Method for preparing low / non-noble metal anode catalyst for PEM electrolyzer by acid etching and application thereof

Abstract

The application provides a method for preparing a low / non-noble metal anode catalyst for a PEM electrolyzer through acid etching and application thereof. Specifically, the application provides a method for improving the oxygen evolution reaction performance of an electrocatalyst through acid etching. After acid etching treatment, the surface morphology and chemical properties of the catalyst can be significantly optimized, the exposure of active sites is increased, and the stability is improved. Experimental results show that the catalyst after acid etching exhibits excellent catalytic activity and long-term stability in a PEM electrolyzer, the overpotential is significantly reduced, and the catalytic efficiency remains high during long-term electrolysis. The electrocatalyst preparation method provided by the application is simple, low in cost, suitable for large-scale production, can be widely applied to PEM water electrolysis for hydrogen production, and has high practical value.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, specifically to a method for preparing low / non-precious metal anode catalysts for PEM electrolyzers by acid etching. The electrocatalyst exhibits higher oxygen evolution performance after acid etching, and has high practical value in the field of PEM water electrolysis for hydrogen production. Background Technology

[0002] Proton exchange membrane (PEM) electrolyzers have important applications in hydrogen production technology due to their high efficiency, environmental friendliness, and adaptability to renewable energy sources. However, the oxygen evolution reaction (OER) kinetics at the anode of PEM electrolyzers are slow, requiring highly active and stable catalysts to reduce overpotential and improve long-term stability. Currently, IrO2 and RuO2 are commonly used OER catalysts, but their high cost and limited reserves restrict large-scale application. Therefore, the development of efficient, low-cost, and stable anode catalysts has become a research hotspot. Perovskite-structured materials, due to their unique electronic structure, good stability, and tunability, show great potential in water electrolysis for hydrogen production, especially in OER and HER catalysts. However, they also have drawbacks such as low intrinsic conductivity, poor stability in acidic environments, and low utilization of active sites. However, acid etching, as an effective surface control method, can selectively remove inactive components from materials, optimize the surface chemical structure, increase the exposure of active sites, and improve conductivity and catalytic stability. This invention proposes an acid etching method to optimize the surface structure and electronic properties of the anode catalyst, thereby improving the activity and durability of OER and achieving superior water electrolysis performance in a PEM electrolyzer. Summary of the Invention

[0003] Objective: This invention aims to provide a method for optimizing the anode catalyst through acid etching to improve the oxygen evolution reaction (OER) performance of a proton exchange membrane (PEM) electrolyzer. This method selectively removes inactive components, optimizes the surface structure, increases the exposure of active sites, and enhances electron transport capabilities, thereby reducing overpotential and improving catalytic stability. This strategy can effectively improve the water electrolysis efficiency of a PEM electrolyzer, achieving efficient, stable, and low-cost hydrogen production.

[0004] Technical solution: In the first aspect of the present invention, acid etching is applicable to a variety of types of materials.

[0005] Preferred oxide precursors for acid etching are simple perovskite oxides, double perovskite oxides, RP layered perovskite oxides, and complex metal oxides.

[0006] Preferably, the simple perovskite oxide has the general structural formula ABO3, wherein the A-site cation is one or more rare earth metal ions or alkaline earth metal ions, more preferably Sr; and the B-site cation is one or more transition metal ions, more preferably Co and Ru.

[0007] Preferably, the double perovskite oxide has the general structural formula A2B2O6, wherein the cation at the A site is one or more rare earth metal ions or alkaline earth metal ions, more preferably Ba or Sr; and the cation at the B site is one or more transition metal ions, more preferably Ru or Co, Ru or Fe, Co or Mn.

[0008] Preferably, the RP layered perovskite oxide has the general structural formula A. n+1 B n O 3n+1 The A-site cation is one or more rare earth metal ions or alkaline earth metal ions, more preferably Sr; the B-site cation is one or more transition metal ions, more preferably Ru.

[0009] Preferably, the complex metal oxide structure has the general formula A4BO6, wherein the A-site cation is one or more alkali metal or alkaline earth metal ions, more preferably Na and Sr; and the B-site cation is one or more transition metal ions, more preferably Ru.

[0010] This invention involves etching a metal oxide precursor in an acid solution (nitric acid, hydrochloric acid, sulfuric acid, etc.), then cleaning and drying the etched sample to obtain a PEM electrolytic cell anode catalyst with optimized surface morphology and chemical properties.

[0011] In this embodiment of the invention, the preferred precursor material for acid etching of the metal oxide is SrCoO. 3-δ SrRuO3, Sr2FeRuO6, Ba2CoRuO6, Sr2CoRuO6, Ba2CoMnO6, Sr2RuO4 and NaSr3RuO6.

[0012] In a second aspect, the present invention provides a specific method for implementing acid etching.

[0013] The specific implementation of acid etching includes the following steps: 1) Prepare a nitric acid solution of a certain concentration; 2) Add the electrocatalyst to the nitric acid solution prepared in step 1) into a glass container; 3) Seal the container in step 2), add a rotor, place it in a magnetic stirrer, and heat and stir; 4) Filter and wash the suspension after etching in step 3); 5) Dry and collect the catalyst obtained in step 4).

[0014] Preferably, the concentration of the nitric acid solution in step (1) is 0.01 ~ 1M.

[0015] Preferably, in step (2), 50 to 100 mg of catalyst and 10 to 30 mL of nitric acid solution are used.

[0016] Preferably, in step (3), the temperature is set to 40 ~ 100 ℃ and the rotor speed is 300 ~ 600 rpm.

[0017] Preferably, in step (4), the filter is washed with deionized water 3 to 5 times.

[0018] Preferably, step (5) involves drying in an oven at 60 °C for 12 h.

[0019] The present invention describes a method for optimizing the performance of PEM anode catalysts through acid etching.

[0020] Acid etching significantly optimizes the surface morphology and chemical properties of the catalyst, increases the exposure of active sites, and improves its stability. Experimental results show that the acid-etched catalyst exhibits excellent catalytic activity and long-term stability in a PEM electrolyzer, with a significantly reduced overpotential and maintaining high catalytic efficiency during long-term electrolysis. The electrocatalyst preparation method provided by this invention is simple, low-cost, and suitable for large-scale production. It can be widely used in PEM water electrolysis for hydrogen production and has high practical value.

[0021] Beneficial effects:

[0022] 1. This invention significantly optimizes the surface morphology and chemical composition of the catalyst through acid etching, increases the exposure of catalytic active sites, improves the activity of oxygen evolution reaction (OER), and reduces overpotential, thereby enhancing catalytic efficiency.

[0023] 2. The acid-etched catalyst exhibits superior long-term stability, maintaining high catalytic performance, reducing activity decay, and improving durability during long-term operation of the PEM electrolyzer.

[0024] 3. The process is simple and suitable for large-scale production. The prepared catalyst has high practical value in PEM water electrolysis for hydrogen production. Attached Figure Description

[0025] Figure 1 The simple perovskite material SrCoO in Example 1 of this invention 3-δ X-ray diffraction pattern before acid etching.

[0026] Figure 2 The simple perovskite material SrCoO in Example 1 of this invention 3-δ X-ray diffraction pattern after acid etching.

[0027] Figure 3The simple perovskite material SrCoO in Example 1 of this invention 3-δ Cyclic voltammetry curve before acid etching.

[0028] Figure 4 The simple perovskite material SrCoO in Example 1 of this invention 3-δ Cyclic voltammetry curves after acid etching.

[0029] Figure 5 This is an X-ray diffraction pattern of the simple perovskite material SrRuO3 before acid etching in Example 2 of the present invention.

[0030] Figure 6 This is an X-ray diffraction pattern of the simple perovskite material SrRuO3 after acid etching in Example 2 of the present invention.

[0031] Figure 7 This is a cyclic voltammetry curve of the simple perovskite material SrRuO3 before acid etching in Example 2 of the present invention.

[0032] Figure 8 This is a cyclic voltammetry curve of the simple perovskite material SrRuO3 after acid etching in Example 2 of the present invention.

[0033] Figure 9 This is the X-ray diffraction pattern of the double perovskite material Sr2FeRuO6 before acid etching in Example 3 of the present invention.

[0034] Figure 10 This is the X-ray diffraction pattern of the double perovskite material Sr2FeRuO6 after acid etching in Example 3 of the present invention.

[0035] Figure 11 This is a cyclic voltammetry curve of the double perovskite material Sr2FeRuO6 before acid etching in Example 3 of the present invention.

[0036] Figure 12 This is a cyclic voltammetry curve of the double perovskite material Sr2FeRuO6 after acid etching in Example 3 of the present invention.

[0037] Figure 13 This is the X-ray diffraction pattern of the double perovskite material Ba2CoRuO6 before acid etching in Example 4 of the present invention.

[0038] Figure 14 This is the X-ray diffraction pattern of the double perovskite material Ba2CoRuO6 after acid etching in Example 4 of the present invention.

[0039] Figure 15 This is a cyclic voltammetry curve of the double perovskite material Ba2CoRuO6 before acid etching in Example 4 of the present invention.

[0040] Figure 16This is a cyclic voltammetry curve of the double perovskite material Ba2CoRuO6 after acid etching in Example 4 of the present invention.

[0041] Figure 17 This is the X-ray diffraction pattern of the double perovskite material Sr2CoRuO6 before acid etching in Example 5 of the present invention.

[0042] Figure 18 This is the X-ray diffraction pattern of the double perovskite material Sr2CoRuO6 after acid etching in Example 5 of the present invention.

[0043] Figure 19 This is a cyclic voltammetry curve of the double perovskite material Sr2CoRuO6 before acid etching in Example 5 of the present invention.

[0044] Figure 20 This is a cyclic voltammetry curve of the double perovskite material Sr2CoRuO6 after acid etching in Example 5 of the present invention.

[0045] Figure 21 This is the X-ray diffraction pattern of the double perovskite material Ba2CoMnO6 before acid etching in Example 6 of the present invention.

[0046] Figure 22 This is the X-ray diffraction pattern of the double perovskite material Ba2CoMnO6 after acid etching in Example 6 of the present invention.

[0047] Figure 23 This is a cyclic voltammetry curve of the double perovskite material Ba2CoMnO6 before acid etching in Example 6 of the present invention.

[0048] Figure 24 This is a cyclic voltammetry curve of the double perovskite material Ba2CoMnO6 after acid etching in Example 6 of the present invention.

[0049] Figure 25 This is the X-ray diffraction pattern of the RP-structured perovskite material Sr2RuO4 before acid etching in Example 7 of the present invention.

[0050] Figure 26 This is the X-ray diffraction pattern of the RP-structured perovskite material Sr2RuO4 after acid etching in Example 7 of the present invention.

[0051] Figure 27 This is a cyclic voltammetry curve of the RP-structured perovskite material Sr2RuO4 before acid etching in Example 7 of the present invention.

[0052] Figure 28 This is a cyclic voltammetry curve of the RP-structured perovskite material Sr2RuO4 after acid etching in Example 7 of the present invention.

[0053] Figure 29This is the X-ray diffraction pattern of the complex oxide material NaSr3RuO6 before acid etching in Example 8 of the present invention.

[0054] Figure 30 This is the X-ray diffraction pattern of the complex oxide material NaSr3RuO6 after acid etching in Example 8 of the present invention. Figure 31 This is a cyclic voltammetry curve of the complex oxide material NaSr3RuO6 before acid etching in Example 8 of the present invention.

[0055] Figure 32 This is a cyclic voltammetry curve of the complex oxide material NaSr3RuO6 after acid etching in Example 8 of the present invention.

[0056] Figure 33 The polarization curves of the proton exchange membrane water electrolyzer assembled in Example 8 of this invention, using an acid-etched catalyst and commercial 40% Pt / C as the anode and cathode catalysts, are shown below at 200 mA cm⁻¹. -2 Stability plot tested at the specified current density. Specific implementation methods:

[0057] This invention provides a method for preparing anode catalysts for PEM electrolyzers by acid etching and its application. The embodiments provided by this invention include metal oxide precursors such as simple perovskite, double perovskite, and RP layered perovskite, with the general structural formulas ABO, respectively. 3-δ A2B2O6, A n+1 B n O 3n+1 The A-site cation is one or more rare earth metal ions or alkaline earth metal ions, and the B-site cation is one or more transition metal ions.

[0058] In the implementation case, A is preferably Sr or Ba; B is preferably Co, Ru, Fe, Mn, or Nb.

[0059] The catalyst material in this invention can be synthesized using conventional methods such as solid-phase reaction, sol-gel method, hydrothermal method, and coprecipitation method. The preparation method of the material in this invention is described below using the solid-phase reaction method as an example.

[0060] According to the target products ABO3, A2B2O6, A n+1 B n O 3n+1Based on the chemical formula and elemental ratio of A4B2O6, weigh out the carbonate or simple monobasic oxide (analytical grade) containing element A and the simple monobasic oxide (analytical grade) containing element B according to the stoichiometric ratio. Dissolve them in acetone or ethanol and ball mill for 1-5 hours until homogeneous. Then, further dry and evaporate the medium to obtain a solid precursor. Finally, place the precursor in a muffle furnace and calcine it at a temperature range of 800-1200 °C for 10-50 hours to obtain the desired catalyst powder before acid etching. The powder after acid etching can be obtained by following the steps described in the invention.

[0061] The evaluation of the oxygen evolution reaction (OER) catalytic performance of the catalyst before and after acid etching in this invention is as follows:

[0062] 1. Preparation of catalyst slurry: The catalyst powder is mixed with a certain amount of conductive carbon black (conductive carbon black mass fraction 10%-90%, which plays the role of conduction and support, and has almost no catalytic effect) and dispersed in ethanol or other organic solvents. Then, an appropriate amount of Nafion (mass fraction 5%) solution is added (catalyst concentration is 1~10 mg / mL, Nafion concentration in solution is 0.2~2 mg / mL). The mixture is then ultrasonically vibrated to obtain the catalyst slurry.

[0063] 2. Electrode preparation: A certain amount of the catalyst slurry prepared above was transferred onto a rotating disk electrode (RDE) using a micropipette, so that its loading on the RDE was 0.1 ~ 1 mg / cm³. 2 Then let it air dry naturally.

[0064] 3. Electrode activity measurement: The prepared electrode is mounted on a rotating disk device for electrochemical testing.

[0065] The testing procedure was as follows: The electrochemical testing system was a three-electrode system (glassy carbon electrode as the working electrode, platinum wire as the counter electrode, and Hg / Hg2SO4 as the reference electrode), and the electrolyte was 0.1 M HClO4. Before the test, oxygen was continuously introduced into the reactor for 30–60 min to saturate the electrolyte solution with oxygen, at a flow rate of 150–250 mL / min. During the test, oxygen was continuously introduced. Cyclic voltammetry was used to evaluate the oxygen evolution reaction (OER) catalytic activity, with a voltage scan range of 0.5–1.0 V, a scan rate of 10 mV / s, and a rotating disk speed of 1600 rpm.

[0066] 4. PEM electrolytic cell testing: The anode used an acid-etched catalyst, and the cathode used a commercial 40% Pt / C. The specific process was as follows: Catalyst powder was added to a certain proportion of water and ball-milled to ensure uniform dispersion. Then, an ion exchange resin solution (Nafion solution, generally 10%~30% by mass) was added, and ball milling was continued for 3~5 times to ensure sufficient contact between the catalyst particles and Nafion, improving proton conductivity. A dispersant (water:isopropanol = 1:8) was added and ultrasonically dispersed. Ultrasonic dispersion or ball milling was used to further homogenize the slurry, prevent catalyst agglomeration, and improve the uniformity of the electrode after spraying. The prepared slurry was uniformly sprayed onto thermal transfer paper using a handheld spray gun, and then transferred to both sides of the proton exchange membrane (Nafion 115) at 130℃ and 2 MPa pressure. The anode used a platinum-plated titanium felt as the gas diffusion layer, and the cathode used carbon paper as the gas diffusion layer for assembly. After the electrolyzer is assembled, deionized water is introduced into the anode side at a flow rate of 20 to 150 mL / min, and the temperature is maintained at 60 to 80 ℃ during the test.

[0067] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0068] Example 1: Preparation of SrCoO3 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0069] SrCoO3 oxide precursor powder was synthesized via a solid-state reaction method. SrCO3 (analytical grade) and Co3O4 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was ball-milled for 1 h until homogeneous. The mixture was then further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was calcined in a muffle furnace at a heating rate of 5 °C / min at 1000 °C for 5 h to obtain the desired SrCoO3 oxide precursor powder. Figure 1 and Figure 2 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0070] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 100 °C, the speed to 300 rpm, and the mixture was stirred for 20 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0071] Evaluation of the oxygen evolution catalytic performance of the SrCoO3 oxide precursor before and after acid etching. 10 mg of SrCoO3 catalyst and 10 mg of conductive carbon black (Super P) were weighed and dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 mL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 3 and Figure 4 As shown.

[0072] Example 2 Preparation of SrRuO3 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0073] SrRuO3 oxide precursor powder was synthesized via a solid-state reaction method. SrCO3 (analytical grade) and RuO2 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was ball-milled for 1 h until homogeneous. The mixture was then further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was calcined in a muffle furnace at a heating rate of 5 °C / min at 1000 °C for 5 h to obtain the desired SrRuO3 oxide precursor powder. Figure 5 and Figure 6 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0074] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 100 °C, the speed to 300 rpm, and the mixture was stirred for 20 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0075] Evaluation of the oxygen evolution catalytic performance of the SrRuO3 oxide precursor before and after acid etching. 10 mg of SrRuO3 catalyst and 10 mg of conductive carbon black (Super P) were weighed and dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 mL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 7 and Figure 8 As shown.

[0076] Example 3: Preparation of Sr2FeRuO6 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0077] Sr2FeRuO6 oxide precursor powder was synthesized via a solid-state reaction method. SrCO3 (analytical grade), Fe2O3 (analytical grade), and RuO2 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was then ball-milled for 1 h until homogeneous. The mixture was further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was calcined in a muffle furnace at 1100 °C for 10 h at a heating rate of 2 °C / min to obtain the desired Sr2FeRuO6 oxide precursor powder. Figure 9 and Figure 10 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0078] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 10 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 80 °C, the speed to 300 rpm, and the mixture was stirred for 10 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0079] Evaluation of the oxygen evolution catalytic performance of the Sr2FeRuO6 oxide precursor before and after acid etching. 10 mg of the Sr2FeRuO6 catalyst before and after acid etching was weighed and dispersed with 10 mg of conductive carbon black (Super P) in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 7 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 11 and Figure 12 As shown.

[0080] Example 4: Preparation of Ba2CoRuO6 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0081] Ba2CoRuO6 oxide precursor powder was synthesized via a solid-state reaction method. BaCO3 (analytical grade), Co3O4 (analytical grade), and RuO2 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was ball-milled for 1 h until homogeneous, then further dried to evaporate the medium and obtain a solid precursor. Finally, the precursor was placed in a muffle furnace and calcined at 1100 °C for 10 h at a heating rate of 2 °C / min to obtain the desired Ba2CoRuO6 oxide precursor powder. Figure 13 and Figure 14 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0082] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 80 °C, the speed to 300 rpm, and the mixture was stirred for 10 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0083] Performance evaluation of the oxygen evolution catalyst before and after acid etching of Ba2CoRuO6 oxide precursor. 10 mg of Ba2CoRuO6 catalyst and 10 mg of conductive carbon black (Super P) were dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 15 and Figure 16 As shown.

[0084] Example 5: Preparation of Sr2CoRuO6 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching.

[0085] Sr2CoRuO6 oxide precursor powder was synthesized via a solid-state reaction method. SrCO3 (analytical grade), Co3O4 (analytical grade), and RuO2 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was ball-milled for 1 h until homogeneous. The mixture was then further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was calcined in a muffle furnace at 1100 °C for 10 h at a heating rate of 2 °C / min to obtain the desired Sr2CoRuO6 oxide precursor powder. Figure 17 and Figure 18 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0086] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 80 °C, the speed to 300 rpm, and the mixture was stirred for 10 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0087] Evaluation of the oxygen evolution catalytic performance of the Sr2CoRuO6 oxide precursor before and after acid etching. 10 mg of Sr2CoRuO6 catalyst and 10 mg of conductive carbon black (Super P) were dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion 9 (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 19 and Figure 20 As shown.

[0088] Example 6: Preparation of Ba2CoMnO6 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0089] Ba2CoMnO6 oxide precursor powder was synthesized via a sol-gel method. Ba(NO3)2 (analytical grade), Co(NO3)2·6H2O (analytical grade), and Mn(NO3)2·4H2O (analytical grade) in the corresponding stoichiometric ratios were weighed, dissolved in deionized water, and stirred on a magnetic stirrer until clear, thus preparing solution 1.

[0090] The relative molecular weight is determined by weighing the metal ion: ethylenediaminetetraacetic acid (EDTA): monohydrate and citric acid (CA) in a ratio of 1:1:2. The volume of ammonia solution is measured as V = (4n(EDTA) + 3n(CA)) / ρ. 氨水

[0091] Place the weighed EDTA in beaker 2, pour the weighed ammonia into the EDTA, and stir with a glass rod until clear to make solution 2.

[0092] Pour solution 2 into solution 1, immediately add CA, place on a magnetic stir bar, set the temperature to 200℃ and the rotation speed to 200-400 rpm, and heat and stir the solution until it reaches a sol-gel state. Remove the rotor, place the beaker containing the sol-gel in an oven at 200℃ and dry for 5 h to obtain our catalyst precursor. Finally, place the precursor in a muffle furnace and calcine at 1100℃ for 12 h at a heating rate of 3℃ / min to obtain the desired Sr2CoRuO6 catalyst powder. Figure 21 and Figure 22 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0093] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 60 °C, the speed to 300 rpm, and the mixture was stirred for 20 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0094] Evaluation of the oxygen evolution catalytic performance of the Sr2CoRuO6 oxide precursor before and after acid etching. 10 mg of Sr2CoRuO6 catalyst and 10 mg of conductive carbon black (Super P) were dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 23 and Figure 24 As shown.

[0095] Example 7 Preparation of Sr2RuO4 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching

[0096] Sr2RuO4 oxide precursor powder was synthesized via a solid-state reaction method. SrCO3 (analytical grade) and RuO2 (analytical grade) in stoichiometric ratios were weighed and dissolved in anhydrous ethanol. The mixture was ball-milled for 1 h until homogeneous. The mixture was then further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was calcined in a muffle furnace at 1200 °C for 20 h at a heating rate of 5 °C / min to obtain the desired Sr2RuO4 catalyst powder. Figure 25 and 26 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0097] The catalyst was acid-etched according to the acid etching method described in the invention. 60 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 80 °C, the speed to 300 rpm, and the mixture was stirred for 10 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0098] Evaluation of the oxygen evolution catalytic performance of the Sr2RuO4 oxide precursor before and after acid etching. 10 mg of Sr2RuO4 catalyst and 10 mg of conductive carbon black (Super P) were dispersed in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 27 and 28 As shown.

[0099] Example 8: Preparation of NaSr3RuO6 oxide precursor and evaluation of its oxygen evolution catalytic performance before and after acid etching, and evaluation of the performance and stability of the PEM electrolyzer.

[0100] NaSr3RuO6 oxide precursor powder was synthesized via a solid-state reaction method. Na2CO3 (analytical grade), SrCO3 (analytical grade), and RuO2 (analytical grade) in stoichiometric proportions were dissolved in anhydrous ethanol and ball-milled for 1 h until homogeneous. The mixture was then further dried to evaporate the medium, yielding a solid precursor. Finally, the precursor was placed in a muffle furnace and calcined at 950 °C for 10 h at a heating rate of 5 °C / min to obtain the desired NaSr3RuO6 oxide precursor powder. Figure 29 and 30 The X-ray diffraction (XRD) curves before and after acid etching are shown.

[0101] The catalyst was acid-etched according to the acid etching method described in the invention. 100 mg of the catalyst was placed in a 20 mL glass bottle, 20 mL of 0.1 M nitric acid solution was added, a rotor was added, and the bottle was placed on a magnetic stirring table. The temperature was set to 160 °C, the speed to 400 rpm, and the mixture was stirred for 20 h. Then the catalyst was filtered and cleaned, and dried at 60 °C for 12 h.

[0102] Evaluation of the oxygen evolution catalytic performance of the NaSr3RuO6 oxide precursor before and after acid etching. 10 mg of the NaSr3RuO6 catalyst before and after acid etching was weighed and dispersed with 10 mg of conductive carbon black (Super P) in 1 mL of ethanol. Then, 0.05 mL of Nafion (5% by mass) solution was added, and the mixture was ultrasonically vibrated for 1 h to obtain a homogeneous catalyst slurry. 5 μL of the catalyst slurry was then transferred to a 5 mm diameter rotating disk electrode (RDE) using a microsyringe and allowed to air dry for 1 h. The resulting electrode was then subjected to oxygen evolution catalytic performance evaluation according to the electrode testing procedures described above. Figure 31 and32 As shown.

[0103] The prepared NaSr3RuO6 acid-etched catalyst (AE-RuO2) was used as the anode catalyst in a proton exchange membrane water electrolyzer, and commercial 40% Pt / C was used as the cathode catalyst for the oxygen evolution reaction at the anode and the hydrogen evolution reaction at the cathode, respectively. The proton exchange membrane water electrolyzer was assembled, and its water electrolysis performance was tested. The proton exchange membrane water electrolyzer device has an effective area of ​​4.0 cm². 2 The system includes components such as anodes and cathodes, proton exchange membranes, gaskets, flow channels, current collectors, and end plates. The proton exchange membrane is model Nafion 115 and requires immersion in 0.5 mol / L solution at 80 °C before use. -1 Pretreatment was completed in sulfuric acid (H2SO4) solution for 2 hours. Both the anode and cathode catalyst electrodes were prepared using a catalyst coating film process. Specifically, 100 mg of catalyst material and 300 mg of a 5 wt.% ionomer solution were dispersed in 10 g of a mixed solvent, which was obtained by mixing deionized water and isopropanol at a mass ratio of 3:8. Then, the mixture was ultrasonically dispersed at room temperature for 1 hour to obtain the AE-RuO2 catalyst slurry. The cathode catalyst was prepared using the same method. The obtained AE-RuO2 catalyst slurry was uniformly sprayed onto transfer paper using an ultrasonic spraying device. The mass loading of the anode catalyst was controlled at 2.0 mg / cm³. -2 The mass loading of the cathode catalyst was controlled at 1.0 mg cm⁻¹. -2 The cathode and anode catalysts were then transferred onto both sides of the proton exchange membrane at 130°C and 2 MPa pressure. The proton exchange membranes with catalyst-loaded sides were then integrated between two titanium bipolar plates, and the proton exchange membrane water electrolyzer was assembled with a torque of 8 N·m. The electrolyte used in this device was ultrapure water, and the electrolyte flow rate at both the anode and cathode was set to 40 mL / min. -1 The electrolytic cell operating temperature was 80 ± 2 ℃. Subsequently, the polarization curve was measured at 80℃ as follows: Figure 33 As shown, only 1.525 V and 1.857 V of electrolytic cell voltage are required to achieve 1 Acm. -2 and 3A cm -2 It exhibits excellent performance at a current density of 200 mA cm⁻¹. -2 It can operate stably for 200 hours under industrial current density, demonstrating good stability.

Claims

1. A method for preparing low / non-precious metal anode catalysts for PEM electrolyzers by acid etching, characterized in that, The method involves etching a metal oxide precursor in an acid solution, cleaning and drying the etched sample, and obtaining a PEM electrolytic cell anode catalyst with optimized surface morphology and chemical properties. The metal oxides include simple perovskite oxides, double perovskite oxides, Ruddlesden-Popper (RP) layered perovskite oxides, and complex metal oxides.

2. The method according to claim 1, characterized in that, Among the materials subjected to acid etching: the general structural formula of simple perovskite materials is ABO3; the general structural formula of double perovskite materials is A2B2O6; and the general structural formula of RP layered perovskite materials is A... n+1 B n O 3n+1 And complex metal oxides A4BO6; wherein the A-site cation is one or more rare earth metal ions or alkaline earth metal ions; and the B-site cation is one or more transition metal ions.

3. The method according to claim 2, characterized in that, The perovskite oxide has the general structural formula ABO3, where the A-site cation is Sr and the B-site cations are Co and Ru.

4. The method according to claim 2, characterized in that, The general structural formula of double perovskite oxides is A2B2O6, where the A-site cation is Ba or Sr, and the B-site cation is Ru or Co, Ru or Fe, Co or Mn.

5. The method according to claim 2, characterized in that, RP layered perovskite oxide has the general structural formula A n+1 B n O 3n+1 The cation at site A is Sr, and the cation at site B is Ru.

6. The method according to claim 2, characterized in that, The general formula for complex metal oxide structures is A4BO6, where the cation at the A site is Na or Sr, and the cation at the B site is Ru.

7. The method according to claim 1, characterized in that, The acidic solutions used for acid etching include nitric acid, hydrochloric acid, or sulfuric acid. The acid etching time and temperature are flexibly adjusted according to the material. The acid solution concentration is 0.1 ~ 0.5 M, the acid etching temperature is 40 ~ 80 ℃, and the time is 10 ~ 30 h.

8. The method according to claim 1, characterized in that, The electrocatalysts are SrCoO3, SrRuO3, Sr2FeRuO6, Ba2CoRuO6, Sr2CoRuO6, Ba2CoMnO6, Sr2RuO4, and NaSr3RuO6.

9. The catalyst obtained by the preparation method according to any one of claims 1 to 8, and the application of said catalyst, characterized in that, The application of the catalyst in a PEM electrolyzer, wherein the catalyst is used as the anode catalyst material in the PEM electrolyzer.

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