the O1s spectral region (Figure 3d), the band of 531-534 eV is related to the carboxyl group on the carbon substrate O-C (531.5eV), O=C (532.6eV), O-C=O (533.8eV). However, no other peak of metallic oxide was seen in these XPS spectra, which is consistent with the corresponding result of XRD. Two peaks at 795.8 and 780.2 eV of Co/N-HPC150/800 can be clearly observed from Figure 3e, assignable to Co 2p3/2 land Co 2p1/2 for Co, respectively. In addition, we can distinguish three peaks from the decomposition of Co 2p3/2 XPS spectrum.The peak at 781.8 eV corresponds to the Co-Nx structure of cobalt associated with N, and other two peaks at 780.4 eV and 786.2 eV are connected with cobalt oxides and Co2+. Figure 3f shows three peaks at 398.6, 400.1 and 401.1eV from high-resolution N 1s spectrum, which are assigned to pyridinic N (32.7%), pyrrolic N (28.8%), and graphitic N (38.5%), respectively. Surprisingly, although the 11 ACS Paragon Plus Environment


signal is less clear due to the relatively low N content (1.64 at %) (Table S1), Co/N-HPC150/800 with small N content exhibits excellent ORR activity relative to other catalysts (Table S2). According to the literature, the ORR performance is related to the graphitic N, which enhanced the limiting current density of the catalyst, and the pyridinic N can increase the oxygen reduction onset potential of the catalyst.43 Both pyridinic N and graphitic N are believed to be coordinated with Co to form Co-Nx moieties, which are the key sites responsible for forming the ORR active site and facilitating the reductive oxygen adsorption.58. Electrochemical activity of Co/N-HPCs To assess the catalytic activity of the catalysts for ORR, CV was performed at a scan rate of 50 mV s-1 in a 0.1 M KOH solution saturated with N2 or O2. Taking Co/N-HPC150/800 as an example, no any appreciable voltammogram peak was observed in the ORR potential range in a N2-saturated solution, and the CV exhibits only a characteristic of non-characteristic quasirectangular trace. However, when oxygen was introduced into the solution, a distinct ORR peak with a peak potential (Ep) of 0.846 V (vs. RHE) and peak current density (Ip) of 2.48 mA cm-2 were clearly observed, manifesting that the catalyst had good ORR performance (Figure 4a). In order to further optimize the catalyst synthesis conditions and explore the most outstanding catalysts, LSV was carried out by RRDE technology. Figure S4a-c show the typical ORR polarization curves of Co/N-HPCs at different hydrothermal temperatures, different calcination temperatures and doping with different amounts of metallic cobalt, respectively, where the RRDE rotation rate was 1600 revolutions per minute. Figure S4a shows the calcination temperature of 800 °C but changed the hydrothermal temperature at 100, 150 and 200 °C for the catalyst, respectively. The reason for this is based on the consideration that the 12 ACS Paragon Plus Environment

Page 12 of 34

Page 13 of 34 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


reaction is incomplete due to the low hydrothermal temperature, whereas too high hydrothermal temperature may cause other side reactions, resulting in deterioration of the catalyst performance. Additionally, since the pyrolysis temperature of non-precious metal catalysts plays a very important role in the formation of oxygen reduction active sites, we have also used different pyrolysis temperature packages of 700, 800, and 900 oC. As shown in Figure S4b, when the pyrolysis temperature was 800 oC, the catalytic activity of ORR is the highest. The pyrolysis at high temperature can lead to the decomposition of active sites, but the low temperature is insufficient to form a high density of active sites, which is related to the special structure formed by different temperatures. To conclude from Figure 4b, it is apparent that Co/N-HPC150/800 exhibited excellent activity than others, which shows the most positive half-wave potentials and the highest current densities of the catalysts at 0.7 V. Further in Figure S4c, 0, 1%, 2%, 3%, and 4% of metallic cobalt were added at the optimum hydrothermal temperature and calcination temperature, respectively. The catalysts’ performance indicates a ‘volcano’ tendency from Figure 4c, where the Co content of 2% for the best catalyst is similar to the cobalt amount of 2.17% as detected by XPS (Table S1). Many theoretical studies have been employed to investigate the importance of the content of metal for the ORR activity.59-60 For further analyzing the ORR performance of the catalyst, Co/N-HPC150/800, and commercial 20% Pt/C catalysts were tested using RRDE, as shown in Figure 4d. At a relatively low loading of 200 μg cm-2, Co/N-HPC150/800 exhibits an excellent ORR performance with Eonset of 0.88 V and E1/2 of 0.82 V, which is strongly close to the E1/2 of the Pt/C catalyst with equivalent loading (0.835 V). The excellent ORR performance of Co/N-HPC150/800 may be due to the high specific surface area, more reasonable micro-, meso- and macroporous structures and active sites. Considering the economic and technical feasibility, the loading of Co/N-HPC150/800 13 ACS Paragon Plus Environment


was further increased to 600 μg cm-2. Very interestingly, the E1/2 increased to 0.85 V, which is 15 mV more positive than the commercial 20% Pt/C catalyst. Similar results were also evinced by the Tafel slope of kinetic current (Figure S4d). Co/N-HPC150/800, conversely, gives a remarkably smaller Tafel slope 59 mV dec-1 (20% Pt/C: 124 mV dec-1), denoting a smallest mass transport resistance and a superior activity. In contrast, the performance of ACTP is far less than that of Co/N-HPC150/800 (Figure S4e), demonstrating further that the calcination, nitrogen and cobalt incorporation has a strong coupling effect on improving the ORR performance. For further clarifying whether the presence of metal Co contributes to the formation of active sites and even construct the active centers, we compared also Co/N-HPC150/800-LH at a loading of 200 μg cm-2. The obtained Eonset and the corresponding E1/2 were 0.83 V and 0.78 V (Figure S4e). The ORR performance of Co/N-HPC150/800-LH is significantly worse than that of Co/N-HPC150/800. In terms of STEM-EDS element mapping (Figure 2c and Figure S3a), both the nitrogen and cobalt elements in the catalyst after acid leaching are reduced, but the transition metals, particularly Fe and Co are considered to be necessary for catalyzing the graphitization of the N-C precursor to form highly graphitized carbon.36 According to recently reported literature, even a very small amount of metallic impurities in carbon materials can have a strong influence on ORR.57 Therefore, we believe that acid leaching leads to reduce the cobalt content in the catalyst and attenuate the properties. In fact, acid leaching also leads to a reduction of nitrogen. It is likely that the acid leaching causes the dissolution of the metallic cobalt to break the Co-Nx bond, resulting in a decrease in the amount of the nitrogen element that constitutes the active site. The reduction of metallic cobalt may also lead to a decrease in the active nitrogen-carbon functional sites formed. In order to accurately quantify the oxygen transport electron transport pathway, the catalyst was subjected to RRDE testing. As expected, the Co/N-HPC150/800 is highly selective for 14 ACS Paragon Plus Environment

Page 14 of 34

Page 15 of 34 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


the four-electron ORR as shown in Figure 4e. The hydrogen peroxide production (H2O2%) of Co/N-HPC150/800 (loading: 200 μg cm-2) is approximately 15 %, and the corresponding number of electron transfer is closer to 3.75. However, the H2O2% of Co/N-HPC150/800 (loading: 600 μg cm2

) sharply deceased to less than 5% across the entire spot, which is close to H2O2% yield of the

commercial Pt/C catalyst. At this stage, the corresponding number of electron transfer is closer to 3.95, which is even slightly higher than the commercial Pt/C one (3.92), indicating that oxygen is directly reduced to water during the reaction. As shown in Figure 4f, the onset potentials of OER were 1.5, 1.61V, 1.42 for Co/N-HPC150/800 (loading: 200 μg cm-2), 20% Pt/C (loading: 200 μg cm-2) and Co/N-HPC150/800 (loading: 600 μg cm-2), and the OER current densities at 2 V and Ej=10 (potential at 10.0 mA cm−2) for them were 30, 15.5, 40 and 1.7, 1.9, 1.73, respectively. Furthermore, the variance of OER and ORR metrics (ΔE=Ej=10−E1/2) were used to evaluate the bifunctional catalytic activity of Co/N-HPC150/800. The smaller the ΔE, the more superior the bifunctional catalytic activity. Co/N-HPC150/800 exhibits a small ΔE value of 0.85, which is close to the advanced non-precious metal-based bifunctional catalysts and, superior to carbon nanomaterials bifunctional catalysts reported before (Table S3). Stability is another important indicator to evaluate the actual application of the catalyst. We evaluated the durability of Co/N-HPC150/800 (load: 200 μg cm-2) and commercial 20% Pt/C catalysts using the US Department of Energy's accelerated durability testing program. From Figure S4f, after 5000 continuous cycles in saturated oxygen, the E1/2 of Co/N-HPC150/800 (load: 200 μg cm-2) only shifted negatively by 15 mV, which is advantageous compared to most nonprecious metal catalysts and Pt/C catalyst. It is noteworthy that Pt/C negative shift of 70 mV can be clearly observed after 5000 continuous cycles under the same experimental conditions (Figure S4f inset), indicating that the Co/N-HPC150/800 catalyst is very stable in alkaline solution. 15 ACS Paragon Plus Environment


Page 16 of 34

Primary and rechargeable zinc-air fabricated by Co/N-HPCs In order to achieve a more realistic battery operating environment, a homemade ZAB was used to verify the actual catalyst activity and stability. The great potential of the catalyst Co/NHPC150/800 as a cathode for the ORR of a ZAB can be further supported by the test results of a home-made cell. Figure 5a shows the polarization curves and corresponding power density curves of Co/N-HPC150/800 at different loadings, which is to optimize the zinc air fuel cell and reduce the cost of the cathode load. Intriguingly, the battery can provide an open circuit voltage in the range of about 1.35-1.5 V, close to the theoretical voltage (1.65V). Both current density and peak power density are significantly improved with cathode catalyst loadings ranging from 1 to 4 mg cm-2. Specifically, for the catalyst loading of 4 mg cm-2, the peak power density reaches 425 mW cm-2. At a voltage of 1.0 V, the current density of Co/N-HPC150/800 even reaches 291 mA cm-2, which outperforms the most non-precious catalyst assembled batteries reported before (Table S4). Co/N-HPC150/800 exhibits a peak power density reduction of 353 mW cm-2 for a loading of 5 mg cm-2, this is reasonable since an excessively thick catalyst layer leads to a mass transfer limitation of the reaction zone. Importantly, even at a low loading of 1.0 mg cm -2, Co/NHPC150/800 can still achieve a perfect peak power density of 185 mW cm-2, whereas only 30~150 mW cm-2 for Pt/C catalyst can be obtained under the same measurement conditions.3,

4, 14

Furthermore, to elucidate the stability of Co/N-HPC150/800 in ZAB, we performed galvanostatic discharge testing at 10 mA cm-2 for 250 hours. As shown in Figure 5b, the voltage remains nearly unchanged until the Zn anode was completely consumed. Further by changing the circulating current with each cycle current increases from 5 to 100 mA cm-2, Co/N-HPC150/800 still shows a long life time discharge operation of 28 hours (Figure 5b inset), indicating the superior discharge stability of Co/N-HPC150/800 in liquid ZAB. To investigate the charge16 ACS Paragon Plus Environment

Page 17 of 34 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 cycling performance using Co/N-HPC150/800 (4 mg cm-2) as air electrode, galvanostatic charge and discharge testing was performed at current density of 1 and 5 mA cm-2 with each cycle being 10 min, respectively. As shown in Figure 5c, the Co/N-HPC150/800 cathode at 1 mA cm-2 exhibited charge and discharge potentials of 2.0 V and 1 V, and showed its excellent rechargeability as evidenced by 2100 stable cycles with pimping degradation for 350 h. Meanwhile, the discharge-charge cycling tests are also conducted to test the voltage gap and the stabilization time at 5 mA cm-2 (Figure 5d). The voltage gap is 1.36 V and it can continue to work about 320 h without visible voltage losses. These results highlight strongly comparable catalytic activity and stability of Co/N-HPC150/800 to the rechargeable liquid battery, and promising potential for application of coal tar pitch in energy storage and conversion systems. CONCLUSIONS

In summary, derived from coal tar pitch, we for the first time developed a simple strategy to fabricate novel nanostructured high-performance ORR electrocatalyst, Co/N-HPCs containing discrete Co-Nx-C active sites. Specifically, with very small amount of aqueous ammonia for the synthesis of Co-oxide precursor, we observed nitrogen-doping in the synthesized Co/N-HPC. This is quite different from other doping strategies reported in literature, whereas realizing Ndoping are particularly treated by introducing N-containing complex.34-40 Through a simple hydrothermal method and calcination, we explored the influence of temperature and metal content on the activity and stability of the catalyst. For the synthesized Co/N-HPC150/800 catalyst, it possesses excellent Eonset and E1/2, outperforming most reported oxygen electrocatalysts, and commercially available 20% Pt/C. All the above are attributed to ultra-high specific surface area and unique hierarchical pore structure of Co/N-HPC150/800 that can provide a rich active site on the catalyst surface and promote electrolyte/reactant diffusion during oxygen reduction. Notably, 17 ACS Paragon Plus Environment


when applied in liquid ZABs, excellent discharging peak power density, catalytic current density, low discharge-charge voltage gap and long cycle life have been achieved, demonstrating the promising electrocatalytic properties and recharge ability of the as-prepared Co/N-HPC. This facile synthetic strategy can easily realize large-scale production, opening a new way for highvalue added coal tar pitch and giving a wide adaptability to commercial applications of both primary and rechargeable ZABs.

ASSOCIATED CONTENT

Supporting Information: Experimental Section, Table S1–S4 and Figure S1–S4. AUTHOR INFORMATION

Corresponding Author Tel: +86-21-67792379. Fax: +86-21-67792159. E-mail: [email protected] (JLQ) ACKNOWLEDGMENT This work is financially supported by the National Natural Science Foundation of China (U1510120, U1510204, 91645110, 51172251), the Graduate degree thesis Innovation Foundation of Donghua University (EG2018022), and the Shanxi Province Coal-based Key Scientific and Technological Project (No. MD2014-09).


Page 18 of 34

Page 19 of 34 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


Figure 1. Proposed mechanism for the synthesis of Co/N-HPCs derived from ACTP and its fabrication for ZAB.


ACS Sustainable Chemistry & Engineering 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

(b)

(a)

(c)

2 μm

5 nm

C

Page 20 of 34

100 nm

O

Co

Figure 2. (a) TEM images (b) SEM images and (c) STEM-EDS element mapping of Co/N-HPC150/800.


N

400 Adsorption Desorption

300

0.04

Intensity (a.u.)

3

V / cm /g

500

0.0

0.2

0.4 0.6 P / P0

0.8

1.0

0.02

0.00 0.1

1

10

100

Pore Diameter / nm

294

292

(d) 4% Co 3% Co 2% Co 1% Co

290

288

286

Binding energy (eV)

284

Co 2P3/2

Co2+ Co-Nx CoO

812

282

Co 2P1/2

805

798

791

784

777

Binding energy (eV)

(f)

O-C O=C O-C=O

Intensity (a.u.)

220

200

111

(b)

(e)

C-C C-N C-O C=O

600

0.06

dV / dlog(D)

(c)

700

Intensity (a.u.)

(a)

Intensity(a.u.)

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


pyridinic N pyrrolic N graphitic N

Intensity (a.u.)

Page 21 of 34

0% Co Co (PDF#15-0806)

30

45

60

2 deg.

75

90

543

540

537

534

531

Binding energy (eV)

528

402

401

400

399

398

397

Binding energy (eV)

Figure 3. (a) Pore size distribution and N2 adsorption-desorption isotherms (inset) (b) XRD patterns of Co/N-HPC150/800. XPS spectra of Co/N-HPC150/800 (c) C 1s, (d) O 1s, (e) Co 2p and (f) N 1s.


0

-1 N2 saturated O2 saturated

-2

-1

Co/N-HPC150/800 (200 μ g cm )

-2

20% Pt/C (200 μ g cm )

1

0.75 00 0/7 15

00 0/9 15

00 0/8 10

00 0/8 15

00 0/8 20

80

-2

-2

Co/N-HPC150/800 (600 μ g cm )

Co/N-HPC150/800 (200 μ g cm-2)

60

-5

3

-2

20% Pt/C (200 μ g cm )

Co/N-HPC150/800 (600 μ g cm-2)

40

-4

0

4

H2O2 %

-3

2

0.78

(e) 100 -2

3

0.81

1.2

0

4

2 1

20

-6 0.2

0.4 0.6 0.8 Potential / V (vs. RHE)

1.0

0 0.0

0.2 0.4 0.6 Potential / V (vs.RHE)

0 0.8

(c)

0.70

V (v s. R HE)

1.0 0.8 0.6

4% Co 3% ba lt c 2 % on 1% ten t 0%

(f)

Electron transfer number

(d)

Current density / (mA cm-2)

0.6 0.8 1.0 Potential / V (vs.RHE)

0.70 V (vs. RHE)


(b) 0.84

1

Half wave potential / V

(a)

Page 22 of 34


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



40 35 30

-2

m

)

c / V (m A al nti ty / e t i po ens ve d wa rent f l Ha Cur 1/4 -2

Co/N-HPC150/800 (200 μ g cm ) -2

20% Pt/C (200 μ g cm ) -2

Co/N-HPC150/800 (600 μ g cm )

25 20 15 10 5 0 1.0

1.2 1.4 1.6 1.8 2.0 Potential / V (vs. RHE)

2.2

Figure 4. (a) CV curves of Co/N-HPC150/800 in N2/O2-saturated. Half-wave potential and current density at 0.7 V of (b) Co/NHPC150/800 (200 μg cm-2), 20% Pt/C (200 μg cm-2) and Co/N-HPC150/800 (600 μg cm-2) (c) Co/N-HPCs containing different cobalt content. (d) ORR polarization curves (e) Hydrogen peroxide yield and electron transfer number (f) OER polarization curves of Co/NHPC150/800 (200 μg cm-2), 20% Pt/C (200 μg cm-2) and Co/N-HPC150/800 (600 μg cm-2) (Media: O2-saturated 0.1 M KOH, rotation speed: 1600 rpm, scan rate: 50 mV s-1).


-2

2.0 mg cm

400

Voltage / mV

3.0 mg cm-2 4.0 mg cm-2

1200

-2

5.0 mg cm

300

900 200 600 100

300 0

0

200

400

600

800

1000

1200

(b)

2.5

(d)

1.5

1.0 1 mA, 5 min charge / discharge

0

100

200

300 349

349.5

0 .9

d is c h a rg e w ith c u rre n t -2 fro m 5 to 1 0 0 m A c m

0 .6

0

-2

1 .2

5

0.0

2.0

0.5

0.6

1 .5

0

0

4 mg cm

350

50

3.0 2.5

Co/N-HPC150/800

10

15 20 T im e / h

100

150

Time / h

25

30

200

250

-2

4 mg cm

2.0 1.5 1.0 0.5

5 mA, 5 min charge / discharge

0

Time / h

10 mA cm-2

1 .8

0.9

0.3

Potential / V (vs.RHE)

Co/N-HPC150/800

-2

Co/N-HPC150/800 4 mg cm

1.2

Current density / mA cm-2

(c)

1.5

V o lta g e / V

-2

1.0 mg cm

Voltage / V

(a)1500

Potential / V (vs.RHE)

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


Power density / mW cm-2

Page 23 of 34

64 128 192 256 319 Time / h

319.5

320

Figure 5. (a) Polarization curve and corresponding power density plots of the primary Zn-air battery with different loadings of Co/NHPC150/800. (b) Long-time discharge curve at 10 mA cm-2 and circulating current discharge curve (inset) of the Zn-air battery using Co/N-HPC150/800. Galvanostatic discharge and charge cycling stability of Co/N-HPC150/800 at current density of (c) 1 mA cm-2 and (d) 5 mA cm-2 with each cycle being 10 min. 23 ACS Paragon Plus Environment


Page 24 of 34

REFERENCES (1) Zhang, D.; Zhao, J.; Feng, C.; Zhao, R.; Sun, Y.; Guan, T.; Han, B.; Tang, N.; Wang, J.; Li, K.; Qiao, J.; Zhang, J. Scalable Synthesis of Hierarchical Macropore-rich Mctivated Carbon Microspheres Assembled by Carbon Nanoparticles for High Rate Performance Supercapacitors. J. Power Sources 2017, 342, 363-370, DOI 10.1016/j.jpowsour.2016.12.072. (2) Ratso, S.; Kruusenberg, I.; Käärik, M.; Kook, M.; Puust, L.; Saar, R.; Leis, J.; Tammeveski, K. Highly Efficient Transition Metal and Nitrogen Co-doped Carbide-derived Carbon Electrocatalysts for Anion Exchange Membrane Fuel Cells. J. Power Sources 2018, 375, 233243, DOI 10.1016/j.jpowsour.2017.08.046. (3) Li, X.; Xu, N.; Li, H.; Wang, M.; Zhang, L.; Qiao, J. 3D Hollow Sphere Co3O4/MnO2-CNTs: Its High-Performance Bi-functional Cathode Catalysis and Application in Rechargeable Zinc-Air Battery. Green Energy Environ. 2017, 2 (3), 316-328, DOI 10.1016/j.gee.2017.02.004. (4) Xu, N.; Qiao, J.; Zhang, X.; Ma, C.; Jian, S.; Liu, Y.; Pei, P. Morphology Controlled La2O3 /Co3O4/MnO2–CNTs Hybrid Nanocomposites with Durable Bi-functional Air Electrode in HighPerformance

Zinc–Air

Energy

Storage.

Appl.

Energy

2016,

175,

495-504,

DOI

10.1016/j.apenergy.2016.04.036. (5) Tang, Q.; Wang, L.; Wu, M.; Xu, N.; Jiang, L.; Qiao, J. Achieving High-Powered Zn/Air Fuel Cell through N and S Co-Doped Hierarchically Porous Carbons with Tunable Active-Sites as

Oxygen

Electrocatalysts.

J.

Power

Sources

2017,

365,

348-353,

DOI

10.1016/j.jpowsour.2017.08.102. (6) Wang, Y. J.; Fang, B. Z.; Zhang, D.; Li, A. J.; Wilkinson, D. P.; Ignaszak, A.; Zhang, L.; Zhang, J.J. A Review of Carbon-Composited Materials as Air-Electrode Bifunctional 24 ACS Paragon Plus Environment

Page 25 of 34 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


Electrocatalysts for Metal–Air Batteries. Electrochemical Energy Reviews 2018, 1, 1-34, DOI 10.1007/s41918-018-0002-3. (7) Jung, W. S.; Popov, B. N. Improved Durability of Pt Catalyst Supported on N-Doped Mesoporous Graphitized Carbon for Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells. Carbon 2017, 122, 746-755, DOI 10.1016/j.carbon.2017.07.028. (8) Zhang, S.; Cai, Y.; He, H.; Zhang, Y.; Liu, R.; Cao, H.; Wang, M.; Liu, J.; Zhang, G.; Li, Y.; Liu, H.; Li, B. Heteroatom Doped Graphdiyne as Efficient Metal-Free Electrocatalyst for Oxygen Reduction eaction in Alkaline Medium. J. Mater. Chem. A 2016, 4 (13), 4738-4744, DOI 10.1039/c5ta10579j. (9) Hao, L.; Zhang, S.; Liu, R.; Ning, J.; Zhang, G.; Zhi, L. Bottom-Up Construction of TriazineBased Frameworks as Metal-Free Electrocatalysts for Oxygen Reduction Reaction. Adv. Mater. 2015, 27 (20), 3190-3195, DOI 10.1002/adma.201500863. (10) Yin, J.; Qiu, Y.; Yu, J. Onion-Like Graphitic Nanoshell Structured Fe–N/C Nanofibers Derived from Electrospinning for Oxygen Reduction Reaction in Acid Media. Electrochem. Commun. 2013, 30, 1-4, DOI 10.1016/j.elecom.2013.01.022. (11) Qiao, J.; Xu, L.; Ding, L.; Zhang, L.; Baker, R.; Dai, X.; Zhang, J. Using pyridine as nitrogen-rich precursor to synthesize Co-N-S/C non-noble metal electrocatalysts for oxygen reduction reaction. Appl. Catal., B 2012, 125, 197-205, DOI 10.1016/j.apcatb.2012.05.050. (12) Liu, Y. L.; Shi, C. X.; Xu, X. Y.; Sun, P.-C.; Chen, T.-H. Nitrogen-Doped Hierarchically Porous Carbon Spheres as Efficient Metal-Free Electrocatalysts for An Oxygen Reduction Reaction. J. Power Sources 2015, 283, 389-396, DOI 10.1016/j.jpowsour.2015.02.151. 25 ACS Paragon Plus Environment


Page 26 of 34

(13) Perazzolo, V.; Durante, C.; Pilot, R.; Paduano, A.; Zheng, J.; Rizzi, G. A.; Martucci, A.; Granozzi, G.; Gennaro, A. Nitrogen and Sulfur Doped Mesoporous Carbon as Metal-Free Electrocatalysts for The in Situ Production of Hydrogen Peroxide. Carbon 2015, 95, 949-963, DOI 10.1016/j.carbon.2015.09.002. (14) Wu, M.; Tang, Q.; Dong, F.; Wang, Y.; Li, D.; Guo, Q.; Liu, Y.; Qiao, J. The Design of Fe, N-doped Hierarchically Porous Carbons as Highly Active and Durable Electrocatalysts for A ZnAir Battery. Phys. Chem. Chem. Phys. 2016, 18 (28), 18665-18669, DOI 10.1039/c6cp02785g. (15) Xiao, M.; Zhu, J.; Feng, L.; Liu, C.; Xing, W. Meso/Macroporous Nitrogen-Doped Carbon Architectures with Rron Carbide Encapsulated in Graphitic Layers as An Efficient and Robust Catalyst for The Oxygen Reduction Reaction in both Acidic and Alkaline Solutions. Adv. Mater. 2015, 27 (15), 2521-2527, DOI 10.1002/adma.201500262. (16) Cui, Z.; Wang, S.; Zhang, Y.; Cao, M. A Simple and Green Pathway toward Nitrogen and Sulfur Dual Doped Hierarchically Porous Carbons from Ionic Liquids for Oxygen Reduction. J. Power Sources 2014, 259, 138-144, DOI 10.1016/j.jpowsour.2014.02.084. (17) Geng, D.; Liu, H.; Chen, Y.; Li, R.; Sun, X.; Ye, S.; Knights, S. Non-Noble Metal Oxygen Reduction Electrocatalysts Based on Carbon Nanotubes with Controlled Nitrogen Contents. J. Power Sources 2011, 196 (4), 1795-1801, DOI 10.1016/j.jpowsour.2010.09.084. (18) Karim, N. A.; Kamarudin, S. K. An Overview on Non-Platinum Cathode Catalysts for Direct

Methanol

Fuel

Cell.

Appl.

Energy

2013,

10.1016/j.apenergy.2012.09.031.


103,

212-220,

DOI

Page 27 of 34 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


(19) Zhu, Y. P.; Liu, Y.; Liu, Y. P.; Ren, T.-Z.; Du, G.-H.; Chen, T.; Yuan, Z.-Y. HeteroatomDoped Hierarchical Porous Carbons as High-Performance Metal-Free Oxygen Reduction Electrocatalysts. J. Mater. Chem. A 2015, 3 (22), 11725-11729, DOI 10.1039/c5ta01611h. (20) Chung, M. W.; Choi, C. H. Carbon Nanofibers as Parent Materials for A Graphene-Based Fe-N-C Catalyst for The Oxygen Reduction Reaction. Catal. Today 2017, 295, 125-131, DOI 10.1016/j.cattod.2017.05.020. (21) Morozan, A.; Jousselme, B.; Palacin, S. Low-Platinum and Platinum-Free Catalysts for The Oxygen Reduction Reaction at Fuel Cell Cathodes. Energy Environ. Sci. 2011, 4 (4), 1238-1254, DOI 10.1039/c0ee00601g. (22) Zhang, L.; Zhang, J.; Wilkinson, D. P.; Wang, H. Progress in Preparation of Non-Noble Electrocatalysts for PEM Fuel Cell Reactions. J. Power Sources 2006, 156 (2), 171-182, DOI 10.1016/j.jpowsour.2005.05.069. (23) Shao, M.; Chang, Q.; Dodelet, J. P.; Chenitz, R. Recent Advances in Electrocatalysts for Oxygen

Reduction

Reaction.

Chem.

Rev.

2016,

116

(6),

3594-3657,

DOI

10.1021/acs.chemrev.5b00462. (24) Byers, J. C.; Guell, A. G.; Unwin, P. R. Nanoscale Electrocatalysis: Visualizing Oxygen Reduction at Pristine, Kinked, and Oxidized Sites on Individual Carbon Nanotubes. J. Am. Chem. Soc. 2014, 136 (32), 11252-11255, DOI 10.1021/ja505708y. (25) Monteverde Videla, A. H. A.; Ban, S.; Specchia, S.; Zhang, L.; Zhang, J. Non-noble Fe–NX Electrocatalysts Supported on The Reduced Graphene Oxide for Oxygen Reduction Reaction. Carbon 2014, 76, 386-400, DOI 10.1016/j.carbon.2014.04.092. 27 ACS Paragon Plus Environment


(26) Liu, R.; Liu, H.; Li, Y.; Yi, Y.; Shang, X.; Zhang, S.; Yu, X.; Zhang, S.; Cao, H.; Zhang, G. Nitrogen-Doped Graphdiyne as A Metal-Free Catalyst for High-Performance Oxygen Reduction Reactions. Nanoscale 2014, 6 (19), 11336-11343, DOI 10.1039/c4nr03185g. (27) Zhang, D.; Hao, Y.; Zheng, L.; Ma, Y.; Feng, H.; Luo, H. Nitrogen and Sulfur Co-Doped Ordered Mesoporous Carbon with Enhanced Electrochemical Capacitance Performance. J. Mater. Chem. A 2013, 1 (26), 7584-7591, DOI 10.1039/c3ta11208j. (28) Yang, W.; Yue, X.; Liu, X.; Zhai, J.; Jia, J. IL-Derived N, S Co-Doped Ordered Mesoporous Carbon for High-Performance Oxygen Reduction. Nanoscale 2015, 7 (28), 1195611961, DOI 10.1039/c5nr02497h. (29) Negro, E.; Videla, A. H. A. M.; Baglio, V.; Aricò, A. S.; Specchia, S.; Koper, G. J. M. Fe– N Supported on Graphitic Carbon Nano-Networks Grown from Cobalt as Oxygen Reduction Catalysts for Low-Temperature Fuel Cells. Appl. Catal., B 2015, 166-167, 75-83, DOI 10.1016/j.apcatb.2014.10.074. (30) Han, C.; Bo, X.; Zhang, Y.; Li, M.; Guo, L. One-Pot Synthesis of Nitrogen and Sulfur CoDoped Onion-Like Mesoporous Carbon Vesicle as An Efficient Metal-Free Catalyst for Oxygen Reduction Reaction in Alkaline Solution. J. Power Sources 2014, 272, 267-276, DOI 10.1016/j.jpowsour.2014.08.104. (31) Li, Y.; Zhang, H.; Wang, Y.; Liu, P.; Yang, H.; Yao, X.; Wang, D.; Tang, Z.; Zhao, H. A Self-Sponsored Doping Approach for Controllable Synthesis of S and N Co-Doped TrimodalPorous Structured Graphitic Carbon Electrocatalysts. Energy Environ. Sci. 2014, 7 (11) 37203726, DOI 10.1039/c4ee01779j.


Page 28 of 34

Page 29 of 34 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


(32) Sahoo, M.; Ramaprabhu, S. Nitrogen and Sulfur Co-Doped Porous Carbon – is An Efficient Electrocatalyst as Platinum or A Hoax for Oxygen Reduction Reaction in Acidic Environment PEM Fuel Cell? Energy 2017, 119, 1075-1083, DOI 10.1016/j.energy.2016.11.066. (33) Du, R.; Zhang, N.; Zhu, J.; Wang, Y.; Xu, C.; Hu, Y.; Mao, N.; Xu, H.; Duan, W.; Zhuang, L.; Qu, L.; Hou, Y.; Zhang, J. Nitrogen-Doped Carbon Nanotube Aerogels for HighPerformance ORR Catalysts. Small 2015, 11 (32), 3903-3908, DOI 10.1002/smll.201500587. (34) Parvez, K.; Yang, S.; Hernandez, Y.; Winter, A.; Turchanin, A.; Feng, X.; Mullen, K. Nitrogen-Doped Graphene and Its Iron-Based Composite as Efficient Electrocatalysts for Oxygen Reduction Reaction. Acs. Nano. 2012, 6, 9541-9550, DOI 10.1021/nn302674k. (35) Chao, S.; Geng, M. 3, 5-Diamino-1, 2, 4-Triazole as A Nitrogen Precursor to Synthesize Highly Efficient Co-N/C Non-Precious Metal Bifunctional Catalyst for Oxygen Reduction Reaction and Oxygen Evolution Reaction. Int. J. Hydrogen Energy 2016, 41 (30), 12995-13004, DOI 10.1016/j.ijhydene.2016.05.269. (36) Choi, C.; Lee, S.; Park, S.; Woo, S. Highly Active N-Doped-CNTs Grafted on Fe/C Prepared by Pyrolysis of Dicyandiamide on Fe2O3/C for Electrochemical Oxygen Reduction Reaction. Appl. Catal., B 2011.103, 362-368, DOI 10.1016/j.apcatb.2011.01.043. (37) Von, D.; Biddinger, E.; Luthman, K.; Ozkan, U. The Effect of Phosphorus in NitrogenContaining Carbon Nanostructures on Oxygen Reduction in PEM Fuel Cells. Carbon 2010, 48, 3637-3639, DOI 10.1016/j.carbon.2010.05.022.



Page 30 of 34

(38) Oh, H.; Kim, H. The Role of Transition Metals in Non-Precious Nitrogen-Modified Carbon-Based Electrocatalysts for Oxygen Reduction Reaction. J. Power Sources. 2012, 212, 220-225, DOI 10.1016/j.jpowsour.2012.03.098. (39) Qiao, J.; Xu, L.; Ding, L.; Zhang, L.; Baker, R.; Dai, X.; Zhang, J. Using Pyridine as Nitrogen-Rich Precursor to Synthesize Co-N-S/C Non-Noble Metal Electrocatalysts for Oxygen Reduction Reaction. Appl. Catal., B 2012, 125, 197-205, DOI 10.1016/j.apcatb.2012.05.050. (40) Charreteur, F.; Jaouen, F.; Dodelet, J. P. Iron Porphyrin-Based Cathode Catalysts for PEM Fuel cells: Influence of Pyrolysis as on Activity and Stability. Electrochim. Acta 2009, 54, 6622– 6630, DOI 10.1016/j.electacta.2009.06.058. (41) Wu, M.; Zhang, E.; Guo, Q.; Wang, Y.; Qiao, J.; Li, K.; Pei, P. N/S-Me (Fe, Co, Ni) Doped Hierarchical Porous Carbons for Fuel Cell Oxygen Reduction Reaction with High Catalytic Activity

and

Long-Term

Stability.

Appl.

Energy

2016,

175,

468-478,

DOI

10.1016/j.apenergy.2016.03.065. (42) Zhang, Q.; Zhu, T.; Qing, X.; Qiao, J.; Sun, S. Effect of Acid-Leaching on CarbonSupported Copper Phthalocyanine Tetrasulfonic Acid Tetrasodium Salt (CuTSPc/C) for Oxygen Reduction Reaction in Alkaline Electrolyte: Active Site Studies. RSC Adv. 2015, 5 (62), 5034450352, DOI 10.1039/c5ra06314k. (43) Ding, L.; Qiao, J.; Dai, X.; Zhang, J.; Zhang, J.; Tian, B. Highly Active Electrocatalysts for Oxygen Reduction from Carbon-Supported Copper-Phthalocyanine Synthesized by High Temperature Treatment. Int. J. Hydrogen Energy 2012, 37 (19), 14103-14113, DOI 10.1016/j.ijhydene.2012.07.046.


Page 31 of 34 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


(44) Osmieri, L.; Escudero-Cid, R.; Monteverde Videla, A. H. A.; Ocón, P.; Specchia, S. Performance of A Fe-N-C Catalyst for The Oxygen Reduction Reaction in Direct Methanol Fuel Cell: Cathode Formulation Optimization and Short-Term Durability. Appl. Catal. B 2017, 201, 253-265, DOI 10.1016/j.apcatb.2016.08.043. (45) Rauf, M.; Zhao, Y.-D.; Wang, Y.-C.; Zheng, Y.-P.; Chen, C.; Yang, X.-D.; Zhou, Z.-Y.; Sun, S.-G. Insight into The Different ORR Catalytic Activity of Fe/N/C between Acidic and Alkaline Media: Protonation of Pyridinic Nitrogen. Electrochem. Commun. 2016, 73, 71-74, DOI 10.1016/j.elecom.2016.10.016. (46) Zhang, J.; Zhao, Z.; Xia, Z.; Dai, L., A Metal-Free Bifunctional Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions. Nat. Nanotechnol. 2015, 10 (5), 444-452, DOI 10.1038/nnano.2015.48. (47) Tian, G. L.; Zhao, M. Q.; Yu, D.; Kong, X. Y.; Huang, J. Q.; Zhang, Q.; Wei, F., NitrogenDoped Graphene/Carbon Nanotube Hybrids: in Situ Formation on Bifunctional Catalysts and Their Superior Electrocatalytic Activity for Oxygen Evolution/Reduction Reaction. Small 2014, 10 (11), 2251-2259, DOI 10.1002/smll.201303715. (48) Guan, T.; Li, K.; Zhao, J.; Zhao, R.; Zhang, G.; Zhang, D.; Wang, J. Template-Free Preparation of Layer-Stacked Hierarchical Porous Carbons from Coal Tar Pitch for High Performance All-Solid-State Supercapacitors. J. Mater. Chem. A 2017, 5 (30), 15869-15878, DOI 10.1039/c7ta02966g. (49) He, X.; Li, X.; Ma, H.; Han, J.; Zhang, H.; Yu, C.; Xiao, N.; Qiu, J. ZnO Template Strategy for The Synthesis of 3D Interconnected Graphene Nanocapsules from Coal Tar Pitch as



Supercapacitor

Lectrode

Materials.

J.

Power

Sources

Page 32 of 34

2017,

340,

183-191,

DOI

10.1016/j.jpowsour.2016.11.073. (50) Xue, Y.; Ge, Z.; Li, F.; Su, S.; Li, B. Modified Asphalt Properties by Blending Petroleum Asphalt and Coal Tar Pitch. Fuel 2017, 207, 64-70, DOI 10.1016/j.fuel.2017.06.064. (51) Zhao, C.; Yu, C.; Zhang, M.; Sun, Q.; Li, S.; Norouzi Banis, M.; Han, X.; Dong, Q.; Yang, J.; Wang, G.; Sun, X.; Qiu, J. Enhanced Sodium Storage Capability Enabled by Super WideInterlayer-Spacing MoS2 Integrated on Carbon Fibers. Nano Energy 2017, 41, 66-74, DOI 10.1016/j.nanoen.2017.08.030. (52) Geng, W.; Ma, F.; Wu, G.; Song, S.; Wan, J.; Ma, D. MgO-Templated Hierarchical Porous Carbon Sheets Derived from Coal Tar Pitch for Supercapacitors. Electrochim. Acta 2016, 191, 854-863, DOI 10.1016/j.electacta.2016.01.148. (53) Lota, G.; Grzyb, B.; Machnikowska, H.; Machnikowski, J.; Frackowiak, E. Effect of Nitrogen in Carbon Electrode on The Supercapacitor Performance. Chem. Phys. Lett. 2005, 404 (1-3), 53-58, DOI 10.1016/j.cplett.2005.01.074. (54) Ma, C.; Xu, N.; Qiao, J.; Jian, S.; Zhang, J. Facile Synthesis of NiCo2O4 NanosphereCarbon Nanotubes Hybrid as An Efficient Bifunctional Electrocatalyst for Rechargeable Zn–Air Batteries.

Int.

J.

Hydrogen

Energy

2016,

41

(21),

9211-9218,

DOI

10.1016/j.ijhydene.2015.12.022. (55) Yu, D.; Zhou, L.; Tang, J.; Li, J.; Hu, J.; Peng, C.; Liu, H. Nitrogen-Doped Porous Carbon Nanosheets Derived from Coal Tar Pitch as an Efficient Oxygen-Reduction Catalyst. Ind. Eng. Chem. Res. 2017, 56 (31), 8880-8887, DOI 10.1021/acs.iecr.7b01941. 32 ACS Paragon Plus Environment

Page 33 of 34 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


(56) Bezerra, C. W. B.; Zhang, L.; Lee, K.; Liu, H.; Marques, A. L. B.; Marques, E. P.; Wang, H.; Zhang, J. A Review of Fe–N/C and Co–N/C Catalysts for The Oxygen Reduction Reaction. Electrochim. Acta 2008, 53 (15), 4937-4951, DOI 10.1016/j.electacta.2008.02.012. (57) Chenitz, R.; Kramm, U. I.; Lefèvre, M.; Glibin, V.; Zhang, G.; Sun, S.; Dodelet, J.-P. A Specific Demetalation of Fe–N4 Catalytic Sites in The Micropores of NC-Ar+ NH3 is at The Origin of The Initial Activity Loss of The Highly Active Fe/N/C Catalyst Used for The Reduction of Oxygen in PEM Fuel Cells. Energy Environ. Sci. 2018, 11 (2), 365-382, DOI 10.1039/c7ee02302b. (58) Ding, L.; Dai, X.; Lin, R.; Wang, H.; Qiao, J. Electrochemical Performance of CarbonSupported Co-Phthalocyanine Modified with Co-Added Metals (M = Fe, Co, Ni, V) for Oxygen Reduction Reaction. J. Electrochem. Soc. 2012, 159 (9), F577-F584, DOI 10.1149/2.058209jes. (59) Jaouen, F.; Dodelet, J.-P. Average Turn-Over Frequency of O2 Electro-Reduction for Fe/N/C and Co/N/C Catalysts in PEFCs. Electrochim. Acta 2007, 52 (19), 5975-5984, DOI 10.1016/j.electacta.2007.03.045. (60) Liu, J.; Sun, X.; Song, P.; Zhang, Y.; Xing, W.; Xu, W. High-Performance Oxygen Reduction Electrocatalysts Based on Cheap Carbon Black, Nitrogen, and Trace Iron. Adv. Mater. 2013, 25 (47), 6879-6883, DOI 10.1002/adma.201302786.



TOC Graphic

Synopsis We developed a novel ORR and OER electrocatalyst from coal tar pitch of large amount but low utilization, which can be used in fuel cells and zinc-air batteries.


Page 34 of 34

Hierarchical Porous Carbon Derived from Coal Tar Pitch Containing

Recommend Documents