Synthesis, Structure, and Electrochemical

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Abstract—Carbon structures with inverse opal lattice modified with nickel compounds are synthesized. The ... based on carbon structures, metal oxides, and polymer electrodes [6–8]. ..... Emel'chenko, G.A., Porous structure of synthetic opals ...
ISSN 2075-1133, Inorganic Materials: Applied Research, 2018, Vol. 9, No. 1, pp. 92–99. © Pleiades Publishing, Ltd., 2018. Original Russian Text © N.S. Sukhinina, V.M. Masalov, A.A. Zhokhov, I.I. Zverkova, Q. Liu, J. Wang, G.A. Emelchenko, 2017, published in Materialovedenie, 2017, No. 7, pp. 3–10.

Synthesis, Structure, and Electrochemical Characteristics of Carbon Inverse Opals N. S. Sukhininaa, *, V. M. Masalova, A. A. Zhokhova, I. I. Zverkovaa, Q. Liub, J. Wangb, and G. A. Emelchenkoa aInstitute

of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Russia b Harbin Engineering University, Harbin, P.R. China *e-mail: [email protected] Received August 3, 2016

Abstract—Carbon structures with inverse opal lattice modified with nickel compounds are synthesized. The thermal treatment effect on phase composition of compounds is studied. The electrochemical characteristics of carbon structures as electrode materials in supercapacitors are measured for samples obtained from various organic precursors. A considerable contribution of Faraday reactions to the specific capacitance of a capacitor with composite-based electrodes is mentioned. Keywords: inverse opals, nickel oxide and sulfide, carbon–nickel oxide composite DOI: 10.1134/S2075113318010264

double electric layer. Hence, synthesis of composites with carbon is a powerful way to enhance the electrochemical characteristics of electrodes. In the last years, various metal sulfides have been extensively studied as electrode materials owing to their advantages over oxides in high conductivity and mechanical stability [11, 12]. The effect of an oxide combined with a sulfide of the same metal on the electrochemical parameters of a composite is of interest. Among the techniques of production of nanostructured carbon materials, the matrix (template) method of synthesis allows the best capabilities for control and management of the porous structure of the material. Opal-like materials are convenient as matrices for nanostructure fabrication [13, 14]. A system of mutually connected micro-, meso-, and macropores in an inverse opal in combination with a high specific surface area improves the sorption, catalytic, and electrochemical properties of the material. The important advantage of nanostructures with an inverse opal lattice is their 3D regular packaging. The present work is aimed at studying the synthesis, structure, and electrochemical properties of carbon inverse opal nanostructures with a surface modified with nickel oxide and sulfide.

INTRODUCTION Nanostructured carbon materials have been extensively used in various fields of engineering, such as electrode materials for ionistors, batteries, and fuel elements, different sorbents, and materials for catalysis [1–3]. The directions devoted to portable supply sources in microelectronics, energy accumulators, components of force pulse devices, and other instruments based on high-speed energy source [4] have been the most extensively developed. Supercapacitors are a kind of intermediate energy storage devices which possess high power of current, long life cycle, and capability of quick recharge [5]. Productivity of a supercapacitor is first of all determined by the material used for electrode fabrication. To date, three types of electrodes have been distinguished, depending on their chemical composition, based on carbon structures, metal oxides, and polymer electrodes [6–8]. The lifetime of supercapacitors can be significantly increased by producing electrodes of carbon composites and metal oxides. Carbon exhibits high electron conductivity, which may improve the conductivity of active materials. It also acts as a barrier, inhibiting the aggregation of active particles and thus increasing the structural stability upon recharge [9]. Carbon-based electrodes in combination with metal oxides (MnO2, RuO2, NiO, and others) are characterized by so-called pseudo-capacitance [10]. Pseudo-capacitance materials make it possible to achieve energy density of accumulator batteries and long life cycle and power density of capacitors with a

EXPERIMENTAL Carbon nanostructures with the inverse opal lattice were obtained via the template method using the opal matrices composed of spherical amorphous silica particles with the diameters of 260 and 25 nm as the template. Silica particles with a diameter of 260 nm were 92

SYNTHESIS, STRUCTURE, AND ELECTROCHEMICAL CHARACTERISTICS

synthesized via the hydrolysis of tetraetoxysylane in an alcohol-aqueous-ammonium solution [15]. Small-size colloidal particles (25 nm) were obtained by the hydrolysis of tetraetoxysylane in the presence of L-arginine amino oxide [16]. Synthesis of bulk 3D samples from spherical SiO2 particles is described in [17]. Carbon was embedded in a SiO2 matrix (260 nm) using a С12Н22О11 aqueous saccharose solution with addition of sulfuric acid by which a sample was impregnated [18]. The samples were put in an aqueous solution (1 g SiO2 : 1.25 g C12H22O11 : 0.14 g H2SO4 : 5 g H2O), exposed at a temperature of 100°C for 5 h, and then dried at 160°C for 18 h; after that, they were repeatedly impregnated with a solution (1 g SiO2 : 0.8 g C12H22O11 : 0.09 g H2SO4 : 5 g H2O). To prepare another sample of inverse opal, a SiO2 precursor matrix (25 nm) was filled with ED-20 epoxy resin (diglycidyl ether/diphenylol propane oligomer) containing isomethyl tetrahydrophtalic anhydride as a curing initiator (iso-MTHPA). To reduce the viscosity, a hardener was added to a resin preheated to a temperature of 80°C, and the opal matrix was impregnated with the obtained mixture. Polymerization of epoxy resin was carried out as follows: 48 h at T = 80°C and 72 h at T = 150°C. The samples were then subjected to carbonization by annealing in an argon flow at 900°C for 3 h. The pyrolized carbon–silica composites were treated with 20% hydrofluoric acid for 24–120 h at room temperature in order to remove silica. The carbon samples were rinsed with distilled water and dried at 100°C. For surface modification of carbon materials with nickel oxide and sulfide, the samples with inverse opal lattice were put in a NiSO4 ⋅ 6H2O nickel sulfate aqueous solution with СO(NH2)2 urea additives, stirred, and exposed at 100°С for 5 h. The cooled material was then rinsed in deionized water and ethanol, dried at 80°С in air for 12 h, and annealed in an argon flux at 350–500°С for 2 h. Urea is decomposed at a temperature of about 70°C with release of carbon dioxide and ammonia. Being solved in aqueous solution, the latter two form CO 32 − and ОН– anions that interact with metal cations (arising in dissolution of nickel sulfate), precipitating hydrocarbonates onto a modified surface, as is described by the following reaction [19]:

2Ni 2 + + 2OH − + CO 32 − → Ni 2(OH) 2CO 3. The final products were examined via X-ray diffraction (Siemens D-500 setup, CuK α1 radiation), scanning electron microscopy (SEM, Zeiss Supra 50 VP microscope), and transmission electron microscopy (TEM, JEM-2100 system). Nitrogen adsorption– desorption was determined via a BET method [20] (Quantachrome QuadraWin measuring unit). The electrochemical properties were measured at Professor Jun Wang’s laboratory of the Harbin Engineering University (China) on a CHI660D electrochemical station. The working electrode was made in accorINORGANIC MATERIALS: APPLIED RESEARCH

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dance with a conventional procedure [21, 22]. The obtained carbon–nickel composite, conductive carbon (acetylene black), and polytetrafluoroethylene (PTFE) were mixed in a weight ratio of 85 : 10 : 5 and dispersed in ethanol to achieve a homogeneous paste. Acetylene black and PTFE were the conductive and binding components, respectively. The obtained mixture was pressed onto a substrate (10 × 10 × 1 mm3) from expanded nickel, which served as a collector. The electrode was then dried at a temperature of 60°С for 8 h in a vacuum furnace. The weight of the active material was 4 mg. The cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance characteristics were measured in a three-electrode electrochemical cell. Expanded nickel covered with a carbon composite served as a working electrode. Platinum foil (1 × 1 cm2) and a saturated calomel electrode were utilized as the ancillary and reference electrodes, respectively. All the electrochemical measurements were performed at room temperature in a 6 М KОН aqueous electrolyte.

RESULTS AND DISCUSSION The phase composition of synthesized carbon composites with various Ni weight contents, subjected to different temperature treatment, was established using XRD (see Table 1). Low-temperature treatment (100°С) of a carbon structure in a NiSO4 ⋅ 6H2O aqueous solution with urea additives СO(NH2)2 results in crystallization of hydrocarbonate, carbonate, oxide, and nickel sulfate from the solution. Water-soluble nickel sulfate crystallohydrates are removed by flushing of samples. Thus, nickel oxide formation upon annealing is predominately from nickel carbonate, which is poorly soluble in water and may decompose upon heating above 300°С. Annealing in an argon flux at 350–500°C favors the formation of nanocrystal NiO at the carbon surface. An increase in the nickel concentration in the composite (to 40 wt %), as well as in the annealing temperature, was accompanied by a buildup of a Ni7S6 nickel sulfide phase in addition to nickel oxide. A further increase in the annealing temperature to 750°С led to the interaction between nickel and carbon with formation of nickel carbide. Figure 1 displays the X-ray profiles of carbon inverse opals that are obtained with use of saccharose (Fig. 1a) and epoxy resin ED-20 (Fig. 1b), modified with nickel compounds at 500°С. SEM and TEM data from the samples are presented in Figs. 2 and 3. As is seen from the small-magnification images of the initial carbon structure (Figs. 2a and 2c), the samples are composed of agglomerates with size of tens of microns and their surface exhibits a cellular structure. At greater magnification, it is obvious that the carbon samples have the ordered structure of spherical cavities formed by etching of SiO2 globules No. 1

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Table 1. Phase composition of composites No.

Ni content, wt %

1 2 3 4 5 6 7

5 5 5 5 20 40 40

Thermal treatment

Phase content а-С; Ni2(CO3)(OH)2; NiCO3; NiO а-С; NiO а-С; NiO а-С; NiC; NiO; Ni7S6; Ni3S2 а-С; NiO; Ni3S2 а-С; NiO а-С; NiO; Ni7S6

100°С, 5 h 350°С, 2 h 500°С, 2 h 750°С, 2 h 500°С, 2 h 350°С, 6 h 500°С, 2 h

(see Fig. 2b and 2d). The shells around empty spheres are 10–15 nm thick. The diameter of spheres corresponds to the silica particle size of the initial matrices: 260 nm (Fig. 3b) and 25 nm (Fig. 3c). The final material (Fig. 3a) is a carbon periodic structure with a surface covered with nickel compounds. Their sizes evaluated via TEM are 10–35 nm. The porous structure characteristics (properties) were established via a gas adsorption–desorption technique

(N2, 77 K, Quantachrome QuadraSorb SI unit). The specific surface area of sachharose-based samples was found to be 847 m2/g, whereas for samples obtained using ED-20 it was 710 m2/g. This parameter for composites with 40 wt % Ni decreased by more than a factor of 3 for a carbon structure from saccharose, being 250 m2/g, and by a factor of 1.5 for a structure from epoxy resin, attaining 494 m2/g. (a)

*

Intensity, arb. units

8000 6000 *

*

4000 2000

+ + + + + ++ ++ +

0 20

40

** +

60 2θ, deg (b)

3000

*

+ +* 80

*

100

* Intensity, arb. units

2500 2000 * *

1500 1000 500

** +

++

**

*

0 40

60

80 2θ, deg

100

120

Fig. 1. X-ray diffraction profiles of carbon inverse opals based on (a) saccharose, (b) ED-20: (*) nickel oxide phase; (+) nickel sulfide phase. INORGANIC MATERIALS: APPLIED RESEARCH

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(а)

3 μm

(b)

(c)

1 μm

(d)

95

100 nm

30 nm

Fig. 2. SEM images of carbon structures with an inverse opal lattice obtained with use of (a, b) saccharose and (c, d) ED-20 epoxy resin after etching of SiO2 globules.

(a)

2 μm (b)

100 nm (c)

50 nm

Fig. 3. Electron microscopy images of composites: (a) general view at low magnification; (b) saccharose-based sample; (c) ED-20based sample.

For composites with inverse opal lattice utilized as electrode materials for supercapacitors, the cyclic voltamperometry characteristics were measured. Figure 4a shows the CV curves for a composite produced from saccharose over the potential range of 0 to 0.65 V at different scanning rates. As is evident from the CV profiles, the main contribution to the observed capacitance is made by the pseudo-capacitance that is based on the reversible redox reaction on the surface. As is seen, the oxidation peak currents increase with increased scanning rate and the oxidation peak shifts toward positive potentials. Meanwhile, the reduction peak potential shifts toward the negative range, which indicates a quasi-reversible behavior of the electrode. Figure 4b displays the specific capacitance of the carbon (saccharose-based) composite with nickel comINORGANIC MATERIALS: APPLIED RESEARCH

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pounds measured via the galvanostatic method. The capacitance was calculated using the formula [23, 24] (1) C = It , Δ Vm where I, t, ΔV, and m are the constant current (A), discharge time (s), potential difference (V), and weight of the active substance (g), respectively. As is seen from Fig. 4b, the discharge curves contain two ranges reflecting a rapidly decreasing potential (0.45–0.3 V) and a slowly decreasing potential (0.3–0.2 V) for a current density of 5 mA/cm2. The first range refers to the internal resistance of the electrolyte and electrodes, and the second is the pseudocapacitance property of the electrode. The specific capacitance of the capacitor with a composite (Ni concentration of ~40 wt %) as electrodes evaluated No. 1

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from Eq. (1) is 603 and 660 F/g for a current density at a discharge of 5 and 10 mA/cm2, respectively. The specific capacitance of a saccharose-based carbon material without modification with nickel oxide and sulfide is found to be 130 F/g at a current density of 5 mA/cm2. This means a considerable contribution of Faraday reactions involving nickel compounds (pseudo-capacitance) to the specific capacitance of a capacitor. Figures 5 and 6 show the electrochemical analysis data for the composite (40 wt % Ni) and the carbon material (without Ni) prepared using ED-20 epoxy resin. Figure 5a shows the CVA curves for the composite over the potential range of 0–0.6 V at the scanning rates of 5 to 100 mV/s. All the CV curves have a pair of redox peaks with an anode peak about 0.2 V and a cathode peak at 0.4 V, which is due to the following electrochemical reaction:

(a)

0.2

5 mV/s 10 mV/s 20 mV/s 25 mV/s 50 mV/s 100 mV/s

0.1 Voltage, V

96

0

–0.1 –0.2 –0.2

0

0.5

0.2 0.4 Voltage, V (b)

0.6

5 mA/cm2 10 mA/cm2 25 mA/cm2 50 mA/cm2 100 mA/cm2

0.4

C =

∫ I (V )dV ,

v mΔ V where I is the instantaneous current on CV curves (A), v is the scanning rate of the potential (V/s), m is the weight of the electroactive material in the electrodes (g), and ΔV is the total deviation of the potential (V). The increase in specific capacitance and speed capability of the sample modified with nickel oxide and sulfide is mainly due to the hierarchic porous architecture that allows sufficient exposition of the active pseudo-capacitance components and hence favors the interface charge transfer process. Figure 5d displays the plotted impedance of the sample. A semicircle in the impedance spectrum has two points of intersection with the axis of real resistance. A value Z' at the left edge of a semicircle is the equivalent series resistance (RS) of the capacitor,

Voltage, V



NiO + OH = NiOOH + e . The potentials of both peaks shift toward negative and positive potentials, respectively, at increased scanning rate, which means a quasi-reversible behavior of the electrode. It is evident that the peak currents of a sample with NiO/Ni7S6 are much greater than without NiO/Ni7S6 (see Fig. 6), which indicates the increased activity of the electrochemical reaction in the first sample. The galvanostatic charge–discharge measurements (see Fig. 5b) were carried out at different current densities in a potential range of 0–0.45 V to gather more information on the capacitance properties of the sample. The charge–discharge characteristics of the sample coincide with the CVA data, which demonstrate the typical pseudo-capacitance behavior. The specific capacitance evaluated for different scanning rates is plotted in Fig. 5c. The specific capacitance obtained from the CVA curves is calculated from the following formula:

0.8

0.3 0.2 0.1 0 0

200

400

600 Time, s

800

1000

1200

Fig. 4. (a) Cyclic voltammogram at different scanning rates and (b) galvanostatic charge–discharge data at various current densities of a saccharose-based composite.

which is the combination of the contact resistance at the capacitor, the bulk resistance of the electrolyte solution, and the resistance of the electrode material itself. The diameter of a semicircle is the resistance of the charge transfer RC. The corresponding resistances in Figs. 5d and 6d are close to each other. Nevertheless, comparing these resistances with the appropriate values of a saccharose-based carbon nanostructure reveals that the resistance in the latter is 2–4 times greater [25]. This can be due to a fullerene-like structure of saccharose-based carbon, including onion-like particles [14, 26, 27]. The improvement in efficiency of a pseudo-capacitor is due to several factors. First, a porous nanostructure reduces the ways of diffusion of electrons and ions, which leads to faster kinetics, which is essential for high-power energy accumulation. Second, a high surface area favors the effective contact between the active materials and the electrolyte, ensuring a greater amount of the active centers for electrochemical reactions. Third, carbon is capable of significantly increas-

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(а)

40

0.4

10 0 5 mV/s 10 mV/s 30 mV/s 50 mV/s 100 mV/s

–10

–30 0

0.1

0.2 0.3 0.4 Voltage, V

0.5

Voltage, V

0.3 0.2 0.1 0

0.6 0

(c)

240

100

200

80

300 Time, s (d)

400

500

2 3 Z ', Ω

4

200 60 –Z '', Ω

160 120 80

40

–Z '', Ω

Current density, A/g

0.5 A/g 1 A/g 2 A/g 4 A/g 8 A/g 10 A/g

20

–20

Specific capacitance, F/g

(b)

0.5

30

97

20

40

5 4 3 2 1 0

0 0

20 40 60 80 Scanning rate, mV/s

100

0

20

40 Z ', Ω

1

60

5

80

Fig. 5. Electrochemical characteristics of the composite (40 wt % Ni) based on epoxy resin ED-20: (a) cyclic voltammetry curves; (b) galvanostatic charge–discharge measurements; (c) specific capacitance at different scanning rates; (d) impedance plot.

ing the electrical conductivity of the electrode, thus allowing a rapid transfer of electrons at high speeds. CONCLUSIONS Carbon structures with inverse opal lattice modified with nickel compounds were synthesized. A polymer ED-20 was for the first time used as carbon precursor, which is characterized by two functional groups—epoxy and hydroxyl. The carbon samples possess an ordered structure of spherical cavities that arose after etching of SiO2 globules. The thickness of shells around the empty spheres was 10–15 nm. The diameter of spherical cavities corresponded to the silica particle size of the initial matrices, i.e., 260 and 25 nm. The cavities were covered with nickel compounds, whose sizes evaluated by TEM were 10–35 nm. The specific surface area of saccharose-based carbon samples was 847 m2/g, and for ED-20-based compounds, it was 710 m2/g. The specific surface area of carbon structures modified with nickel-containing INORGANIC MATERIALS: APPLIED RESEARCH

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composites was reduced by a factor of 1.5–3 owing to partial filling of pores and closing of small pores. The effect of thermal treatment on the phase composition of composites that were obtained by impregnation of a nickel sulfate aqueous solution into a porous space of the carbon inverse structure was investigated. As was shown, low-temperature treatment (100°С) of the composite led to the formation of hydrocarbonate, carbonate, and nickel oxide. Annealing in argon flux at 350–500°С led to the emergence of nanocrystal nickel oxide NiO. At increased nickel concentration in the composite (to 40 wt %) and annealing temperature of 500°С, besides the nickel oxide, there was formation of nickel sulfide. At a further increase in annealing temperature to 750°С, nickel interacted with carbon with formation of nickel carbide with oxide and sulfides. The samples exhibited high specific capacitance values that were comparable with those reported in the literature: the gravitational capacitance of a sample based on ED-20 polymer was 220 F/g at a current density of 0.5 A/g, whereas that for a saccharose-based No. 1

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(b)

(а) 5 mV/s 10 mV/s 30 mV/s 50 mV/s 100 mV/s

Current density, A/g

12 8 4 0

0 –0.2 Voltage, V

16

0.5 A/g 1 A/g 2 A/g 4 A/g 8 A/g 10 A/g

–0.4 –0.6

–4 –0.8

–8

–1.0

–12 –1.0

–0.8

–0.2

0

0

100

200

28

300 Time, s (d)

400

500

24

120

20

60

4

16 –Z '', Ω

90

–Z '', Ω

Specific capacitance, F/g

150

–0.6 –0.4 Voltage, V (c)

12 8

30

0

4 2

4 6 8 Current density, A/g

10

0

3 2 1 1

0

4

8

2 Z ', Ω

12 16 Z ', Ω

3

20

4

24

28

Fig. 6. Electrochemical characteristics of a composite (without Ni modification) based on epoxy resin ED-20: (a) cyclic voltammetry curves; (b) galvanostatic charge–discharge measurements; (c) specific capacitance at different current densities; (d) impedance plot.

sample it was greater—600 F/g—for a discharge current density of 5 mA/cm2 (0.625 A/g). The RS and RC impedance resistances measured for ED-20-based polymer were 0.5 Ω and 1.0 Ω, respectively, which was 2 and 4 times lower than in the saccharose-based sample. One may thus assume that polymer ED-20 is a promising precursor for synthesis of materials of electrochemical electrodes in ionistors with high power density of stored energy. A considerable contribution of Faraday reactions to the specific capacitance of the capacitor with composite-based electrodes was mentioned as well. REFERENCES 1. Nguyen, B.H. and Nguyen, V.H., Promising applications of graphene and graphene-based nanostructures, Adv. Nat. Sci.: Nanosci. Nanotechnol., 2016, vol. 7, no. 2, p. 023002.

2. Nishihara, H. and Kyotani, T., Templated nanocarbons for energy storage, Adv. Mater., 2012, vol. 24, no. 33, pp. 4473–4498. 3. Turanov, A.N., Karandashev, V.K., Masalov, V.M., Zhokhov, A.A., and Emelchenko, G.A., Adsorption of lanthanides(III), uranium(VI) and thorium(IV) from nitric acid solutions by carbon inverse opals modified with tetraphenylmethylenediphospine dioxide, J. Colloid Interface Sci., 2013, vol. 405, pp. 183–188. 4. Supercapacitors: Materials, Systems, and Applications, Lu, M., Béguin, F., and Frackowiak, E., Eds., New York: Wiley, 2013. 5. Kötz, R. and Carlen, M., Principles and applications of electrochemical capacitors, Electrochim. Acta, 2000, vol. 45, pp. 2483–2498. 6. Gong, Ch., Wang, X., Ma, D., Chen, H., Zhang, Sh., and Liao, Zh., Microporous carbon from a biological waste-stiff silkworm for capacitive energy storage, Electrochim. Acta, 2016, vol. 220, pp. 331–339. 7. Gao, J.J., Qiu, H.-J., Wen, Y.R., Chiang, F.-K., and Wang, Y., Enhanced electrochemical supercapacitance of binder-free nanoporous ternary metal oxides/metal

INORGANIC MATERIALS: APPLIED RESEARCH

Vol. 9

No. 1

2018

SYNTHESIS, STRUCTURE, AND ELECTROCHEMICAL CHARACTERISTICS

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

electrode, J. Colloid Interface Sci., 2016, vol. 474, pp. 18–24. Zeigler, D.F., Candelaria, S.L., Mazzio, K.A., Martin, T.R., Uchaker, E., Suraru, S.L., Kang, L.J., Cao, G.Z., and Luscombe, C.K., N-type hyper branched polymers for supercapacitor cathodes with variable porosity and excellent electrochemical stability, Macromolecules, 2015, vol. 48, no. 15, pp. 5196–5203. Lee, K.T., Jung, Y.S., and Oh, S.M., Synthesis of tinencapsulated spherical hollow carbon for anode material in lithium secondary batteries, J. Am. Chem. Soc., 2003, vol. 125, pp. 5652–5658. Lee, M.E., Kim, N.R., Song, M.Y., and Jin, H.J., Microporous carbon nanoplate/amorphous ruthenium oxide hybrids as supercapacitor electrodes, J. Nanosci. Nanotechnol., 2016, vol. 16, no. 10, pp. 10431–10436. Rui, X., Tan, H., and Yan, Q., Nanostructured metal sulfides for energy storage, Nanoscale, 2014, vol. 6, pp. 9889–9924. Cai, F., Sun, R., Kang, Y., Chen, H., Chen, M., and Li, Q., One-step strategy to a three-dimensional NiS reduced graphene oxide hybrid nanostructure for high performance supercapacitors, RSC Adv., 2015, vol. 5, pp. 23073–23079. Inagaki, M., Toyoda, M., Soneda, Y., Tsujimura, S., and Morishita, T., Templated mesoporous carbons: synthesis and applications, Carbon, 2016, vol. 107, pp. 448–473. Emel’chenko, G.A., Masalov, V.M., Zhokhov, A.A., and Khodos, I.I., Microporous and mesoporous carbon nanostructures with the inverse opal lattice, Phys. Solid State, 2013, vol. 55, no. 5, pp. 1105–1110. Stöber, W., Fink, A., and Bohn, E., Controlled growth of monodisperse silica spheres in the micron size range, J. Coll. Interface Sci., 1968, vol. 26, no. 1, pp. 62–69. Masalov, V.M., Sukhinina, N.S., and Emel’chenko, G.A., Colloidal particles of silicon dioxide for the formation of opal-like structures, Phys. Solid State, 2011, vol. 53, no. 6, pp. 1135–1139. Bardyshev, I.I., Mokrushin, A.D., Pribylov, A.A., Samarov, E.N., Masalov, V.M., Karpov, I.A., and Emel’chenko, G.A., Porous structure of synthetic opals, Colloid J., 2006, vol. 68, no. 1, pp. 20–25.

INORGANIC MATERIALS: APPLIED RESEARCH

Vol. 9

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18. Jun, S., Joo, S.H., Ryoo, R., Kruk, M., Jaroniec, M., Liu, Z., Ohsuna, T., and Terasaki, O., Synthesis of new, nanoporous carbon with hexagonally ordered mesostructure, J. Am. Chem. Soc., 2000, vol. 122, no. 43, pp. 10712–10713. 19. Li, B., Xie, Y., Wu, Ch., Li, Zh., and Zhang, J., Selective synthesis of cobalt hydroxide carbonate 3D architectures and their thermal conversion to cobalt spinel 3D superstructures, Mater. Chem. Phys., 2006, vol. 99, pp. 479–486. 20. Brunauer, S., Emmett, P.H., and Teller, E., Adsorption of gases in multimolecular layers, J. Am. Chem. Soc., 1938, vol. 60, pp. 309–319. 21. Chen, S., Zhu, J., Wu, X., Han, Q., and Wang, X., Graphene oxide–MnO2 nanocomposites for supercapacitors, ACS Nano, 2010, vol. 4, no. 5, pp. 2822–2830. 22. Zhao, X., Wang, A., Yan, J., Sun, G., Sun, L., and Zhang, T., Synthesis and electrochemical performance of heteroatom-incorporated ordered mesoporous carbons, Chem. Mater., 2010, vol. 22, no. 19, pp. 5463– 5473. 23. Jahromi, S.P., Pandikumar, A., Goh, B.T., Lim, Y.S., Basirun, W.J., Lim, H.N., and Huang, N.M., Influence of particle size on performance of a nickel oxide nanoparticle-based supercapacitor, RSC Adv., 2015, vol. 5, no. 18, pp. 14010–14019. 24. Wang, G.Q., Zhang, J., Kuang, S., Zhou, J., Xing, W., and Zhuo, S.P., Nitrogen-doped hierarchical porous carbon as an efficient electrode material for supercapacitors, Electrochim. Acta, 2015, vol. 153, pp. 273–279. 25. Sukhinina, N.S., Masalov, V.M., Zhokhov, A.A., Zverkova, I.I., and Emelchenko, G.A., C– IOP/NiO/Ni7S6 composite with the inverse opal lattice as an electrode for supercapacitors, in Nanotechnology VII, Proceedings of SPIE, Tiginyanu, I.M., Ed., Bellingham, WA: Soc. Photo-Opt. Instrum. Eng., 2015, vol. 9519, pp. 95190N-1–95190N-6. 26. Harris, P.J.F., Burian, A., and Duber, S., High-resolution electron microscopy of a microporous carbon, Philos. Mag. Lett., 2000, vol. 80, no. 6, pp. 381–386. 27. Harris, P.J.F. and Tsang, S.C., High-resolution electron microscopy studies of non-graphitizing carbons, Philos. Mag. A, 1997, vol. 76, no. 3, pp. 667–677.

Translated by O. Maslova

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