Nickel single-atom bridged MoS2 / carbon composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of potassium ion batteries, and particularly relates to a nickel monatomic bridged MoS2 / carbon composite material and a preparation method and application thereof. The composite material has a layered structure of carbon-Ni / MoS2-carbon, Ni / MoS2 nanosheets are uniformly distributed on the hollow cubic carbon shell, nickel monatomic atoms bridge MoS2 and the carbon layer through O-Ni-S covalent bonds, and an atomic level electron transmission channel is constructed. The preparation method comprises three steps: firstly, a hollow cubic carbon shell is prepared; secondly, Ni / MoS2 nanosheets are in-situ grown on the surface thereof; and finally, nickel monatomic atoms are bridged through dopamine polymerization and carbonization treatment. The composite material exhibits excellent rate performance and cycle stability as a negative electrode material of a potassium ion battery. The high conductivity of the carbon material and the interface regulation of the nickel monatomic bridging are integrated, and multi-dimensional synergistic effects of structural stability, continuous conductivity and reversible reaction are realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of potassium ion batteries, in particular to a nickel single-atom bridged MoS2 / carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries have promoted the rapid development of portable devices and electric vehicles due to their high energy density and long cycle life, greatly improving the convenience of society. However, due to the high cost and scarcity of lithium resources, lithium ion batteries face resource bottlenecks and cost pressures in large-scale application fields such as renewable energy storage. To address this issue, researchers have turned their attention to other alkali metal ion battery systems.

[0003] Potassium ion batteries have attracted widespread attention due to the abundant resources, low cost and similar chemical properties of potassium. The standard redox potential of potassium (~2.93 V vs. SHE) is close to that of lithium (~3.04 V vs. SHE), enabling potassium ion batteries to achieve a working voltage comparable to lithium ion batteries, thereby having high energy density potential. In addition, the smaller Stokes radius of potassium ions results in weaker solvation effects and lower ion transport resistance in electrolytes, thereby facilitating fast charge transfer dynamics. On the other hand, potassium metal does not alloy with aluminum current collectors, so aluminum foil can be directly used as the negative electrode current collector, thereby effectively reducing the manufacturing cost and weight of the battery.

[0004] However, the larger ionic radius of potassium ions (1.38 Å) can easily cause significant volume expansion, lattice stress accumulation and structure pulverization during charging and discharging, resulting in poor rate performance and cycle performance of the material. To alleviate these problems, transition metal sulfides (TMSs) are widely explored as negative electrode materials for potassium ion batteries. Among them, molybdenum disulfide (MoS2) is considered one of the most promising negative electrode materials for potassium ion batteries due to its layered structure, large interlayer spacing (about 0.62 nm) and abundant active sites. MoS2 can achieve a high theoretical capacity through intercalation and conversion reactions (MoS2 Mo + K2S) during potassium storage. However, pure MoS2 has poor electrical conductivity (about 10 -4 S / cm), severe volume expansion and long ion diffusion paths, resulting in slow electrochemical reaction kinetics, poor cycle and rate performance, and difficulty in meeting the needs of high-performance energy storage devices.

[0005] To improve the conductivity and structural stability of MoS2, researchers have tried various modification strategies, including carbon material composite, metal doping, heterostructure construction and phase engineering regulation, etc. Among them, carbon coating and composite can improve the overall conductive network, but the electronic coupling between the interfaces is still limited; metal ion doping (such as Co, Fe, Ni, etc.) can adjust the local electronic structure, but it is easy to cause lattice distortion and even destroy the layered structure of MoS2 due to uneven doping or aggregation; and simple physical composite or weak chemical bond interface is easy to fail under long cycle conditions, resulting in increased interface contact resistance and blocked electron / ion transmission.

[0006] Therefore, the existing modification methods generally have the following shortcomings:

[0007] (1) The doped metal is unevenly distributed or aggregated in the lattice, reducing the continuity of the interface electronic coupling;

[0008] (2) The metal-sulfide interface has weak bonding force and lacks stable chemical anchoring, which is easy to separate during the cycle;

[0009] (3) The electronic transmission channel is discontinuous, the interface charge transfer efficiency is low, and the reaction kinetics is affected;

[0010] (4) There is a lack of atomic-level regulation means for interface charge distribution and chemical bond configuration, making it difficult to simultaneously consider conductivity and structural stability.

[0011] In summary, there is an urgent need in the art for a regulation strategy that realizes stable interface connection and charge bridging at the atomic scale, to significantly improve the interface electronic conduction efficiency, optimize the ion diffusion kinetics, and enhance the cycle stability and rate response of the electrode while maintaining the integrity of the MoS2 layered structure.

[0012] The above information disclosed in the background technology is only used to increase the understanding of the background technology of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0013] To solve the problems existing in the prior art, the present application provides a nickel monatomic bridged MoS2 / carbon composite material, a preparation method and application thereof.

[0014] A nickel monatomic bridged MoS2 / carbon composite material has a layered structure of carbon-Ni / MoS2-carbon, and nickel monatomic atoms are connected to MoS2 and carbon layers through O-Ni-S chemical bonds to form an atomic-level electronic transmission channel.

[0015] A preparation method of a nickel monatomic bridged MoS2 / carbon composite material includes the following steps:

[0016] (1) Preparation of hollow cubic carbon shell: cubic ferric oxide templates are prepared by hydrothermal reaction using ferric chloride and sodium hydroxide as raw materials; the templates are subjected to polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and the obtained polymer is collected as a precursor after centrifugation, washing and drying; the precursor is carbonized in an inert atmosphere, and the carbonized product is obtained after removing the templates by etching with a hydrochloric acid solution and washing and drying;

[0017] (2) Preparation of hollow cubic carbon shell supported Ni / MoS2 nanosheet: the hollow cubic carbon shell obtained in step (1), a nickel source, a molybdenum source, a sulfur source and glucose are dispersed in a mixed solvent of water and ethanol, and after hydrothermal reaction, centrifugation, washing and drying, the hollow cubic carbon shell supported Ni / MoS2 nanosheet is obtained;

[0018] (3) Preparation of nickel single-atom bridged MoS2 / carbon composite material: the hollow cubic carbon shell supported Ni / MoS2 nanosheet obtained in step (2) is subjected to polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and after centrifugation, washing and drying, carbonization treatment is carried out in a reducing atmosphere, and finally the nickel single-atom bridged MoS2 / carbon composite material is obtained.

[0019] Preferably, the temperature of the hydrothermal reaction in step (1) is 180-220 ℃, the reaction time is 4-7 days, the polymerization reaction time is 8-24 h, and the pH of the reaction system is 7-9.

[0020] Preferably, the temperature of the carbonization treatment in step (1) is 500-700 ℃, the heating rate is 1-5 ℃ / min, and the holding time is 1-4 h; the inert atmosphere is nitrogen or argon; the concentration of the hydrochloric acid solution is 2-6 mol / L, and the etching temperature is 30-50 ℃.

[0021] Preferably, the nickel source in step (2) includes one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, and nickel sulfate hexahydrate; the molybdenum source is one or more of sodium molybdate dihydrate or ammonium molybdate tetrahydrate; and the sulfur source is one or more of thiourea, thioacetamide or L-cysteine.

[0022] Preferably, the volume ratio of water to anhydrous ethanol in step (2) is 1:2; the mass ratio of hollow cubic carbon shell to molybdenum source is 1:5-1:10; the mass ratio of hollow cubic carbon shell to glucose is 1:10; and the molar ratio of nickel source to molybdenum source is 1:3-1:12.

[0023] Preferably, the hydrothermal reaction temperature in step (2) is 180-220 ℃, and the holding time is 8-24 h.

[0024] Preferably, the mass ratio of the hollow cubic carbon shell supported Ni / MoS2 nanosheet and dopamine hydrochloride in step (3) is 1:1-4:1; the polymerization reaction time is 2-8 h, and the reaction system pH is 7-9.

[0025] Preferably, the carbonization treatment temperature in step (3) is 500-700 DEG C, the heating rate is 1-5 DEG C / min, and the holding time is 1-4 h; the reducing atmosphere is argon-hydrogen mixed gas.

[0026] The application of the nickel single-atom bridged MoS2 / carbon composite material exhibits excellent rate performance and cycle stability when the composite material is used as a potassium ion battery negative electrode material.

[0027] Compared with the prior art, the application has the following beneficial effects:

[0028] (1) The application adopts a three-dimensional layered confinement structure of "inner hollow cubic carbon shell-intermediate MoS2 nanosheet-outer carbon layer", uniformly fixes the MoS2 nanosheet in the middle of the inner hollow cubic carbon shell and the outer carbon layer, and forms a continuous conductive network. The structure provides a buffer space for MoS2 volume expansion in the charging and discharging process, effectively inhibits particle pulverization and electrode peeling, enhances the structural integrity of the electrode material, simultaneously, the bidirectional electron transmission path of the carbon layer significantly improves the overall conductivity, thereby improving the cycle life and rate response performance;

[0029] (2) By regulating the nickel atom to form a stable O-Ni-S covalent bridge bond between MoS2 and the carbon interface, an atomic-level electron channel is established. The nickel atom plays a role of interface electronic bridge and charge regulation center, can effectively reduce the interface resistance, enhance the interface electron coupling strength, establish an efficient charge transmission channel, promote the reversible conversion reaction of Mo / K2S, and the bridging mechanism changes the traditional physical contact into a firm chemical connection, greatly inhibits the MoS2 from falling off the carbon base in the cycle process, and overcomes the drawbacks of metal aggregation or interface detachment in the traditional doping system, fundamentally improves the reaction kinetics;

[0030] (3) The application integrates the high conductivity of the carbon material and the interface regulation of the nickel single-atom bridging, realizes the multi-dimensional synergistic effect of structure stability, continuous conductivity and reaction reversibility, thereby effectively enhances the electrochemical performance of the potassium ion battery negative electrode, solves the problem that stability and kinetics cannot be achieved simultaneously in the field of potassium ion battery negative electrode materials. The application provides a new structural design idea for constructing a high-performance potassium ion battery negative electrode material, and can be applied to the preparation of other composite materials and various energy storage systems. BRIEF DESCRIPTION OF DRAWINGS

[0031] ​To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the following description is only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The images shown are scanning electron microscope (SEM) images of the NC@Ni / MoS2@NC composite material prepared in Example 1, where the scale bar for A is 500 nm, the scale bar for B is 200 nm, and the scale bar for C is 50 nm.

[0033] Figure 2 The X-ray diffraction patterns are those of the NC@Ni / MoS2@NC composite material prepared in Example 1 and the NC@MoS2@NC composite material prepared in Comparative Example 1.

[0034] Figure 3 The rate performance diagrams show the NC@Ni / MoS2@NC composite material prepared in Example 1, the NC@MoS2@NC composite material prepared in Comparative Example 1, and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as anode materials.

[0035] Figure 4 The graph shows the short-cycle performance of the NC@Ni / MoS2@NC composite material prepared in Example 1, the NC@MoS2@NC composite material prepared in Comparative Example 1, and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as anode materials.

[0036] Figure 5 The graph shows the long-cycle performance of the NC@Ni / MoS2@NC composite material prepared in Example 1 as an anode material.

[0037] Figure 6 The graph shows the long-cycle performance of the NC@MoS2@NC composite material prepared in Comparative Example 1 and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as anode materials. Detailed Implementation

[0038] This invention proposes a nickel single-atom-bridged MoS2 / carbon composite material, its preparation method, and its application. To facilitate understanding of this invention by those skilled in the art, specific embodiments are described below with reference to the accompanying drawings. The technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other. Unless otherwise specified, the raw materials used in the embodiments are conventional and commercially available. Unless otherwise specified, the methods used in the embodiments are prior art.

[0039] Example 1

[0040] A preparation method of a nickel monatomic bridged MoS2 / carbon composite material, the specific steps are as follows:

[0041] (1) Under strong magnetic stirring, 18 mL (6.0 mol / L) of sodium hydroxide solution was slowly added to 20 mL (2.0 mol / L) of ferric chloride solution, and the mixed solution was transferred to a 100 mL high-pressure reactor, and reacted at 100°C for 7 days. After centrifugation, washing and drying, a cubic ferric oxide template was obtained. Then, 400 mg of ferric oxide particles were dispersed in a 10 mmol / L tris (hydroxymethyl) aminomethane buffer solution (400 mL), stirred for 30 min, and then 200 mg of dopamine hydrochloride was added and dissolved. The pH value of the solution was adjusted to about 8.5 by 2 mol / L HCl solution, and continuously stirred for 12 h under this condition. After the reaction was completed, the product was collected by centrifugation and dried, and then carbonization treatment was carried out under argon atmosphere (heating rate 2 ℃ / min, 550 ℃ for 3 h). Then, the carbonized product was etched in a 45 ℃ hydrochloric acid solution (4 mol / L) for 72 h to remove the template, and after drying, a hollow cubic carbon shell material (denoted as NC) was obtained;

[0042] (2) Hollow cubic carbon shell (10 mg), nickel acetate tetrahydrate (0.05 mmol), sodium molybdate dihydrate (0.3 mmol), L-cysteine (210 mg) and glucose (100 mg) were dispersed in a mixture of 10 mL water and 20 mL anhydrous ethanol. Then, the mixed solution was transferred to a 50 mL high-pressure reactor and kept at 200°C for 12 h. After centrifugation and drying, a hollow cubic carbon shell supported Ni / MoS2 nanosheet (denoted as Ni / MoS2@NC) was obtained, wherein the glucose not only acts as a dispersant to control the uniform growth of MoS2 on the hollow carbon shell, but also acts as a reducing agent to facilitate the incorporation of Ni monatomic;

[0043] (3) Ni / MoS2@NC (50 mg) and dopamine hydrochloride (25 mg) were dispersed in a tris (hydroxymethyl) aminomethane buffer solution (100 mL, 10 mmol / L), and continuously stirred for 5 h. The product was collected by centrifugation and dried. Then, carbonization treatment was carried out under argon-hydrogen mixed gas atmosphere (heating rate 2 ℃ / min, 500 ℃ for 2 h), and a nickel monatomic bridged MoS2 / carbon composite material (denoted as NC@Ni / MoS2@NC) was obtained.

[0044] Example 2

[0045] A preparation method of a nickel monatomic bridged MoS2 / carbon composite material, the specific steps are as follows:

[0046] Example 2 differs from Example 1 in that the amount of nickel acetate tetrahydrate added is changed to 0.025 mmol, and other parameters remain unchanged.

[0047] Example 3

[0048] A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows:

[0049] Example 3 differs from Example 1 in that the amount of nickel acetate tetrahydrate added is changed to 0.1 mmol, and other parameters remain unchanged.

[0050] Example 4

[0051] A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows:

[0052] Example 4 differs from Example 1 in that L-cysteine is changed to thiourea, and other parameters remain unchanged.

[0053] Comparative Example 1

[0054] A preparation method of a MoS2 / carbon composite material, the specific steps are as follows:

[0055] Comparative Example 1 differs from Example 1 in that no nickel acetate tetrahydrate is added, and other parameters remain unchanged (denoted as NC@MoS2@NC).

[0056] Comparative Example 2

[0057] A preparation method of a hollow cubic carbon shell supported Ni / MoS2 composite material, the specific steps are as follows:

[0058] Comparative Example 2 differs from Example 1 in that step (3) in Example 1 is not implemented, and other parameters remain unchanged.

[0059] Material characterization and electrochemical performance test

[0060] The nickel single-atom bridged MoS2 / carbon composite material with a layered hollow structure is successfully prepared in the embodiments of the application. Through physical characterization and electrochemical performance test, it is confirmed that the material exhibits significant advantages in microstructure design and electrochemical performance, and is particularly suitable for high-performance potassium ion battery negative materials. The following describes the NC@Ni / MoS2@NC composite material prepared in Example 1 as a representative, and compares it with the comparative examples.

[0061] As Figure 1As shown in A and B, the NC@Ni / MoS2@NC composite material prepared in Example 1 has a cubic morphology, and the average size is 400±50 nm. The Ni / MoS2 nanosheet is uniformly distributed on the surface of the hollow cubic carbon shell, and shows a highly uniform morphology characteristic, as shown in Figure 1 As shown in C, the double-dashed line is the inner carbon layer with a certain thickness, and the outer dashed line is the outer carbon layer. The structure shows that the prepared NC@Ni / MoS2@NC composite material has good hierarchical distribution and spatial confinement characteristics, which provides favorable conditions for electron transmission and structural stability.

[0062] Figure 2 The X-ray diffraction patterns of the composite materials of the NC@Ni / MoS2@NC prepared in Example 1 and the NC@MoS2@NC prepared in Comparative Example 1 are shown. It can be seen that the diffraction peaks at 32.6° and 58.3° correspond to the (100) and (110) crystal planes of 2H-MoS2 (standard card JCPDS No. 37-1492), respectively. Compared with NC@MoS2@NC, the (002) crystal plane diffraction peak of NC@Ni / MoS2@NC is obviously shifted from 9.7° to 9.2°, and a new peak of (004) crystal plane appears at 17.5°, which indicates that the introduction of nickel monatomic atoms causes the expansion of the MoS2 interlayer spacing, and at the same time, the composite structure of the carbon layer and the MoS2 layer is alternately stacked.

[0063] The NC@Ni / MoS2@NC obtained in Example 1, the NC@MoS2@NC obtained in Comparative Example 1 and the Ni / MoS2@NC obtained in Comparative Example 2 were respectively used as negative electrode materials for potassium ion half-batteries, and the electrochemical performance was tested, and the specific steps were as follows:

[0064] The NC@Ni / MoS2@NC obtained in Example 1, the NC@MoS2@NC obtained in Comparative Example 1 and the Ni / MoS2@NC obtained in Comparative Example 2 were respectively used as active materials, and the active materials, conductive carbon black and carboxymethyl cellulose were mixed with deionized water / anhydrous ethanol (volume ratio 3:1) in a mass ratio of 8:1:1, and then ground uniformly. The obtained slurry was uniformly coated on a copper foil, and dried in a vacuum oven at 70°C to obtain an active material electrode. With the active material electrode as the negative electrode, metallic potassium as the counter electrode, glass fiber as the separator, and 1.5 mol / L potassium bisfluorosulfonylimide (KFSI) dissolved in ethylene carbonate and diethyl carbonate (volume ratio 1:1) as the electrolyte, all the test electrodes were assembled into CR2032 type coin cells in an argon-filled glove box.

[0065] As shown in Figure 3The rate performance of the NC@Ni / MoS2@NC prepared in Example 1 of the present application, the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material was compared. At a current density of 0.1, 0.2, 0.5, 1, 2, 5 and 10 A / g, the NC@Ni / MoS2@NC electrode maintained a reversible capacity of 457, 424, 401, 369, 333, 288 and 255 mAh / g, respectively. When the current density returned to 0.1 A / g, the capacity could still rise to 430 mAh / g, showing excellent rate recovery performance. In contrast, the NC@MoS2@NC without the introduction of nickel monatomic and the Ni / MoS2@NC lacking the outer carbon coating both showed obvious capacity decay, indicating that the interface bridging of the nickel monatomic and the double carbon layer confinement structure played a significant role in enhancing the electrochemical reaction kinetics.

[0066] As shown in Figure 4 , the short-term cycle stability of the NC@Ni / MoS2@NC prepared in Example 1 of the present application, the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material at 0.1 A / g was compared. The NC@Ni / MoS2@NC still maintained a high reversible capacity of 427 mAh / g after 100 cycles, while the capacity of the comparative sample decayed obviously. This shows that the bridging effect of the nickel monatomic and the stability of the double carbon layer confinement structure are indispensable for achieving high performance, and the two produce a synergistic enhancement effect.

[0067] Figure 5 Further, the long-term cycle performance of the NC@Ni / MoS2@NC composite material prepared in Example 1 of the present application as the negative electrode material at 1 A / g was demonstrated, and after 1200 cycles, the reversible capacity could reach 244 mAh / g, Figure 6 The long-term cycle performance of the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material at 1 A / g was demonstrated, and after 500 cycles, the specific capacity of both decayed to 100 mAh / g. The NC@Ni / MoS2@NC was obviously superior to the NC@MoS2@NC and the Ni / MoS2@NC, indicating that the nickel monatomic bridging structure effectively improved the cycle stability of MoS2. In combination with Figure 3 , Figure 4 the results can be seen that the nickel monatomic bridging structure plays a key role in improving the electron transmission rate, stabilizing the interface combination and promoting the MoS2 reversibility of the Mo / K2S conversion reaction.

[0068] In summary, the structural characterization and electrochemical test results jointly verify the synergistic enhancement effect of the nickel single-atom bridging and the layered limited structure in the nickel single-atom bridging MoS2 / carbon composite material designed in the application. The nickel atom forms a stable O-N-S bond bridge between the carbon and MoS2 interface, which not only improves the electronic coupling efficiency and interface stability, but also improves the reaction kinetics of potassium ion intercalation and deintercalation, so that the specific capacity, rate performance and cycle life of the material are significantly improved compared with the unmodified MoS2 / carbon composite material.

[0069] It can be understood that the embodiments of the application described above do not constitute a limitation on the protection scope of the application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application shall be included in the protection scope of the claims of the application.

Claims

1. Use of a nickel single-atom bridged MoS2 / carbon composite material, characterized in that: The nickel single-atom bridged MoS2 / carbon composite material is applied to a potassium ion battery as a negative electrode material; The nickel single-atom bridged MoS2 / carbon composite material has a carbon-Ni / MoS2-carbon layered structure, and the nickel single atoms are connected to MoS2 and the carbon layer through O-Ni-S chemical bonds to form an atomic-level electron transmission channel. The preparation method of the nickel single-atom bridged MoS2 / carbon composite material comprises the following steps: (1) Preparation of hollow cubic carbon shells: cubic ferroferric oxide templates are prepared by a hydrothermal reaction with ferric chloride and sodium hydroxide as raw materials; the templates are subjected to a polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and the obtained polymer is collected after centrifugation, washing and drying as a precursor; the precursor is carbonized in an inert atmosphere, and the obtained carbonized product is subjected to etching removal of the templates with a hydrochloric acid solution, and after cleaning and drying, hollow cubic carbon shells are obtained; (2) Preparation of hollow cubic carbon shell supported Ni / MoS2 nanosheets: the hollow cubic carbon shells obtained in step (1), a nickel source, a molybdenum source, a sulfur source and glucose are dispersed in a mixed solvent of water and ethanol, and after a hydrothermal reaction, centrifugation, washing and drying, hollow cubic carbon shell supported Ni / MoS2 nanosheets are obtained; (3) Preparation of the nickel single-atom bridged MoS2 / carbon composite material: the hollow cubic carbon shell supported Ni / MoS2 nanosheets obtained in step (2) are subjected to a polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and after centrifugation, washing and drying, carbonization treatment is carried out in a reducing atmosphere, and finally the nickel single-atom bridged MoS2 / carbon composite material is obtained; In step (1), the temperature of the hydrothermal reaction is 180-220 ℃, the reaction time is 4-7 days, the polymerization reaction time is 8-24 h, and the pH of the reaction system is 7-9.

2. Use according to claim 1, characterized in that: In step (1), the temperature of the carbonization treatment is 500-700 ℃, the heating rate is 1-5 ℃ / min, and the holding time is 1-4 h; the inert atmosphere is nitrogen or argon; the concentration of the hydrochloric acid solution is 2-6 mol / L, and the etching temperature is 30-50 ℃.

3. Use according to claim 1, characterized in that: In step (2), the nickel source is one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate and nickel sulfate hexahydrate; the molybdenum source is one or more of sodium molybdate dihydrate or ammonium molybdate tetrahydrate; and the sulfur source is one or more of thiourea, thioacetamide or L-cysteine.

4. Use according to claim 1, characterized in that: In step (2), the volume ratio of water to ethanol is 1:2; the mass ratio of hollow cubic carbon shells to molybdenum source is 1:5-1:10; the mass ratio of hollow cubic carbon shells to glucose is 1:10; and the molar ratio of nickel source to molybdenum source is 1:3-1:

12.

5. The use according to claim 1, characterized in that: In step (2), the temperature of the hydrothermal reaction is 180-220 ℃, and the holding time is 8-24 h.

6. Use according to claim 1, characterized in that: In step (3), the mass ratio of hollow cubic carbon shell supported Ni / MoS2 nanosheets to dopamine hydrochloride is 1:1-4:1; the polymerization reaction time is 2-8 h, and the pH of the reaction system is 7-9.

7. The use according to claim 1, characterized in that: The temperature of the carbonization treatment in step (3) is 500-700 DEG C, the heating rate is 1-5 DEG C / min, and the holding time is 1-4 h; and the reducing atmosphere is argon-hydrogen mixed gas.

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