A prussian blue analogue self-supporting anode for anion exchange membrane water electrolyzer and a preparation method thereof

Abstract

The application discloses a Prussian blue analogue self-supporting anode for an anion exchange membrane water electrolyzer, and a preparation method thereof, which comprises the following steps: reacting pretreated nickel foam (NF) with a metal salt solution, and then performing sulfidation treatment and nitrogen reduction treatment to prepare a metal sulfide nanomaterial rich in defects; and performing coordination reaction on the metal sulfide nanomaterial with citric acid and potassium ferricyanide to obtain Fe-coordinated Prussian blue analogue material CoFePBA@NiCo2S4 / NF. The self-supporting anode obtained by the application has excellent catalytic activity and stability, and the preparation method involved is relatively simple, the reaction condition is mild, the cost is relatively low, and the application is suitable for popularization and application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalytic materials, and particularly relates to a Prussian blue analogue self-supporting anode for an anion exchange membrane water electrolyzer and a preparation method thereof. BACKGROUND

[0002] Low-temperature electrochemical water splitting is expected to provide a method for converting electricity generated from renewable energy into clean hydrogen fuel. At present, there are three types of water electrolysis, including alkaline liquid electrolyte (AE), proton exchange membrane (PEM) water electrolysis and anion exchange membrane (AEM) water electrolysis. Among them, alkaline AEM water electrolysis is of great concern due to its advantages of AE electrolysis and PEM electrolysis.

[0003] The oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) two half-reactions constitute the water splitting reaction. The OER involves the transfer of four electrons and is a slow reaction in kinetics, and the high overpotential limits the water splitting efficiency. The commonly used OER catalysts at present are mainly noble metal iridium dioxide (IrO2) and ruthenium dioxide (RuO2), etc. Due to their high price and scarcity, they cannot be used on a large scale, so it is very important to develop high-activity non-noble metal electrocatalysts to reduce the overpotential of electrocatalytic reaction and improve the energy and power density of renewable energy devices. Transition metal sulfides have excellent electronic transfer ability and unique atomic structure, and show excellent electrocatalytic performance, and become a very promising catalytic material. However, most transition metal sulfides only show limited electrocatalytic performance, so it is necessary to design and synthesize more efficient and stable multifunctional transition metal sulfides to further improve their application.

[0004] Prussian blue (PB) and Prussian blue analogues (PBAs) are typical coordination framework materials. PBAs not only have a nanoporous open framework structure and a large specific surface area, but also have the characteristics of low cost and easy preparation. And due to the tunability of metal active sites and the uniformity of catalytic centers, PBAs have broad application prospects in electrocatalytic water splitting. However, PBAs themselves have low conductivity, resulting in low catalytic current density and high overpotential required. In addition, they will be deactivated during the reaction process due to the collapse of the framework, so it is a promising method to combine PBAs nanostructure with other similar compounds to form materials with multi-layer nanostructure. For example, Pang et al. proposed a multi-layer nanostructure Ni-MIL-77@PBA synthesized by in-situ growth strategy in A new strategy for the controllable growth of MOF@PBA architectures, Journal of Materials Chemistry A, 2019, 7, 17266-17271. Due to the synergistic effect between different composite materials, the multi-layer nanostructure Ni-MIL-77@PBA can expose more active sites and promote the charge transfer process. When Ni-MIL-77@PBA is applied to the electrocatalytic OER reaction of water splitting, due to its unique three-dimensional structure, the advantages of the combination of metal organic framework (MOFs) and PBA nanoparticle materials, its overpotential at a current density of 10 mA cm -2 Although the current density loss is negligible (about 3.6%) in the 5000 s stability test; but in the long-term cycle stability test, there are still problems such as the shedding of active sites from the surface of the catalyst, which ultimately affects the subsequent electrochemical performance of the sample collapse. SUMMARY

[0005] The main purpose of the present application is to solve the problems and deficiencies of the prior art, provide a prussian blue analogue self-supporting anode for anion exchange membrane water electrolyzer, first prepare a defect-rich metal sulfide nanomatrix material (NiCo2S4 / NF), then grow CoFePBAs nanoparticles and the like on the surface thereof in situ, prepare Fe-coordinated prussian blue analogue material CoFePBA@NiCo2S4 / NF; the 3D structure formed by the PBAs nanoparticles and the defect-rich NiCo2S4 nanomatrix can provide abundant catalytic active sites and accelerate the electron transmission rate, at the same time, the introduction of Fe in the PBAs can further adjust the electronic structure of Ni and Co, further improve the OER electrocatalytic performance of the obtained composite material; when applied to assemble an anion exchange membrane water electrolyzer, the problems of high price of the current catalytic material, low specific surface area of the material, few catalytic active sites, and insufficient stability and the like can be effectively solved.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0007] A preparation method of a prussian blue analogue self-supporting anode for an anion exchange membrane water electrolyzer, comprising the following steps:

[0008] 1) Preparation of NiCo2S4 / NF catalytic material:

[0009] Nickel salt, cobalt salt and urea are added to water and uniformly mixed to obtain a mixed solution I; foam nickel (NF) is added to the mixed solution I and subjected to hydrothermal reaction; the obtained product is subjected to water washing, drying and air reduction; then the obtained reduced product is added to a Na2S solution and subjected to sulfidation treatment; after being taken out, the product is subjected to nitrogen reduction treatment to obtain the NiCo2S4 / NF catalytic material.

[0010] 2) Citric acid and potassium ferricyanide are added to water and uniformly mixed to obtain a mixed solution II; the NiCo2S4 / NF catalytic material obtained in step 1) is added to the mixed solution II and subjected to room temperature reaction, water washing and drying; then calcination is performed under a protective atmosphere to obtain the CoFePBA@NiCo2S4 / NF prussian blue analogue composite material.

[0011] In the above scheme, the nickel salt can be one or more of nickel chloride, nickel nitrate, nickel acetate and the like; the cobalt salt can be one or more of cobalt chloride, cobalt nitrate, cobalt acetate and the like.

[0012] In the above scheme, the molar ratio of the nickel salt, the cobalt salt and the urea is (1-4):(1-4):8.

[0013] In the above scheme, the concentration of the nickel salt in the mixed solution I is 10-50 mM.

[0014] In the above scheme, the hydrothermal reaction temperature is 100-150 DEG C, and the time is 4-16 h.

[0015] In the above scheme, the air reduction temperature is 300-500 DEG C, and the time is 1-3 h.

[0016] In the above scheme, the concentration of the Na2S solution is 0.1-0.3 mM.

[0017] In the above scheme, the sulfidation treatment time is 4-8 h.

[0018] In the above scheme, the temperature increasing rate of the nitrogen reduction treatment is 2-5 DEG C / min, the temperature is 300-500 DEG C, the time is 1-3 h, and the nitrogen flow rate is 20-100 sccm.

[0019] In the above scheme, the molar ratio of citric acid to potassium ferricyanide is 1:3-3:1, and the room temperature reaction time is 12-36 h.

[0020] In the above scheme, the concentration of potassium ferricyanide in the mixed solution II is 5-20 mM.

[0021] In the above scheme, the molar ratio of the introduced potassium ferricyanide in the mixed solution II to the introduced nickel salt in the mixed solution I is 1:2-2:1.

[0022] In the above scheme, the protective atmosphere can be nitrogen or the like.

[0023] In the above scheme, the calcination temperature is 200-400 DEG C, the temperature increasing rate is 2-5 DEG C / min, the time is 1-3 h, and the protective gas flow rate is 20-100 sccm.

[0024] The self-supporting anode of the Prussian blue analogue prepared according to the above scheme comprises a foam nickel substrate and a NiCo2S4 nanotube array grown on the surface of the substrate, wherein CoFePBA nanoparticles are further grown on the surface of the nanotube; the inner diameter of the nanotube is 80-100 nm, and the wall thickness is 10-20 nm.

[0025] Further, the self-supporting anode of the Prussian blue analogue further contains Fe3S4, Ni3S4 and Co3S4; wherein

[0026] The application further provides an application of the above Prussian blue analogue material CoFePBA@NiCo2S4 / NF in an anion exchange membrane water electrolyzer.

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

[0028] 1) The present application takes NiCo2S4 / NF as a substrate, carries out ion coordination with citric acid and potassium ferricyanide, and then carries out nitrogen reduction to prepare a Fe-coordinated Prussian blue type material; compared with the precursor sulfide, only through room temperature standing treatment, coordination with the sulfide is realized, in-situ growth and modification of the Prussian blue type material in the precursor sulfide are realized, and more active sites are formed; in a three-electrode system test, the overpotential of the Prussian blue type material CoFePBA@NiCo2S4 / NF at a current density of 100 mA cm -2 of the present application is only 298 mV, and the Tafel slope is only 68.2 mV dec -1 -1; in the composite system obtained by the present application, the charge balance after electron transfer between Ni, Co and Fe forms the best bonding strength with the active intermediate, and is beneficial to the adsorption of the intermediate or the release of the catalytic product, and the OER catalytic activity can be excellent.

[0029] 2) The preparation method involved in the present application is relatively simple, the reaction conditions are mild, the cost is low, and the environment is not polluted; in an anion exchange membrane water electrolysis cell, the current density at a current density of 1.8 V in 1M KOH electrolyte can reach 1520 mA cm -2 -1, and the voltage attenuation is negligible in 50h stability test, and the obtained electrode material can exhibit higher catalytic activity and stability than the commercial traditional electrode. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 X-ray diffraction (XRD) pattern of CoFePBA@NiCo2S4 / NF prepared in Example 1 of the present application;

[0031] Figure 2 Scanning electron microscope (SEM) pattern of material (A) NiCo2O4 / NF, (B) NiCo2S4 / NF, (C) CoFePBA@NiCo2S4 / NF prepared in Example 1 of the present application, and transmission electron microscope (TEM) pattern of Prussian blue type material (D) CoFePBA@NiCo2S4 / NF.

[0032] Figure 3 Transmission electron microscope (TEM) pattern of nanotubes in CoFePBA@NiCo2S4 / NF prepared in Example 1 of the present application;

[0033] Figure 4(A) LSV curves, (B) overpotential comparison under different current densities, (C) Tafel slope curves and (D) voltage-time curves of CoFePBA@NiCo2S4 / NF under a certain current density of the different catalytic materials NiCo2S4 / NF and CoFePBA@NiCo2S4 / NF prepared for the embodiment 1 of the present application.

[0034] Figure 5 Electrochemical active area (ECSA) and (E) layer double electric layer capacitance (C dl ) diagrams of different materials (A) NF, (B) NiCo2O4 / NF, (C) NiCo2S4 / NF and (D) CoFePBA@NiCo2S4 / NF prepared for the embodiment 1 of the present application.

[0035] Figure 6 (A) Voltage-current density curves and (B) cell voltage-energy efficiency-time relationship curves under a certain current density of the Prussian blue material CoFePBA@NiCo2S4 / NF prepared for the embodiment 1 of the present application applied to anion exchange membrane water electrolyzer. DETAILED DESCRIPTION

[0036] The present application is not limited to the above-mentioned embodiments, and for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements are also considered to be within the scope of protection of the present application. The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

[0037] Embodiment 1

[0038] A Prussian blue analogue self-supporting anode for anion exchange membrane water electrolyzer, the preparation method thereof comprises the following steps:

[0039] 1) Preparation of NiCo2S4 / NF catalytic material:

[0040] 0.2 g of nickel chloride hexahydrate, 0.4 g of cobalt chloride hexahydrate, and 0.4 g of urea were added to 25 ml of water and mixed thoroughly to obtain mixed solution I (the molar ratio of nickel chloride hexahydrate, cobalt chloride hexahydrate, and urea was 1:2:8). A 3 cm × 3 cm nickel foam (NF) with an oxide layer removed and a thickness of approximately 280–300 nm was added to this solution. The mixture was then reacted at 100 °C under hydrothermal conditions for 12 h. After rinsing and drying with deionized water, the mixture was placed in a tube furnace and reduced in air at 450 °C for 2 h. The resulting reduction product was then added to 200 mL of 0.10 mM Na₂S solution for sulfidation treatment for 6 h. The resulting sulfidation product was then subjected to nitrogen reduction treatment at a temperature of 300 °C, a heating rate of 5 °C / min, and a time of 2 h. The flow rate was controlled at N₂ = 100 sccm. This yielded the NiCo₂S₄ / NF catalyst.

[0041] 2) Add 0.105g of citric acid monohydrate and 0.165g of potassium ferricyanide to 100ml of water (the molar ratio of citric acid monohydrate to potassium ferricyanide is 1:1), mix well to obtain a mixed solution of citric acid monohydrate and potassium ferricyanide, then add the NiCo2S4 / NF catalyst material obtained in step 1), let it stand at room temperature for 24h, rinse with deionized water, dry in an oven at 60℃ for 12h; place in a tube furnace, calcine at 300℃ for 2h under a nitrogen atmosphere (N2 flow rate of 100sccm) at a rate of 5℃ / min, to obtain CoFePBA@NiCo2S4 / NF Prussian blue composite material.

[0042] The XRD pattern of the product obtained in this invention is shown in the figure. Figure 1 It can be seen that the obtained product contains CoFe PBA, as well as NiCo2S4 and Fe3S4, Ni3S4 and Co3S4 phases, among which Fe 3+ The presence of [something] can stabilize Ni in a lower oxidation state, hindering Ni [something]. 4+ The formation of [a specific substance] gives the sample high catalytic activity and stability.

[0043] Figure 2 C and 2D are the SEM and TEM images of the Prussian blue-like material CoFePBA@NiCo2S4 / NF obtained in this embodiment, respectively. Compared with the NiCo2S4 / NF precursor, the obtained CoFePBA@NiCo2S4 / NF material exhibits a larger specific surface area; since the PBA nanoparticles and TMSs form a heterostructure, they can provide more sites for catalytic reactions. At the same time, the interplanar spacings of 0.20 nm and 0.28 nm correspond to the NiFe(111) crystal plane and the NiCo2S4(311) crystal plane, respectively, proving that Fe has been successfully incorporated into the prepared material.

[0044] Example 2

[0045] A Prussian blue analogue self-supporting anode for use in anion exchange membrane water electrolyzers is prepared by the following steps:

[0046] 0.105 g of citric acid monohydrate and 0.33 g of potassium ferricyanide were added to 100 ml of water (the molar ratio of citric acid monohydrate to potassium ferricyanide was 1:2), and mixed evenly to obtain a mixed solution of citric acid monohydrate and potassium ferricyanide. NiCo2S4 / NF catalyst (preparation method as in Example 1) was added to the solution, and the mixture was allowed to stand at room temperature for 24 h. The solution was then rinsed with deionized water and dried in an oven at 60 °C for 12 h. The solution was then placed in a tube furnace and calcined at 300 °C for 2 h under a nitrogen atmosphere (N2 flow rate of 100 sccm) at a rate of 5 °C / min to obtain CoFePBA@NiCo2S4 / NF Prussian blue composite material.

[0047] Example 3

[0048] A Prussian blue analogue self-supporting anode for use in anion exchange membrane water electrolyzers is prepared by the following steps:

[0049] 0.105 g of citric acid monohydrate and 0.495 g of potassium ferricyanide were added to 100 ml of water (the molar ratio of citric acid monohydrate to potassium ferricyanide was 1:3) and mixed evenly to obtain a mixed solution of citric acid monohydrate and potassium ferricyanide. NiCo2S4 / NF catalyst (prepared by the same method as in Example 1) was added to the above solution and allowed to stand at room temperature for 24 h. The mixture was then rinsed with deionized water and dried in an oven at 60 °C for 12 h. The mixture was then placed in a tube furnace and calcined at 300 °C for 2 h at a rate of 5 °C / min under a nitrogen atmosphere (100 sccm) to obtain CoFePBA@NiCo2S4 / NF Prussian blue composite material.

[0050] Example 4

[0051] A method for preparing a Prussian blue analogue self-supporting anode for anion exchange membrane water electrolyzers includes the following steps:

[0052] 0.21 g of citric acid monohydrate and 0.165 g of potassium ferricyanide were added to 100 ml of water (the molar ratio of citric acid monohydrate to potassium ferricyanide was 2:1), and mixed evenly to obtain a mixed solution of citric acid monohydrate and potassium ferricyanide. NiCo2S4 / NF catalyst (preparation method as in Example 1) was added to the solution, and the mixture was allowed to stand at room temperature for 24 h. The solution was then rinsed with deionized water and dried in an oven at 60 °C for 12 h. The solution was then placed in a tube furnace and calcined at 300 °C for 2 h under a nitrogen atmosphere (N2 flow rate of 100 sccm) at a rate of 5 °C / min to obtain CoFePBA@NiCo2S4 / NF Prussian blue composite material.

[0053] Example 5

[0054] A Prussian blue analogue self-supporting anode for use in anion exchange membrane water electrolyzers is prepared by the following steps:

[0055] 0.315 g of citric acid monohydrate and 0.165 g of potassium ferricyanide were added to 100 ml of water (the molar ratio of citric acid monohydrate to potassium ferricyanide was 3:1), and mixed evenly to obtain a mixed solution of citric acid monohydrate and potassium ferricyanide. The NiCo2S4 / NF catalyst material obtained in step 1) (preparation method is the same as in Example 1) was added to the solution, and the mixture was allowed to stand at room temperature for 24 h. The solution was then rinsed with deionized water and dried in an oven at 60 °C for 12 h. The solution was then placed in a tube furnace and calcined at 300 °C for 2 h under a nitrogen atmosphere (N2 flow rate of 100 sccm) at a rate of 5 °C / min to obtain the CoFePBA@NiCo2S4 / NF Prussian blue composite material.

[0056] Comparative Example 1

[0057] A method for preparing NiCo2O4 / NF catalytic material is largely the same as step 1) of Example 1, except that no sulfidation treatment is performed.

[0058] The obtained NiCo2O4NF catalyst was tested using scanning electron microscopy, and the results are as follows: Figure 2 As shown in Figure A, the obtained NiCo2O4NF catalytic material has a nanoneedle array structure, which provides a stable structural basis for subsequent processing. However, its specific surface area is limited to the surface of the nanoneedle array, and the number of catalytic sites is relatively small.

[0059] Comparative Example 2

[0060] A method for preparing NiCo2S4 / NF catalytic material, the preparation method is the same as step 1) of Example 1.

[0061] To investigate the effect of sulfidation treatment on the samples, scanning electron microscopy was performed on the obtained NiCo2S4 / NF samples, such as... Figure 2 As shown in Figure B, compared to the sample in Comparative Example 1, its structure changes from a single nanoneedle array to a defect-rich nanotube array, which effectively increases the specific surface area of ​​the sample. Simultaneously, the number of active sites also increases, which is beneficial for the desorption of the generated gas during the OER reaction. Sulfur atom doping not only modulates the electronic structure of the catalyst and enhances conductivity, but the presence of the multiphase interface also facilitates the full exposure of active sites. The metal-sulfur bond achieves a prominent electronic regulation effect, thereby effectively improving both catalytic activity and conductivity. However, in long-term stability tests, its surface sulfides transform into hydroxyl oxides (hydroxyl radicals), and its surface structure is prone to collapse, causing irreversible damage to its stability.

[0062] Based on the results of Example 1 and Comparative Examples 1 and 2, it can be seen that the nanotube array structure of the precursor NiCo2S4 / NF provides support for the growth of subsequent PBA nanoparticles, enabling them to be firmly adsorbed and dispersed more uniformly. This has a significant impact on the synergistic catalytic effect between metals. Furthermore, the preparation method is simple and the reaction conditions are mild, achieved by room temperature static treatment at an appropriate molar ratio of citric acid to potassium ferricyanide. This method can effectively improve the electrical conductivity and electrochemical stability of the composite material, thereby significantly enhancing the electrochemical performance of the obtained catalyst material.

[0063] The process of applying the material obtained in Example 1 of the present invention and its preparation to electrochemical testing in a standard three-electrode system includes the following steps:

[0064] 1) Cut the 3cm×3cm material prepared in Example 1 into 1cm×1cm pieces to be used as the working electrode material:

[0065] 2) Using Hg / HgO as the reference electrode and a stone rod as the counter electrode, the electrolyte was 1M KOH solution. The obtained system was tested using a three-electrode electrochemical assay, and the results are as follows: Figure 4 As shown in Figure 5.

[0066] Specifically, their electrocatalytic performance on OER was evaluated using a 1M KOH electrolyte solution:

[0067] Figure 4 The linear current-voltage sweep (LSV) curve described in A indicates that when the current density reaches 100 mA cm⁻¹ -2 At that time, the overpotential of the Prussian blue-like material CoFePBA@NiCo2S4 / NF was 294mV; Figure 4 B compiled the overpotentials of different systems at different voltages, even at 500 mA cm⁻¹. -2 At high current densities, the overpotential of the CoFePBA@NiCo2S4 / NF catalytic material described in this invention is only 389 mV, which is much lower than that of other existing catalytic materials (as shown in Table 1). Because Ni... 2+ The valence electron orbital occupies the 3d state. 8 (t 2g 6 e g 2 ), where t 2g The track is completely occupied. And Co 2+ and Fe 3+ The valence electron orbitals occupy 3d states respectively 7 (t 2g 5 e 2g 2 ) and 3D5 (t 2g 3 e 2g 2 ), respectively presenting t 2g The characteristics of unpaired and half-filled electronic states of the orbitals. The main interactions of these three metallic elements, from strongest to weakest, are strong electron repulsion, strong 2π contribution, and weak electron repulsion, in that order. Therefore, in this material, Ni... 2+ With Co 2+ and Fe 3+ Some electron transfer occurred between them, and due to weak electron repulsion, Fe... 3+ From Ni 2+ The gained electrons tend to transfer to Co 2+ According to the Sabatier principle, the charge rebalancing following electron transfer among Ni, Co, and Fe in the unit system results in optimal bonding strength with the active intermediate, while also facilitating the adsorption of the intermediate or the release of catalytic products. To elucidate the electrocatalytic kinetics, the Tafel slope of the catalyst was calculated. Figure 4 C indicates that the Tafel slope of the CoFePBA@NiCo2S4 / NF catalyst is 68.2 mV dec. -1 This indicates that the conductivity is improved due to the trimetallic synergistic effect among Ni, Fe, and Co. Figure 4 D is a Prussian blue material, CoFePBA@NiCo2S4 / NF, at 100 mA cm⁻¹. -2 The stability under current density, after 100 hours of cycling test, showed that the voltage increased by only 0.7%, proving that the catalytic material obtained in this invention has excellent stability.

[0068] Table 1. Basic OER performance of existing self-supporting catalyst materials

[0069]

[0070] Figure 5 The image above shows the CV curves of each sample obtained by selecting different scan rates within a certain voltage range. The double-layer capacitance C is calculated from the CV curves. dl Place Figure 5 As shown in E. The prepared C dl The maximum value corresponds to a larger ECSA, which promotes electron transfer and enhances the kinetics of the catalytic process. This further indicates that the composite material obtained in this invention possesses a large active surface area and significant conductivity, explaining its high catalytic activity for OER.

[0071] The prepared Prussian blue-like material CoFePBA@NiCo2S4 / NF exhibits excellent catalytic activity in alkaline solution, attributed to the synergistic effect among Ni, Co, and Fe. Furthermore, after calcination, the cyano ligands in the structure uniformly encapsulate the active metal particles with a carbon layer following inert gas pyrolysis, further preventing corrosion of the active particles in the alkaline environment. ECSA also indirectly confirms the high-efficiency OER catalytic performance of all samples; the ECSA value is derived from C. dl .

[0072] The Prussian blue material CoFePBA@NiCo2S4 / NF prepared in Example 1 of this invention was used to prepare an anion exchange membrane water electrolyzer. The specific preparation steps are as follows:

[0073] The obtained Prussian blue-based material CoFePBA@NiCo2S4 / NF was cut into 2.5cm × 2.5cm pieces (approximately 280–300nm thick) to serve as the anode, Pt / C as the cathode, and 1M KOH as the electrolyte. The cathode was fabricated by spraying a catalyst slurry onto an AEM (Alternating Electrode). The cathode used 47wt% and 0.94mg of [a specific chemical composition]. pt cm -2 Pt / C. A PAP-TP-85 membrane with a thickness of approximately 30–40 μm was used. The membrane was soaked in 1M KOH solution for 1 hour, and then rinsed with deionized water before use. 20 mg of 47 wt% Pt / C was weighed into a centrifuge tube, and 2 g of aqueous solution was added. The mixture was ultrasonically dispersed until homogeneous. 0.8 g of isopropanol solution was added, followed by 0.175 g of Nafion solution, and the mixture was ultrasonically dispersed for 1 hour. The resulting membrane thickness was approximately 30–40 μm.

[0074] Figure 6 A shows the voltage-current density curve of the Prussian blue-based material CoFePBA@NiCo2S4 / NF after assembly into an AEMWE. After activation... Figure 6 The AEMWE device constructed by B can provide 1520 mA cm at 1.8V in an alkaline medium. -2 The current density shows that the catalytic material obtained in this invention operates at 500 mA cm⁻¹. -2 The performance remained stable within 50 hours at the specified current density, with the battery voltage stabilizing at around 1.9V and the energy efficiency remaining stable at around 74%. It can be seen that the Prussian blue-based material CoFePBA@NiCo2S4 / NF obtained in this invention has more advantages in terms of electronic conductivity and catalytic sites compared to other catalytic materials (as shown in Table 2).

[0075] Table 2 Performance Comparison of Existing AEMWE

[0076]

[0077] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made that deviate from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A method for preparing a Prussian blue analogue self-supporting anode for anion exchange membrane water electrolyzer, characterized in that, Includes the following steps: 1) Preparation of NiCo2S4 / NF catalytic material: Nickel salt, cobalt salt, and urea are added to water and mixed evenly to obtain mixture I; nickel foam is added to it and a hydrothermal reaction is carried out; the resulting product is washed with water, dried, and reduced in air at a temperature of 300~500 ℃ for 1~3 h; then the resulting reduced product is added to Na2S solution for sulfidation treatment. The material is then subjected to nitrogen reduction treatment at a temperature of 300-500 °C for 1-3 h to obtain NiCo2S4 / NF catalyst. 2) Add citric acid and potassium ferricyanide to water and mix well to obtain mixed solution II; add the NiCo2S4 / NF catalyst obtained in step 1) to it, react at room temperature, wash with water, and dry; Then, calcination is carried out under a protective atmosphere to obtain a Prussian blue analog self-supporting anode, which includes a nickel foam substrate and an array of NiCo2S4 nanotubes grown on its surface, wherein CoFePBA nanoparticles are also grown on the surface of the nanotubes.

2. The preparation method according to claim 1, characterized in that, The nickel salt is one or more of nickel chloride, nickel nitrate, and nickel acetate; the cobalt salt is one or more of cobalt chloride, cobalt nitrate, and cobalt acetate.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the nickel salt, cobalt salt, and urea is (1~4):(1~4):

8.

4. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature is 100~150℃, and the time is 4~16 h.

5. The preparation method according to claim 1, characterized in that, The concentration of the Na2S solution is 0.1~0.3 mM; the sulfidation treatment time is 4~8 h.

6. The preparation method according to claim 1, characterized in that, The molar ratio of citric acid to potassium ferricyanide is 1:3 to 3:

1.

7. The preparation method according to claim 1, characterized in that, The reaction time at room temperature is 12~36 h.

8. The preparation method according to claim 1, characterized in that, The calcination temperature is 200~400℃, and the time is 1~3 h.

9. A Prussian blue analogue self-supporting anode prepared by the preparation method according to any one of claims 1 to 8.

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