A transition metal-doped CoWO4 water electrolysis catalyst, its preparation method and application

Abstract

The application discloses a transition metal element doped CoWO4 water electrolysis catalyst and a preparation method and application thereof, and belongs to the technical field of catalyst preparation. The preparation method comprises the following steps: dissolving a Co source, a W source, an Fe source and / or a Ni source and a complexing agent in water and uniformly mixing, grinding the mixture after drying to prepare a powder, pre-burning the powder, grinding the powder once, calcining the powder, and grinding the powder twice to obtain a catalyst powder; and then mixing the catalyst powder with a perfluorosulfonic acid ion exchange resin solution, a solvent and a conductive carbon material to prepare a slurry, and dropping and coating the slurry on a foamed nickel substrate to dry and form. The synergistic doping of Fe and Ni in the CoWO4 crystal lattice in the obtained catalyst is beneficial to the regulation of the electronic structure and the charge transport performance of the material, and the oxygen evolution reaction, the hydrogen evolution reaction and the overall water splitting performance under alkaline conditions are improved. The raw materials are easy to obtain, the preparation process is simple, and the catalyst is suitable for hydrogen production by water electrolysis.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy is a clean and efficient secondary energy source and one of the core carriers for achieving energy structure transformation and contributing to dual-carbon goals. Water electrolysis for hydrogen production utilizes renewable energy power to produce high-purity hydrogen, offering advantages such as clean processes, high product purity, and zero carbon emissions, making it the mainstream technology for large-scale green hydrogen production. The water electrolysis reaction includes the cathode hydrogen evolution reaction and the anode oxygen evolution reaction. These two steps have slow reaction kinetics and high overpotentials, which are key bottlenecks restricting the improvement of energy efficiency and reduction of hydrogen production energy consumption in water electrolysis devices.

[0003] Currently, most commercially available high-efficiency water electrolysis catalysts are based on noble metals such as Pt, Ir, and Ru. While they possess excellent hydrogen evolution and oxygen evolution catalytic activity, they suffer from drawbacks such as scarce reserves, high preparation costs, and poor long-term cycle stability, which greatly limit the large-scale industrialization of water electrolysis hydrogen production technology. Therefore, developing non-noble metal bifunctional electrocatalysts with abundant raw material reserves, excellent catalytic activity, strong structural stability, and combined hydrogen evolution and oxygen evolution performance has become a key research focus and core challenge in the field of water electrolysis catalysis.

[0004] CoWO4 possesses a stable crystal framework structure, tunable metal active sites, and good electrochemical tolerance, demonstrating promising application potential in the field of electrocatalytic water splitting. However, pure-phase CoWO4 suffers from insufficient intrinsic catalytic activity, low charge transport efficiency, and poor adsorption and desorption behavior of reaction intermediates, making its overall water splitting catalytic performance insufficient to meet the demands of industrial applications. Existing single-metal doping modification methods can only selectively optimize certain catalytic properties, failing to simultaneously improve the catalytic efficiency of hydrogen evolution reaction and oxygen evolution reaction, thus hindering the synergistic enhancement of water splitting performance.

[0005] Therefore, there is an urgent need for a method to prepare a modified CoWO4 water electrolysis catalyst to optimize the electrocatalytic performance of the material and prepare a high-performance, highly stable electrocatalyst to meet the practical application requirements of water electrolysis for hydrogen production. Summary of the Invention

[0006] The purpose of this invention is to provide a transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method, and its application, in order to solve the above-mentioned problems.

[0007] This invention provides a method for preparing a transition metal element-doped CoWO4 water electrolysis catalyst, comprising the following steps: S1. Add the Co source, W source, Fe source and / or Ni source and complexing agent to the solvent and mix evenly to obtain the precursor solution; S2. The precursor solution is dried and then ground to obtain powder. The obtained powder is pre-calcined, ground once, calcined and ground twice to obtain catalyst powder doped with one or more of Fe or Ni. S3. The catalyst slurry is obtained by ultrasonically mixing the catalyst powder, perfluorosulfonic acid ion exchange resin solution, solvent and conductive carbon material. S4. The catalyst slurry is dripped onto the nickel foam substrate and dried to obtain the water electrolysis catalyst.

[0008] Preferably, in S1, the Co source is Co(NO3)2·6H2O, the W source is (NH4)10·H2·(W2O7)6, the Fe source is Fe(NO3)3·9H2O, the Ni source is Ni(NO3)2·6H2O, the complexing agent is C6H8O7·H2O, and the solvent is deionized water; when preparing Fe single-doped samples, no Ni source is added, and when preparing Ni single-doped samples, no Fe source is added.

[0009] Preferably, in the catalyst powder obtained in S2, the total molar amount of Co, Fe, and Ni provided by the Co source, Fe source, and Ni source is in a ratio of 1:1 to the molar amount of W provided by the W source; at least one of the Fe source and Ni source participates in doping, and at least one of Fe and Ni replaces part of the Co in the CoWO4 lattice.

[0010] Preferably, the drying temperature in S2 is 190–210°C, and the drying time is 3–5 hours.

[0011] Preferably, the pre-firing temperature in S2 is 400-500℃ and the pre-firing time is 2h; the calcination temperature is 750-850℃ and the calcination time is 4h.

[0012] Preferably, the grinding in S2 is mechanical grinding or manual grinding, and the grinding time is 30 to 60 minutes each time.

[0013] Preferably, the mass fraction of the perfluorosulfonic acid ion exchange resin solution in S3 is 5%; the solvent is anhydrous ethanol; the conductive carbon material is at least one of conductive carbon black, acetylene black, carbon nanotubes, or graphene (Super P Li is selected as the conductive carbon black); the ratio of catalyst powder, perfluorosulfonic acid ion exchange resin solution, solvent, and conductive carbon material is 10 mg: 0.1 mL: 1 mL: 10 mg; the catalyst powder, perfluorosulfonic acid ion exchange resin solution, solvent, and conductive carbon material are mixed to form a catalyst slurry, which is then loaded onto a nickel foam matrix.

[0014] Preferably, the ultrasonic power in S3 is 100W and the ultrasonic time is 25-35min.

[0015] A transition metal element-doped CoWO4 water electrolysis catalyst is provided, which is prepared by the above preparation method.

[0016] The aforementioned transition metal element-doped CoWO4 water electrolysis catalyst is used in water electrolysis for hydrogen production, particularly in alkaline water electrolysis for oxygen evolution, hydrogen evolution, and water electrolysis.

[0017] Therefore, the present invention employs the above-mentioned transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method, and its application, which has the following beneficial effects: (1) By introducing Fe and / or Ni elements into CoWO4, the metal active sites and local electronic structure of the catalyst can be regulated, which is beneficial to improve the adsorption and desorption behavior of reaction intermediates and enhance the charge transport capacity of the catalyst, thereby improving its water electrolysis catalytic performance.

[0018] (2) By adopting Fe single doping, Ni single doping and Fe / Ni co-doping designs, the catalyst composition can be adjusted while maintaining the structural stability of CoWO4 material. Among them, the Fe / Ni co-doped sample exhibits a lower overpotential in the oxygen evolution reaction and a lower hydrogen evolution overpotential at a higher current density. Combined with the water electrolysis test results, it is shown that Fe / Ni co-doping is beneficial to improving the overall performance of the catalyst in water electrolysis.

[0019] (3) The catalyst preparation method adopts a process route of solution mixing, drying, pre-calcination and calcination. The raw materials are readily available, the preparation conditions are mild, the process steps are simple, the repeatability is good, and it is suitable for batch preparation.

[0020] (4) The catalyst can form a stable slurry with perfluorosulfonic acid ion exchange resin solution, conductive carbon material and organic solvent, and be loaded onto conductive substrates such as nickel foam to form an electrode. It has good electrode construction feasibility and can be used for alkaline water electrolysis to produce hydrogen.

[0021] (5) The electrocatalytic performance of Fe-doped, Ni-doped, and Fe / Ni co-doped catalysts was improved. Among them, the Fe / Ni co-doped catalyst had better OER performance and water electrolysis performance, and better HER performance at higher current densities.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of a method for preparing a CoWO4 water electrolysis catalyst doped with transition metal elements according to the present invention. Figure 2The XRD patterns are of the catalyst powders prepared in Examples 1-3 and Comparative Example 1 of the present invention, which are a transition metal element doped CoWO4 electrolytic water catalyst, its preparation method and application. Figure 3 This invention relates to a transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. Example 1 shows the TEM image and elemental distribution diagram of the catalyst powder. Figure 4 The LSV curves of the oxygen evolution reaction in 1M KOH electrolyte are shown for the catalyst prepared in Examples 1-3 and Comparative Example 1 of the present invention, which are a transition metal element doped CoWO4 water electrolysis catalyst, its preparation method and application. Figure 5 Electrochemical impedance spectroscopy (EIS) spectra of the catalysts prepared in Examples 1-3 and Comparative Example 1 of the present invention, which are a transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method and application, at a potential of 1.52 V vs. RHE in 1M KOH electrolyte; Figure 6 The LSV curves of the hydrogen evolution reaction in 1M KOH electrolyte are shown for the catalysts prepared in Examples 1-3 and Comparative Example 1 of the present invention, which are a transition metal element doped CoWO4 water electrolysis catalyst, its preparation method and application. Figure 7 Electrochemical impedance spectroscopy spectra of the catalysts prepared in Examples 1-3 and Comparative Example 1 of the present invention, which are doped with transition metal elements CoWO4 for water electrolysis, their preparation method and application, at a potential of -0.18V vs. RHE in 1M KOH electrolyte; Figure 8 This invention relates to a transition metal-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3 LSV curve obtained from water electrolysis test of WO4 electrode in 1M KOH electrolyte; Figure 9 This invention relates to a transition metal-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3 Comparison of impedance spectra of WO4 electrode pair under different electrolysis voltages in water electrolysis test in 1M KOH electrolyte; Figure 10This invention relates to a transition metal-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 electrode pair in 1M KOH electrolyte at 10 mA cm -2 Figure showing the stability test results at current density. Detailed Implementation

[0024] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0026] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0027] Example 1 A Fe / Ni co-doped CoWO4 water electrolysis catalyst, such as Figure 1 As shown, its preparation method includes the following steps: S1. Combine Co(NO3)2·6H2O, Fe(NO3)3·9H2O, Ni(NO3)2·6H2O and (NH4) 10 ∙H2∙(W2O7)6 was prepared with Co, Fe, Ni and W in a molar ratio of 1:1:1:3, and C6H8O7∙H2O was added in 1.5 times the total number of metal cations. The mixture was dissolved in 200 mL of deionized water and placed on a magnetic stirrer and stirred continuously at 500 r / min at room temperature for 30 min to obtain the precursor solution.

[0028] S2. The obtained precursor solution was dried in an electrically heated drying oven at 200℃ for 4 hours. After drying, it was removed, crushed, and ground for 30 minutes. The resulting powder was placed in a muffle furnace and pre-calcined at 450℃ for 2 hours. After naturally cooling to room temperature, it was ground for 30 minutes. Then, it was calcined in a muffle furnace at 800℃ for 4 hours. After naturally cooling to room temperature, it was ground for 60 minutes to obtain Co. 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 catalyst powder.

[0029] S3. Mix 10 mg of catalyst powder, 0.1 mL of 5% perfluorosulfonic acid ion exchange resin solution, 1 mL of anhydrous ethanol and 10 mg of Super P Li, and sonicate at 100 W for 30 min to obtain catalyst slurry. S4. Immerse a 2cm long, 1cm wide, and 1mm thick nickel foam substrate in deionized water and sonicate at 100W for 30 minutes to remove surface impurities. Then dry at 50℃ for 6 hours. Next, use a pipette to drop 0.23mL of catalyst slurry onto the dry nickel foam substrate, alternating between the front and back sides to ensure uniform adhesion of the slurry to the nickel foam surface. After all the slurry has been dropped, transfer the electrode to the bottom of an inverted beaker and dry at 30℃ for 1 hour. The resulting water electrolysis catalyst is labeled Co. 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4.

[0030] Example 2 A Fe-doped CoWO4 water electrolysis catalyst, the preparation method of which includes the following steps: S1. Mix Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and (NH4) 10 The ·H2·(W2O7)6 was prepared with the molar ratio of Co, Fe and W being 1:1:2, and C6H8O7∙H2O was added in 1.5 times the total number of metal cations. The mixture was dissolved in 200 mL of deionized water and placed on a magnetic stirrer and stirred continuously at 500 r / min at room temperature for 30 min to obtain the precursor solution.

[0031] S2. The obtained precursor solution was dried in an electrically heated drying oven at 200℃ for 4 hours. After drying, it was removed, crushed, and ground for 30 minutes. The resulting powder was placed in a muffle furnace and pre-calcined at 450℃ for 2 hours. After naturally cooling to room temperature, it was ground for 30 minutes. Then, it was calcined in a muffle furnace at 800℃ for 4 hours. After naturally cooling to room temperature, it was ground for 60 minutes to obtain Co. 0.5 Fe 0.5 WO4 catalyst powder.

[0032] S3. Mix 10 mg of catalyst powder, 0.1 mL of 5% perfluorosulfonic acid ion exchange resin solution, 1 mL of anhydrous ethanol and 10 mg of Super P Li, and sonicate at 100 W for 30 min to obtain catalyst slurry. S4. Immerse a 2cm long, 1cm wide, and 1mm thick nickel foam substrate in deionized water and sonicate at 100W for 30 minutes to remove surface impurities. Then dry at 50℃ for 6 hours. Next, use a pipette to drop 0.23mL of catalyst slurry onto the dry nickel foam substrate, alternating between the front and back sides to ensure uniform adhesion of the slurry to the nickel foam surface. After all the slurry has been dropped, transfer the electrode to an inverted beaker and dry at 30℃ for 1 hour. The resulting catalyst is labeled Co. 0.5 Fe 0.5 WO4.

[0033] Example 3 A Ni-doped CoWO4 water electrolysis catalyst, the preparation method of which includes the following steps: S1. Mix Co(NO3)2·6H2O, Ni(NO3)2·6H2O, and (NH4) 10 The precursor solution was prepared by mixing ·H2·(W2O7)6 with a molar ratio of Co, Ni and W of 1:1:2, and adding C6H8O7·H2O at 1.5 times the total number of metal cations. The mixture was dissolved in 200 mL of deionized water and placed on a magnetic stirrer and stirred continuously at 500 r / min at room temperature for 30 min to obtain the precursor solution.

[0034] S2. The obtained precursor solution was dried in an electrically heated drying oven at 200℃ for 4 hours. After drying, it was removed, crushed, and ground for 30 minutes. The resulting powder was placed in a muffle furnace and pre-calcined at 450℃ for 2 hours. After naturally cooling to room temperature, it was ground for 30 minutes. Then, it was calcined in a muffle furnace at 800℃ for 4 hours. After naturally cooling to room temperature, it was ground for 60 minutes to obtain Co. 0.5 Ni 0.5 WO4 catalyst powder.

[0035] S3. Mix 10 mg of catalyst powder, 0.1 mL of 5% perfluorosulfonic acid ion exchange resin solution, 1 mL of anhydrous ethanol and 10 mg of Super P Li, and sonicate at 100 W for 30 min to obtain catalyst slurry. S4. Immerse a 2cm long, 1cm wide, and 1mm thick nickel foam substrate in deionized water and sonicate at 100W for 30 minutes to remove surface impurities. Then dry at 50℃ for 6 hours. Next, use a pipette to drop 0.23mL of catalyst slurry onto the dry nickel foam substrate, alternating between the front and back sides to ensure uniform adhesion of the slurry to the nickel foam surface. After all the slurry has been dropped, transfer the electrode to an inverted beaker and dry at 30℃ for 1 hour. The resulting catalyst is labeled Co. 0.5 Ni 0.5 WO4.

[0036] Comparative Example 1 An electrolysis catalyst for water, the preparation method of which includes the following steps: S1, mix Co(NO3)2·6H2O and (NH4) 10 The precursor solution was prepared by mixing ·H2·(W2O7)6 with a molar ratio of Co to W of 1:1, and adding C6H8O7·H2O at a ratio of 1.5 times the total number of metal cations. The mixture was dissolved in 200 mL of deionized water and stirred continuously at 500 r / min at room temperature for 30 min on a magnetic stirrer to obtain the precursor solution.

[0037] S2. The obtained precursor solution was dried in an electric heating drying oven at 200°C for 4 hours. After drying, it was taken out, crushed, and ground for 30 minutes. The obtained powder was placed in a muffle furnace and pre-calcined at 450°C for 2 hours. After naturally cooling to room temperature, it was ground for 30 minutes. Then, it was placed in a muffle furnace and calcined at 800°C for 4 hours. After naturally cooling to room temperature, it was ground for 60 minutes to obtain CoWO4 catalyst powder.

[0038] Steps S3 and S4 are the same as in Example 1, and the prepared catalyst is labeled CoWO4.

[0039] To verify the phase structure, microstructure, elemental distribution, and electrocatalytic performance of the transition metal-doped CoWO4 catalyst prepared in this invention, systematic structural characterization and electrochemical testing were performed on the samples of each embodiment and comparative example, as follows: 1. The catalyst powders prepared in Examples 1-3 and Comparative Example 1 were analyzed by X-ray diffraction. Figure 2 As shown, the XRD patterns of the samples in Examples 1-3 and Comparative Example 1 show that the diffraction peaks of each sample are consistent with the standard card of monoclinic CoWO4, and no obvious impurity phase appears after doping, indicating that the target product was successfully formed.

[0040] 2. The Co prepared in Example 1 was examined using a transmission electron microscope. 1 / 3 Fe 1 / 3 Ni 1 / 3The morphology of the WO4 catalyst powder was characterized, and its elemental distribution was analyzed using energy-dispersive X-ray spectroscopy. Figure 3 As shown, the catalyst exhibits a particulate morphology with a certain degree of agglomeration between particles. Elemental distribution results indicate that Co, Fe, Ni, W, and O are all distributed within the catalyst particles, and no obvious enriched or deficient areas were observed, suggesting that Fe and Ni are uniformly dispersed within the catalyst.

[0041] 3. OER performance was tested using a three-electrode system. The electrochemical workstation was a DH7000. The Hg / HgO (1M KOH) electrode was used as the reference electrode, the graphite rod as the counter electrode, and the catalyst electrodes prepared in Examples 1-3 and Comparative Example 1 were used as the working electrodes. The electrolyte was a 1M KOH solution. Figure 4 As shown, at a current density of 10 mA cm⁻¹ -2 In Example 1, Co 1 / 3 Fe 1 / 3 Ni 1 / The OER overpotential of the 3WO4 catalyst is 308 mV; in Example 2, Co 0.5 Fe 0.5 The OER overpotential of the WO4 catalyst is 358 mV; in Example 3, Co 0.5 Ni 0.5 The OER overpotential of the WO4 catalyst was 424 mV; the OER overpotential of the CoWO4 catalyst in Comparative Example 1 was 440 mV. At a current density of 50 mA / cm²... -2 At that time, Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4, Co 0. 5Fe 0.5 WO4, Co 0.5 Ni 0.5 The OER overpotentials of WO4 and CoWO4 catalysts were 439 mV, 546 mV, 623 mV, and 682 mV, respectively. These results indicate that the OER catalytic performance is ranked as follows: CoWO4 > ... 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4>Co 0.5 Fe 0.5 WO4>Co 0.5 Ni 0.5 WO4 > CoWO4, and Fe / Ni co-doping can significantly reduce the OER overpotential and improve catalytic activity.

[0042] 4. For example Figure 5 The image shows the OER electrochemical impedance spectroscopy (OER) spectra of Examples 1-3 and Comparative Example 1 at 1.52 V vs. RHE potential. The impedance arc radii of the samples show significant differences, with Co...1 / 3 Fe 1 / 3 Ni 1 / 3 The WO4 catalyst has the smallest impedance arc radius, indicating that it has low interfacial charge transport resistance in the OER process, which is beneficial to improving the oxygen evolution reaction kinetics.

[0043] 5. For example Figure 6 As shown, the HER performance of Examples 1-3 and Comparative Example 1 was tested using the same test system. The current density was 10 mA cm⁻¹. -2 At that time, Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4, Co 0.5 Fe 0.5 WO4, Co 0.5 Ni 0.5 The HER overpotentials of WO4 and CoWO4 catalysts were 201 mV, 111 mV, 211 mV, and 224 mV, respectively. At a current density of 50 mA / cm²... -2 At that time, Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4, Co 0.5 Fe 0.5 WO4, Co 0.5 Ni 0.5 The HER overpotentials of WO4 and CoWO4 catalysts were 377 mV, 449 mV, 406 mV, and 449 mV, respectively. These results indicate that Co... 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 exhibits a lower HER overpotential at higher current densities, indicating that it has good hydrogen evolution performance at high current densities.

[0044] 6. Figure 7 The images show the HER electrochemical impedance spectroscopy (EIS) spectra of Examples 1-3 and Comparative Example 1 at -0.18 V vs. RHE potential. Significant differences exist in the impedance arc radii among the samples, with Co... 0.5 Fe 0.5 The WO4 catalyst has the smallest impedance arc radius, indicating that it has low interfacial charge transport resistance under the test conditions.

[0045] 7. The Co prepared in Example 1 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 catalyst was used as both anode and cathode to assemble Co 1 / 3Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3The electrolysis performance of a WO4 dual-electrode system in a 1M KOH electrolyte solution was tested. Figure 8 As shown, at a current density of 10 mA cm⁻¹ -2 At that time, the voltage of the electrolytic cell in the dual-electrode system was 1.82V; and the current density was 50mA / cm². -2 At that time, the voltage of the water electrolysis cell in the dual-electrode system was 2.18V. The results show that Co... 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 catalyst can be used as both oxygen evolution electrode and hydrogen evolution electrode, and exhibits good catalytic performance in water electrolysis.

[0046] 8. Regarding Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3 Electrochemical impedance spectroscopy of water was performed using WO4 electrode pairs in 1M KOH electrolyte. For example... Figure 9 As shown, the impedance arc radius of the two-electrode system exhibits significant differences at electrolysis voltages of 1.40V, 1.50V, and 1.60V. The smallest impedance arc radius is observed at 1.50V, indicating relatively low interfacial charge transport resistance at this voltage, which is beneficial for improving the kinetics of the water electrolysis reaction.

[0047] 9. Regarding Co 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4||Co 1 / 3 Fe 1 / 3 Ni 1 / 3 Stability tests were performed on the WO4 electrode pair, such as... Figure 10 As shown, at 10mAcm -2 After 350 hours of continuous operation, there was no significant voltage decay. The operating voltage of the dual-electrode system remained consistently within the range of approximately 1.90–2.00 V without any significant increase, indicating that Co… 1 / 3 Fe 1 / 3 Ni 1 / 3 WO4 catalyst exhibits excellent long-term stability in water electrolysis.

[0048] Therefore, this invention employs a transition metal element-doped CoWO4 water electrolysis catalyst, its preparation method, and its application. By introducing Fe and / or Ni elements into CoWO4, the metal active sites and local electronic structure of the catalyst are modulated, which is beneficial to improving the adsorption and desorption behavior of reaction intermediates and enhancing the charge transport capacity of the catalyst, thereby improving its water electrolysis catalytic performance. Using Fe single-doping, Ni single-doping, and Fe / Ni co-doping designs, the catalyst composition can be adjusted while maintaining the structural stability of the CoWO4 material. Among these, the Fe / Ni co-doped sample exhibits a lower overpotential in the oxygen evolution reaction and a lower hydrogen evolution overpotential at higher current densities. Combined with water electrolysis test results, this indicates that Fe / Ni co-doping is beneficial to improving the overall water electrolysis performance of the catalyst.

[0049] The catalyst preparation method employs a process route of solution mixing, drying, pre-calcination, and calcination. The raw materials are readily available, the preparation conditions are mild, the process steps are simple, and the reproducibility is good, making it suitable for batch production. The prepared catalyst can form a stable slurry with perfluorosulfonic acid ion exchange resin solution, conductive carbon materials, and organic solvents, and can be loaded onto conductive substrates such as nickel foam to form electrodes. This demonstrates good electrode construction feasibility and allows for its use in alkaline water electrolysis for hydrogen production.

[0050] Fe-doped, Ni-doped, and Fe / Ni co-doped samples all showed varying degrees of improved electrocatalytic performance compared to undoped CoWO4. Among them, the Fe / Ni co-doped sample exhibited superior OER and water electrolysis performance, and demonstrated better HER performance at higher current densities.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a transition metal element-doped CoWO4 water electrolysis catalyst, characterized in that, Includes the following steps: S1. Add the Co source, W source, Fe source and / or Ni source and complexing agent to the solvent and mix evenly to obtain the precursor solution; S2. The precursor solution is dried and then ground to obtain powder. The obtained powder is pre-calcined, ground once, calcined and ground twice to obtain catalyst powder doped with one or more of Fe or Ni. S3. The catalyst slurry is obtained by ultrasonically mixing the catalyst powder, perfluorosulfonic acid ion exchange resin solution, solvent and conductive carbon material. S4. The catalyst slurry is dripped onto the nickel foam substrate and dried to obtain the water electrolysis catalyst.

2. The preparation method of a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, In S1, the Co source is Co(NO3)2∙6H2O, and the W source is (NH4). 10 The complexing agent is C6H8O7·H2O, the Fe source is Fe(NO3)3·9H2O, the Ni source is Ni(NO3)2·6H2O, the complexing agent is C6H8O7·H2O, and the solvent is deionized water.

3. The preparation method of a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, In the catalyst powder obtained by S2, the total molar amount of Co, Fe, and Ni metal elements provided by the Co source, Fe source, and Ni source is in a ratio of 1:1 to the molar amount of W provided by the W source; at least one of the Fe source and Ni source participates in doping, and at least one of Fe and Ni replaces part of the Co in the CoWO4 lattice.

4. The preparation method of a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, The drying temperature in S2 is 190–210℃, and the drying time is 3–5 hours.

5. The preparation method of a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, The pre-firing temperature of S2 is 400-500℃, and the pre-firing time is 2h; the calcination temperature is 750-850℃, and the calcination time is 4h.

6. The method for preparing a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, In S2, grinding can be done mechanically or manually, with each grinding session lasting 30 to 60 minutes.

7. The method for preparing a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, The mass fraction of the perfluorosulfonic acid ion exchange resin solution in S3 is 5%; the solvent is anhydrous ethanol; the conductive carbon material is at least one of conductive carbon black, acetylene black, carbon nanotubes, or graphene; the ratio of catalyst powder, perfluorosulfonic acid ion exchange resin solution, solvent, and conductive carbon material is 10 mg: 0.1 mL: 1 mL: 10 mg.

8. The preparation method of a transition metal element-doped CoWO4 water electrolysis catalyst according to claim 1, characterized in that, In S3, the ultrasonic power is 100W and the ultrasonic time is 25-35min.

9. The transition metal element-doped CoWO4 water electrolysis catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the transition metal element-doped CoWO4 water electrolysis catalyst as described in claim 9 in water electrolysis for hydrogen production.

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