A cobalt-based sulfide self-supporting catalytic material, a preparation method and applications thereof

Abstract

The application provides a cobalt-based sulfide self-supporting catalytic material, a preparation method and application thereof, the cobalt-based sulfide self-supporting catalytic material has rich Co9S8 and CuCo2S4 heterojunction interfaces, promotes electron transfer of the interfaces, optimizes the adsorption capacity of oxygen intermediates, and helps to improve the bifunctional catalytic activity of the material in oxygen evolution reaction and oxygen reduction reaction. The preparation method of the cobalt-based sulfide catalytic material in the application only involves a simple two-step hydrothermal reaction, compared with using an organic solvent, water is used as the solvent in the application, which is safer and more environmentally friendly, and the hydrothermal temperature only needs to be 80-200 DEG C, and the condition is mild. The cobalt-based sulfide self-supporting catalytic material provided by the application is applied to a zinc-air battery as a battery positive electrode, and the charge-discharge cycle life is significantly better than that of a commercial 20%Pt / C+RuO2 catalyst, and has a good market application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy materials, and particularly relates to a cobalt-based sulfide self-supporting catalytic material, a preparation method and application thereof. BACKGROUND

[0002] A zinc-air battery is an energy storage and conversion device that uses metal zinc as the negative electrode and directly obtains oxygen from the air as the positive electrode reactant. Its theoretical energy density is as high as 1086 Wh / kg, and it has the characteristics of low cost, high energy density, long cycle life, environmental friendliness, etc., and is highly concerned in the field of electrochemical energy storage.

[0003] Although the zinc-air battery has high theoretical energy density and many advantages, its commercial application still faces great challenges. The high polarization phenomenon and rapid decay problem of the air electrode result in that the actual energy density of the zinc-air battery is much lower than the theoretical expectation. This bottleneck is mainly due to the slow reaction kinetics of the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) processes, which seriously restricts the overall performance of the battery, and therefore it is necessary to explore high-efficiency bifunctional catalysts to reduce the overpotential of the ORR and OER processes, so as to improve the energy conversion efficiency.

[0004] Among various electrocatalytic materials, cobalt-based sulfides are ideal materials for replacing noble metal-based catalysts due to their low cost, good stability and good electrocatalytic activity. However, the single cobalt-based sulfide has poor intrinsic conductivity and limited catalytic active sites, which hinders its wide application in the field of zinc-air batteries. In related technologies, Chinese patent CN111841577A discloses a preparation method of a sheet-shaped copper-cobalt bimetallic sulfide catalytic material, which uses the synergistic effect between copper and cobalt atoms to enhance the oxygen evolution reaction (OER) catalytic activity of the material. However, this method uses octylamine as an organic solvent, which has high toxicity and can cause potential harm to the environment and human health. Patent CN110790318A reports a preparation method of a Co9S8 / MoS2 multi-level structure composite material, which uses interface chemical interaction or electrical coupling as the synergistic effect between the two components, to some extent, to improve the catalytic performance and stability of the material. However, its preparation process requires high-temperature calcination, which has high energy consumption and cost, and its oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic performance still has deficiencies compared with the actual demand.

[0005] In summary, at present, the cobalt-based sulfide catalysts applied in zinc-air batteries have high preparation cost and insufficient catalytic activity, and still cannot meet the actual demand. Therefore, it is of great significance to develop a cobalt-based sulfide positive electrode material with high-efficiency bifunctional catalytic activity and good cycle stability. SUMMARY

[0006] The technical problems to be solved by the present application are to provide a cobalt-based sulfide self-supporting catalytic material, a preparation method and application, aiming to solve the problems of high preparation cost and poor stability of cobalt-based catalysts in the related art.

[0007] To solve the above technical problems, the present application is implemented as follows: a cobalt-based sulfide self-supporting catalytic material, comprising a substrate and a Co9S8 / CuCo2S4 heterostructure loaded on the substrate.

[0008] Further, the Co9S8 / CuCo2S4 heterostructure is a hollow tubular structure.

[0009] Further, the loading amount of the Co9S8 / CuCo2S4 heterostructure on the substrate is 0.5-3 mg·cm -2 .

[0010] The second aspect of the present application provides a preparation method of a cobalt-based sulfide self-supporting catalytic material, comprising the following steps:

[0011] S1: dissolving metal compounds and urea in water at room temperature to obtain a mixed solution, wherein the metal compounds are cobalt metal compounds and copper metal compounds;

[0012] S2: placing a substrate in the mixed solution and reacting at a temperature of 80-150 DEG C for 4-12 h to in-situ grow a double-metal hydroxide precursor on the substrate;

[0013] S3: placing the substrate with the double-metal hydroxide precursor obtained in step S2 in a sulfide aqueous solution and performing a hydrothermal sulfuration reaction at a temperature of 100-200 DEG C for 3-12 h to form a Co9S8 / CuCo2S4 heterostructure on the substrate, thereby obtaining the required cobalt-based sulfide self-supporting catalytic material.

[0014] Further, in step S1, the molar ratio of the metal compounds to urea is 1:(0.5-10), and the molar ratio of the cobalt metal compounds to the copper metal compounds in the metal compounds is 1:(0.05-0.5).

[0015] Further, in step S1, the cobalt metal compounds are any one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate and hydrates thereof; and the copper metal compounds are any one of copper nitrate, copper chloride, copper acetate, copper sulfate and hydrates thereof.

[0016] Further, before step S2 is performed, the substrate is pretreated with an acidic solution.

[0017] Further, in step S3, the sulfide is any one of sodium sulfide, thioacetamide, thiourea and their hydrates, and its concentration is 0.05~0.5 mol / L.

[0018] A third aspect of the present invention provides a battery cathode comprising the aforementioned cobalt-based sulfide self-supporting catalytic material.

[0019] A fourth aspect of the present invention provides a zinc-air battery, comprising the above-described battery positive electrode.

[0020] Compared with existing technologies, the cobalt-based sulfide self-supporting catalytic material, its preparation method, and its applications in this invention have the following advantages:

[0021] (1) The cobalt-based sulfide self-supporting catalytic material of the present invention has abundant Co9S8 and CuCo2S4 hetero interfaces, which promotes electron transfer at the interface, optimizes the adsorption capacity of oxygen intermediates, and helps to improve the dual-function catalytic activity of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0022] (2) The preparation method of cobalt-based sulfide self-supporting catalytic material in this invention involves only a simple two-step hydrothermal reaction. Compared with the use of organic solvents, the use of water as a solvent in this invention is safer and more environmentally friendly. The hydrothermal temperature is only 80~200℃, and the conditions are mild.

[0023] (3) The preparation method of the cobalt-based sulfide self-supporting catalytic material in this invention has high stability. Each preparation step can effectively control the morphology and composition of the product, ensuring the high stability and uniformity of the obtained material. The proportion of biphase sulfides in the heterostructure can be adjusted by controlling the concentration of added cobalt and copper metal compounds.

[0024] (4) When the cobalt-based sulfide self-supporting catalyst provided by the present invention is used as the positive electrode of the battery in zinc-air batteries, its charge-discharge cycle life is significantly better than that of commercial 20%Pt / C+RuO2 catalyst, and it has good market application prospects. Attached Figure Description

[0025] Figure 1 This is the XRD pattern of the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 of this invention;

[0026] Figure 2 This is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 of this invention;

[0027] Figure 3 In Figure 3 (a) Figure 3 (b) and Figure 3(c) is a transmission electron microscopy (TEM) characterization graph of the cobalt-based sulfide self-supported catalytic material prepared in Example 1 of the present application at different magnifications, Figure 3 (d) is a selected electron diffraction (SAED) graph;

[0028] Figure 4 is a LSV polarization curve graph of the oxygen reduction reaction catalytic activity test of the cobalt-based sulfide self-supported catalytic material prepared in Example 1 of the present application and a commercial 20% Pt / C catalyst; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0029] Figure 5 is a LSV polarization curve graph of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supported catalytic material prepared in Example 1 of the present application and a commercial RuO2 catalyst; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0030] Figure 6 is an XRD graph of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present application;

[0031] Figure 7 is a scanning electron microscope (SEM) graph of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present application;

[0032] Figure 8 is a LSV polarization curve graph of the oxygen reduction reaction catalytic activity test of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present application; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0033] Figure 9 is a LSV polarization curve graph of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present application; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0034] Figure 10 is an XRD graph of the cobalt-based sulfide self-supported catalytic material prepared in Example 3 of the present application;

[0035] Figure 11 is a scanning electron microscope (SEM) graph of the cobalt-based sulfide self-supported catalytic material prepared in Example 3 of the present application;

[0036] Figure 12 is a LSV polarization curve graph of the oxygen reduction reaction catalytic activity test of the cobalt-based sulfide self-supporting catalytic material prepared in Embodiment 3 of the present application; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); and the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0037] Figure 13 is a LSV polarization curve graph of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supporting catalytic material prepared in Embodiment 3 of the present application; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); and the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 );

[0038] Figure 14 is a discharge curve and power density curve graph of a zinc-air battery assembled by the cobalt-based sulfide self-supporting catalytic material prepared in Embodiment 1 of the present application and a commercial 20% Pt / C+RuO2 catalyst; wherein the abscissa represents the current density, in milliamperes per square centimeter (mA·cm -2 ); the left ordinate represents the voltage, in volts (V); and the right ordinate represents the power density, in milliwatts per square centimeter (mW·cm -2 );

[0039] Figure 15 is a cycle life test graph of the cobalt-based sulfide self-supporting catalytic material prepared in Embodiment 1 of the present application and the commercial 20% Pt / C+RuO2 catalyst in a zinc-air battery at a current density of 10 mA·cm -2 ; wherein the abscissa represents the time, in hours (h); and the ordinate represents the voltage, in volts (V). DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0041] The present embodiment provides a preparation method of a cobalt-based sulfide self-supporting catalytic material, comprising the following steps:

[0042] S1: dissolving metal compounds in water to obtain a mixed solution at room temperature, wherein the metal compounds are cobalt metal compounds and copper metal compounds;

[0043] S2: placing a substrate in the mixed solution and reacting at a temperature of 80-150°C for 4-12h to in-situ grow a double-metal hydroxide precursor on the substrate.

[0044] S3: placing the substrate with the double-metal hydroxide precursor obtained in step S2 into a sulfide aqueous solution, and performing a hydrothermal sulfidation reaction at a temperature of 100-200°C for 3-12h to form a Co9S8 / CuCo2S4 heterostructure on the substrate, thereby obtaining the desired cobalt-based sulfide self-supporting catalytic material.

[0045] In this embodiment, a hydrothermal method is used to grow a double-metal hydroxide precursor in situ on a substrate, and a simple in-situ hydrothermal sulfidation treatment is used to successfully prepare a Co9S8 / CuCo2S4 heterostructure supported on the substrate. Compared with the traditional physical coating method of powder catalysts, the self-supporting electrode with the double-metal sulfide directly grown on the substrate in this embodiment has a structural advantage, avoids the use of a binder, exposes more catalytically active sites, and improves the electrocatalytic performance of the material. The combination of the catalyst and the conductive substrate is more robust, which can effectively enhance the overall conductivity and stability of the positive electrode of the battery.

[0046] During the synthesis of the material, based on the Kirkendall Effect, the solid needle-shaped double-metal hydroxide precursor acts as a self-sacrificial template and is converted into a hollow tubular structure through hydrothermal sulfidation. Since the radii of the metal ions Co 2 + , Cu 2+ are significantly smaller than the radius of S 2- , the rate of outward transmission of Co 2+ , Cu 2+ is greater than the rate of inward transmission of S 2- , and as the reaction proceeds, the double-metal hydroxide precursor gradually dissolves and disappears, releasing metal ions that react with external S 2- to form a sulfide shell on the surface of the catalyst, and ultimately forming a hollow tubular Co9S8 / CuCo2S4 heterostructure. The hollow tubular morphology can effectively promote the transmission of electrons and the diffusion of oxygen, and provide a large number of catalytically active sites, thereby improving catalytic efficiency, slowing down the volume change during charging and discharging, and enhancing the stability of the electrode material of the battery.

[0047] In step S1, the metal compound and urea are dissolved in water to obtain a mixed solution, which includes:

[0048] The metal compound and urea are dissolved in deionized water, and stirred for 20-30min to obtain a mixed solution.

[0049] Preferably, in step S2, the drying specifically includes: drying at a temperature of 50-90°C for 6-12h.

[0050] Preferably, in step S3, the drying specifically comprises: vacuum drying at a temperature of 50-70℃ for 6-12h.

[0051] Further, in step S1, the molar ratio of the metal compound to urea in the mixed solution is 1:(0.5-10), and the molar ratio of the cobalt metal compound to the copper metal compound in the metal compound is 1:(0.05-0.5).

[0052] Preferably, the molar ratio of the metal compound to urea is 1:(1-5).

[0053] Further, in step S1, the cobalt metal compound is any one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, and hydrates thereof; and the copper metal compound is any one of copper nitrate, copper chloride, copper acetate, copper sulfate, and hydrates thereof.

[0054] Preferably, the cobalt metal compound is cobalt chloride hexahydrate, the concentration of the cobalt chloride hexahydrate is preferably 0.10-0.15mol / L; the copper metal compound is preferably anhydrous copper chloride, the concentration of the anhydrous copper chloride is preferably 0.005-0.045mol / L; and the concentration of the urea is preferably 0.15-0.75mol / L.

[0055] Further, before step S2, the substrate is pretreated with an acidic solution.

[0056] The substrate is pretreated with an acidic solution, wherein the substrate is any one of carbon cloth, carbon paper, or nickel foam, and the acidic solution is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0057] Preferably, the substrate is carbon cloth, and the area of the substrate is 1-12cm 2 Preferably, the substrate is a rectangular substrate with an area of 2cm×3cm.

[0058] Preferably, the acidic solution is a concentrated nitric acid solution with a concentration of 65-68%.

[0059] Further, the substrate is pretreated with an acidic solution, including the steps of:

[0060] Cutting the substrate, and immersing the substrate in the acidic solution;

[0061] Soaking the substrate immersed in the acidic solution at a temperature of 40-100℃ for 6-24h;

[0062] Taking out the substrate immersed in the acidic solution, washing the substrate, and drying the substrate at a temperature of 50-90℃ for 6-12h to complete the pretreatment of the substrate.

[0063] Further, in step S3, the sulfide is any one of sodium sulfide, thioacetamide, thiourea and hydrates thereof, and the concentration thereof is 0.05-0.5 mol / L.

[0064] Preferably, the sulfide is selected from sodium sulfide nonahydrate.

[0065] The following provides a specific embodiment of a method for preparing a cobalt-based sulfide self-supporting catalytic material.

[0066] Embodiment 1

[0067] S1: Prepare a carbon cloth substrate, cut the carbon cloth substrate into 2 cm x 3 cm, and immerse the carbon cloth substrate in a concentrated nitric acid solution with a concentration of 65-68 wt%;

[0068] Place the carbon cloth substrate immersed in the concentrated nitric acid solution in an oven at 60°C for 12 h;

[0069] Remove the carbon cloth substrate immersed in the concentrated nitric acid solution, wash the carbon cloth substrate with deionized water and anhydrous ethanol for 3 times respectively, and dry the carbon cloth substrate in a 60°C air drying oven for 10 h to complete the pretreatment of the carbon cloth substrate.

[0070] S2: Weigh 1.2848 g (5.4 mmol) of cobalt chloride hexahydrate and 0.0807 g (0.6 mmol) of anhydrous copper chloride, add 40 mL of deionized water, and magnetically stir for 10 min to obtain a mixed solution of metal compounds; then weigh 0.7207 g (12 mmol) of urea and add it to the above mixed solution of metal compounds, and magnetically stir for 10 min to obtain a mixed solution.

[0071] S3: Transfer the mixed solution to a reaction kettle, and place the carbon cloth substrate vertically in the reaction kettle;

[0072] Place the reaction kettle in an oven and perform a hydrothermal reaction at a temperature of 90°C for 6 h;

[0073] After cooling to room temperature, remove the carbon cloth substrate, wash it with deionized water and anhydrous ethanol respectively, and dry the carbon cloth substrate in a 60°C air drying oven for 10 h to obtain a bimetallic hydroxide precursor grown in situ on the carbon cloth substrate;

[0074] S4: Weigh 2.8820 g (12 mmol) of sodium sulfide nonahydrate, add 30 mL of deionized water, and magnetically stir for 20 min to obtain a sulfide solution, and then transfer the sulfide solution to the reaction kettle and immerse the bimetallic hydroxide precursor in the sulfide solution;

[0075] The reaction vessel was placed in an oven and subjected to hydrothermal sulfidation at 150°C for 6 hours. After the reaction was completed, the reaction vessel was cooled to room temperature. The product from the hydrothermal sulfidation reaction of the bimetallic hydroxide precursor was removed and washed three times with deionized water and anhydrous ethanol, respectively. The product was then placed in a vacuum drying oven and dried under vacuum at 60°C to obtain the desired cobalt-based sulfide self-supporting catalytic material. This cobalt-based sulfide self-supporting catalytic material comprises a carbon cloth substrate and a Co9S8 / CuCo2S4 heterostructure supported on the carbon cloth substrate. The loading of the Co9S8 / CuCo2S4 heterostructure on the carbon cloth substrate was 1.3 mg·cm³. -2 .

[0076] The cobalt-based sulfide catalyst material prepared by the method described in this embodiment was characterized by X-ray diffraction (XRD). Figure 1 The image shows the XRD pattern of the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 of this invention. Figure 1 As can be seen from the data, the XRD diffraction peaks of the cobalt-based sulfide self-supporting catalytic material correspond to the standard cards PDF#04-006-5681 and PDF#042-1450, indicating that there are two phases of sulfides, Co9S8 and CuCo2S4, in the material, and no other impurity phases.

[0077] like Figure 2 As shown, Figure 2 The image shown is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supporting catalytic material prepared in Example 1. It can be seen that the prepared cobalt-based sulfide self-supporting array is a hollow tubular structure that grows uniformly in all directions on a carbon cloth substrate.

[0078] Figure 3 This is a transmission electron microscope (TEM) characterization image of the cobalt-based sulfide catalyst material prepared in Example 1. Figure 3 The morphology of the Co9S8 / CuCo2S4 catalyst in (a) and (b) are similar to those in (b). Figure 2 The material is uniform in size and has a hollow tubular structure with a rough surface composed of many fine particles, which helps to increase the contact area between the catalyst and the electrolyte. For example... Figure 3 As shown in (c), a coexistence region of Co9S8 and CuCo2S4 can be observed in high-magnification TEM, with a clear interface between them, verifying the existence of the Co9S8 / CuCo2S4 heterogeneous interface in the material. Furthermore, Figure 3 (d) Selecting the electron diffraction (SAED) pattern, it can be observed that its diffraction rings belong to a polycrystalline structure, corresponding to the (311), (222), and (440) crystal planes of Co9S8 and the (113), (004), (115), and (044) crystal planes of CuCo2S4, respectively, further confirming the existence of two phases, Co9S8 and CuCo2S4, in the heterogeneous region.

[0079] Test Example 1: Oxygen Electrocatalytic Activity Test

[0080] To test the oxygen electrocatalytic activity of the electrode made from the cobalt-based sulfide self-supporting catalytic material, an electrochemical test was performed on the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 above using a three-electrode system, with a commercial 20% Pt / C and RuO2 noble metal catalyst used as a reference.

[0081] The oxygen reduction reaction catalytic activity was tested under the following conditions: 0.1 M KOH solution saturated with O2 was used as the electrolyte; an Ag / AgCl electrode was used as the reference electrode; a platinum wire was used as the counter electrode; and a glassy carbon electrode (5 mm in diameter) coated with the aforementioned cobalt-based sulfide catalyst was used as the working electrode. The loading of the cobalt-based sulfide catalyst on the glassy carbon electrode was 0.510 mg·cm³ during the test. -2 The rotating disk electrode rotates at 1600 rpm.

[0082] The catalytic activity test conditions for the oxygen evolution reaction were as follows: the electrolyte was 1 M KOH solution, the reference electrode was a Hg / HgO electrode, the counter electrode was a platinum sheet, and the prepared cobalt-based sulfide self-supporting catalytic material was fixed with electrode clamps and directly used as the working electrode. The loading of the Co9S8 / CuCo2S4 heterostructure on the carbon cloth substrate was approximately 1.3 mg·cm³. -2 .

[0083] Figure 4 The LSV polarization curves are used to test the oxygen reduction reaction catalytic activity of the cobalt-based sulfide catalyst prepared in Example 1 of this invention and the commercial 20% Pt / C catalyst. The horizontal axis represents the reversible hydrogen electrode potential in volts (V), and the vertical axis represents the current density in milliamperes per square centimeter (mA·cm²). -2 ),like Figure 4 As shown, the oxygen reduction reaction half-wave potential of the cobalt-based sulfide catalyst prepared in Example 1 is 0.790 V (vs. RHE), which is close to the half-wave potential of 0.836 V (vs. RHE) of the commercial 20% Pt / C noble metal catalyst.

[0084] Figure 5 This is an LSV polarization curve of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 of this invention and the commercial RuO2 catalyst; where the horizontal axis represents the reversible hydrogen electrode potential in volts (V); and the vertical axis represents the current density in milliamperes per square centimeter (mA·cm²). -2 ),like Figure 5 As shown, the cobalt-based sulfide self-supporting catalytic material prepared in Example 1 exhibits high performance at 10 mA·cm⁻¹. -2The overpotential of the catalyst at a current density of 10 mA / cm2was 264 mV, which was lower than the overpotential of 330 mV of a commercial RuO2 noble metal catalyst, indicating that the oxygen evolution catalytic activity of the catalyst was obviously superior to that of the noble metal catalyst.

[0085] Example 2

[0086] S1: Prepare a carbon cloth substrate, cut the carbon cloth substrate into 2 cm x 3 cm, and immerse the carbon cloth substrate in a concentrated nitric acid solution with a concentration of 65-68 wt%;

[0087] Place the carbon cloth substrate immersed in the concentrated nitric acid solution in an oven at 60°C for 12 h;

[0088] Take out the carbon cloth substrate immersed in the concentrated nitric acid solution, and clean the carbon cloth substrate with deionized water and anhydrous ethanol for 3 times respectively, and dry the carbon cloth substrate in a 60°C air drying oven for 10 h to complete the pretreatment of the carbon cloth substrate.

[0089] S2: Take 1.3562 g of cobalt chloride hexahydrate and 0.0403 g of anhydrous copper chloride, the molar ratio of cobalt chloride hexahydrate to anhydrous copper chloride is 1:0.05, add 40 mL of deionized water, and magnetically stir for 10 min to obtain a metal compound mixed solution; then take 0.7207 g of urea and add it to the above metal compound mixed solution, and magnetically stir for 10 min to obtain a mixed solution.

[0090] S3: Transfer the mixed solution to a reaction kettle, and place the carbon cloth substrate vertically in the reaction kettle;

[0091] Place the reaction kettle in an oven and perform a hydrothermal reaction at a temperature of 90°C for 6 h;

[0092] After cooling to room temperature, take out the carbon cloth substrate, wash the carbon cloth substrate with deionized water and anhydrous ethanol respectively, and dry the carbon cloth substrate in a 60°C air drying oven for 10 h to obtain a bimetallic hydroxide precursor grown in situ on the carbon cloth substrate;

[0093] S4: Take 2.8820 g (12 mmol) of sodium sulfide nonahydrate, add 30 mL of deionized water, and magnetically stir for 20 min to obtain a sulfide solution, and then transfer the sulfide solution to the reaction kettle and immerse the bimetallic hydroxide precursor in the sulfide solution;

[0094] The reactor is placed in an oven for hydrothermal sulfidation at a temperature of 150℃ for 6h. After the reaction is completed, the reactor is cooled to room temperature, and the product of the double-metal hydroxide precursor after hydrothermal sulfidation is taken out, washed with deionized water and anhydrous ethanol three times, respectively, and placed in a vacuum drying oven for vacuum drying at a temperature of 60℃ to obtain the desired cobalt-based sulfide self-supported catalytic material, which comprises a carbon cloth substrate and a Co9S8 / CuCo2S4 heterostructure supported on the carbon cloth substrate.

[0095] The cobalt-based sulfide self-supported catalytic material prepared by the above method of the present embodiment is subjected to X-ray diffraction (XRD) characterization. Figure 6 The XRD spectrum of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present embodiment is shown in FIG. 2, which shows that the XRD diffraction peaks of the cobalt-based sulfide catalytic material correspond to the standard cards of PDF#04-006-5681 and PDF#042-1450, indicating that there are Co9S8 and CuCo2S4 two-phase sulfides in the material, and no other impurities. Figure 6

[0096] As shown in FIG. 3, which is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supported catalytic material prepared in Example 2, it can be seen that the prepared cobalt-based sulfide self-supported array is a hollow tubular structure, which grows uniformly in all directions on the carbon cloth substrate. Figure 7 Figure 7 As shown in FIG. 3, which is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supported catalytic material prepared in Example 2, it can be seen that the prepared cobalt-based sulfide self-supported array is a hollow tubular structure, which grows uniformly in all directions on the carbon cloth substrate.

[0097] Test Example 2: Oxygen electrocatalytic activity test

[0098] To test the oxygen electrocatalytic activity of the electrode prepared from the cobalt-based sulfide self-supported catalytic material, the cobalt-based sulfide self-supported catalytic material prepared in the above Example 2 is subjected to electrochemical test by using a three-electrode system, and the test conditions and test steps of the oxygen reduction reaction catalytic activity test and the oxygen evolution reaction catalytic activity test are the same as those of Test Example 1.

[0099] Figure 8 FIG. 4 is an LSV polarization curve of the oxygen reduction reaction catalytic activity test of the cobalt-based sulfide self-supported catalytic material prepared in Example 2 of the present embodiment; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 Figure 8 As shown in FIG. 4, the oxygen reduction reaction half-wave potential of the cobalt-based sulfide catalytic material prepared in Example 2 is 0.758 V (vs. RHE).

[0100] Figure 9 ​​​This is an LSV polarization curve of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supporting catalytic material prepared in Example 2 of this invention; where the horizontal axis represents the reversible hydrogen electrode potential in volts (V); and the vertical axis represents the current density in milliamperes per square centimeter (mA·cm²). -2 ),like Figure 9 As shown, the cobalt-based sulfide self-supporting catalytic material prepared in Example 2 exhibits high performance at 10 mA·cm⁻¹. -2 The overpotential at the current density is 271 mV.

[0101] Example 3

[0102] S1: Prepare the carbon cloth substrate. Cut the carbon cloth substrate into 2cm×3cm pieces and immerse the carbon cloth substrate in a 65~68wt% concentrated nitric acid solution.

[0103] The carbon cloth substrate immersed in concentrated nitric acid solution was placed in an oven at 60°C and soaked for 12 hours.

[0104] Remove the carbon cloth substrate that has been placed in concentrated nitric acid solution, wash the carbon cloth substrate three times with deionized water and anhydrous ethanol respectively, and place the carbon cloth substrate in a 60°C drying oven for 10 hours to complete the pretreatment of the carbon cloth substrate.

[0105] S2: Weigh 0.9517 g of cobalt chloride hexahydrate and 0.2689 g of anhydrous copper chloride, with a molar ratio of cobalt chloride hexahydrate to anhydrous copper chloride of 1:0.5. Add 40 mL of deionized water and stir magnetically for 10 min to obtain a mixed solution of metal compounds. Then weigh 0.7207 g of urea and add it to the above mixed solution of metal compounds. Stir magnetically for 10 min to obtain a mixed solution.

[0106] S3: Transfer the mixed solution to the reactor and place the carbon cloth substrate vertically inside the reactor;

[0107] The reactor was placed in an oven and subjected to a hydrothermal reaction at 90°C for 6 hours.

[0108] After cooling to room temperature, the carbon cloth substrate was removed and washed with deionized water and anhydrous ethanol, respectively. The carbon cloth substrate was then placed in a 60°C forced-air drying oven and dried for 10 hours to obtain a bimetallic hydroxide precursor grown in situ on the carbon cloth substrate.

[0109] S4: Weigh 2.8820 g (12 mmol) sodium sulfide nonahydrate, add 30 mL of deionized water, and magnetically stir for 20 min to obtain a sulfide solution. Transfer the sulfide solution to the reaction vessel and immerse the bimetallic hydroxide precursor in the sulfide solution.

[0110] The reactor is placed in an oven for hydrothermal sulfidation at a temperature of 150℃ for 6h. After the reaction is completed, the reactor is cooled to room temperature, and the product of the double-metal hydroxide precursor after hydrothermal sulfidation is taken out, washed with deionized water and anhydrous ethanol three times, respectively, and placed in a vacuum drying oven for vacuum drying at a temperature of 60℃ to obtain the desired cobalt-based sulfide self-supported catalytic material, which comprises a carbon cloth substrate and a Co9S8 / CuCo2S4 heterostructure supported on the carbon cloth substrate.

[0111] The cobalt-based sulfide self-supported catalytic material prepared by the above method of the present embodiment is subjected to X-ray diffraction (XRD) characterization. Figure 10 The XRD spectrum of the cobalt-based sulfide catalytic material prepared in Example 3 of the present embodiment is shown in FIG. 4, which shows that the XRD diffraction peaks of the cobalt-based sulfide self-supported catalytic material correspond to the standard cards of PDF#04-006-5681 and PDF#042-1450, indicating that there are two-phase sulfides of Co9S8 and CuCo2S4 in the material, and no other impurities. Figure 10

[0112] As shown in FIG. 5, which is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supported catalytic material prepared in Example 3, it can be seen that the prepared cobalt-based sulfide self-supported array is a hollow tubular structure, which grows uniformly in all directions on the carbon cloth substrate. Figure 7 Figure 11 As shown in FIG. 5, which is a scanning electron microscope (SEM) image of the cobalt-based sulfide self-supported catalytic material prepared in Example 3, it can be seen that the prepared cobalt-based sulfide self-supported array is a hollow tubular structure, which grows uniformly in all directions on the carbon cloth substrate.

[0113] Test Example 3: Oxygen electrocatalytic activity test

[0114] To test the oxygen electrocatalytic activity of the electrode prepared from the cobalt-based sulfide self-supported catalytic material, the cobalt-based sulfide self-supported catalytic material prepared in the above Example 3 is subjected to electrochemical test by using a three-electrode system, and the test conditions and test steps of the oxygen reduction reaction catalytic activity test and the oxygen evolution reaction catalytic activity test are the same as those of Test Example 1.

[0115] Figure 12 FIG. 6 is an LSV polarization curve of the oxygen reduction reaction catalytic activity test of the cobalt-based sulfide catalytic material prepared in Example 3 of the present embodiment; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 Figure 12 As shown in FIG. 6, it can be concluded that the half-wave potential of the oxygen reduction reaction of the cobalt-based sulfide catalytic material prepared in Example 3 is 0.785 V (vs. RHE).

[0116] Figure 13 ​​​is the LSV polarization curve of the oxygen evolution reaction catalytic activity test of the cobalt-based sulfide self-supporting catalytic material prepared in Example 3 of the present application; wherein the abscissa represents the reversible hydrogen electrode potential, in volts (V); the ordinate represents the current density, in milliamperes per square centimeter (mA·cm -2 ), as shown in Figure 13 , the overpotential of the cobalt-based sulfide self-supporting catalytic material prepared in Example 3 at a current density of 10 mA·cm -2 is 268 mV.

[0117] In summary, under the same test conditions, the oxygen reduction reaction half-wave potential of the cobalt-based sulfide self-supporting catalytic material prepared in Examples 1 to 3 is slightly lower than that of the commercial Pt / C noble metal catalyst, and the oxygen evolution reaction overpotential of the cobalt-based sulfide self-supporting catalytic material prepared in Examples 1 to 3 is lower than that of the commercial RuO2 noble metal catalyst, showing excellent bifunctional catalytic activity.

[0118] Test Example 4: Battery performance test of cobalt-based sulfide self-supporting catalytic material applied to the positive electrode of zinc-air battery

[0119] The cobalt-based sulfide self-supporting catalytic material prepared in the above Example 1 was used as a zinc-air self-supporting air positive electrode, and the zinc-air battery assembled therefrom was subjected to battery performance tests such as discharge polarization curve and cycle life.

[0120] The assembly method of the aqueous zinc-air battery is as follows: the cobalt-based sulfide self-supporting catalytic material prepared in the above Example 1 is used as the positive electrode of the zinc-air electrode, polished zinc sheet is used as the negative electrode of the battery, and a mixed solution of 6M potassium hydroxide and 0.2M zinc acetate is used as the electrolyte to assemble the aqueous zinc-air battery. As a reference, a commercial 20% Pt / C+RuO2 noble metal catalyst is dispersed in an isopropanol / Nafion solution, which is then drop-coated onto a carbon cloth substrate with a loading of 1.3 mg·cm -2 , which is used as the positive electrode of the zinc-air battery.

[0121] Figure 14 is the discharge polarization curve and power density curve of the zinc-air battery based on the cobalt-based sulfide self-supporting catalytic material obtained in the above specific Example 1. As can be seen from Figure 14 , the zinc-air battery assembled using the cobalt-based sulfide self-supporting catalytic material obtained in the present Example 1 has a limiting power density of 89.24 mW·cm -2 , while the zinc-air battery assembled using the commercial 20% Pt / C+RuO2 noble metal catalyst has a limiting power density of 108.49 mW·cm -2It can be seen that the limit power density of the zinc-air battery assembled by the cobalt-based sulfide self-supporting catalytic material obtained in the embodiment is close to the limit power density of the zinc-air battery assembled by the commercial 20% Pt / C+RuO2 noble metal catalyst, and can meet the application scenarios of most portable devices or light electronic products.

[0122] Figure 15 The zinc-air battery assembled by the cobalt-based sulfide self-supporting catalytic material obtained in the embodiment 1 has a limit power density of 1,000 mW·cm-2 at 10 mA·cm-2. -2 The charge-discharge cycle stability test under a constant current density is carried out. Figure 15 As shown in the figure, the zinc-air battery using the cobalt-based sulfide self-supporting catalytic material prepared by the application has a stable cycle life of 450 h, while the zinc-air battery assembled by the commercial 20% Pt / C+RuO2 noble metal catalyst has a significant mutation of the charge-discharge platform after 110 h of charge-discharge cycle, and finally fails due to serious attenuation. The test results show that the zinc-air battery assembled by the cobalt-based sulfide self-supporting catalytic material prepared by the application can maintain long-term stable charge-discharge performance during the stability test process, which is much higher than the charge-discharge stability of the zinc-air battery assembled by the commercial 20% Pt / C+RuO2 noble metal catalyst.

[0123] In summary, the cobalt-based sulfide self-supporting catalytic material prepared by the application has oxygen reduction and oxygen evolution dual-function catalytic performance. In the application of the zinc-air battery, the limit power density of the zinc-air battery assembled by the cobalt-based sulfide self-supporting catalytic material is equivalent to that of the zinc-air battery assembled by the commercial 20% Pt / C+RuO2 noble metal catalyst, which proves that it has a wide application scenario, and the cobalt-based sulfide self-supporting catalytic material also shows a more stable cycle life than the traditional noble metal catalyst. Overall, the preparation method provided by the application has good economic benefits and environmental benefits. The cobalt-based sulfide self-supporting catalytic material prepared by the application can be applied to energy storage and conversion devices such as rechargeable zinc-air batteries, and has high practical application value and market application prospect.

[0124] The above only describes the preferred embodiments of the application and should not be used to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A cobalt-based sulfide self-supporting catalytic material, characterized in that, The cobalt-based sulfide self-supporting catalytic material includes a substrate and a Co9S8 / CuCo2S4 heterostructure supported on the substrate, wherein the Co9S8 / CuCo2S4 heterostructure is a hollow tubular structure; the preparation method of the cobalt-based sulfide self-supporting catalytic material includes the following steps: S1: At room temperature, a metal compound and urea are dissolved in water to obtain a mixed solution, wherein the metal compound is a cobalt metal compound and a copper metal compound; S2: After placing the substrate in the mixed solution, react at a temperature of 80~150℃ for 4~12h to grow a bimetallic hydroxide precursor in situ on the substrate; S3: The substrate with the bimetallic hydroxide precursor obtained in step S2 is placed in an aqueous sulfide solution and subjected to a hydrothermal sulfidation reaction at a temperature of 100~200℃ for 3~12h to form a Co9S8 / CuCo2S4 heterostructure on the substrate, thereby obtaining the desired cobalt-based sulfide self-supporting catalytic material.

2. The catalytic material according to claim 1, characterized in that, The loading of the Co9S8 / CuCo2S4 heterostructure on the substrate is 0.5~3 mg·cm³. -2 .

3. A method for preparing a cobalt-based sulfide self-supporting catalytic material, characterized in that, Including the following steps: S1: At room temperature, a metal compound and urea are dissolved in water to obtain a mixed solution, wherein the metal compound is a cobalt metal compound and a copper metal compound; S2: After placing the substrate in the mixed solution, react at a temperature of 80~150℃ for 4~12h to grow a bimetallic hydroxide precursor in situ on the substrate; S3: The substrate with the bimetallic hydroxide precursor obtained in step S2 is placed in an aqueous sulfide solution and subjected to a hydrothermal sulfidation reaction at a temperature of 100~200℃ for 3~12h to form a Co9S8 / CuCo2S4 heterostructure on the substrate, thereby obtaining the desired cobalt-based sulfide self-supporting catalytic material; wherein the Co9S8 / CuCo2S4 heterostructure is a hollow tubular structure.

4. The method according to claim 3, characterized in that, In step S1, the molar ratio of the metal compound to urea is 1:(0.5~10), and the molar ratio of the cobalt metal compound to the copper metal compound is 1:(0.05~0.5).

5. The method according to claim 3, characterized in that, In step S1, the cobalt metal compound is any one of cobalt nitrate, cobalt chloride, cobalt acetate, cobalt sulfate, and their hydrates; the copper metal compound is any one of copper nitrate, copper chloride, copper acetate, copper sulfate, and their hydrates.

6. The method according to claim 3, characterized in that, Before step S2, the substrate is pretreated with an acidic solution.

7. The method according to claim 3, characterized in that, In step S3, the sulfide is any one of sodium sulfide and its hydrate, thioacetamide, and thiourea, and its concentration is 0.05~0.5 mol / L.

8. A battery positive electrode, characterized in that, Including the cobalt-based sulfide self-supporting catalytic material as described in claim 1 or 2.

9. A zinc-air battery, characterized in that, Includes the battery positive electrode as described in claim 8.

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