A transition metal sulfide catalyst and its preparation method and application

Abstract

The present invention relates to the field of fuel cell technology, and more particularly to a transition metal sulfide catalyst, its preparation method, and application. The specific preparation method is as follows: in a first solvent system, a Ni-Fe Prussian blue analogue and an alkaline solution are mixed to obtain a precursor; in a second solvent system, the precursor and a sulfur source are placed at 150°C to 200°C for a hydrothermal reaction to release Fe from the precursor. 3+ and Ni 2+ and S in the sulfur source 2 ⁻ A sulfurization reaction occurs to generate an amorphous FeNi sulfide, obtaining a Fe-Ni-S precursor; the Fe-Ni-S precursor is calcined under a protective atmosphere to convert the amorphous FeNi sulfide into spinel FeNi2S4, thereby obtaining a transition metal sulfide catalyst. The transition metal sulfide catalyst prepared by the present invention exhibits a relatively good electrochemical reaction for methanol oxidation catalysis and maintains high stability during the electrochemical reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a transition metal sulfide catalyst, a preparation method and an application thereof. Background Art

[0002] Direct methanol fuel cells (DMFCs) are fuel cells that use methanol as the anode active material. With their high energy density, low operating temperature, renewable fuel, and low pollutant emissions, DMFCs are considered one of the most promising clean energy technologies for portable electronic devices, distributed power generation, and transportation.

[0003] In DMFCs, the anode catalyst is responsible for catalyzing the methanol oxidation reaction, and its performance directly determines the cell's output power, energy conversion efficiency, and long-term stability. Platinum-based catalysts are currently the most widely used methanol oxidation catalysts in DMFCs. However, platinum-based catalysts are easily poisoned by CO intermediates during the catalytic process, resulting in decreased activity, and precious metals are expensive. Therefore, the development of low-cost, highly active, and CO-poisoning-resistant non-precious metal alternative catalysts has become a key challenge in the DMFC field.

[0004] Transition metal sulfides have shown excellent electrocatalytic performance due to their rich variety, fast electron transfer characteristics and good stability, making them candidate materials to replace Pt-based catalysts. Among them, by regulating the formation of metal sulfide heterostructures, it is beneficial to obtain more available active sites and use strong electronic interactions to improve electrochemical properties. For example, Literature 1: Applications to energy storage in a symmetric supercapacitor and electrocatalytic methanol oxidation [J]. Journal of Alloys and Compounds, 2023, 938: 168450. Literature 1 constructs Ni3S2 / Cu on multi-walled carbon nanotubes by a two-step hydrothermal-sulfurization method. x S composite heterojunction catalyst, and used for methanol oxidation catalysis, Ni3S2 / Cu xS composite heterojunction catalysts exhibit long-term durability and high stability. Reference 2: Wu F, Guo X, Wang Q, et al. A hybrid of MIL-53(Fe) and conductive sulfide as a synergistic electrocatalyst for the oxygen evolution reaction[J]. Journal of Materials Chemistry A, 2020, 8(29): 14574-14582. Reference 2 designed a hybrid Ni3S2 / FeS heterostructure catalyst with strong electronic synergy at the interface, optimizing the adsorption energy of OH species and promoting the catalytic reaction by removing toxic intermediates.

[0005] However, during the synthesis process, the above-mentioned transition metal sulfide catalysts still have the problems of disordered sulfide accumulation, excessive metal-sulfur bond strength inhibiting intermediate adsorption, and lack of mass transfer channels, which leads to limited active site density of transition metal sulfide catalysts and thus insufficient catalyst activity. Summary of the Invention

[0006] In order to solve the technical problems in the above-mentioned synthesis method, such as disordered accumulation of sulfides, insufficient optimization of the electronic structure of the sulfide surface, and lack of mass transfer channels, which lead to insufficient activity of the catalyst, the present invention provides a transition metal sulfide catalyst, a preparation method and application thereof.

[0007] The present invention is based on the in-situ conversion strategy of Prussian blue analogues. The morphology of the original Prussian blue analogues is regulated by etching to provide nucleation sites, sulfur vacancies are introduced by further hydrothermal sulfurization, and a spinel-type transition metal sulfide catalyst with a nanocage structure is prepared after thermal decomposition and calcination.

[0008] The present invention utilizes the specific framework structure of a Prussian blue analogue to inhibit the agglomeration of active sites. At the same time, by etching the Ni-Fe Prussian blue analogue, an etching interface rich in unsaturated coordination sites is formed, providing nucleation sites for the subsequent generation of sulfur vacancies. Then, the metal-sulfur bond strength is regulated by the introduction of sulfur vacancies to optimize the adsorption energy of the intermediate. At the same time, the three-dimensional interconnected pores formed accelerate the reaction mass transfer, effectively improving the catalytic performance of methanol oxidation. The present invention solves the technical problems in the prior art of disordered accumulation of sulfides, insufficient optimization of the electronic structure of the sulfide surface, and lack of mass transfer channels, which lead to insufficient activity of the catalyst.

[0009] The first object of the present invention is to provide a method for preparing a transition metal sulfide catalyst, comprising the following steps:

[0010] In a first solvent system, a Ni-Fe Prussian blue analogue and an alkaline solution are mixed so that the alkaline solution etches the Ni-Fe Prussian blue analogue to obtain a precursor; in a second solvent system, the precursor and a sulfur source are placed at 150°C to 200°C for a hydrothermal reaction so that the precursor releases Fe 3+ and Ni 2+ and S in the sulfur source 2- A sulfurization reaction occurs to generate amorphous FeNi sulfide to obtain a Fe-Ni-S precursor; under a protective atmosphere, the Fe-Ni-S precursor is calcined to convert the amorphous FeNi sulfide into spinel FeNi2S4 to obtain a transition metal sulfide catalyst with a nanocage structure.

[0011] Preferably, the specific preparation method of Ni-Fe Prussian blue analogues is as follows:

[0012] Dissolve the soluble nickel salt and the complexing agent in water so that the complexing agent reacts with the Ni in the soluble nickel salt. 2+ react to form a soluble complex to obtain a first mixed solution; dissolve the complex salt in water to obtain a second mixed solution; mix the first mixed solution and the second mixed solution by stirring, and under the action of a complexing agent, the nickel ions in the soluble nickel salt and the [Fe(CN)6] 3- Coordination occurs, and after aging at room temperature, a precursor of a Prussian blue analogue containing nickel and iron is formed to obtain a Ni-Fe Prussian blue analogue.

[0013] Preferably, the complex salt is potassium ferrocyanide or sodium ferrocyanide.

[0014] Preferably, Ni in the soluble nickel salt 2+ and [Fe(CN)6] in complex salts 3- The molar ratio is 1:0.5~0.8.

[0015] Preferably, Ni in the soluble nickel salt 2+ The molar ratio of the complexing agent is 1:1.5~2.0.

[0016] Preferably, the complexing agent is sodium citrate. The present invention utilizes the citrate in sodium citrate to react with Ni 2+ The reaction forms a soluble complex, slowing the release rate of nickel ions and retarding the nucleation rate of the Prussian blue analog precursor containing nickel and iron, thereby regulating the anisotropic growth of the crystals and ultimately forming a uniform nanocubic structure. If the nickel ion release rate is too fast, it will lead to local supersaturation of nickel ions in the solution, instantly forming a large number of tiny crystal nuclei, triggering disordered aggregation, and affecting the formation of the final cubic morphology.

[0017] Preferably, the room temperature aging time is 24h~48h. The present invention promotes the [Fe(CN)6] 3- and Ni 2+ The reaction is complete; at the same time, the crystal growth and morphology are controlled by aging. During the aging process, the nanoparticles with high surface energy will gradually dissolve, and the ions will be redeposited on the surface of large particles, making the crystal size more uniform. The lattice defects are repaired by atomic rearrangement, the crystallinity is improved, and the cubic structure tends to be complete.

[0018] The present invention utilizes a Ni-Fe Prussian blue analogue to selectively etch in an alkaline solution, promoting controlled degradation of the metal-organic framework structure within the Ni-Fe Prussian blue analogue. This results in localized reconstruction of the surface lattice, forming an etched interface rich in unsaturated coordination sites, which provide nucleation sites for subsequent sulfur vacancy generation. Different bases have varying strengths, coordination abilities, solubility, and effects on material morphology and structure. Preferably, the alkaline solution is aqueous ammonia, aqueous ethylenediamine, or aqueous ammonium carbonate.

[0019] Preferably, Ni-Fe Prussian blue analogue and OH in alkaline solution - The molar ratio is 1:50~100.

[0020] Preferably, the etching time is 30 minutes.

[0021] It should be noted that in an aqueous solvent system, the precursor and the sulfur source are placed at 150°C to 200°C for hydrothermal reaction to thermally decompose the sulfur source and release S 2- ; Precursor releases Fe 3+ and Ni 2+ , and with S 2 ⁻Sulfidation occurs, forming amorphous FeNi sulfide and obtaining an Fe-Ni-S precursor. Due to the localized Ni enrichment in the precursor caused by etching, Ni-S bonds preferentially form during the sulfurization process, leaving the sulfur coordination around the Fe sites unsaturated and forming intrinsic sulfur vacancies. These sulfur vacancies act as electron defect centers, significantly reducing the charge transfer barrier and improving electron mobility by inducing delocalization of Fe 3d orbital electrons.

[0022] Preferably, the mass ratio of the precursor to the sulfur source is 1-2:1.

[0023] Preferably, the hydrothermal reaction time is 5 h to 8 h.

[0024] The Fe-Ni-S precursor is calcined to convert the amorphous FeNi sulfide into spinel FeNi2S4. The Fe / Ni multivalent state after calcination provides redox active sites. At the same time, the calcination removes residual organic matter. Preferably, the calcination conditions are: calcination at 300°C to 350°C for 2 hours.

[0025] The FeNi sulfide undergoes lattice reconstruction by high temperature calcination. The Fe / Ni multivalent states provide redox active sites. Nitrogen as an inert atmosphere inhibits excessive oxidation, so that high-valent species are retained in a metastable form. At the same time, the lattice vibration during the calcination process intensifies the electronic coupling between valence states. 3+ / Fe 2+ and Ni 3+ / Ni 2+ The redox couple forms a two-site cooperative system: Fe 3+ As an electron acceptor, Ni 2+ Electrons can be released through valence state transitions. This dynamic electron transfer process forms continuous active sites for the electrocatalytic reaction, improves the methanol oxidation activity of the catalyst, and maintains good stability.

[0026] Preferably, the soluble nickel salt is Ni(NO3)2·6H2O, NiSO4, NiCl2 or Ni(CH3COO)2; and the sulfur source is thioacetamide, thiourea or sulfur powder.

[0027] Preferably, the first solvent is ethanol and the second solvent is water.

[0028] The second object of the present invention is to provide a transition metal sulfide catalyst prepared by the above preparation method.

[0029] The third object of the present invention is to provide the use of the above transition metal sulfide catalyst in catalyzing methanol oxidation reaction.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] 1. The present invention is based on the in-situ conversion of Prussian blue analogs and prepares a transition metal sulfide catalyst with a nanocage structure through the coordinated regulation of etching, sulfurization, and calcination. The specific framework structure of the Prussian blue analog is used to inhibit the agglomeration of active sites. The Ni-Fe Prussian blue analog is etched to form an etched interface rich in unsaturated coordination sites, providing nucleation sites for the subsequent generation of sulfur vacancies. The introduction of sulfur vacancies then regulates the metal-sulfur bond strength to optimize the adsorption energy of the intermediate. At the same time, the three-dimensional interconnected pores formed accelerate the reaction mass transfer. Finally, high-temperature calcination causes the FeNi sulfide lattice to reconstruct, and the Fe / Ni multivalent states provide redox active sites, effectively improving the catalytic performance of methanol oxidation. This solves the technical problems of the existing technology, such as disordered sulfide accumulation, insufficiently optimized sulfide surface electronic structure, and lack of mass transfer channels, which lead to insufficient catalyst activity.

[0032] 2. The transition metal sulfide catalyst prepared by the present invention has a current density of 9.9 mA cm in an electrolyte solution containing methanol. -2 , showing a relatively good electrochemical reaction for methanol oxidation catalysis. At the same time, the hollow nanocage structure and intercomponent interactions of the transition metal sulfide catalyst enhance its durability and resistance to carbon monoxide poisoning during electrochemical testing; the transition metal sulfide catalyst maintains good stability during electrochemical testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 These are transmission electron micrographs of the Fe-Ni PBA prepared in comparative example 1 and the FeNi2S4 prepared in example 1; wherein, a is a transmission electron micrograph of the Fe-Ni PBA prepared in comparative example 1, and b is a transmission electron micrograph of the FeNi2S4 prepared in example 1.

[0034] Figure 2 This is the X-ray diffraction pattern of the Fe-Ni PBA prepared in Comparative Example 1.

[0035] Figure 3 This is the X-ray diffraction pattern of FeNi2S4 prepared in Example 1.

[0036] Figure 4 This is the cyclic voltammetry curve of methanol oxidation by the Fe-Ni PBA material prepared in Comparative Example 1.

[0037] Figure 5 This is the cyclic voltammetry curve of methanol oxidation by FeNi2S4 prepared in Example 1.

[0038] Figure 6 This is the methanol oxidation catalytic curve of the Fe-Ni PBA material prepared in Comparative Example 1 at different scan rates.

[0039] Figure 7 This is the methanol oxidation catalytic curve of FeNi2S4 prepared in Example 1 at different scan rates.

[0040] Figure 8 Statistical graphs of the chronoamperometric test results of the Fe-Ni PBA prepared in comparative example 1 and the FeNi2S4 prepared in example 1; wherein, a is a statistical graph of the chronoamperometric test results of the Fe-Ni PBA prepared in comparative example 1, and b is a statistical graph of the chronoamperometric test results of the FeNi2S4 prepared in example 1. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings.

[0042] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0043] Example 1

[0044] A method for preparing a transition metal sulfide catalyst comprises the following steps:

[0045] 150 mg of Ni(NO3)2·6H2O and 200 mg of sodium citrate were dissolved in 20 mL of deionized water to obtain a first mixed solution; 120 mg of K3[Fe(CN)6] was dissolved in 20 mL of deionized water to obtain a second mixed solution; the first mixed solution and the second mixed solution were stirred and mixed, aged at room temperature for 24 h, centrifuged, washed, and dried to obtain a Ni-Fe Prussian blue analogue, recorded as Fe-Ni PBA.

[0046] Under stirring conditions, 40 mg of Fe-Ni PBA and 10 mL of ethanol were mixed, and then 5 mL of H2O and 0.5 mL of NH3H2O ​​were added. After etching for 30 min, the mixture was centrifuged and washed with water and ethanol in sequence to obtain a precipitate.

[0047] Under stirring conditions, the precipitate was mixed with 30 mL of water, 20 mg of thioacetamide was added and dissolved, and the mixture was placed in a reactor for reaction at 180° C. for 6 h, and then centrifuged, washed, and dried to obtain a reactant.

[0048] Under N2 atmosphere, the reactants were calcined at 350°C for 2h to obtain a transition metal sulfide catalyst, namely FeNi2S4.

[0049] Example 2

[0050] A method for preparing a transition metal sulfide catalyst comprises the following steps:

[0051] 200 mg of Ni(NO3)2·6H2O and 240 mg of sodium citrate were dissolved in 30 mL of deionized water to obtain a first mixed solution; 150 mg of K3[Fe(CN)6] was dissolved in 30 mL of deionized water to obtain a second mixed solution; and the first mixed solution and the second mixed solution were stirred and mixed, aged at room temperature for 24 h, centrifuged, washed, and dried to obtain a Ni-Fe Prussian blue analogue, recorded as Fe-Ni PBA.

[0052] Under stirring conditions, 40 mg of Fe-Ni PBA and 10 mL of ethanol were mixed, and then 5 mL of H2O and 0.5 mL of NH3H2O ​​were added. After etching for 30 min, the mixture was centrifuged and washed with water and ethanol in sequence to obtain a precipitate.

[0053] Under stirring conditions, the precipitate was mixed with 30 mL of water, 40 mg of sulfur powder was added, and after dissolution, the mixture was placed in a reactor and reacted at 200° C. for 5 h, and then centrifuged, washed, and dried to obtain a reactant.

[0054] Under N2 atmosphere, the reactants were calcined at 300°C for 2h to obtain a transition metal sulfide catalyst, namely FeNi2S4.

[0055] Example 3

[0056] A method for preparing a transition metal sulfide catalyst comprises the following steps:

[0057] 150 mg of Ni(NO3)2·6H2O and 200 mg of sodium citrate were dissolved in 20 mL of deionized water to obtain a first mixed solution; 120 mg of K3[Fe(CN)6] was dissolved in 20 mL of deionized water to obtain a second mixed solution; the first mixed solution and the second mixed solution were stirred and mixed, aged at room temperature for 24 h, centrifuged, washed, and dried to obtain a Ni-Fe Prussian blue analogue, recorded as Fe-Ni PBA.

[0058] Under stirring conditions, 40 mg of Fe-Ni PBA and 10 mL of ethanol were mixed, and then 5 mL of H2O and 0.5 mL of NH3H2O ​​were added. After etching for 30 min, the mixture was centrifuged and washed with water and ethanol in sequence to obtain a precipitate.

[0059] Under stirring conditions, the precipitate was mixed with 30 mL of water, 20 mg of thiourea was added, and after dissolution, the mixture was placed in a reactor for reaction at 150° C. for 8 h, and then centrifuged, washed, and dried to obtain a reactant.

[0060] Under N2 atmosphere, the reactants were calcined at 350°C for 2h to obtain a transition metal sulfide catalyst, namely FeNi2S4.

[0061] Comparative Example 1

[0062] A method for preparing a Ni-Fe Prussian blue analogue comprises the following steps:

[0063] 150 mg of Ni(NO3)2·6H2O and 200 mg of sodium citrate were dissolved in 20 mL of deionized water to obtain a first mixed solution; 120 mg of K3[Fe(CN)6] was dissolved in 20 mL of deionized water to obtain a second mixed solution; the first mixed solution and the second mixed solution were stirred and mixed, aged at room temperature for 24 h, centrifuged, washed, and dried to obtain a Ni-Fe Prussian blue analogue, recorded as Fe-Ni PBA.

[0064] Examples 1 to 3 of the present invention all produced transition metal sulfide catalysts that solved the problems of disordered sulfide accumulation, insufficiently optimized sulfide surface electronic structure, and lack of mass transfer channels. The crystal structure data of the transition metal sulfide catalysts of Examples 2 to 3 were similar to that of Example 1. The transition metal sulfide catalyst produced in Example 1 was used as an example for research, and the specific research methods and results are shown below:

[0065] Experimental test.

[0066] 1. Transmission electron microscopy test:

[0067] like Figure 1 As shown in a, the Fe-Ni PBA prepared in Comparative Example 1 has a nanocubic structure and exhibits good dispersibility. Figure 1 As shown in b, the transition metal sulfide catalyst prepared in Example 1 gradually transforms from nanocubes to nanocages, and the etching of the nanocubes starts from the top corners. The overall framework does not collapse, forming a unique hollow nanocage structure.

[0068] This shows that the specific surface area of ​​the transition metal sulfide catalyst prepared by the in-situ conversion of Fe-Ni PBA in the present invention, including etching, sulfidation and calcination, is increased, so that the reactive species can more easily contact the catalytic sites of the material, thereby improving the catalytic efficiency of the transition metal sulfide catalyst.

[0069] 2. X-ray diffraction test:

[0070] like Figure 2 As shown in FIG. 1 , the characteristic diffraction peaks of the Fe-Ni PBA prepared in Comparative Example 1 are highly consistent with the diffraction data of the Ni[Fe(CN)5NO]·5H2O standard card JCPDS: 43-0772.

[0071] like Figure 3 As shown, the characteristic peaks of the transition metal sulfide catalyst prepared in Example 1 correspond to the (311), (222) and (400) crystal planes of FeNi2S4, which are completely consistent with the diffraction data of the standard card JCPDS 47-1740.

[0072] This demonstrates the structural evolution of the Fe-Ni PBA precursor to the metal sulfide phase and confirms the successful synthesis of the target product, FeNi2S4, in crystalline form. Furthermore, both the Fe-Ni PBA material prepared in Comparative Example 1 and the transition metal sulfide catalyst material prepared in Example 1 are pure phases.

[0073] 3. Electrochemical test:

[0074] The FeNi2S4 prepared in Example 1 and the Ni-Fe Prussian blue analogue prepared in Comparative Example 1 were used as catalysts to perform an electrochemical oxidation reaction on an electrolyte solution containing methanol, referred to as the catalyst. The catalyst was directly used as the working electrode, a platinum wire was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode, using a three-electrode system. The electrolyte solution was 1M KOH, or a mixed solution of 1M KOH and 0.5M methanol, with a volume ratio of KOH to methanol of 49:1. The catalysts were tested for their methanol electrochemical oxidation activity using a Shanghai Chenhua CHI660E electrochemical workstation.

[0075] like Figure 4 As shown in FIG1 , compared with the case where the electrolyte solution is KOH, when the electrolyte solution is a mixed solution of KOH and methanol, with the addition of methanol in the electrolyte solution, the reaction current of the Fe-Ni PBA prepared in Comparative Example 1 increases to a certain extent, and the current density of the Fe-Ni PBA material prepared in Comparative Example 1 is 3.3 mA cm -2 .

[0076] like Figure 5 As shown in Figure 2, compared with the case where the electrolyte solution is KOH, when the electrolyte solution is a mixed solution of KOH and methanol, the current of the FeNi2S4 catalyst increases significantly with the addition of methanol, a methanol oxidation peak appears, and the current density increases to 9.9 mA cm -2 , FeNi2S4 catalyst showed the highest methanol oxidation current density, indicating that the FeNi2S4 catalyst prepared in Example 1 has a relatively good electrochemical reaction for methanol oxidation catalysis.

[0077] like Figure 6 As shown in FIG, with the increase of the scan rate, the current density of the Fe-Ni PBA prepared in Comparative Example 1 shows an upward trend, indicating that the methanol oxidation reaction is a diffusion-controlled process.

[0078] like Figure 7 As shown in the figure, under the same test conditions, when the scan rate increases from 10 mV / s to 200 mV / s, the anode peak current density of the FeNi2S4 catalyst prepared in Example 1 is significantly improved; this shows that the FeNi2S4 catalyst prepared in Example 1 has a relatively good electrochemical reaction for methanol oxidation catalysis.

[0079] 4. Stability test.

[0080] In order to test the stability of the prepared catalytic material, a 2000-second chronoamperometric test was performed in the embodiment of the present invention.

[0081] like Figure 8As shown, compared with the Fe-Ni PBA material prepared in Comparative Example 1, the FeNi2S4 catalyst prepared in Example 1 maintained better stability in the electrochemical test. This is because the hollow nanocage structure and the interaction between the components of the material help to enhance the durability of the electrochemical test and the ability to resist carbon monoxide poisoning.

[0082] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, the present invention describes preferred embodiments to avoid redundancy. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts, and such changes and modifications fall within the scope of the present invention.

[0083] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a transition metal sulfide catalyst, characterized in that: The steps include: In a first solvent system, a Ni-Fe Prussian blue analogue and an alkali solution are mixed so that the alkali etches the Ni-Fe Prussian blue analogue to obtain a precursor; In the second solvent system, the precursor and the sulfur source are placed at 150℃~200℃ for hydrothermal reaction to release Fe 3+ and Ni 2+ and S in the sulfur source 2- A sulfidation reaction occurs to generate amorphous FeNi sulfide and obtain a Fe-Ni-S precursor; Under a protective atmosphere, the Fe-Ni-S precursor is calcined to convert the amorphous FeNi sulfide into spinel FeNi2S4, thereby obtaining a transition metal sulfide catalyst with a nanocage structure. The mass ratio of the precursor to the sulfur source is 1~2:

1.

2. The method for preparing a transition metal sulfide catalyst according to claim 1, wherein The specific preparation method of Ni-Fe Prussian blue analogues is as follows: Dissolve the soluble nickel salt and the complexing agent in water so that the complexing agent reacts with the Ni in the soluble nickel salt. 2+ reacting to form a soluble complex to obtain a first mixed solution; dissolving the complex salt in water to obtain a second mixed solution; The first mixed solution and the second mixed solution are mixed by stirring, and under the action of the complexing agent, the nickel ions in the soluble nickel salt and the [Fe(CN)6] 3- Coordination occurs, and after aging at room temperature, a precursor of a Prussian blue analogue containing nickel and iron is formed to obtain a Ni-Fe Prussian blue analogue; The complex salt is potassium ferrocyanide or sodium ferrocyanide; The complexing agent is sodium citrate.

3. The method for preparing a transition metal sulfide catalyst according to claim 2, wherein: Ni in soluble nickel salts 2+ and [Fe(CN)6] in complex salts 3- The molar ratio is 1:0.5~0.8; Ni in soluble nickel salts 2+ The molar ratio of the complexing agent is 1:1.5~2.

0.

4. The method for preparing a transition metal sulfide catalyst according to claim 2, wherein: The soluble nickel salt is Ni(NO3)2·6H2O, NiSO4, NiCl2 or Ni(CH3COO)2.

5. The method for preparing a transition metal sulfide catalyst according to claim 1, wherein: The sulfur source is thioacetamide, thiourea or sulfur powder.

6. The method for preparing a transition metal sulfide catalyst according to claim 1, wherein: The etching time is 30 minutes; the hydrothermal reaction time is 5 hours to 8 hours; The calcination conditions are: calcination at 300℃~350℃ for 2h.

7. The method for preparing a transition metal sulfide catalyst according to claim 1, wherein: Ni-Fe Prussian blue analogues and OH in alkaline solutions - The molar ratio is 1:50~100; the alkaline solution is an aqueous ammonia solution, an aqueous ethylenediamine solution or an aqueous ammonium carbonate solution.

8. The method for preparing a transition metal sulfide catalyst according to claim 1, wherein: The first solvent is ethanol, and the second solvent is water.

9. A transition metal sulfide catalyst, characterized in that The transition metal sulfide catalyst is prepared by the preparation method of the transition metal sulfide catalyst according to any one of claims 1 to 8.

10. Application of a transition metal sulfide catalyst in a catalytic methanol fuel cell, characterized in that: The transition metal sulfide catalyst is the transition metal sulfide catalyst according to claim 9.

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