In-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of electrocatalytic materials, and specifically discloses in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, a preparation method and application thereof. The preparation method comprises the following steps: dissolving cobalt nitrate hydrate, zinc nitrate hydrate and hexamethylenetetramine in decarburized water to prepare a precursor; performing sulfurization annealing on the precursor to obtain an intermediate product; and preparing a composite material by ultrasonic treatment of the intermediate product with hydrochloric acid. The in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, the preparation method and the application thereof are used, and the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material with a porous structure is successfully prepared through hydrothermal treatment, calcination and etching. The specific surface area is improved, and the catalytic performance is improved. Since the carbon-coated cobalt sulfide / cobalt zinc sulfide composite material is prevented from being corroded in an alkaline electrolyte, good durability and conductivity are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, in particular to in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material and preparation method and application. BACKGROUND

[0002] Electrochemical water splitting is widely considered as a promising method for converting and storing renewable hydrogen energy. Electrolysis of water consists of two half-reactions, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), which require efficient catalysts to reduce the overpotential, accelerate the reaction kinetics, and improve the stability. The most efficient electrocatalysts for HER and OER are platinum (Pt)-based and ruthenium / iridium (Ru / Ir)-based materials, respectively, which are limited by high cost, scarcity, and low stability. Transition metal sulfides, such as cobalt disulfide, are promising and cost-effective alternatives to noble metal catalysts due to their redox-dependent electrochemical properties and the presence of unsaturated transition metal sites. Cobalt disulfide is beneficial for the adsorption of hydroxyl ions and hydroxide intermediates in the oxygen evolution reaction due to its unsaturated transition metal sites. In addition, cobalt disulfide exhibits decent hydrogen evolution reaction performance because of the coupling between the unfilled cobalt d orbitals and the oxygen p orbitals of water, which accelerates the water dissociation process. However, in addition to its unsatisfactory electrical conductivity and stability, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities of transition metal sulfides are still lower than those of noble metals. Recently, multi-component composites have become an attractive approach to designing catalytic performance by modulating the electronic structure, improving the electrical conductivity and corrosion resistance, thereby optimizing the electrocatalytic activity and stability.

[0003] The present application successfully prepares in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material with a porous structure through three steps of hydrothermal, calcination, and etching. The porous carbon structure not only improves the specific surface area, but also allows the rapid penetration of liquid electrolyte and protons, thereby further improving the catalytic performance. SUMMARY

[0004] The purpose of the present application is to provide in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material and preparation method and application. The present application successfully prepares in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material with a porous structure through three steps of hydrothermal, calcination, and etching. The porous carbon structure not only improves the specific surface area, but also allows the rapid penetration of liquid electrolyte and protons, thereby further improving the catalytic performance. The carbon-coated cobalt sulfide / cobalt zinc sulfide composite material avoids corrosion in alkaline electrolyte, thereby achieving good durability and electrical conductivity.

[0005] To achieve the above-mentioned purpose, the present application provides a preparation method of in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, comprising the following steps:

[0006] Step one: under nitrogen atmosphere, dissolve cobalt nitrate hydrate and zinc nitrate hydrate and hexamethylenetetramine in decarburized water without carbon dioxide, and stir vigorously, add m-aminobenzenesulfonic acid solution, adjust to pH = 7, transfer the solution to a stainless steel autoclave, react at 110-130℃ for 12h, take out after cooling, wash with water and ethanol several times, and dry in a vacuum drying oven at 60℃ to obtain CoZn-m-aminobenzenesulfonic acid-LDH precursor;

[0007] Step two: place the CoZn-m-aminobenzenesulfonic acid-LDH precursor in step one into a tube furnace, place sulfur-containing substances in the tube furnace in an inert atmosphere, and perform sulfidation annealing treatment at a heating rate of 2-5℃ / min and a calcination temperature of 500℃, and obtain the intermediate product of multi-particle carbon-coated flower-shaped structure after natural cooling;

[0008] Step three: take the intermediate powder in step two, perform ultrasonic treatment with hydrochloric acid, wash with water and ethanol several times, and dry in a vacuum drying oven at 60℃ to finally obtain CoS2 / Zn 0.76 Co 0.24 S@C nanocomposite.

[0009] Preferably, in step one, the decarburized water is prepared by mixing 500mL of deionized water and 100mL of ethanol, and boiling under nitrogen atmosphere.

[0010] Preferably, in step two, place the sulfur-containing substances at the windward of the tube furnace, and place the CoZn-m-aminobenzenesulfonic acid-LDH precursor at a position 2cm away from the leeward of the sulfur-containing substances, and perform sulfidation annealing treatment under inert atmosphere protection.

[0011] Preferably, in step two, the mass ratio of sulfur-containing substances to CoZn-m-aminobenzenesulfonic acid-LDH precursor is 3:1-4:1.

[0012] Preferably, in step two, the inert gas is nitrogen or argon, and the sulfur-containing substances are sulfur powder.

[0013] Preferably, in step three, the concentration of hydrochloric acid is 3mol / L, and the amount used is 450-500mL.

[0014] The application also provides an in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material prepared by the preparation method of the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material.

[0015] The application also provides applications of the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, which are applied to electrocatalytic hydrogen evolution reaction and oxygen evolution reaction catalysts.

[0016] The in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, the preparation method and the application have the advantages and beneficial effects that:

[0017] 1、The present application utilizes the carbon-coated structure and the introduction of heterogeneous elements, and CoS2 / Zn 0.76 Co 0.24 S@C composite structure is synthesized for the first time, compared with single CoS2@C structure, the composite structure promotes the electron transfer between the metal and the carbon layer, which is beneficial to the hydrogen evolution reaction and the oxygen evolution reaction.

[0018] 2、The graphitized carbon layer wraps CoS2 and Zn 0.76 Co 0.24 S nanoparticles, which can protect the transition metal sulfide from corrosion by strong alkaline electrolyte, promote the electron transfer between the metal and the carbon layer; the conductive porous carbon skeleton is not only beneficial to the exposure of the active metal, but also provides an effective channel for the directional transport of gas; the introduction of zinc atoms further improves the conductivity of the sulfide.

[0019] 3、The present application only uses hydrothermal, calcination and etching methods, and the preparation process is simple and efficient, the equipment requirement is simple, the energy consumption is low, the requirements of green chemistry are met, it is suitable for large-scale industrial production, and has great application potential.

[0020] The technical solutions of the present application will be further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The SEM diagram of the CoS2 / Zn 0.76 Co 0.24 S@C composite structure prepared in example 1 of the present application;

[0022] Figure 2 The XRD diagram of the CoS2 / Zn 0.76 Co 0.24 S@C composite structure prepared in example 1 of the present application;

[0023] Figure 3 The TEM diagram of the CoS2 / Zn 0.76 Co 0.24 S@C composite structure prepared in example 1 of the present application;

[0024] Figure 4 The HRTEM diagram of the CoS2 / Zn 0.76 Co 0.24 S@C composite structure prepared in example 1 of the present application, wherein A is Zn 0.76 Co 0.24 S, and B is CoS2;

[0025] Figure 5 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Polarization curve of the S@C composite structure as an OER catalyst;

[0026] Figure 6 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Polarization curve of the S@C composite structure as an HER catalyst;

[0027] Figure 7 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Tafel slope converted from the polarization curve of the S@C composite structure as an OER catalyst;

[0028] Figure 8 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Tafel slope converted from the polarization curve of the S@C composite structure as an HER catalyst;

[0029] Figure 9 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Electrochemical impedance spectrogram of the S@C composite structure as an OER catalyst;

[0030] Figure 10 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Electrochemical impedance spectrogram of the S@C composite structure as an HER catalyst;

[0031] Figure 11 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Stability curve of the S@C composite structure at 10 mA / cm 2 Potential;

[0032] Figure 12 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24 Stability curve of the S@C composite structure at -10 mA / cm 2 Potential;

[0033] Figure 13 CoS2 / ZnS composite structure prepared in Example 1 of the present application 0.76 Co 0.24Polarization curve of S@C composite structure in a two-electrode electrolytic cell;

[0034] Figure 14 SEM image of CoS2 / Zn prepared in Example 1 of the present application 0.76 Co 0.24 Stability curve of S@C composite structure in a two-electrode electrolytic cell at 1.66V voltage;

[0035] Figure 15 SEM image of CoS2@C prepared in Comparative Example 1 of the present application

[0036] Figure 16 XRD pattern of CoS2@C prepared in Comparative Example 1 of the present application

[0037] Figure 17 Polarization curve of CoS2@C prepared in Comparative Example 1 of the present application as an OER catalyst

[0038] Figure 18 Polarization curve of CoS2@C prepared in Comparative Example 1 of the present application as an HER catalyst

[0039] Figure 19 SEM image of CoS2 prepared in Comparative Example 2 of the present application

[0040] Figure 20 XRD pattern of CoS2 prepared in Comparative Example 2 of the present application

[0041] Figure 21 Polarization curve of CoS2 prepared in Comparative Example 2 of the present application as an OER catalyst

[0042] Figure 22 Polarization curve of CoS2 prepared in Comparative Example 2 of the present application as an HER catalyst DETAILED DESCRIPTION

[0043] The technical solutions of the present application are further described below by means of the accompanying drawings and examples.

[0044] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those with ordinary skills in the art to which the present application pertains.

[0045] Unless otherwise defined, the reagents, devices and the like materials used in the present application are all obtained from conventional commercial sources.

[0046] Example 1

[0047] The present application discloses a preparation method of in-situ carbon-coated cobalt sulfide / cobalt sulfide zinc composite material, and the prepared in-situ carbon-coated cobalt sulfide / cobalt sulfide zinc composite material, and the preparation method comprises the following steps:

[0048] (1) Decarbonated water was prepared by mixing 500 mL of deionized water and 100 mL of ethanol and boiling under a nitrogen atmosphere.

[0049] (2) Under a nitrogen atmosphere, 4 mmol of Co(N03)2-6H20, 1 mmol of Zn(N03)2-6H20 and 10 mmol of hexamethylenetetramine were dissolved in 20 mL of decarbonated water free of carbon dioxide and stirred vigorously, 15 mmol of m-aminobenzenesulfonic acid solution was added, adjusted to pH = 7, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene, heated to 110°C for 12 h, after cooling, it was taken out, washed several times with water and ethanol, and dried in a vacuum drying oven at 60°C to obtain a CoZn-m-aminobenzenesulfonic acid-LDH precursor.

[0050] (3) The CoZn-m-aminobenzenesulfonic acid-LDH precursor was placed in a tube furnace, a certain amount of sulfur powder was placed at the upwind of the tube furnace, the mass ratio of sulfur powder to CoZn-m-aminobenzenesulfonic acid-LDH was 3:1, CoZn-m-aminobenzenesulfonic acid-LDH was placed at a position 2 cm downwind from the sulfur powder, heated to 500°C at a heating rate of 5°C / min under Ar atmosphere, and kept for 2-3 h, after cooling to room temperature, a carbon-coated flower-like structure with multi-particle intermediates was obtained.

[0051] (4) The intermediate powder was treated with ultrasonic waves for 6 h in the presence of 500 mL of 3 mol / L hydrochloric acid (HCl), washed with water and ethanol several times, and dried in a vacuum drying oven at 60°C to obtain CoS2 / Zn 0.76 Co 0.24 S@C nanocomposite.

[0052] Test Example

[0053] FEI Quanta FEG250 high-resolution field emission scanning electron microscope was used for SEM test.

[0054] CoS2 / Zn 0.76 Co 0.24 S@C obtained in Example 1 was adhered to black conductive glue and then subjected to gold spraying treatment, and then subjected to SEM test. The SEM result Figure 1 ) showed that the structure was a three-dimensional spherical flower-like nanosheet with uniformly dispersed nanoparticles fixed on the surface, indicating the feasibility of using hydrothermal, calcination and etching methods to synthesize CoS2 / Zn 0.76 Co 0.24 S@C composite. The nanosheet structure provided a large specific surface area, which was beneficial to the exposure of active sites. XRD test was performed using a SmartLab type X-ray diffractometer, and the phase composition and crystal structure of the material surface were analyzed by using a grazing incidence method. The XRD resultFigure 2 This indicates that the main component of the material is Zn. 0.76 Co 0.24 S and CoS2. The morphology and phase distribution of the materials were further analyzed using a JEOL-JEM 2100F transmission electron microscope. Figure 3 This indicates that CoS2 / Zn 0.76 Co 0.24 S@C is composed of a porous carbonaceous framework, and the pore structure (Pore) is clearly visible in the image. (HRTEM image) Figure 4 This indicates that CoS2 and Zn 0.76 Co 0.24 S nanoparticles encapsulated in a graphitized carbon layer can protect transition metal sulfides from corrosion by strongly alkaline electrolytes and promote electron transfer between the metal and the carbon layer.

[0055] A three-electrode system was used to study CoS2 / Zn 0.76 Co 0.24 S@C is measured. The specific steps are as follows: CoS2 / Zn 0.76 Co 0.24 The S@C electrode was used as the working electrode on a platinum electrode holder, with Ag / AgCl as the reference electrode and a carbon rod as the counter electrode. Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were measured in a 1 mol KOH solution. Polarization curves were measured at a scan rate of 5 mV / s, with the difference being that the scan range for HER was -1 to -2 V, and the scan range for OER was 0 to 1 V. Electrochemical impedance spectroscopy was performed from 100 kHz to 0.01 Hz, with the voltage for HER being -0.15 V vs. HER and the voltage for OER being 0.26 V vs. HER. Figure 5 and Figure 6 The polarization curves of OER and HER indicate that this material operates at 10 mA / cm². 2 Below this, the overpotentials for OER and HER are 260 mV and 152 mV, respectively. The Tafel slope obtained based on the polarization curve conversion ( Figure 7 and Figure 8 This material exhibits excellent kinetic properties in OER and HER reactions. Figure 9 and Figure 10 The charge transfer impedance of this material and other comparative materials is shown. This material has a small charge transfer impedance, indicating that it has good catalytic kinetics. Figure 11 and Figure 12 This demonstrates the excellent stability of FeP-Co / Co3ZnC@CN, exhibiting stability at 10 mA cm⁻¹. -2 (OER) and -10mA cm -2 (HER) remained stable for more than 80 hours and 40 hours respectively. Figure 13 andFigure 14 This indicates that in CoS2 / Zn 0.76 Co 0.24 S@C||CoS2 / Zn 0.76 Co 0.24 In an S@C dual-electrode electrolytic cell, at 10 mA / cm 2 Under these conditions, the electrolysis voltage is 1.66V and can be maintained for more than 40 hours.

[0056] CoS2 / Zn 0.76 Co 0.24 The S@C composite structure achieves an OER current density of 10 mA cm⁻¹ under alkaline conditions. -2 It requires an overpotential of 260 mV, which is 40 mV lower than that of the noble metal oxide RuO2, and this overpotential is within 10 mA cm⁻¹. -2 It can be stably maintained for more than 80 hours at the potential; CoS2 / Zn 0.76 Co 0.24 The S@C composite structure exhibits a HER current density of 10 mA cm⁻¹ under alkaline conditions. -2 An overpotential of 152mV is required, and it needs to be within 10mA cm⁻¹. -2 It can maintain stability for at least 40 hours at the potential; when CoS2 / Zn 0.76 Co 0.24 When S@C is used as both the cathode and anode of the electrolytic cell, at 10 mA cm -2 The electrolysis voltage required at this current density is only 1.66 V, and it can be maintained for over 40 hours. Electrochemical impedance spectroscopy (EIS) tests show that this electrode has lower electron migration resistance and higher electron mobility than a single CoS2 / ZnS electrode, which is consistent with the Tafel curve results obtained from the linear voltammetry curve. This heterostructure exhibits superior catalytic performance and reaction kinetics. The test results demonstrate that the CoS2 / ZnS electrode possesses superior catalytic performance and reaction kinetics. 0.76 Co 0.24 The S@C composite structure exhibits excellent OER and HER properties, making it a potential practical material for electrocatalytic hydrogen evolution and oxygen evolution catalysts.

[0057] Comparative Example 1

[0058] The preparation method of in-situ carbon-coated cobalt sulfide material includes the following steps:

[0059] (1) Preparation of decarbohydrate: Mix 500 mL of deionized water and 100 mL of ethanol and boil under a nitrogen atmosphere.

[0060] (2) 4 mmol of Co(N03)2-6H20 and 10 mmol of hexamethylenetetramine (HMTA) were dissolved in 20 mL of carbon dioxide-free decarbonated water, and stirred vigorously under N2atmosphere, then 15 mmol of m-aminobenzenesulfonic acid solution was added, and the pH was adjusted to 7.0. The mixture was transferred to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner, heated to 110°C, and kept in an oven for 12 h. After the high-pressure reaction kettle was cooled to room temperature, the Co-m-aminobenzenesulfonic acid-LDH product was filtered and washed with water and ethanol several times, and then vacuum dried at 60°C for 12 h.

[0061] (3) The Co-m-aminobenzenesulfonic acid-LDH precursor obtained in step (2) was placed in a tube furnace, and a certain amount of sulfur powder was placed at the upwind of the tube furnace, with a mass ratio of sulfur powder to Co-m-aminobenzenesulfonic acid-LDH precursor of 3:1. The Co-m-aminobenzenesulfonic acid-LDH was placed at a position 2 cm downwind from the sulfur powder, and heated to 500°C at a heating rate of 5°C / min under Ar atmosphere protection, and kept for 2-3 h. After cooling to room temperature, a carbon-coated flower-like structure with a multi-particle intermediate was obtained, designated as CoS2@C.

[0062] (4) SEM testing of the material obtained in step (3) gave Figure 15 , a nanoparticle and flower-like carbon skeleton structure, again indicating the feasibility of the hydrothermal and calcination preparation method. Compared to Example 1, the method of Example 2 did not use hydrochloric acid etching of zinc nanoparticles, so it did not exhibit the porous structure presented in Example 1, which reduced the active area required for the reaction and was not conducive to the diffusion of gas bubbles. Figure 16 The XRD results of the material are shown, indicating the formation of CoS2@C. The same electrochemical test method as in Example 1 was used, Figure 17 and Figure 18 The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) polarization curves of Example 1 and Comparative Example 1 are shown, and the catalytic performance of Comparative Example 1 is poorer.

[0063] Comparative Example 2

[0064] (1) Decarbonated water preparation: 500 mL of deionized water, 100 mL of ethanol were mixed, and boiled under a nitrogen atmosphere.

[0065] (2) 4 mmol of Co(N03)2-6H20 and 10 mmol of hexamethylenetetramine (HMTA) were dissolved in 20 mL of carbon dioxide-free decarbonated water, and stirred vigorously under N2atmosphere. The mixture was transferred to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner, heated to 110°C, and kept in an oven for 12 h. After the high-pressure reaction kettle was cooled to room temperature, the Co-LDH product was filtered and washed with water and ethanol several times, and then vacuum dried at 60°C for 12 h.

[0066] (3) Place the Co-LDH precursor obtained in step (2) into a tube furnace. Place a certain amount of sulfur powder at the upwind position of the tube furnace. The mass ratio of sulfur powder to precursor is 3:1. Place the Co-LDH at a position 2 cm away from the downwind position of the sulfur powder. Under Ar atmosphere protection, heat to 500℃ at a heating rate of 5℃ / min and hold for 2-3 hours. After cooling to room temperature, remove and name it CoS2.

[0067] (4) The material obtained in step (3) is subjected to SEM testing to obtain Figure 19 It exhibits a nanoscale sheet-like structure. Compared to Example 1, the sheet-like structure shows an accumulation, which reduces the active area required for the reaction and also hinders bubble diffusion. Figure 20 The XRD results of the material are shown, indicating the formation of CoS2.

[0068] The same electrochemical testing method as in Example 1 was used. Figure 21 and Figure 22 The OER and HER polarization curves of Example 1, Comparative Example 1, and Comparative Example 2 are shown, with Comparative Example 2 exhibiting worse catalytic performance.

[0069] Therefore, this invention utilizes the aforementioned in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, its preparation method, and its application. Through three steps—hydrothermal treatment, calcination, and etching—a porous in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material was successfully prepared. The porous carbon structure not only improves the specific surface area but also allows for rapid penetration of liquid electrolytes and protons, thereby further enhancing catalytic performance. Because the carbon-coated cobalt sulfide / cobalt zinc sulfide composite material is protected from corrosion in alkaline electrolytes, it achieves excellent durability and conductivity.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, characterized in that, Comprising the following steps: Step one: under nitrogen atmosphere, dissolve cobalt nitrate hydrate and zinc nitrate hydrate and hexamethylenetetramine in decarburized water without carbon dioxide, and stir vigorously, add m-aminobenzenesulfonic acid solution, adjust to pH = 7, transfer the solution to a stainless steel autoclave, react at 110-130℃ for 12h, cool and take out, wash with water and ethanol several times, and dry in a vacuum drying oven at 60℃ to obtain CoZn-m-aminobenzenesulfonic acid-LDH precursor; Step two: put the CoZn-m-aminobenzenesulfonic acid-LDH precursor in step one into a tube furnace, put sulfur-containing material in the tube furnace in an inert atmosphere, and perform sulfidation annealing treatment at a heating rate of 2-5℃ / min and a calcination temperature of 500℃, and obtain a multi-particle carbon-coated flower-shaped intermediate product after natural cooling; Step three: take the intermediate powder of step two, use hydrochloric acid ultrasonic treatment, through multiple water washing and ethanol washing, drying in vacuum drying oven at 60°C, finally CoS2 / Zn 0.76 Co 0.24 S@C nanocomposite.

2. The method for preparing in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material according to claim 1, characterized in that: In step one, the decarburized water is prepared by mixing 500mL of deionized water and 100mL of ethanol, and boiling under nitrogen atmosphere.

3. The method for preparing the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material according to claim 1, characterized in that: In step two, the sulfur-containing material is placed at the windward of the tube furnace, and the CoZn-m-aminobenzenesulfonic acid-LDH precursor is placed 2cm away from the sulfur-containing material at the leeward, and the sulfidation annealing treatment is carried out under inert atmosphere protection.

4. The method for preparing in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material according to claim 1, characterized in that: In step two, the mass ratio of sulfur-containing material to CoZn-m-aminobenzenesulfonic acid-LDH precursor is 3:1-4:

1.

5. The method for preparing the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material according to claim 1, characterized in that: In step two, the inert gas is nitrogen or argon, and the sulfur-containing material is sulfur powder.

6. The method for preparing the in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material according to claim 1, characterized in that: In step three, the concentration of hydrochloric acid is 3mol / L, and the amount used is 450-500mL.

7. In-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composite material, characterized in that: It is prepared by the preparation method of any one of claims 1-6.

8. Use of in-situ carbon-coated cobalt sulfide / cobalt zinc sulfide composites according to claim 7, characterized in that: It is applied to electrocatalytic hydrogen evolution reaction and oxygen evolution reaction catalyst.

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