CoS2 / co (oh) f heterostructure self-supporting water electrolysis oxygen evolution catalyst and application thereof

Abstract

The application discloses a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst and application thereof. The catalyst is prepared by the following method: transferring pretreated foamed cobalt, a sulfur source aqueous solution and a fluorine source aqueous solution into a high-pressure reaction container, sealing the high-pressure reaction container and then performing a hydrothermal reaction, naturally cooling the high-pressure reaction kettle after the reaction is completed, taking out the reaction product, washing and drying the reaction product, and obtaining the CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst. The catalyst can be applied in alkaline water electrolysis oxygen evolution and industrial large-current density water electrolysis oxygen evolution in an alkaline membrane electrode system. The catalyst can be prepared by only one-step hydrothermal method, the test steps are simple, the catalyst can be applied in alkaline water electrolysis oxygen evolution and large-current density, has long-time stability, and can be applied in full water decomposition in an alkaline membrane electrolytic cell device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water decomposition electrocatalysts, and particularly relates to a CoS2 / Co(OH)F heterostructure self-supporting electrolytic water oxygen evolution catalyst and application thereof. BACKGROUND

[0002] Energy depletion and environmental pollution have become global problems that need to be solved urgently. Developing green energy is of great importance to the sustainable development of human society. Compared with traditional fossil fuels, hydrogen energy has a series of advantages such as zero emission, high efficiency and renewable, and plays an important role in realizing the carbon peak and carbon neutral strategies. Hydrogen energy has become one of the most ideal energies due to its environmental friendliness, high calorific value and recyclable production, and the use of renewable energy to drive electrolytic water to produce hydrogen is expected to alleviate the problems of environmental pollution and energy shortage. Among them, the hydrogen production methods in China are 1) fossil fuel hydrogen production, 2) coal gasification hydrogen production, 3) biomass hydrogen production and 4) electrolytic water hydrogen production. At present, the main way of hydrogen production in the world is still fossil energy hydrogen production, which has low cost and large output, and can be produced on a large scale, but it depends on fossil fuels, has low energy efficiency, causes serious environmental pollution in the hydrogen production process, and the produced hydrogen needs to be purified. Electrolytic water hydrogen production is a green, environmentally friendly, clean and high-purity hydrogen production method, which produces hydrogen and oxygen under the action of direct current. However, the high consumption of electricity makes it not economical enough, and thus its development is greatly limited.

[0003] The oxygen evolution reaction (OER) of the anode four-electron transfer process has the problems of slow kinetic rate and high thermodynamic energy barrier, which seriously restricts its industrial application. Compared with the two-electron process HER, OER involves a multi-step proton-coupled electron transfer process (PCET), and the high thermodynamic energy barrier is the main bottleneck restricting the energy efficiency of electrolytic water and industrial application.

[0004] Therefore, developing efficient and inexpensive oxygen evolution catalysts is still a key scientific problem that needs to be solved in the process of promoting the industrial application of electrolytic water technology. At present, noble metal catalysts (Ru, Ir, etc.) and their derivatives have been considered as the most effective electrolytic water oxygen evolution catalysts, but their low reserves and high prices hinder their large-scale commercial application. Transition metal cobalt sulfide has the characteristics of abundant resources, wide application range and structural diversity, and is a promising substitute for noble metal catalysts.

[0005] Among them, pyrite CoS2 is one of the many cobalt sulfides, which has good electrical conductivity and excellent catalytic activity, and is an economical and effective water electrolysis oxygen evolution catalyst that can replace noble metals. In order to further improve the intrinsic activity of cobalt-based sulfides, the method of constructing a heterostructure can be used to improve the electrocatalytic reaction kinetics of the electrode. Among them, the heterojunction structure catalyst is composed of two or more components with different properties and functions. A common strategy is to composite the catalytically active phase with the conductive carrier material to construct an integrated electrocatalyst. This integrated structure can avoid the use of adhesives in the catalytic process, improve the efficiency of electron transfer, improve the activity of the catalytic site, achieve large current density electrocatalytic water splitting, and thus reduce the energy consumption of the reaction. By forming a heterojunction, the catalyst can induce charge redistribution and electron transfer at the interface, thereby adjusting the reaction path and enhancing the reaction rate. In the catalytic process, cobalt-based sulfides play a pre-catalytic role, and their surfaces will be oxidized to oxides / hydroxides, which act as true catalytically active substances, and the nanostructure of the reconstructed metal oxide / hydroxide has a higher surface area, and its performance is better than that of directly synthesized metal oxides / hydroxides, which can exhibit higher activity in OER. By constructing a heterostructure, the electronic structure of the active site on the catalyst surface is optimized, the formation of reconstructed species is promoted, and the catalytic activity of the catalyst is improved.

[0006] Therefore, the present application aims to introduce a heterojunction into the CoS2 structure by designing and synthesizing a unique integrated CoS2 / Co(OH)F heterostructure with a large number of defects, adjust the active edge state length and electronic interaction of the heterostructure, expose more catalytically active sites and strong electronic interactions, promote water dissociation kinetics and reconstruction processes, and improve its catalytic activity and long-term stability, which is of great significance to meet the practical needs of efficient oxygen evolution at high current density. SUMMARY

[0007] The present application aims to overcome the shortcomings of the prior art and provide a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst.

[0008] The present application also aims to provide the application of the above-mentioned CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst in alkaline water electrolysis oxygen evolution and in alkaline membrane electrode (MEA) water electrolysis system to realize industrialized high current density oxygen evolution.

[0009] The above-mentioned first object of the present application can be achieved by the following technical solution: a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst is prepared by a method comprising the following steps:

[0010] (1) taking a cobalt foam (CF) as a conductive substrate and a cobalt source, and performing pretreatment;

[0011] (2) transferring the pretreated cobalt foam, a sulfur source aqueous solution and a fluorine source aqueous solution into a high-pressure reaction container, performing a hydrothermal reaction after sealing the high-pressure reaction container, and after the reaction is completed, naturally cooling the high-pressure reaction container, taking out the reaction product, and washing and drying the reaction product to obtain a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst grown in situ on the cobalt foam.

[0012] The heterojunction interface can modify the electronic state of the material itself and the coordination environment around the atom, can fundamentally improve the inherent activity of the active site, promote the adsorption of water in the solution and the dissociation and activation reaction process of the material, reduce the reaction energy barrier, accelerate the catalyst reconstruction process and reaction kinetics, and thus improve the electrocatalytic performance.

[0013] The CoS2 / Co(OH)F heterostructure with rich defects is successfully prepared by the one-step hydrothermal method, which can not only enhance the charge transfer, but also improve the activity of the catalytic site. The catalyst carrier in the integrated structure can adjust the binding energy of the reaction intermediates by changing the electronic structure of the active site or directly participating in the reaction. By forming a heterojunction interface, the catalyst can form defects at the interface, induce S, F and Co charge redistribution and electron transfer, induce CoS2 / Co(OH)F lattice distortion, adjust the reaction path and enhance the reaction rate, and expose a large number of active sites, so that the material has excellent electrocatalytic oxygen evolution performance in alkaline conditions and full water splitting performance in alkaline membrane water electrolysis devices.

[0014] In the above CoS2 / Co(OH)F heterostructure self-supporting water decomposition electrocatalyst:

[0015] Preferably, the pretreatment in step (1) includes first ultrasonic cleaning the cobalt foam with acetone to remove surface organic matter, then ultrasonic cleaning the cobalt foam with dilute hydrochloric acid to remove surface oxides, then rinsing the surface residues with deionized water and anhydrous ethanol, and finally drying in a vacuum drying oven.

[0016] More preferably, the pretreatment in step (1) includes first ultrasonic cleaning the cobalt foam with acetone for 10 min to remove surface organic matter, then ultrasonic cleaning the cobalt foam with dilute hydrochloric acid with a concentration of 3 mol / L for 10 min to remove surface oxides, then rinsing the surface residues with deionized water and anhydrous ethanol, and finally drying in a vacuum drying oven at 60℃ for 6 h.

[0017] Preferably, the sulfur source aqueous solution in step (2) is a thiourea aqueous solution, and the concentration of the thiourea aqueous solution is 5 mmol / L to 100 mmol / L.

[0018] Preferably, the aqueous solution of the sulfur source in step (2) is an aqueous solution of thiourea, and the concentration of the aqueous solution of thiourea is 5 mmol / L to 50 mmol / L.

[0019] Preferably, the aqueous solution of the fluorine source in step (2) is an aqueous solution of ammonium fluoride, and the concentration of the aqueous solution of ammonium fluoride is 2 mmol / L to 20 mmol / L.

[0020] Preferably, the aqueous solution of the fluorine source in step (2) is an aqueous solution of ammonium fluoride, and the concentration of the aqueous solution of ammonium fluoride is 2 mmol / L to 10 mmol / L.

[0021] Preferably, in the hydrothermal reaction in step (2), the hydrothermal reaction temperature is 100 to 180 DEG C, and the hydrothermal reaction time is 2 to 20 h; more preferably, the hydrothermal reaction time is 2 to 10 h.

[0022] Preferably, in step (2), the reaction product is washed with deionized water and ethanol, and vacuum dried.

[0023] The above-mentioned second object of the present application can be achieved by the following technical solution: application of the CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst in alkaline water electrolysis oxygen evolution.

[0024] The present application also provides application of the CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst in alkaline membrane electrode water electrolysis system to realize industrial large current density oxygen evolution.

[0025] Preferably, the range of industrial large current density is 0.5 A / cm 2 ~ 1.5 A / cm 2 .

[0026] Therefore, the CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst of the present application can be prepared by one-step hydrothermal method, the test steps are simple, the prepared product can be used for alkaline water electrolysis oxygen evolution and under large current density, and has long-term stability, and can also be applied in alkaline membrane electrolytic cell devices to realize large current density water splitting.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1) The prepared CoS2 / Co(OH)F of the present application is an integrated catalyst, wherein the foam cobalt (CF) not only serves as a substrate for stabilizing the heterostructure, but also serves as a sacrificial cobalt source, thereby avoiding the use of additional Co cations, effectively promoting the contact of the substrate with the active sites, without the aid of a polymer binder, and effectively promoting the rapid diffusion of bubbles and ions and the rapid transfer of electrons, accelerating the reaction process;

[0029] (2) The application adopts the method of constructing a heterojunction interface, changes the electronic structure and atomic arrangement of the CoS2 / Co(OH)F material, optimizes the adsorption free energy of water on the active site, and reduces the reaction energy barrier; under the synergistic effect of CoS2, Co(OH)F and CF (foamed cobalt), the overall catalytic activity of the catalyst is improved;

[0030] (3) The integrated CoS2 / Co(OH)F water electrolysis catalyst in the application can realize efficient oxygen evolution under industrial high current density and alkaline membrane electrolysis cell device. BRIEF DESCRIPTION OF DRAWINGS

[0031] The application will be further described below with reference to the accompanying drawings and examples;

[0032] Figure 1 The SEM image of the CoS2 / Co(OH)F integrated water electrolysis anode oxygen evolution catalyst prepared in Example 1 is shown;

[0033] Figure 2 The TEM image of the CoS2 / Co(OH)F integrated water electrolysis anode oxygen evolution catalyst prepared in Example 1 is shown;

[0034] Figure 3 The HRTEM image of the CoS2 / Co(OH)F integrated water electrolysis anode oxygen evolution catalyst prepared in Example 1 is shown;

[0035] Figure 4 The Raman images of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown;

[0036] Figure 5 The oxygen evolution polarization curve images of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown;

[0037] Figure 6 The water electrolysis anode oxygen evolution performance curve image of Example 1 under industrial condition high current density is shown;

[0038] Figure 7 The long-term stability image of the water electrolysis anode oxygen evolution of Example 1 is shown;

[0039] Figure 8 The performance image of Example 1 in the industrial alkaline membrane water electrolysis device is shown;

[0040] Figure 9 The long-term stability image of the alkaline membrane water electrolysis device of Example 1 is shown. DETAILED DESCRIPTION

[0041] The specific embodiments of the present application are further described below. It is to be understood that the description of these embodiments is intended to help understand the present application and is not intended to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0042] The materials, reagents, etc. used in the following examples can be obtained commercially unless otherwise specified.

[0043] The experimental methods used in the following implementation methods are conventional experimental methods unless otherwise specified.

[0044] The terms used in the following implementation methods and examples generally have the meanings commonly understood by those of ordinary skill in the art unless otherwise specified.

[0045] First part CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst

[0046] Example 1

[0047] The CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst provided in this embodiment is prepared by a method comprising the following steps:

[0048] (1) Foam cobalt pretreatment:

[0049] A piece of commercially available foam cobalt (1x3cm 2 ) was immersed in an acetone solution and ultrasonicated for 10 min, then immersed in a 3 mol / L hydrochloric acid solution and ultrasonicated for 10 min, then rinsed with deionized water and anhydrous ethanol to remove surface residues, and placed in a vacuum drying oven and dried at 60°C for 6h;

[0050] (2) Preparation of CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst

[0051] The pretreated foam cobalt was immersed in a 30mM thiourea aqueous solution and a 10mM ammonium fluoride aqueous solution, then transferred to a high-pressure reaction kettle, the reaction kettle was sealed, then placed in a blast drying oven and reacted at 140°C for 5h, after the reaction was completed, the reaction kettle was naturally cooled, the reaction product was taken out and washed with deionized water and ethanol, then vacuum dried, and the CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst was obtained.

[0052] Example 2

[0053] The CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst provided in this embodiment is prepared by a method comprising the following steps:

[0054] (1) Foam cobalt pretreatment:

[0055] A piece of commercially available foam cobalt (1 x 3 cm 2 ) was immersed in an acetone solution and ultrasonicated for 10 min, then immersed in a 3M hydrochloric acid solution and ultrasonicated for 10 min, and then rinsed with deionized water and anhydrous ethanol to remove surface residues, and placed in a vacuum drying oven and dried at 60°C for 6 h;

[0056] (2) Preparation of a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst

[0057] After the pretreated foam cobalt was immersed in a 30 mM aqueous thiourea solution and a 10 mM aqueous ammonium fluoride solution, it was transferred to a high-pressure reaction kettle, the reaction kettle was sealed, and then placed in a blast drying oven and reacted at 140°C for 10 h. After the reaction was completed, the reaction kettle was naturally cooled, the reaction product was taken out, washed with deionized water and ethanol, and then vacuum dried to obtain a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst.

[0058] Example 3

[0059] The CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst provided in this example is prepared by a method comprising the following steps:

[0060] (1) Pretreatment of foam cobalt

[0061] A piece of commercially available foam cobalt (1 x 3 cm 2 ) was immersed in an acetone solution and ultrasonicated for 10 min, then immersed in a 3M hydrochloric acid solution and ultrasonicated for 10 min, and then rinsed with deionized water and anhydrous ethanol to remove surface residues, and placed in a vacuum drying oven and dried at 60°C for 6 h;

[0062] (2) Preparation of a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst

[0063] After the pretreated foam cobalt was immersed in a 30 mM aqueous thiourea solution and a 10 mM aqueous ammonium fluoride solution, it was transferred to a high-pressure reaction kettle, the reaction kettle was sealed, and then placed in a blast drying oven and reacted at 140°C for 10 h. After the reaction was completed, the reaction kettle was naturally cooled, the reaction product was taken out, washed with deionized water and ethanol, and then vacuum dried to obtain a CoS2 / Co(OH)F heterostructure self-supporting water electrolysis oxygen evolution catalyst.

[0064] Example 4

[0065] Different from Example 1, the concentration of the aqueous thiourea solution in step (2) was 15 mmol / L, and the concentration of the aqueous ammonium fluoride solution was 5 mmol / L.

[0066] Example 5

[0067] Different from example 1, the concentration of thiourea aqueous solution in step (2) is 45 mmol / L, and the concentration of ammonium fluoride aqueous solution is 15 mmol / L.

[0068] Example 6

[0069] Different from example 1, the concentration of thiourea aqueous solution in step (2) is 80 mmol / L, and the concentration of ammonium fluoride aqueous solution is 20 mmol / L.

[0070] Comparative example 1

[0071] Compared with example 1, the difference is that no fluorine source aqueous solution is added in the preparation of CoS2 / Co(OH)F electrode, and the obtained electrode is CoS2.

[0072] Comparative example 2

[0073] Compared with example 1, the difference is that no sulfur source aqueous solution is added in the preparation of CoS2 / Co(OH)F electrode, and the obtained electrode is Co(OH)F.

[0074] Second part CoS2 / Co(OH)F heterostructure self-supporting electrolytic water oxygen evolution catalyst structure and performance test

[0075] 1) The CoS2 / Co(OH)F in example 1 and CoS2 in comparative example 1 and Co(OH)F in comparative example 2 were subjected to SEM test.

[0076] The SEM image of CoS2 / Co(OH)F in example 1 is shown in Figure 1 It can be seen that the catalyst is anchored by nanoparticles on the edge and surface of nanosheet, wherein the smooth surface morphology becomes more rough and dense, forming a CoS2 / Co(OH)F heterojunction, which can not only enhance the charge transfer, but also expose more active sites, which is beneficial to improve the catalytic efficiency.

[0077] 2) The CoS2 / Co(OH)F in example 1 was subjected to TEM test

[0078] The TEM image of CoS2 / Co(OH)F in example 1 is shown in Figure 2 As expected, the TEM image shows that CoS2 nanoparticles are anchored on Co(OH)F nanosheet, which is consistent with the SEM result.

[0079] 3) The CoS2 / Co(OH)F in example 1 was subjected to HRTEM test

[0080] The HRTEM image of CoS2 / Co(OH)F in example 1 is shown in Figure 3As shown, the lattice fringes with a spacing of 0.488 nm are attributed to the (010) plane of the crystallographic Co(OH)F, while the lattice fringes with a spacing of 0.248 nm are attributed to the (012) plane of the CoS2 crystal, thus verifying that the material is composed of a heterojunction interface of Co(OH)F and CoS2.

[0081] 4) Raman test of CoS2 / Co(OH)F in Example 1 and CoS2 in Comparative Example 1, Co(OH)F in Comparative Example 2

[0082] The Raman spectrum of CoS2 / Co(OH)F in Example 1 is shown in Figure 4 The spectrum shows a set of characteristic signals at 286, 334 and 396 cm -1 in the wavelength range of 200 to 800 cm -1 , which are attributed to the bond vibrations of CoS2. The characteristic peak set at 478, 517 and 685 cm -1 corresponds to the characteristic peaks of Co(OH)F. Compared with the peaks in Co(OH)F, these peaks in CoS2 / Co(OH)F are slightly negatively shifted, implying a strong electronic interaction between CoS2 and Co(OH)F.

[0083] 5) Test of water splitting electrocatalytic performance of Examples 1-3 and Comparative Examples 1-2

[0084] The electrochemical performance test adopts the standard three-electrode system of CHI 760E electrochemical workstation, and the test of water splitting electrocatalytic performance is as follows:

[0085] The polarization curve (LSV) is tested in 1M KOH solution, with Hg / HgO as the reference electrode and carbon rod as the counter electrode, and the working electrode is the sample prepared in the example or comparative example, and the test scan rate is 5 mV / s.

[0086] The oxygen evolution polarization curve of CoS2 / Co(OH)F in Example 1, CoS2 in Comparative Example 1 and Co(OH)F in Comparative Example 2 is shown in Figure 5 As can be seen from Figure 5 , when the oxygen evolution current density is 100 mA / cm 2 and 200 mA / cm 2 , the overpotential of CoS2 / Co(OH)F is 318 mV and 339 mV respectively, the overpotential of CoS2 is 342 mV and 368 mV respectively, and the overpotential of Co(OH)F is 398 mV and 419 mV respectively.

[0087] The oxygen evolution performance of CoS2 / Co(OH)F catalyst in Example 1 under large current density of industrial conditions is shown in Figure 6As shown in Figure 6 As can be seen, the CoS2 / Co(OH)F catalyst can drive the industrial current density of 0.5 A / cm 2 and 412 mV at a small overpotential of 374 mV. 2 , the OER activity exceeds that of commercial RuO2 on CF, indicating its potential practical application in the field of hydrogen production by water electrolysis. In general, the industrial current density refers to > 200 mA / cm 2 .

[0088] The long-term stability diagram of oxygen evolution of CoS2 / Co(OH)F in Example 1 is shown in Figure 7 As can be seen, the CoS2 / Co(OH)F electrode material exhibits OER catalytic stability in alkaline electrolyte for at least 50 h. Figure 7

[0089] The alkaline membrane electrolysis cell water splitting performance diagram of CoS2 / Co(OH)F in Example 1 is shown in Figure 8 . Anion exchange membrane water electrolyzer was assembled using CoS2 / Co(OH)F as the anode and commercial Pt / C electrocatalyst supported on gas diffusion layer (carbon cloth) as the cathode. In the industrial water electrolysis system, the working temperature is usually about 50-80℃, in order to further reduce the total voltage required for water splitting. As can be seen from Figure 8 , under the condition of industrial electrolysis water 80℃, CoS2 / Co(OH)F electrode full water splitting requires only 1.57 V and 1.77 V to make the current density reach 100 mA / cm 2 and 500 mA / cm 2 . It shows excellent alkaline membrane electrolysis cell device water splitting performance, indicating the potential application of the material in the industrial water electrolysis system.

[0090] The MEA full water splitting long-term stability diagram of CoS2 / Co(OH)F in Example 1 is shown in Figure 9 As can be seen, the CoS2 / Co(OH)F electrode material exhibits water splitting catalytic stability in alkaline electrolyte for up to 120 h. Figure 9

[0091] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of these embodiments without departing from the principles and spirits of the present application still fall within the protection scope of the present application.​​

Claims

1. A CoS2 / Co(OH)F heterostructure self-supported electrolytic water oxygen evolution catalyst, characterized in that, Preparation is obtained by the method comprising the following steps: (1) the foam cobalt as a conductive substrate and cobalt source, and pretreatment; (2) the pretreated foam cobalt, sulfur source aqueous solution and fluorine source aqueous solution are transferred to a high-pressure reaction vessel, the high-pressure reaction vessel is sealed and subjected to hydrothermal reaction, after the reaction, the high-pressure reaction kettle is naturally cooled, the reaction is taken out, washed, dried, and the CoS2 / Co(OH)F heterostructure self-supporting electrolytic water oxygen evolution catalyst grown in situ on the foam cobalt is obtained.

2. The CoS2 / Co(OH)F heterostructure self-supported water electrolysis oxygen evolution catalyst of claim 1, wherein, The pretreatment in step (1) includes first ultrasonic cleaning the foam cobalt with acetone to remove surface organic matter, then ultrasonic cleaning with dilute hydrochloric acid to remove surface oxides, then rinsing the surface residues with deionized water and anhydrous ethanol, and finally drying in a vacuum drying oven.

3. The CoS2 / Co(OH)F heterostructure self-supported water splitting oxygen evolution catalyst of claim 1, wherein, The sulfur source aqueous solution in step (2) is a thiourea aqueous solution, and the concentration of the thiourea aqueous solution is 5-100 mmol / L.

4. The CoS2 / Co(OH)F heterostructure self-supported water splitting oxygen evolution catalyst of claim 1, wherein, The fluorine source aqueous solution in step (2) is an ammonium fluoride aqueous solution, and the concentration of the ammonium fluoride aqueous solution is 2-20 mmol / L.

5. The CoS2 / Co(OH)F heterostructure self-supported electrolytic water oxygen evolution catalyst of claim 1, wherein, In step (2), the hydrothermal reaction temperature is 100-180℃, and the hydrothermal reaction time is 2-20h.

6. The CoS2 / Co(OH)F heterostructure self-supported electrolytic water oxygen evolution catalyst of claim 1, wherein, In step (2), the reaction is washed with deionized water and ethanol, and vacuum dried.

7. The CoS2 / Co(OH)F heterostructure self-supporting electrolytic water oxygen evolution catalyst of any one of claims 1-6 is used in alkaline electrolytic water oxygen evolution.

8. The CoS2 / Co(OH)F heterostructure self-supporting electrolytic water oxygen evolution catalyst of any one of claims 1-6 is used in alkaline membrane electrode electrolytic water system to realize industrial large current density oxygen evolution.

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