Supramolecule-Inspired Fabrication of Carbon Nanoparticles In Situ

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Supramolecule-inspired Fabrication of Carbon Nanoparticles In-situ Anchored Graphene Nanosheets Material for High-Performance Supercapacitors Yulan Huang, Aimei Gao, Xiaona Song, Dong Shu, Fenyun Yi, Jie Zhong, Ronghua Zeng, Shixu Zhao, and Tao Meng ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b08511 • Publication Date (Web): 21 Sep 2016 Downloaded from http://pubs.acs.org on September 23, 2016

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ACS Applied Materials & Interfaces

Supramolecule-inspired Fabrication of Carbon Nanoparticles In-situ Anchored Graphene Nanosheets Material for High-Performance Supercapacitors Yulan Huang a, Aimei Gao a, Xiaona Song a, Dong Shu a, b, c *, Fenyun Yi a, Jie Zhong a, Ronghua Zeng a, b, c, Shixu Zhao a, Tao Meng a a

School of Chemistry and Environment, South China Normal University, Guangzhou

510006, P. R. China b

Guangzhou Key Laboratory of Materials for Energy Conversion and Storage，

Guangzhou 510006, P. R. China c

Engineering Research Center of Materials and Technology for Electrochemical

Energy Storage (Ministry of Education) , Guangzhou 510006, P. R. China *Corresponding author E-mail: [email protected] (Dong Shu). Abstract The remarkable electrochemical performance of graphene-based materials has been drawn a tremendous attention for their application in supercapacitors. Inspired by supramolecular chemistry, the supramolecular hydrogel is prepared by linking β-cyclodextrin to graphene oxide. The carbon nanoparticles anchored graphene nanosheets are then assembled after the hydrothermal reduction and carbonization of the supramolecular hydrogels, here the β-cyclodextrin is carbonized to carbon nanoparticles that uniformly anchored on the graphene nanosheets. Transmission electron microscopy (TEM) reveals that carbon nanoparticles with several nanometers are uniformly anchored on the both side of graphene nanosheets, and X-Ray 1

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diffraction (XRD) spectra demonstrates that the interlayer spacing of graphene is enlarged due to the anchored nanoparticles among the graphene nanosheets. The as-prepared carbon nanoparticles anchored graphene nanosheets material (C/r-GO-1:3) possesses a high specific capacitance (310.8 F g-1, 0.5 A g-1), superior rate capability (242.5 F g-1, 10 A g-1) and excellent cycle stability (almost 100% after 10000 cycles, at the scan rate of 50 mV s-1). The outstanding electrochemical performance of the resulting C/r-GO-1:3 is mainly attributed to: i) the presence of the carbon nanoparticles, ii) the enlarged interlayer spacing of the graphene sheets, and iii) the accelerated ion transport rates towards the interior of the electrode material. The supramolecule-inspired approach for the synthesis of high-performance carbon nanoparticles modified graphene sheets material is promising for future application in graphene-based energy storage devices. Keywords:

Supercapacitors,

Graphene,

Supramolecular,

β-Cyclodextrin,

Electrochemical behavior Introduction Supercapacitors, also called electrochemical capacitors, have been attracted wider attention due to their many positive features, including high specific power, rapid charge-discharge, long cycle life, low cost and environmental compatibility.1-3 As the electrochemical performance of supercapacitors is largely associated with the electrode material, most research studies mainly focus on that aspect. As a result, different materials have been explored, such as carbon materials, metal oxide, and conducting polymer. Graphene is one of the best candidate electrode material for

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supercapacitor due to its larger theoretical specific surface area, higher conductivity, and excellent mechanical performance.4-6 Unfortunately, the aggregation feature of graphene significantly influence the capacitance performance of the supercapacitors by reducing the accessible surface areas to the ions and electron transport caused by the narrowed pathways.7,8 The superior electrochemical capacitance performance of graphene is only shown when it exhibits a single two-dimensional structure, therefore, it is important to prevent graphene from aggregating and restacking. In order to meet above challenges, many strategies have been employed based on the design of a three-dimensional network or production of the graphene-based composite material.9-11 Recently, Liu et al9 designed a three-dimensional bicontinuous graphene monolith using a CVD method based on versatile polymer and Ni as templates, and the 3D structure obviously restrained the aggregation and restacking of the graphene sheets. However, the utilized synthetic processes are somewhat complicated that require several procedures and need the previously prepared polymer and Ni as template. Kong and his co-workers10 prepared an Nb2O5 anchored graphene nanosheets material, which was found efficient in preventing aggregation of graphene sheets and hence increased the specific capacitance of the composite material. Nevertheless, the preparation procedure of Nb2O5/ graphene are also complex and require high-temperature treatment. For these reasons, a facile and simpler synthesis procedure for preparing non-aggregated graphene nanosheets is still challenging and requires further research. Supramolecular chemistry focuses on the molecular assembly and the

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intermolecular bonding, where the chemical system with particular organization and high complexity is combined through intermolecular forces, such as hydrogen bonds, Van der Waals' forces, electrostatic interactions, hydrophobic effects, and stacking interactions. Cyclodextrins (denoted as CD) are oligosaccharides consisting of 6, 7, or 8 glucose units, also called α-, β-, γ- CD. They are cyclic in shape with a hydrophilic exterior and a hydrophobic inner cavity.12,13 Cyclodextrin is one of the most important host molecules in supramolecular systems. Simultaneously, it is feasible to prepare carbon-based material from cyclodextrins through a facile hydrothermal carbonization approach that is easily handleable, environmentally friendly and inexpensive.14 Graphene oxide (GO), a two-dimensional structure of one atom thickness, is commonly synthesized by chemical oxidation and exfoliation procedure of graphite powder.15 GO is a crucial precursor of the synthesis of graphene-based materials, where graphene is generally prepared by heat reduction or chemical reduction of GO. In terms of properties, GO is characterized by hydrophilic surface due to the presence of multiple oxygen-containing functional groups, such as hydroxyls, carboxyls, carbonyls and epoxides.13,16 Therefore, the hydrophilic exterior of CD is effectively attached to the hydrophilic surface of GO by hydrogen bonding interaction in the supramolecular system.17 In this paper, we propose a supramolecule-inspired strategy for the synthesis of carbon nanoparticles in-suit anchored graphene nanosheets material with a favorable structure as a supercapacitor electrode. The CD is used to modify GO through hydrogen bonding interaction to form supramolecular hydrogels. Subsequently, β-CD

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becomes carbon nanoparticles in-situ anchored graphene nanosheets after the hydrothermal reduction and carbonization process. The resulting carbon nanoparticles among graphene sheets enlarge the interlayer spacing of graphene and prevent their agglomeration. Furthermore, the larger interlayer distance enable the rapid transfer of the electrolyte ions throughout the electrode material to yield the improved capacitance performance of material. The as-prepared carbon nanoparticles anchored graphene nanosheets material (C/r-GO-1:3) delivers a high specific capacitance of 310.8 F g-1 at 0.5 A g-1 and outstanding cycle stability of almost 100% capacity retention after 10000 cycles at the scan rate of 50 mV s-1. Results and discussion The fabrication procedure of C/r-GO is schematically illustrated in Figure 1. GO is generally synthesized using a chemical oxidation and exfoliation procedure of graphite powder, which possesses multiple oxygen-containing functional groups with a hydrophilic surface. During the reduction process of GO for the preparation of reduced graphene oxide (r-GO), the oxygen-containing functional groups of GO are removed. The resulting reduced graphene oxide tends to aggregate due to the π-π stacking interaction and van der Waals forces of the r-GO layers.18 CD are oligosaccharides consisting of 6, 7, or 8 glucose units, which are cyclic in shape with hydrophilic exteriors and hydrophobic interior cavities. Therefore, β-CD with the hydrophilic exterior and weak reducibility can effectively combine with GO due to its hydrophilic surface and weak oxidizability to form supramolecular hydrogels. The hydrothermal treatment of the supramolecular hydrogels in an oven turns β-CD into

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carbon nanoparticles, which are in-situ anchored on the graphene nanosheets to prevent the aggregation of r-GO layers. Further details on the procedures are provided in the Experimental section, Supporting Information.

Figure 1. Scheme illustration of the synthesis of carbon nanoparticles anchored reduced graphene oxide nanosheets (C/r-GO). The FT-IR spectra of β-CD, GO and the mixtures of β-CD/GO at different ratios are shown in Figure S1, Supporting Information. The FT-IR spectrum of β-CD/GO displays typical absorption features of both β-CD and GO. Several peaks can be seen in the spectra, including the coupled C-C / C-O stretching / O-H bending vibrations at 1028 cm-1, the combined C-O-C stretching / O-H bending vibrations at 1159 cm-1, CH2 stretching vibrations at 2929 cm-1, and C=O stretching vibrations at 1737 cm-1.19, 20

In particular, the O-H stretching vibrations peak of β-CD/GO (β-CD/GO-1:1, 3244

cm-1; β-CD/GO-1:3, 3176 cm-1; β-CD/GO-1:5, 3144 cm-1) are found distinctly red-shifted compared to pure β-CD (3337 cm-1), indicating that there is a strong hydrogen bonding interaction between β-CD and few oxygen-containing groups of GO.21 These data suggests the successful functionalization of GO nanosheets by β-CD. 6


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The morphologies and nanostructures of as-synthesized graphene-based materials are characterized by SEM and TEM, and the results are presented in Fig. 2. The pure r-GO, which is synthesized by directly hydrothermal reduction of GO, exhibits a prominently crumpled and wrinkled nanosheets morphology with the aggregation of r-GO nanosheets (Figure 2a and 2b). As can be seen from the SEM image of r-GO, the average thickness of r-GO is about ten nanometers, and the r-GO looks like crumpled nanopillars rather than smooth nanosheets due to aggregation. The insufficient β-cyclodextrin transforms into the less and small carbon nanoparticles dispersed on graphene nanosheets after the hydrothermal treatment of β-CD/GO-1:5 supramolecular hydrogel. The morphology and nanostructure of C/r-GO-1:5 also display the wrinkled nanopieces with aggregation, which is analogous to that r-GO (Figure 2c and 2d). However, when the appropriate amount of β-cyclodextrin is introduced to the graphene oxide hydrogel, the carbon nanoparticles carbonized from β-cyclodextrin uniformly disperse on and separate the graphene nanosheets after the hydrothermal process. The representative SEM image of Figure 2e reveals that C/r-GO-1:3 is composed of ultrathin and unwrinkled graphene nanosheets assemblies. The clear differences of morphology between pure r-GO and C/r-GO-1:3 can be ascribed to the formation of carbon nanoparticles which efficiently restraining the aggregation of graphene nanosheets and enlarging the interlayer spacing of graphene. It could be observed that carbon nanoparticles with the diameter of about several to tens of nanometers are homogeneously and consistently anchored on both sides of r-GO nanosheets, representing slices inlayed with particles structure

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of C/r-GO-1:3, which is verified by the TEM images (Figure 2f and Figure S2a, Supporting Information). High-resolution transmission electron microscopy (HRTEM) image of C/r-GO-1:3 further confirms the presence of carbon nanoparticles on the r-GO nanofilms (Figure S2b, Supporting Information).The carbon nanoparticles can prevent the aggregation of graphene nanosheets and increase the ion channel in the interior of material effectively. The SEM and TEM images of C/r-GO-1:1 (Figure 2g and 2h), which is prepared by hydrothermal carbonization and reduction of β-CD/GO-1:1 supramolecular hydrogels, show the massive carbon structure covering the surface of r-GO. The excessive β-cyclodextrin maybe form carbon blocks with reduced graphene oxide due to aggregation after the hydrothermal process.The presence of the massive carbon blocks on graphene sheets suffer the sheets structure of the pristine r-GO. The C/r-GO-1:1 mainly manifests the morphology and structure of an amorphous-like activated carbon.

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Figure 2. SEM images and TEM images of r-GO (a and b), C/r-GO-1:5 (c and d), C/r-GO-1:3 (e and f) and C/r-GO-1:1 (g and h), respectively. The X-ray diffraction analysis (XRD, Figure 3a) provides crystal structure information of all samples. The GO powder shows an intensive peak at approximately

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11.72°, indicating the superior crystallinity of GO and the enhanced interlayer spacing due to the existence of oxygen-containing functional groups and water molecules.22, 23 The r-GO powder shows the two typical peaks at about 25.02° and 42.87° respectively assigned to (002) and (100) crystal plane.24 This result demonstrates that GO is reduced during the hydrothermal process. More importantly, the diffraction peak at 25.65° of C/r-GO-1:1 is slightly right-shifting with respect to pure r-GO, illustrating the formation of carbon bulk that damages the intrinsic structure of graphene and lessens the interlayer distance. By contrast, the diffraction peak at 24.85° of C/r-GO-1:3 is slightly left-shifting towards lower angles if compared to pure r-GO, suggesting the interlayer spacing of C/r-GO-1:3 is enlarged that may be attributed to the presence of carbon nanoparticles.25 Furthermore, the diffraction peak of C/r-GO-1:5 is close to the counterpart of r-GO, indicating a similar interlayer distance of C/r-GO-1:5 to pure r-GO. These results are consistent with those obtained by SEM. The Raman spectra of all the as-formed samples present a broad disorder D-band at 1340 cm-1 and an in-plane vibrational G-band at 1582 cm-1 (Figure 3b). The D-band is related to the disordered and defected carbon in the samples, while the G-band is associated with the graphitized carbon in the samples.26, 27 The intensity ratio of the graphitized carbon to disordered carbon (IG/ID) is used to reckon the degree of graphitization. A value of IG/ID ratio close to 1, which signifies a relatively lowly graphitized GO due to the presence of oxygen-containing functional groups. The estimated IG/ID ratio of r-GO is 1.90, and as β-CD in the β-CD/GO supramolecular

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hydrogels increased, the IG/ID ratio is significantly reduced (C/r-GO-1:1, 0.99; C/r-GO-1:3, 1.02; C/r-GO-1:5, 1.31). These results demonstrate that the increased carbon blocks or particles in r-GO enhance the defect and disorder of graphene sheets, hence reducing both the degree of graphitization and electrical conductivity of graphene-based materials.26, 28

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Figure 3. a) XRD patterns, b) Raman spectra of GO, r-GO, C/r-GO-1:1, C/r-GO-1:3 and C/r-GO-1:5, respectively. The surface chemical identification of GO, r-GO and C/r-GO-1:3 are performed by X-ray photoelectron spectroscopy (XPS). Figure 4a, 4b and 4e display the survey spectrum of the samples, the XPS analysis reveal that the GO (68.16% C, 29.98% O), r-GO (83.54% C, 14.70% O) and C/r-GO-1:1 (89.72% C, 9.39% O) are composed of carbon and oxygen atoms (Table S1). The high-resolution C 1s spectra can be deconvoluted into four peaks located at approximately 284.74 eV, 285.35 eV, 286.62 eV and 288.73 eV, corresponding to the functionalities of C=C, C-O, C=O and O-C=O, respectively.29, 30 The C=C peak of r-GO at 284.74 eV becomes more intense (according to the peak area) due to the reduction and deoxygenation of the oxygen-containing functional groups after the hydrothermal process of GO. The

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C=O, C-O and O-C=O peaks are shown at low percentage. More importantly, the C/r-GO-1:3 exhibits a higher proportion of C=C peak and lower percent of C=O, C-O and O-C=O peaks when comparing to pure r-GO. These data testify that the existence of β-CD can increase the carbon content after the process of reduction and carbonization of β-CD/GO-1:3. The enhanced C=C peak accounts for r-GO and C/r-GO-1:3 with good graphitization.

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(c and d) and C/r-GO-1:3 (e and f), respectively. The N2 adsorption/desorption isotherms of the as-prepared r-GO and C/r-GO present characteristics of typical type ІV curves (Figure 5a) with a distinct hysteresis loop at the relative pressures (P/P0) ranging from 0.44 to 0.93, which can be ascribed to the presence of abundant mesopores.31, 32 The recorded specific surface areas of r-GO, C/r-GO-1:1, C/r-GO-1:3 and C/r-GO-1:5 are 102.6 m2 g-1, 196.5 m2 g-1, 192.7 m2 g-1 and 133.2 m2 g-1, respectively (Table S2). The relatively low surface area of r-GO is attributed to the multiple-layer structure with heavier aggregation, while the presence of carbon nanoparticles or carbon blocks increases the specific surface area of the C/r-GO materials due to the formation of multiple defects in the graphene interlayer and the grown carbon sheet.33, 34 Moreover, it is observed that the narrow pore size distribution locates at 3.78 nm for C/r-GO-1:1 and C/r-GO-1:3, while that r-GO and C/r-GO-1:5 are located at 3.37 nm (Figure 5b). The pore size distribution is estimated from the desorption curve of the isotherms according to the density functional theory (DFT). 200 0.4 0.45

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The electrochemical performance of graphene-based electrode materials is characterized by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in an aqueous solution of 6 M KOH. The CV curves of as-prepared electrode materials at the scan rates of 10 mV s-1 are displayed in Figure 6a. It will be noted that all the CV curves depict superior rectangular in shape and close to mirror symmetry, indicating a perfect and ideal capacitance behavior. A couple of obvious and symmetrical oxidation and reduction peaks appear in the CV curve of r-GO, which are attributed to the presence of oxygen-containing functional groups.35 The reductive degree of GO is enhanced with the increase of β-CD (weak reducibility) in the supramolecular hydrogels, resulting in unobvious oxidation and reduction peaks of C/r-GO. The integrated areas of the CV curves of C/r-GO-1:3 are found larger than those of the other samples, demonstrating the higher specific capacitance for C/r-GO-1:3. Furthermore, the CV curves of r-GO, C/r-GO-1:5 and C/r-GO-1:3 still maintain a quasi-rectangular shape with a little distortion at a higher scan rate of 100 mV s-1 (Figure S3a, S3e and S3g, Supporting Information), suggesting a smaller equivalent series resistance and superior rate capability. However, the CV curve of C/r-GO-1:1 shows obvious distortion at 100 mV s-1 (Figure S3c, Supporting Information), it may be attributed to the formation of carbon block that results in the destruction of graphene matrix and reduction of the electrical conductivity. The GCD curves of as-prepared graphene-based electrodes at the current density of 2 A g-1 are shown in Figure 6b. All the GCD curves exhibit linear and symmetrical

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shapes without distinct IR drop, except the GCD curve of C/r-GO-1:1. The gravimetric specific capacitance of C/r-GO-1:3 electrode material is calculated from GCD curve according to the Equation two (Experimental section, Supporting information) at a current density of 2 A g-1 to be 278.8 F g-1. This value is higher than those of many carbon materials, including r-GO (230.6 F g-1), C/r-GO-1:5 (216.5 F g-1), C/r-GO-1:1 (154.7 F g-1) and other carbon materials reported in previous literature (Table S2 and S3).36-41 The GCD measurements of the samples are further conducted under various current densities ranging from 0.5 A g-1 to 10 A g-1 and the results are shown in Figure S3b, S3d, S3f and S3h, Supporting Information. The curves depict linear and symmetric triangular shapes, demonstrating a perfect electric double layer capacitance (EDLC) behavior. Figure 6c represents the relationships between the gravimetric specific capacitance and the current densities. It is observed that the specific capacitance of C/r-GO-1:3 is higher than those of other samples over all the current densities. At higher current density, the electrolyte ions only reach to the exterior surface of electrode. The accessible surface area of ions is minimized as elevating the current density, thus the gravimetric specific capacitance of all samples decreases with the increase of current densities. The gravimetric specific capacitance of C/r-GO-1:3 decreases from 310.8 F g-1 to 242.5 F g-1 when the current density is elevated by 20-folds from 0.5 A g-1 to 10 A g-1, suggesting the excellent rate response of C/r-GO-1:3. Similarly, the gravimetric specific capacitance of r-GO reduces from 251.7 F g-1 to 210.3 F g-1 when the current density is incremented by 20-folds. The

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superior rate capability of r-GO is ascribed to the intrinsic feature of excellent electrical conductivity of r-GO. However, the presence of carbon nanoparticles enhances the interlayer spacing of graphene, facilitating the transport of electrolyte ions through the inner surface of the electrode materials, hence improving the gravimetric specific capacitance of C/r-GO-1:3. Although the electrical conductivity of C/r-GO-1:3 is declined as a result of the presence of carbon nanoparticles and the enlargement of the interlayer distance, the rate capability is kept substantial for pure r-GO because of the rapid transport of the electrolyte ions through the interlayer of C/r-GO-1:3. The cycling life of C/r-GO-1:3 electrode material is evaluated by repeating the CV tests for 10000 cycles at the scan rate of 50 mV s-1 (Figure S4, Supporting Information). The specific capacitance is calculated by the Equation one (Experimental Section). The capacitance retention of C/r-GO-1:3 is found to be nearly 100% after 10000 cycles, demonstrating that the excellent cycle stability. The beginning CV curve and that after 10000 cycles are compared in the inset of Figure S4, Supporting Information. No significant difference can be seen, demonstrating further the good electrochemical stability. The electrochemical performance of the as-prepared graphene-based electrode materials are further analyzed by EIS. The Nyquist plots are obtained over the frequency region ranging from 0.01 Hz to 100 kHz (Figure 6d), with an enlarged view in the inset. All samples exhibit the vertical-like slope in the plot at the over low-frequency section, demonstrating the good electrochemical capacitor behavior

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close to the ideal supercapacitor.42 The semicircular diameter at the high-frequency regions of the Nyquist plots represents the charge transfer resistance. The semicircle of r-GO is smaller than that of C/r-GO-1:3, which is likely attributed to the outstanding electrical conductivity of r-GO. For C/r-GO-1:3, a resistance of 3.4 ohms is acquired by a extrapolating the vertical section of the Nyquist plot to the real axis, which is considered to be a relatively low equivalent series resistance (ESR).43 Due to the intrinsic merit of the ultrahigh electrical conductivity of r-GO, the resulting ESR of r-GO is smaller than those of other samples. 400


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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


20


80

4

2

10 0 0

2

4

6

8

10

Z'(ohm )

0

0 0

2

4

6

8

10

0

10

-1

20

30

40

50

60

Z'(ohm)

Current density (A g )

Figure 6. Electrochemical performance of active materials based on three electrodes system. a) CV curves at scan rate of 10 mV s-1, b) GCD curves at current density of 2 A g-1, c) Specific capacitance at different current density, and d) Nyquist plots of r-GO, C/r-GO-1:1, C/r-GO-1:3 and C/r-GO-1:5, respectively.

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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 electrode material of C/r-GO-1:3 displays a enhanced specific capacitance of 310.8 F g-1 at the current density of 0.5 A g-1, a good rate retention of 78% when the current density is increased by 20-folds from 0.5 A g-1 to 10 A g-1, as well as a long cycle stability of almost 100% capacity retention at scan rate of 50 mV s-1 for 10000 cycles. These excellent electrochemical performance could be attributed to the carbon nanoparticles anchored graphene nanosheets structure of C/r-GO-1:3, which restrains the aggregation and restacking of r-GO. Also, the nanoparticles enlarge the interlayer spacing of graphene nanosheets, facilitating the electrolyte ions to reach the interior surface of electrode material and eventually resulting in the improved charge storage performance. Meanwhile, the larger specific surface areas and the rich mesoporous structures also contribute to the excellent electrochemical performance of C/r-GO-1:3. Conclusions In summary, carbon nanoparticles anchored graphene nanosheets material with a favorable structure is successfully prepared by first forming supramolecular hydrogels and subsequently hydrothermal reduction and carbonization of the supramolecular hydrogels. The as-synthesized C/r-GO-1:3 is found to have elevated specific surface area and greater interlayer spacing comparing with pure r-GO, which promotes the electrolyte ions to access the interior surface of electrode material and results in the enhanced charge storage. The C/r-GO-1:3 electrode material exhibits superior gravimetric specific capacitance of 310.8 F g-1 at the current density of 0.5 A g-1, and 242.5 F g-1 at the current density of 10 A g-1. The carbon nanoparticles anchored graphene nanosheets material would be promising for use in high-performance

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supercapacitors, lead-carbon cells and lithium ion batteries. Acknowledgments The authors wish to acknowledge the following financial supporters of this work: the National Natural Science Foundation of China (Grant No. 21273085 and 21673086), the Natural Science Foundation of Guangdong Province, China (Grant No. 2015A030313376), the Scientific and Technological Plan of Guangdong Province (lithium ion capacitor, No. 2015A040404043 and 2016A050502054 ). Associated content Supporting Information Available: the description of experimental materials and methods. FT-IR spectra of β-CD, GO and the mixture of β-CD / GO with different ratios. TEM and HRTEM images of C/r-GO-1:3, Electrochemical measurements of graphene-based materials. References 1. Conway, B. E. Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications; Plenum Publishers: New York, 1999. 2. Ramadoss, A.; Saravanakumar, B.; Kim, S. J., Thermally Reduced Graphene Oxide-Coated Fabrics for Flexible Supercapacitors and Self-Powered Systems. Nano Energy 2015, 15, 587–597. 3. Frackowiak, E. Carbon Materials for Supercapacitor Application. Phys. Chem. Chem. Phys. 2007, 9, 1774–1785. 4. Novoselov, K. S.; Falko, V. I.; Colombo, L.; Gellert, P. R.; Schwab, M. G.; Kim, K. A Roadmap for Graphene. Nature 2012, 490, 192–200.

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Graphical Abstract 30 20 -1

Current density (A g )

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10 0 -10

5 mV s-1 20 mV s-1

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50 mV s-1 100 mV s-1

-30 -1.0

-0.8

-0.6

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Graphical abstract

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-0.2

Supramolecule-Inspired Fabrication of Carbon Nanoparticles In Situ

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