A phosphorus-doped zirconium phosphate and manganese dioxide co-supported iridium catalyst, a preparation method and application thereof

Abstract

This invention discloses a co-supported iridium catalyst based on cobalt tetroxide and manganese dioxide doped with zirconium phosphate, its preparation method, and its application, belonging to the field of electrochemical catalysis technology. This invention overcomes the insufficient proton conductivity of existing multi-metal doped catalysts. The catalyst preparation method of this invention is as follows: First, cobalt salt, manganese salt, ammonium fluoride, urea, and water are mixed and subjected to a hydrothermal reaction to obtain cobalt-manganese hydroxide; then, the cobalt-manganese hydroxide and zirconium phosphate are mixed to form a slurry and sprayed onto a substrate, followed by calcination to obtain a precursor; finally, an iridium source is hydrothermally reacted with the precursor to obtain the catalyst. This invention uses cobalt tetroxide and manganese dioxide as a composite active phase and support, doped with zirconium phosphate and loaded with iridium on the support. While ensuring strong acid stability and effective anchoring of the active components, zirconium phosphate also maintains the conductivity of the catalyst material. In an acidic water electrolysis environment, it exhibits high intrinsic activity, long-term operational stability, and low noble metal content, thus improving the overall performance of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of electrochemical catalysis technology, and in particular to an iridium-cobalt tetroxide and manganese dioxide co-supported catalyst doped with zirconium phosphate, its preparation method and application. Background Technology

[0002] In water electrolysis for hydrogen production, the oxygen evolution reaction (OER) under acidic conditions is a key factor limiting the efficiency and cost of proton exchange membrane electrolyzers. Iridium-based (Ir) catalysts are considered crucial materials due to their excellent catalytic activity and stability under acidic conditions. However, iridium is extremely rare in the Earth's crust and is very expensive, which severely restricts its feasibility for large-scale industrial applications.

[0003] To reduce catalyst costs and further improve the overall performance of water electrolysis systems, multi-metal doping strategies have shown significant advantages. This method introduces multiple metal elements, such as cobalt, nickel, and manganese, into the catalytic material, allowing for precise control of the material's electronic structure at the atomic scale. This effectively optimizes the adsorption energy of reaction intermediates, thereby lowering the reaction energy barrier. Chinese patent CN119346110A discloses a method for preparing an iron-doped cobalt tetroxide catalyst, addressing the problem of insufficient activity of existing cobalt tetroxide as an oxygen evolution catalyst. Chinese patent CN119588349 discloses a method for preparing an iridium oxide-manganese dioxide catalyst, achieving excellent acidic oxygen evolution activity and short-term operational stability while reducing the amount of iridium used.

[0004] Although the metal-doped catalysts in the aforementioned patents and studies can enhance intrinsic catalytic activity through the synergistic effect between different metal sites, they often face problems such as insufficient interaction between the support and the active component and insufficient proton conductivity. Summary of the Invention

[0005] To address the problem of insufficient proton conductivity in existing multi-metal doped catalysts, this invention provides a zirconium phosphate-supported iridium catalyst doped with cobalt tetroxide and manganese dioxide, along with its preparation method and applications.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: One objective of this invention is to provide a method for preparing a zirconium phosphate-supported iridium catalyst doped with cobalt tetroxide and manganese dioxide, the method comprising the following steps: Step 1: Mix soluble cobalt salt, soluble manganese salt, ammonium fluoride, urea and water, stir to obtain a mixed solution, subject the mixed solution to a hydrothermal reaction, and wash, dry and grind the reaction product to obtain a mixture of cobalt hydroxide and manganese hydroxide. Step 2: Dissolve the mixture of cobalt hydroxide and manganese hydroxide with zirconium phosphate in isopropanol to form a slurry. Spray the slurry onto a conductive substrate, calcine it in air, and then cool it to room temperature to obtain a mixture of cobalt hydroxide and manganese hydroxide doped with zirconium phosphate loaded on a conductive substrate, which is the catalyst precursor. Step 3: Mix the iridium source with sulfuric acid, then add the catalyst precursor and carry out a hydrothermal reaction. After the reaction is completed, the product is washed, dried and calcined in air to obtain a co-supported iridium catalyst of cobalt tetroxide and manganese dioxide doped with zirconium phosphate.

[0007] Preferably, in step one, the soluble cobalt salt is cobalt nitrate hexahydrate, anhydrous cobalt chloride, cobalt sulfate heptahydrate, or cobalt acetate, and the soluble manganese salt is manganese sulfate monohydrate, manganese nitrate tetrahydrate, or manganese acetate.

[0008] Preferably, the Co in the mixed solution of step one 2+ The molar concentration is 0.05 mol / L to 0.1 mol / L, more preferably 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L.

[0009] Preferably, the Mn in the mixed solution of step one 2+ molar concentration of Co 2+ The molar concentration is 10-30%, more preferably 10%, 15%, 20%, 25% or 30%, and 10% of 0.06 mol / L, 0.07 mol / L, 0.08 mol / L or 0.09 mol / L, 15% of 0.06 mol / L, 0.07 mol / L, 0.08 mol / L or 0.09 mol / L, 20% of 0.06 mol / L, 0.07 mol / L, 0.08 mol / L or 0.09 mol / L, 25% of 0.06 mol / L, 0.07 mol / L, 0.08 mol / L or 0.09 mol / L, and 30% of 0.06 mol / L, 0.07 mol / L, 0.08 mol / L or 0.09 mol / L. Excessive manganese doping will exacerbate the overall resistance of the catalyst, hinder the rapid transport of electrons within the electrode, and increase the overpotential; insufficient manganese doping will make it difficult to achieve the expected effect of multi-metal synergy. Preferably, the Mn in the mixed solution of step one 2+ The molar concentration is 0.005 mol / L-0.01 mol / L.

[0010] Preferably, the urea concentration in the mixed solution in step one is 0.1-0.3 mol / L, more preferably 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L.

[0011] Preferably, the concentration of ammonium fluoride in the mixed solution of step one is 0.1-0.3 mol / L.

[0012] Preferably, the hydrothermal reaction temperature in step one is 110-130℃, more preferably 110℃, 120℃ or 130℃, etc.

[0013] Preferably, the hydrothermal reaction time in step one is 5-8 hours, more preferably 5 hours, 6 hours, 7 hours or 8 hours.

[0014] Preferably, the drying temperature in step one is 60-80℃, more preferably 60℃, 70℃ or 80℃, etc.

[0015] Preferably, the drying time in step one is 2-4 hours, more preferably 2 hours, 3 hours or 4 hours.

[0016] Preferably, the method for synthesizing zirconium phosphate in step two is as follows: zirconium oxychloride octahydrate is dissolved in deionized water to form a zirconium salt solution, phosphoric acid is prepared into a phosphoric acid solution with a concentration of 6 mol / L, and the zirconium salt solution is added to the phosphoric acid solution while stirring. The resulting gel-like mixture is subjected to hydrothermal reaction to obtain zirconium phosphate.

[0017] Preferably, the calcination heating rate in step two is 2-5℃ / min, more preferably 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, etc.

[0018] Preferably, the calcination temperature in step two is 250-450℃, more preferably 250℃, 300℃, 350℃, 400℃ or 450℃, etc.

[0019] Preferably, in step two, the spraying method is to use an ultrasonic sprayer and the spraying temperature is 80°C to rapidly evaporate the isopropanol.

[0020] Preferably, the conductive substrate in step two is a platinum-plated titanium felt with a porosity of 40-60% and a thickness of 0.3-0.6 μm, more preferably 40%, 50% or 60%, and 0.3 μm, 0.4 μm, 0.5 μm or 0.6 μm.

[0021] Preferably, the hydrothermal reaction temperature in step three is 110-130℃, more preferably 110℃, 120℃ or 130℃.

[0022] Preferably, the hydrothermal reaction time in step three is 5-8 hours, more preferably 5 hours, 6 hours, 7 hours or 8 hours.

[0023] Preferably, the drying temperature in step three is 60-80°C, more preferably 60°C, 70°C or 80°C.

[0024] Preferably, the drying time in step three is 2-4 hours, more preferably 2 hours, 3 hours or 4 hours.

[0025] Preferably, the calcination heating rate in step three is 2-5℃ / min, more preferably 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, etc.

[0026] Preferably, the calcination temperature in step three is 250-450℃, more preferably 250℃, 300℃, 350℃, 400℃ or 450℃, etc.

[0027] Preferably, the concentration of sulfuric acid in step three is 0.01-0.05 mol / L, more preferably 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L or 0.05 mol / L.

[0028] Preferably, the iridium source in step three is a potassium hexachloroiridate solution with a concentration of 1 mg / mL.

[0029] Preferably, the iridium loading in the catalyst during step three is 0.125 mg / cm³. 2 That is, 0.125 mg of iridium is loaded on each square centimeter of conductive substrate.

[0030] Preferably, in the co-supported iridium catalyst of zirconium phosphate doped with cobalt tetroxide and manganese dioxide in step three, the zirconium phosphate content is 10-30% of the sum of the mass of cobalt tetroxide and manganese dioxide.

[0031] The second objective of this invention is to provide an iridium-doped cobalt tetroxide and manganese dioxide co-supported catalyst prepared by the above method.

[0032] A third objective of this invention is to provide an anodic oxygen evolution working electrode comprising the aforementioned cobalt tetroxide and manganese dioxide co-supported iridium catalyst doped with zirconium phosphate and a conductive substrate.

[0033] The fourth objective of this invention is to provide an application of the above-mentioned anodic oxygen evolution working electrode in the preparation of a membrane electrode for hydrogen production by water electrolysis.

[0034] Further specifying, the preparation method of the membrane electrode is to coat one side of the proton exchange membrane with a cathode catalyst slurry, attach the anolyte oxygen evolution working electrode to the other side of the proton exchange membrane, and hot-press to obtain the membrane electrode.

[0035] The present invention has the following beneficial effects: This invention provides a solid acid catalyst of multi-metal oxide doped with zirconium phosphate. Using a conductive material such as platinum-plated titanium felt as a substrate, a cobalt tetroxide and manganese dioxide supported iridium catalyst doped with zirconium phosphate was prepared. This catalyst was used in the electrolysis of water to produce oxygen and hydrogen. Zirconium phosphate (ZrP) possesses excellent proton conductivity, strong acid stability, and a strong anchoring effect on metal species. Doping a certain amount of zirconium phosphate into a metal catalyst is beneficial due to its good proton conductivity. Doping with a small amount of zirconium phosphate can effectively change the intrinsic catalytic activity of the catalyst, promote water molecule activation and mass transfer processes, thereby achieving a synergistic enhancement effect in reducing overpotential, increasing current density, and extending catalyst lifespan. Compared with the prior art, this invention also has the following advantages.

[0036] (1) The final step of this invention uses a two-step hydrothermal-calcination method with mild process conditions, no need for complex equipment or expensive organic reagents, and the whole process is green and controllable. The direct hydrothermal synthesis method realizes the simultaneous growth of cobalt tetroxide nanostructures and manganese dioxide active phase on a three-dimensional porous titanium felt substrate, and completes the uniform loading of zirconium phosphate and trace amounts of iridium. The steps have high integration and good repeatability.

[0037] (2) In this invention, zirconium phosphate is doped into cobalt tetroxide and manganese dioxide. The introduction of zirconium phosphate not only effectively anchors the active components cobalt tetroxide and manganese dioxide as a strong solid acid, preventing them from dissolving and agglomerating at high potentials, but also provides an additional proton conduction pathway, accelerating the reaction kinetics.

[0038] (3) In the catalyst of this invention, cobalt tetroxide is the main component, and therefore the microstructure is an octahedral structure. The iridium loading causes Ir to displace some Co and enter the lattice in the form of hexavalent iridium. This reduces the electron cloud density around the cobalt sites, forming electron-deficient centers, thereby regulating the electronic structure of the active centers. The intrinsic catalytic activity is greatly improved with extremely low amounts of noble metals. The synergistic effect of multiple components enables the material to exhibit abundant active sites and excellent stability in acidic media.

[0039] (4) In steps one and three of this invention, the hydrothermal reaction is carried out at 110-140℃ for 5-10h. If the temperature is too low or the time is too short, the precursor conversion will be incomplete. If the temperature is too high or the time is too long, the crystallinity will be too high and the precursor will agglomerate. The washing in steps one and three is to fully remove the inorganic salt ions and water-soluble impurities remaining in the reaction. Therefore, deionized water is used for multiple washings. At the same time, in order to promote the dispersion of materials and prevent agglomeration during the subsequent drying process, anhydrous ethanol is used for washing. The drying in steps one and three needs to be carried out under mild conditions to avoid the material surface from forming a crust too quickly or the internal moisture remaining. Therefore, the drying temperature is controlled at 60-80℃ and the time is 2-4h. The air calcination temperature in steps two and three is controlled at 250-450℃ and the time is 2-5h. If the temperature is too low or the time is too short, the crystallinity will be too low. If the temperature is too high or the time is too long, the precursor will sinter and agglomerate.

[0040] (4) This invention successfully constructed an oxygen evolution catalyst using a two-step hydrothermal and calcination method. The catalyst is supported by a three-dimensional conductive substrate, with zirconium phosphate, cobalt tetroxide, and manganese dioxide as the composite active phase and stable carrier, and loaded with trace amounts of iridium. In this structure, the introduction of zirconium phosphate (doped at 10-30% of the sum of the masses of cobalt tetroxide and manganese dioxide) ensures strong acid stability and effective anchoring of the active components while also maintaining the overall conductivity of the catalyst material. Excessive zirconium phosphate doping significantly reduces electron transport efficiency, while insufficient doping makes it difficult to fully utilize its stabilizing and synergistic catalytic effects. The catalyst of this invention exhibits high intrinsic activity, excellent long-term operational stability, and low precious metal content in acidic water electrolysis environments, significantly improving the overall performance and cost-effectiveness of the catalyst. It has promising application prospects in fields such as proton exchange membrane water electrolysis. Attached Figure Description

[0041] Figure 1 This is a process flow diagram for preparing the co-supported iridium catalyst of zirconium phosphate doped with cobalt tetroxide and manganese dioxide according to the present invention. Figure 2 SEM images of zirconium phosphate synthesized from phosphoric acid solutions of different concentrations: (a) 3 mol / L, (b) 6 mol / L, and (c) 9 mol / L. Figure 3 SEM image of the catalyst without zirconium phosphate in Comparative Example 1; Figure 4 The membrane electrode polarization curves were obtained by electrochemical characterization of the catalysts obtained in Examples 1-5 and Comparative Example 1. Figure 5 The electrochemical impedance spectroscopy results are for the membrane electrodes prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0042] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0044] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0046] Before proceeding with the following embodiments, the concentration of the phosphoric acid solution during the synthesis of zirconium phosphate was optimized. The method for synthesizing zirconium phosphate is as follows: 1.6 g of zirconium oxychloride octahydrate was dissolved in 1 mL of deionized water to form a zirconium salt solution. At the same time, 85% phosphoric acid (commercial) was diluted to prepare 15 mL of phosphoric acid solutions with concentrations of 3 mol / L, 6 mol / L, and 9 mol / L, respectively, and stirred. During the stirring process, the zirconium salt solution was added dropwise, which formed a gel-like mixture. The mixture was transferred to a reaction vessel and hydrothermally heated at 200°C for 24 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed with deionized water, centrifuged to obtain α-ZrP crystals, dried at 60~80°C for 2~4 h, and ground into powder to obtain zirconium phosphate for doping.

[0047] Figure 2 (a)-(c) are SEM images of zirconium phosphate synthesized from phosphoric acid solutions with concentrations of 3 mol / L, 6 mol / L, and 9 mol / L, respectively. Figure 2 As can be seen in (a), the crystal plates are relatively large and clearly stacked. Figure 2 (c) The flakes are too densely stacked, while Figure 2 (b) shows that the zirconium phosphate synthesized with 6 mol / L phosphoric acid solution is uniformly dispersed and of suitable size. Therefore, the zirconium phosphate used in the following examples is all synthesized with 6 mol / L phosphoric acid solution.

[0048] Example 1 (1) 145.5 mg cobalt nitrate, 13.7 mg manganese sulfate, 49.3 mg ammonium fluoride and 150 mg urea were added to 10 mL of deionized water and stirred at room temperature for 20 min to fully dissolve the powder until the solution was clear and homogeneous. The mixed solution was transferred to a 10 mL polytetrafluoroethylene liner and sealed in a stainless steel high-pressure reactor. The high-pressure reactor was placed in a forced-air drying oven and reacted at 120 °C for 6 h. After the reaction was completed and cooled to room temperature, the precipitate was first washed with deionized water and then washed with anhydrous ethanol. It was then placed in a vacuum oven and dried at 60 °C for 4 h. The dried material was ground into powder through a mortar and pestle to obtain a mixture of cobalt hydroxide and manganese hydroxide powder. (2) Weigh 10 mg of a mixture of cobalt hydroxide and manganese hydroxide powder and disperse 1.6 mg of zirconium phosphate in 1185 μL of isopropanol to prepare a slurry. Use an ultrasonic sprayer to uniformly coat the slurry onto a 1×1 cm thick sheet with a porosity of 40% and a thickness of 0.4 μm placed on a heating table at 80℃ (i.e., the spraying temperature). 2 Platinum-plated titanium felt (conductive substrate) was transferred to an air calcination furnace and calcined at 350°C for 4 hours. After natural cooling to room temperature, a catalyst precursor loaded on the conductive substrate was obtained, namely a mixture of cobalt hydroxide and manganese hydroxide doped with zirconium phosphate loaded on the conductive substrate. (3) Mix 125 μL of 1 mg / L potassium hexachloroiridate solution with 5 mL of 0.05 mol / L sulfuric acid solution to adjust the iridium source to a strong acidity. Then transfer the solution to a polytetrafluoroethylene (PTFE) liner and place the catalyst precursor inside. Seal the liner in a stainless steel high-pressure reactor and place the high-pressure reactor in a forced-air drying oven. Perform a hydrothermal reaction at 130°C for 6 h. After the reaction, clean the platinum-titanium felt with deionized water and ethanol, and dry it in a vacuum oven at 60°C for 4 h. After the reaction, calcine it in an air calcination furnace at 450°C for 5 h. After naturally cooling to room temperature, obtain a co-supported iridium catalyst doped with zirconium phosphate, cobalt tetroxide, and manganese dioxide. The zirconium phosphate in this catalyst is 20% of the sum of the mass of cobalt tetroxide and manganese dioxide, denoted as 20% ZrP. The preparation process of this example is as follows: Figure 1 As shown.

[0049] Example 2 The difference between this embodiment and embodiment 1 is that: in step (2), the mass of zirconium phosphate is 0.8 mg, the volume of isopropanol is 1100 μL, the remaining process steps and parameter settings are the same as in embodiment 1, and the zirconium phosphate in the obtained catalyst is 10% of the sum of the masses of cobalt tetroxide and manganese dioxide, which is denoted as 10%ZrP.

[0050] Example 3 The difference between this embodiment and embodiment 1 is that: in step (2), the mass of zirconium phosphate is 1.2 mg, the volume of isopropanol is 1145 μL, the remaining process steps and parameter settings are the same as in embodiment 1, and the zirconium phosphate in the obtained catalyst is 15% of the sum of the masses of cobalt tetroxide and manganese dioxide, which is denoted as 15%ZrP.

[0051] Example 4 The difference between this embodiment and embodiment 1 is that: in step (2), the mass of zirconium phosphate is 2.0 mg, the volume of isopropanol is 1225 μL, the remaining process steps and parameter settings are the same as in embodiment 1, and the zirconium phosphate in the obtained catalyst is 25% of the sum of the masses of cobalt tetroxide and manganese dioxide, which is denoted as 25%ZrP.

[0052] Example 5 The difference between this embodiment and embodiment 1 is that: in step (2), the mass of zirconium phosphate is 2.4 mg, the volume of isopropanol is 1265 μL, the remaining process steps and parameter settings are the same as in embodiment 1, and the zirconium phosphate in the obtained catalyst is 30% of the sum of the masses of cobalt tetroxide and manganese dioxide, which is denoted as 30%ZrP.

[0053] Comparative Example 1 The difference between this embodiment and Example 1 is that zirconium phosphate is not added in step (2), the volume of isopropanol is 1020 μL, and the remaining process steps and parameter settings are the same as in Example 1, resulting in a cobalt tetroxide-manganese dioxide supported iridium atom catalyst without zirconium phosphate doping, with the morphology as shown in Example 1. Figure 3 As shown, the catalyst without zirconium phosphate exhibits severely agglomerated flower-like three-dimensional aggregates, with disordered stacking of nanosheets and extremely poor dispersion.

[0054] Application Example 1 A method for assembling a membrane electrode using the catalysts prepared in Examples 1-5 and Comparative Example 1 as the anode catalyst layer and then testing its electrochemical performance. The specific steps are as follows: (1) Preparation of cathode catalyst slurry Weigh 1 mg of commercial 40% platinum-carbon (Pt / C) catalyst powder and place it in a sample vial. Add the dispersion medium and binder in the following order and proportion: first, add 10 mg of deionized water (10 μL), then add 80 mg of isopropanol (102 μL), and finally add 10 mg of 5 wt% Nafion solution (9.5 μL) to obtain the cathode catalyst slurry. The mass ratio of catalyst, water, isopropanol, and Nafion solution is 1:10:80:10. Disperse the cathode catalyst slurry ultrasonically in an ice bath for 20 min. The platinum loading corresponding to this slurry formulation is 0.4 mg. Pt / cm² (with 1cm) 2 (Titanium felt active area meter). It should be noted that the cathode noble metal loading Pt here is designed to be excessive, which is intended to ensure that the cathode hydrogen evolution reaction kinetics are fast enough, so as to avoid it becoming a limiting factor for the overall performance of the membrane electrode, thereby more accurately evaluating the anode catalyst, without affecting the actual performance of the catalyst; (2) Preparation of cathode catalyst layer The Nafion 212 proton exchange membrane was laid flat on an 80°C heating stage. The cathode catalyst slurry was then ultrasonically sprayed onto one side of the proton exchange membrane, with the sprayed area controlled to be 1 × 1 cm. 2 After spraying, allow it to air dry, forming a cathode catalytic layer on one side of the proton exchange membrane. Cut a 1×1cm piece. 2 Commercially available carbon paper is used as the cathode gas diffusion layer. The carbon paper is attached to the cathode catalyst layer. (3) Preparation of the working electrode for oxygen evolution at the anode Since the catalysts prepared in any of Examples 1-5 and Comparative Example 1 have been loaded onto the porous transport layer titanium felt of the anode during the synthesis stage, this whole assembly is used as the working electrode for oxygen evolution at the anode (hereinafter referred to as the anode electrode). The geometric active area of ​​this anode electrode is also 1×1 cm. 2 The iridium loading was 0.125 mg. Ir / cm 2 The platinum-plated titanium felt serves the dual function of both the anode catalyst support and the anode porous transport layer. (4) Membrane electrode assembly The anode electrode prepared in step (3) is aligned and bonded with the proton exchange membrane with its catalyst layer side facing the proton exchange membrane and the other side of the proton exchange membrane with the cathode catalyst layer formed in step (2). The above anode electrode-proton exchange membrane (with cathode catalyst layer)-cathode porous transport layer sandwich structure is placed between two flat hot press plates and hot-pressed for 2 minutes under high temperature and high pressure conditions of 130°C and 1.5MPa. After hot pressing, it is naturally cooled to room temperature to obtain a complete membrane electrode.

[0055] Performance testing The membrane electrode assembly (MEA) was installed in the proton exchange membrane electrolyzer (PEMWE) test fixture and connected to the electrochemical workstation. Circulating deionized water was introduced to the anode side, while no external gas supply was provided to the cathode side. After the system temperature stabilized at 80°C, polarization spectroscopy (LSV) and electrochemical impedance spectroscopy (EIS) were performed to evaluate its water electrolysis performance. The test results are as follows: Figure 4 and Figure 5 As shown.

[0056] The electrochemical performance of the membrane electrodes prepared in Examples 1-5 and the comparative examples was tested, and the results are as follows: Figure 4 As shown in the figure, within the scope of protection of this invention, the addition amount of ZrP can achieve performance improvement over a wide range (10%~30%), and the polarization voltage at the same current density is lower than that of Comparative Example 1 (0% ZrP). Among them, the addition amount represented by 20% ZrP (Example 1) has the best effect: at this addition amount, the film exhibits the lowest polarization voltage across the entire current density range.

[0057] Electrochemical impedance spectroscopy was performed on the membrane electrodes prepared in Example 1 and Comparative Example 1, and the results are as follows: Figure 5 As shown in the figure, Example 1 (20% ZrP) exhibits a smaller and smoother impedance arc, indicating lower interfacial charge transfer resistance and unobstructed proton transport channels. In contrast, Comparative Example 1 (0% ZrP) shows a large impedance arc, indicating poor interfacial bonding leading to severe mass transfer resistance and hindering proton migration. Therefore, adding an appropriate amount of ZrP can effectively optimize the microscopic electrical transport characteristics of the material and significantly improve proton conduction performance.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an iridium catalyst co-supported with cobalt tetroxide and manganese dioxide doped with zirconium phosphate, characterized in that, Step 1: Mix soluble cobalt salt, soluble manganese salt, ammonium fluoride, urea and water, stir to obtain a mixed solution, subject the mixed solution to a hydrothermal reaction, and wash, dry and grind the reaction product to obtain a mixture of cobalt hydroxide and manganese hydroxide. Step 2: Dissolve a mixture of cobalt hydroxide and manganese hydroxide with zirconium phosphate in isopropanol to form a slurry. Spray the slurry onto a conductive substrate, calcine it in air, and then cool it to room temperature to obtain the catalyst precursor. Step 3: Mix the iridium source with sulfuric acid, then add the catalyst precursor and carry out a hydrothermal reaction. After the reaction is completed, the product is washed, dried and calcined in air to obtain a co-supported iridium catalyst of cobalt tetroxide and manganese dioxide doped with zirconium phosphate.

2. The preparation method according to claim 1, characterized in that, In step one, the soluble cobalt salt is cobalt nitrate hexahydrate, anhydrous cobalt chloride, cobalt sulfate heptahydrate, or cobalt acetate, and the soluble manganese salt is manganese sulfate monohydrate, manganese nitrate tetrahydrate, or manganese acetate.

3. The preparation method according to claim 1, characterized in that, Co in the mixed solution of step one 2+ The molar concentration is 0.05 mol / L-0.1 mol / L, Mn 2+ molar concentration of Co 2+ The molar concentration is 10-30%, the urea concentration is 0.1-0.3 mol / L, and the ammonium fluoride concentration is 0.1-0.3 mol / L.

4. The preparation method according to claim 1, characterized in that, In steps one and three, the hydrothermal reaction temperature is 110-130℃ and the reaction time is 5-8h; the drying temperature is 60-80℃ and the drying time is 2-4h.

5. The preparation method according to claim 1, characterized in that, In steps two and three, the calcination heating rate is 2-5℃ / min, the calcination temperature is 250-450℃, and the calcination time is 2-5h.

6. The preparation method according to claim 1, characterized in that, In step three, the iridium source is a potassium hexachloroiridate solution with a concentration of 1 mg / mL. In the co-supported iridium catalyst of cobalt tetroxide and manganese dioxide doped with zirconium phosphate, the zirconium phosphate is 10-30% of the sum of the mass of cobalt tetroxide and manganese dioxide.

7. An iridium-doped zirconium phosphate co-supported catalyst of cobalt tetroxide and manganese dioxide prepared by the method of any one of claims 1-6.

8. An anode oxygen evolution working electrode, characterized in that, The electrode comprises a co-supported iridium catalyst of cobalt tetroxide and manganese dioxide doped with zirconium phosphate and prepared by the preparation method according to any one of claims 1-6, and a conductive substrate.

9. The application of the anodic oxygen evolution working electrode of claim 8 in the preparation of a membrane electrode for hydrogen production by water electrolysis.

10. A method for preparing a membrane electrode in the application of claim 9, characterized in that, The method is as follows: The membrane electrode is prepared by coating a cathode catalyst slurry onto one side of a proton exchange membrane, attaching an anode oxygen evolution working electrode to the other side of the proton exchange membrane, and hot pressing to obtain the membrane electrode.

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