Metal oxide modified doped tin oxide film monolithic electrode and preparation method and application thereof

Abstract

The invention discloses a metal oxide modified doped tin oxide film monolithic electrode and a preparation method and application thereof. The preparation method comprises the following steps: placing a substrate in a solution at least containing tin salt and doped metal salt for electrochemical deposition, and then performing first annealing treatment to prepare a substrate coated with a doped tin oxide film; and dipping the substrate coated with the doped tin oxide thin film in a metal salt solution, and performing second annealing treatment to obtain the doped tin oxide thin film integral electrode modified by metal oxide. The preparation method of the metal oxide modified doped tin oxide thin film monolithic electrode provided by the invention is simple and low in cost, and the prepared metal oxide modified doped tin oxide thin film monolithic electrode has excellent performance in an acidic water oxidation electrocatalytic reaction; meanwhile, the method is high in universality and repeatability, wide in raw material source and easy to amplify, and is expected to replace precious metal to be applied to industrial large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical fields of metal oxide materials and electrolytic water technology, and particularly relates to a monolithic electrode of a metal oxide-modified doped tin oxide film, a preparation method thereof, and an application thereof. Background Art

[0002] The over-reliance on fossil fuels will trigger a series of energy and environmental problems. Hydrogen has the characteristics of high calorific value, cleanliness, and zero carbon emissions, and is expected to become a new energy carrier for industry and human activities. At present, the mature industrial hydrogen production is based on fossil energy and carried out through a complex high-energy-consuming water-gas shift process, accompanied by a large amount of carbon dioxide generation. The electrolytic water hydrogen production technology can be driven by green electricity converted from renewable energy and can play a unique role in the future hydrogen energy layout. Among many electrolytic water technologies, the acid proton exchange membrane electrolytic water technology, which has been attracting increasing attention, has the advantages of high hydrogen purity, large working current density, high energy efficiency, etc. However, the anodic oxygen evolution half-reaction in acidic media mainly uses noble metal catalysts, which limits its commercialization process. Developing high-performance non-noble metal catalysts has become a research direction that urgently needs to be broken through. There are many types of non-noble metal oxide materials, some of which have been theoretically predicted to have high catalytic activity and have been verified in alkaline electrolytic water technology. The diversified composition characteristics of mono-, bi- to high-entropy metal oxides make them show rich structural and property tunability in the catalytic process, but it also brings the problem that multiple preparation methods are required to synthesize different metal oxide materials. Especially in some methods such as hydrothermal method and chemical vapor deposition method, cross-reactions occur between multiple metals and the segregation order of different metal salts is inconsistent, which easily leads to the non-uniformity of the obtained metal oxides and the lack of certain metal components. In addition, metal oxides are usually less stable in acidic media and are prone to electrochemical corrosion under anodic oxidizing working conditions. Therefore, developing a new preparation technology with strong universality to apply a wide range of non-noble metal oxide materials to acidic electrolytic water hydrogen production technology has important scientific significance and application value. Summary of the Invention

[0003] The main purpose of the present invention is to provide a monolithic electrode of a metal oxide-modified doped tin oxide film, a preparation method thereof, and an application thereof to overcome the deficiencies of the prior art.

[0004] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include: An embodiment of the present invention provides a preparation method of a monolithic electrode of a metal oxide-modified doped tin oxide film, which includes: Placing a substrate in a solution containing at least a tin salt and a doped metal salt for electrochemical deposition, and then performing a first annealing treatment to obtain a substrate coated with a doped tin oxide film; Further, the substrate coated with the doped tin oxide film is immersed in a metal salt solution and then subjected to a second annealing treatment to obtain a metal oxide-modified doped tin oxide film monolithic electrode.

[0005] An embodiment of the present invention also provides a metal oxide-modified doped tin oxide film monolithic electrode prepared by the foregoing preparation method, which includes: a substrate, a doped tin oxide film layer coated on the surface of the substrate, and metal oxide nanomaterials uniformly distributed on the doped tin oxide film layer.

[0006] An embodiment of the present invention also provides an application of the foregoing metal oxide-modified doped tin oxide film monolithic electrode in an acidic electrocatalytic oxygen evolution reaction.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: The preparation method of the metal oxide-modified doped tin oxide film monolithic electrode provided by the present invention is simple and low-cost, and the prepared metal oxide-modified doped tin oxide film monolithic electrode has excellent performance in an acidic water oxidation electrocatalytic reaction; at the same time, this method has strong universality, high repeatability, wide raw material sources, is easy to scale up, and is expected to replace noble metals for industrial scale production. Description of the Drawings

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0009] Figure 1 It is an X-ray diffraction (XRD) pattern of the cobalt oxide-modified antimony-doped tin oxide film monolithic electrode prepared in Example 1 of the present invention; Figure 2 It is a scanning electron microscope (SEM) image of the cobalt oxide-modified antimony-doped tin oxide film monolithic electrode prepared in Example 1 of the present invention; Figure 3 It is an X-ray diffraction (XRD) pattern of the cobalt oxide-modified tin oxide film monolithic electrode prepared in Comparative Example 1 of the present invention; Figure 4 It is a scanning electron microscope (SEM) image of the cobalt oxide-modified tin oxide film monolithic electrode prepared in Comparative Example 1 of the present invention; Figure 5 It is an X-ray diffraction (XRD) pattern of the antimony-doped tin oxide film prepared in Comparative Example 2 of the present invention; Figure 6 It is a scanning electron microscope (SEM) image of the antimony-doped tin oxide film prepared in Comparative Example 2 of the present invention; Figure 7 This is the linear sweep voltammetry (LSV) graph of the acid oxygen evolution activity of the cobalt oxide modified antimony-doped tin oxide thin film monolithic electrode in Application Example 1 of the present invention; Figure 8 This is the chronopotentiometry (CP) graph of the acid oxygen evolution stability of the cobalt oxide modified antimony-doped tin oxide thin film monolithic electrode in Application Example 2 of the present invention. Detailed implementation manners

[0010] In view of the defects of the prior art, the inventors of this case have, through long-term research and a large number of practices, been able to propose the technical solution of the present invention. Specifically, a method with simple process, strong universality and easy amplification is developed to prepare a metal oxide modified doped tin oxide thin film monolithic electrode, providing an efficient and stable electrocatalyst to achieve an efficient acid water oxidation electrocatalytic process. The specific solution is to control the concentration of the first mixed solution, deposition time and potential, drying time and temperature, annealing temperature and time to prepare a substrate coated with a doped tin oxide thin film, and to control the concentration of the metal salt in the second mixed solution, dipping times, drying time and temperature, annealing temperature and time to obtain a monolithic electrode material with controllable morphology.

[0011] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0012] Specifically, as an aspect of the technical solution of the present invention, a preparation method of a metal oxide modified doped tin oxide thin film monolithic electrode includes: Placing a substrate in a solution containing at least a tin salt and a doped metal salt for electrochemical deposition, and then performing a first annealing treatment to obtain a substrate coated with a doped tin oxide thin film; And, dipping the substrate coated with the doped tin oxide thin film in a metal salt solution, and then performing a second annealing treatment to obtain a metal oxide modified doped tin oxide thin film monolithic electrode.

[0013] In some preferred embodiments, the preparation method specifically includes: Uniformly mixing a tin salt, a doped metal salt and a first solvent to form a first mixed solution; And, placing the substrate in the first mixed solution for electrochemical deposition, then drying and performing a first annealing treatment in air to obtain a substrate coated with a doped tin oxide thin film.

[0014] Further, the tin salt includes any one or a combination of two or more of tin pentachloride, stannous sulfate, stannous chloride, stannous propane sulfonate, stannous ethane sulfonate, stannous methane sulfonate, and is not limited thereto.

[0015] Further, the doping metal elements contained in the doping metal salt include any one or a combination of two or more of titanium, niobium, tantalum, molybdenum, tungsten, copper, bismuth, germanium, antimony, tellurium, and is not limited thereto.

[0016] Still further, the doping metal salt includes any one or a combination of two or more of titanium sulfate, niobium chloride, tantalum chloride, ammonium molybdate, ammonium metatungstate, copper nitrate, bismuth nitrate, ammonium hexafluorogermanate, antimony chloride, sodium tellurite, and is not limited thereto.

[0017] Further, the first solvent includes any one or a combination of two or more of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, and is not limited thereto.

[0018] Further, the concentration of the tin salt in the first mixed solution is 1 to 100 mmol / L.

[0019] Further, the concentration of the doping metal salt in the first mixed solution is 0.2 to 20 mmol / L.

[0020] Further, the concentration of the dilute acid in the first mixed solution is 0.5 to 3 mol / L.

[0021] Further, the electrochemical deposition potential used for the electrochemical deposition is -1.3 to -2.3 V, and the time is 50 to 500 s.

[0022] Still further, the electrochemical deposition potential is -1.3 to -2 V, and the time is 100 to 300 s.

[0023] Further, the temperature of the drying is 60 to 200 °C, and the time is 3 to 24 h.

[0024] Still further, the temperature of the drying is 60 to 180 °C, and the time is 3 to 12 h.

[0025] Further, the temperature of the first annealing treatment is 300 to 800 °C, and the time is 2 to 10 h.

[0026] Still further, the temperature of the first annealing treatment is 300 to 600 °C, and the time is 3 to 6 h.

[0027] In some preferred embodiments, the preparation method specifically includes: Uniformly mixing the metal salt with the second solvent to form a second mixed solution; And, place the substrate coated with the doped tin oxide film into the second mixed solution, take it out after dip-coating and dry it, repeat the operations of dip-coating and drying, and then perform a second annealing treatment in air to obtain an integrally formed electrode of a metal oxide-modified doped tin oxide film.

[0028] Further, the metal salt includes any one or a combination of two or more of magnesium nitrate, aluminum nitrate, manganese sulfate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, and is not limited thereto.

[0029] Further, the second solvent includes any one or a combination of two or more of water, methanol, ethanol, propanol, isopropanol, and is not limited thereto.

[0030] Further, the concentration of the metal salt in the second mixed solution is 0.1 - 5 mol / L.

[0031] Further, the preparation method specifically includes: placing the substrate coated with the doped tin oxide film into the second mixed solution for dip-coating, taking it out and drying it at 60 - 180 °C for 5 - 60 min, repeating the above operations multiple times, and then performing a second annealing treatment in air to obtain an integrally formed electrode of a metal oxide-modified doped tin oxide film.

[0032] Further, the number of times of repeating the above operations is 1 - 10 times.

[0033] Further, the temperature of the second annealing treatment is 300 - 800 °C.

[0034] Still further, the temperature of the second annealing treatment is 300 - 600 °C.

[0035] Further, the time of the second annealing treatment is 2 - 10 h.

[0036] Still further, the time of the second annealing treatment is 3 - 6 h.

[0037] In some preferred embodiments, the preparation method further includes: before performing the electrochemical deposition treatment, first placing the substrate into a dilute acid aqueous solution and heating it at 40 - 90 °C for 20 - 90 min, and then ultrasonically cleaning the substrate with acetone, ethanol, and water in sequence and drying it. The present invention uses a dilute acid aqueous solution to treat the substrate, making the surface of the substrate rougher, which is beneficial to the combined growth of catalytic materials on its surface.

[0038] Further, the dilute acid aqueous solution includes any one or a combination of two or more of dilute sulfuric acid, dilute nitric acid, dilute hydrochloric acid, dilute phosphoric acid, and is not limited thereto.

[0039] Further, the concentration of the dilute acid aqueous solution is 0.1 - 5 mol / L.

[0040] In some preferred embodiments, the substrate includes, but is not limited to, any one of stainless steel felt, titanium felt, copper foam, nickel foam, and carbon cloth.

[0041] In some more specific embodiments, the method for preparing the metal oxide-modified doped tin oxide thin film monolithic electrode includes the following steps: Place the substrate in an aqueous solution of dilute acid, heat it in a constant temperature water bath, with the heating temperature being 40 - 90 °C and the time being 20 - 90 min. Then ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; Dissolve a certain proportion of tin salt and doped metal salt in a solvent, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2). After electrochemical deposition, take it out and dry it at 60 - 200 °C for 3 - 24 h. Then, perform a first annealing treatment on the obtained sample in air to obtain a substrate coated with a doped tin oxide thin film (the aforementioned "substrate coated with a doped tin oxide thin film"); Dissolve a certain proportion of metal salt in a solvent, and stir evenly at room temperature to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4). After dip-coating 1 - 10 times, dry the obtained sample. Then, perform a second annealing treatment on the obtained sample in air to obtain a monolithic electrode with a metal oxide catalyst surface-modified on the substrate coated with a doped tin oxide thin film, that is, the aforementioned metal oxide-modified doped tin oxide thin film monolithic electrode.

[0042] In some embodiments, in step (1), the substrate can be at least any one of stainless steel felt, titanium felt, copper foam, nickel foam, and carbon cloth, etc., but is not limited thereto.

[0043] In some embodiments, in step (1), the aqueous solution of dilute acid can be any one or a combination of two or more of dilute sulfuric acid, dilute nitric acid, dilute hydrochloric acid, and dilute phosphoric acid, etc., but is not limited thereto.

[0044] Furthermore, in step (1), the concentration of the aqueous solution of dilute acid is 0.1 - 5 mol / L.

[0045] In some embodiments, in step (2), the tin salt can be any one or a combination of two or more of tin pentachloride pentahydrate, stannous sulfate, stannous chloride, tin propane sulfonate, tin ethane sulfonate, tin methanesulfonate, etc., but is not limited thereto.

[0046] In some embodiments, in step (2), the doping metal element contained in the doping metal salt can be any one or a combination of two or more of titanium, niobium, tantalum, molybdenum, tungsten, copper, bismuth, germanium, antimony, tellurium, etc., but not limited thereto. Specifically, the doping metal salt can be any one or a combination of two or more of titanium sulfate, niobium chloride, tantalum chloride, ammonium molybdate, ammonium metatungstate, copper nitrate, bismuth nitrate, ammonium hexafluorogermanate, antimony chloride, sodium tellurite, etc., but not limited thereto.

[0047] The preparation method of the present invention has the characteristic of universality. The doping metal salt used has a wide source and strong operability.

[0048] In some embodiments, in step (2), the solvent can be any one or a combination of two or more of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, etc., but not limited thereto.

[0049] In some embodiments, in step (2), the concentration of the tin salt in the first mixed solution is 1 to 100 mmol / L.

[0050] Furthermore, the concentration of the doping metal salt in the first mixed solution is 0.2 to 20 mmol / L.

[0051] In some embodiments, in step (2), the concentration of the dilute acid in the solvent of the first mixed solution is 0.5 to 3 mol / L.

[0052] In some embodiments, in step (3), the electrochemical deposition potential when the substrate is placed in the first mixed solution obtained in step (2) is -1.3 V to -2.3 V, and the electrochemical deposition time is 50 to 500 s. The effect is to form a coating layer containing doping metal and tin elements on the surface of the substrate.

[0053] In some embodiments, in step (3), the drying temperature is 60 to 200 °C, and the time is 3 to 24 h.

[0054] In some embodiments, in step (3), the temperature of the first annealing treatment is 300 to 800 °C, and the time is 2 to 10 h.

[0055] In some embodiments, in step (5), the metal salt can be any one or a combination of two or more of magnesium nitrate, aluminum nitrate, manganese sulfate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, etc., but not limited thereto. The metal salt used in the present invention has a wide source and is relatively inexpensive compared to precious metals.

[0056] In some embodiments, in step (5), the solvent can be any one or a combination of two or more of water, methanol, ethanol, propanol, isopropanol, etc., but not limited thereto.

[0057] In some embodiments, in step (5), the concentration of the metal salt in the second mixed solution is 0.1 - 5 mol / L.

[0058] In some embodiments, in step (6), the drying temperature is 60 - 180 °C and the drying time is 5 - 60 min. In some embodiments, in step (6), the temperature of the second annealing treatment is 300 - 800 °C and the time is 2 - 10 h.

[0059] In summary, the preparation method of the present invention has the characteristics of simple process, easy to scale up, and strong universality.

[0060] The preparation method of the monolithic electrode of the metal oxide modified doped tin oxide film provided by the present invention coats the doped tin oxide on the substrate by controlling the time, potential, concentration of the first mixed solution, drying temperature, annealing temperature and time of electrochemical deposition, and then obtains a monolithic electrode material with controllable morphology by controlling the concentration of the metal salt in the second mixed solution, the number of dip coating times, the drying temperature, the annealing temperature and time.

[0061] Another aspect of the embodiments of the present invention also provides a monolithic electrode of a metal oxide modified doped tin oxide film prepared by the foregoing preparation method, which includes: a substrate, a doped tin oxide film layer coated on the surface of the substrate, and metal oxide nanomaterials uniformly distributed on the doped tin oxide film layer.

[0062] In some preferred embodiments, the thickness of the doped tin oxide film layer is 50 - 800 nm.

[0063] In some preferred embodiments, the mass ratio of the doped tin oxide film layer to the metal oxide nanomaterials is 20 - 40:60 - 80.

[0064] In some preferred embodiments, in the monolithic electrode of the metal oxide modified doped tin oxide film, the content of the doped tin oxide film layer except the substrate is 20 - 40 wt%, and the content of the metal oxide nanomaterials is 60 - 80 wt%.

[0065] In some preferred embodiments, the metal oxide nanomaterials include metal oxide nanosheets.

[0066] Furthermore, the diameter of the metal oxide nanosheets is 100 - 500 nm. The nanosheet structure in the present invention has a higher specific surface area compared with the disordered accumulation of nanoparticles, which is beneficial to the improvement of the electrocatalytic performance.

[0067] The corrosion-resistant and highly conductive doped tin oxide thin film prepared by the present invention based on electrochemical deposition can stabilize the metal oxide catalyst on the surface, and at the same time, the metal oxide can interact with the doped tin oxide thin film electronically to enhance the catalytic activity. The monolithic electrode of the metal oxide-modified doped tin oxide thin film has high activity and stability for the oxygen evolution reaction in acidic electrolytic water.

[0068] Furthermore, the monolithic electrode of the metal oxide-modified doped tin oxide thin film obtained in the present invention can be directly used as an electrode material in an electrolytic cell, eliminating the process of coating the catalytic material on the electrode.

[0069] Another aspect of the embodiment of the present invention also provides the application of the aforementioned monolithic electrode of the metal oxide-modified doped tin oxide thin film in the acidic electrocatalytic oxygen evolution reaction.

[0070] Specifically, the monolithic electrode of the metal oxide-modified doped tin oxide thin film prepared in the present invention has excellent performance in the acidic water oxidation electrocatalytic reaction.

[0071] By means of the above technical solutions, the present invention in-situ prepares metal oxide nanomaterials directly on the corrosion-resistant doped tin oxide thin film and then applies it to the acidic electrocatalytic oxygen evolution reaction. This method has the characteristics of simple process, easy amplification, and strong universality, and is expected to replace noble metals for industrial scale production.

[0072] The following further elaborates on the technical solutions of the present invention in conjunction with several preferred embodiments and the accompanying drawings. These embodiments are implemented on the premise of the technical solutions of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0073] The experimental materials used in the following embodiments can be purchased from conventional biochemical reagent companies without special instructions.

[0074] Example 1 Place the titanium felt in a 0.5 mol / L dilute sulfuric acid aqueous solution and heat it in a constant temperature water bath at 90 °C for 60 minutes. Then ultrasonically clean the substrate with acetone, ethanol, and deionized water in sequence and dry it; Dissolve 10 mmol / L of tin chloride pentahydrate and 2 mmol / L of antimony chloride in 1 mol / L dilute hydrochloric acid and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.7 V, electrochemically deposit for 150 s, take it out and dry it at 80 °C for 12 h, and then perform a first annealing treatment in air at an annealing temperature of 400 °C for 5 h to obtain a substrate coated with antimony-doped tin oxide thin film; Dissolve cobalt nitrate of 1 mol / L in water to form a second mixed solution; Immerse the sample obtained in step (3) in the second mixed solution obtained in step (4), and dry it at 80 °C for 10 min. Then repeat the above steps 5 times, and perform a second annealing treatment on the obtained sample in air at 350 °C for 5 h to obtain a cobalt oxide catalyst with a surface modified by antimony-doped tin oxide film-coated substrate (i.e., a monolithic electrode of cobalt oxide-modified antimony-doped tin oxide film).

[0075] As Figure 1 shown, it is the XRD pattern of the monolithic electrode of cobalt oxide-modified antimony-doped tin oxide film prepared in Example 1. It shows that, in addition to the diffraction peaks of the titanium metal substrate, obvious diffraction peaks of antimony-doped tin oxide and cobalt oxide appear, proving that a cobalt oxide catalyst has grown on the surface of the titanium substrate coated with the doped tin oxide film.

[0076] As Figure 2 shown, it is the SEM image of the monolithic electrode of cobalt oxide-modified antimony-doped tin oxide film prepared in Example 1. It shows that cobalt oxide nanosheets are uniformly distributed on the antimony-doped tin oxide film, proving that a cobalt oxide catalyst has grown on the surface of the titanium felt substrate coated with antimony-doped tin oxide.

[0077] Example 2 Place the stainless steel felt in an aqueous solution of 0.1 mol / L dilute hydrochloric acid, and heat it in a constant temperature water bath at 40 °C for 90 minutes. Then ultrasonically treat the substrate with acetone, ethanol, and deionized water in sequence, and dry it; Dissolve 1 mmol / L tin chloride pentahydrate and 0.2 mmol / L titanium sulfate in 0.5 mol / L dilute sulfuric acid, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) in the first mixed solution obtained in step (2), with a deposition potential of -1.3 V, perform electrochemical deposition for 500 s, take it out and dry it at 60 °C for 24 h, and then perform a first annealing treatment in air at an annealing temperature of 300 °C for 10 h to obtain a substrate coated with titanium-doped tin oxide; Dissolve 0.1 mol / L nickel nitrate in methanol to form a second mixed solution; Immerse the sample obtained in step (3) in the second mixed solution obtained in step (4), and dry it at 60 °C for 60 min. Then repeat the above steps 1 time, and perform a second annealing treatment on the obtained sample in air at 300 °C for 10 h to obtain a nickel oxide catalyst with a surface modified by titanium-doped tin oxide film-coated substrate (i.e., a monolithic electrode of nickel oxide-modified titanium-doped tin oxide film).

[0078] Example 3 Place the copper foam in a 2 mol / L dilute nitric acid aqueous solution and heat it in a constant temperature water bath at 50 °C for 80 minutes. Then ultrasonically clean the substrate with acetone, ethanol, and deionized water in sequence, and dry it; Dissolve 10 mmol / L stannous chloride and 2 mmol / L niobium chloride in 1 mol / L dilute nitric acid, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.4 V, electrochemically deposit for 450 s, take it out and dry it at 80 °C for 21 h, and then perform a first annealing treatment in air at an annealing temperature of 350 °C for 9 h to obtain a substrate coated with niobium-doped tin oxide film; Dissolve 0.5 mol / L iron nitrate in ethanol to form a second mixed solution; Dip-coat the sample obtained in step (3) into the second mixed solution obtained in step (4) and dry it at 80 °C for 55 min. Then repeat the above steps 2 times, and perform a second annealing treatment on the obtained sample in air at 350 °C for 9 h to obtain an iron oxide catalyst-modified surface of the substrate coated with niobium-doped tin oxide film (i.e., an integrated electrode of iron oxide-modified niobium-doped tin oxide film).

[0079] Example 4 Place the nickel foam in a 3 mol / L dilute phosphoric acid aqueous solution and heat it in a constant temperature water bath at 60 °C for 70 minutes. Then ultrasonically clean the substrate with acetone, ethanol, and deionized water in sequence, and dry it; Dissolve 20 mmol / L stannous sulfate and 4 mmol / L tantalum chloride in 1 mol / L dilute hydrochloric acid, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.5 V, electrochemically deposit for 400 s, take it out and dry it at 100 °C for 18 h, and then perform a first annealing treatment in air at an annealing temperature of 400 °C for 8 h to obtain a substrate coated with tantalum-doped tin oxide film; Dissolve 1 mol / L cobalt nitrate and iron nitrate in water to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4) and dry it at 100 °C for 50 min. Then repeat the above steps 3 times, and perform a second annealing treatment on the obtained sample in air at 400 °C for 8 h to obtain a cobalt-iron bimetallic oxide catalyst-modified surface of the substrate coated with tantalum-doped tin oxide film (i.e., an integrated electrode of cobalt-iron bimetallic oxide-modified tantalum-doped tin oxide film).

[0080] Example 5 Place carbon in an aqueous solution of hydrochloric acid at 3 mol / L and heat it in a constant temperature water bath at 70 °C for 60 minutes. Then, ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; Dissolve stannous propane sulfonate at 30 mmol / L and ammonium molybdate at 8 mmol / L in dilute hydrochloric acid at 2 mol / L, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.6 V, and perform electrochemical deposition for 350 s. After taking it out, dry it at 120 °C for 15 h, and then perform a first annealing treatment in air at an annealing temperature of 450 °C for 7 h to obtain a substrate coated with a molybdenum-doped tin oxide film; Dissolve cobalt nitrate and nickel nitrate at 2 mol / L in propanol to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4) and dry it at 120 °C for 45 min. Then repeat the above steps 4 times, and perform a second annealing treatment on the obtained sample in air at 450 °C for 7 h to obtain a catalyst with cobalt-nickel bimetallic oxide modified on the surface of a substrate coated with a molybdenum-doped tin oxide film (i.e., a monolithic electrode with cobalt-nickel bimetallic oxide modified molybdenum-doped tin oxide film).

[0081] Example 6 Place the titanium felt in an aqueous solution of dilute hydrochloric acid at 3 mol / L and heat it in a constant temperature water bath at 80 °C for 50 minutes. Then, ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; Dissolve stannous ethane sulfonate at 40 mmol / L and ammonium metatungstate at 10 mmol / L in dilute sulfuric acid at 2 mol / L, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.7 V, and perform electrochemical deposition for 300 s. After taking it out, dry it at 140 °C for 12 h, and then perform a first annealing treatment in air at an annealing temperature of 500 °C for 6 h to obtain a substrate coated with tungsten-doped tin oxide; Dissolve cobalt nitrate, iron nitrate, and nickel nitrate at 3 mol / L in isopropanol to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4) and dry it at 140 °C for 40 min. Then repeat the above steps 5 times, and perform a second annealing treatment on the obtained sample in air at 500 °C for 6 h to obtain a catalyst with iron-cobalt-nickel trimetallic oxide modified on the surface of a substrate coated with a tungsten-doped tin oxide film (i.e., a monolithic electrode with iron-cobalt-nickel trimetallic oxide modified tungsten-doped tin oxide film).

[0082] Example 7 Place the stainless steel felt in a 4 mol / L dilute nitric acid aqueous solution and heat it in a constant temperature water bath at 90 °C for 40 minutes. Then ultrasonically treat this substrate successively with acetone, ethanol, and deionized water, and dry it; Dissolve 50 mmol / L stannous methanesulfonate and 12 mmol / L copper nitrate in 2 mol / L dilute nitric acid, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.9 V, electrochemically deposit for 250 s, take it out and dry it at 160 °C for 9 h, and then perform a first annealing treatment in air, with an annealing temperature of 550 °C and a time of 5 h, to obtain a substrate coated with a copper-doped tin oxide film; Dissolve 3 mol / L cobalt nitrate, iron nitrate, nickel nitrate, and copper nitrate in water to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4), and dry it at 160 °C for 30 min. Then repeat the above steps 6 times, and perform a second annealing treatment on the obtained sample in air at 550 °C for 5 h, to obtain a catalyst with a quaternary metal oxide of iron, cobalt, nickel, and copper modified on the surface of a substrate coated with a copper-doped tin oxide film (i.e., a monolithic electrode with a quaternary metal oxide of iron, cobalt, nickel, and copper modified on a copper-doped tin oxide film).

[0083] Example 8 Place the titanium felt in a 1 mol / L dilute sulfuric acid aqueous solution and heat it in a constant temperature water bath at 80 °C for 30 minutes. Then ultrasonically treat this substrate successively with acetone, ethanol, and deionized water, and dry it; Dissolve 50 mmol / L stannous chloride and 10 mmol / L antimony nitrate in 1 mol / L dilute hydrochloric acid, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.8 V, electrochemically deposit for 150 s, take it out and dry it at 100 °C for 10 h, and then perform a first annealing treatment in air, with an annealing temperature of 500 °C and a time of 4 h, to obtain a substrate coated with an antimony-doped tin oxide film; Dissolve 2 mol / L cobalt nitrate, iron nitrate, nickel nitrate, copper chloride, and zinc nitrate in water to form a second mixed solution; The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and dried at 100 °C for 20 min. Then the above steps were repeated 6 times, and the obtained sample was subjected to a second annealing treatment in air at 400 °C for 4 h, thus obtaining a catalyst with a surface modified by antimony-doped tin oxide film-coated iron cobalt nickel copper zinc high-entropy metal oxide (i.e., an integrated electrode of iron cobalt nickel copper zinc high-entropy metal oxide-modified antimony-doped tin oxide film).

[0084] Example 9 The nickel foam was placed in an aqueous solution of dilute sulfuric acid at 5 mol / L and heated in a constant temperature water bath at 90 °C for 20 minutes. Then the substrate was ultrasonically treated with acetone, ethanol, and deionized water in sequence and dried; 90 mmol / L of stannous sulfate and 20 mmol / L of ammonium hexafluorogermanate were dissolved in dilute sulfuric acid at 3 mol / L and stirred evenly at room temperature to form a first mixed solution; The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), the deposition potential was -2.2 V, and electrochemical deposition was carried out for 100 s. After taking out, it was dried at 200 °C for 3 h, and then subjected to a first annealing treatment in air at an annealing temperature of 700 °C for 3 h to obtain a substrate coated with germanium-doped tin oxide film; 5 mol / L of cobalt nitrate, iron nitrate, nickel nitrate, copper nitrate, and aluminum nitrate were dissolved in water to form a second mixed solution; The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and dried at 180 °C for 10 min. Then the above steps were repeated 9 times, and the obtained sample was subjected to a second annealing treatment in air at 700 °C for 3 h, thus obtaining a catalyst with a surface modified by germanium-doped tin oxide film-coated iron cobalt nickel copper aluminum high-entropy metal oxide (i.e., an integrated electrode of iron cobalt nickel copper aluminum high-entropy metal oxide-modified germanium-doped tin oxide film).

[0085] Example 10 The carbon cloth was placed in an aqueous solution of dilute sulfuric acid at 5 mol / L and heated in a constant temperature water bath at 90 °C for 20 minutes. Then the substrate was ultrasonically treated with acetone, ethanol, and deionized water in sequence and dried; 100 mmol / L of stannous chloride pentahydrate and 20 mmol / L of sodium tellurite were dissolved in dilute nitric acid at 3 mol / L and stirred evenly at room temperature to form a first mixed solution; The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), the deposition potential was -2.3 V, and electrochemical deposition was carried out for 50 s. After taking out, it was dried at 200 °C for 3 h, and then subjected to a first annealing treatment in air at an annealing temperature of 800 °C for 2 h to obtain a substrate coated with tellurium-doped tin oxide film; Dissolve cobalt nitrate, iron nitrate, nickel nitrate, copper nitrate and magnesium nitrate with a concentration of 5 mol / L in water to form a second mixed solution; Place the sample obtained in step (3) into the second mixed solution obtained in step (4), and dry it at 180 °C for 5 min. Then repeat the above steps 10 times, and perform a second annealing treatment on the obtained sample in air at 800 °C for 2 h, thus obtaining a catalyst of iron-cobalt-nickel-copper-magnesium high-entropy metal oxide coated on the surface of a tellurium-doped tin oxide film-coated substrate (i.e., an integrated electrode of iron-cobalt-nickel-copper-magnesium high-entropy metal oxide modified tellurium-doped tin oxide film).

[0086] Comparative Example 1 Place the titanium felt into an aqueous solution of dilute sulfuric acid with a concentration of 0.5 mol / L, and heat it in a constant-temperature water bath at 90 °C for 60 minutes. Then ultrasonically treat the substrate with acetone, ethanol and deionized water in sequence, and dry it; Dissolve stannous chloride pentahydrate with a concentration of 10 mmol / L in dilute hydrochloric acid with a concentration of 1 mol / L, and stir evenly at room temperature to form a first mixed solution; Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.7 V, perform electrochemical deposition for 150 s, take it out and dry it at 80 °C for 12 h, and then perform a first annealing treatment in air, with an annealing temperature of 400 °C and a time of 5 h, to obtain a substrate coated with a tin oxide film; Dissolve cobalt nitrate with a concentration of 1 mol / L in water to form a second mixed solution; Dip-coat the sample obtained in step (3) into the second mixed solution obtained in step (4), and dry it at 80 °C for 10 min. Then repeat the above steps 5 times, and perform a second annealing treatment on the obtained sample in air at 350 °C for 5 h, thus obtaining a catalyst of cobalt oxide coated on the surface of a tin oxide film-coated substrate (i.e., an integrated electrode of cobalt oxide modified tin oxide film).

[0087] As Figure 3 shown, it is the XRD pattern of the integrated electrode of cobalt oxide modified tin oxide film prepared in Comparative Example 1, showing that obvious diffraction peaks of tin oxide and cobalt oxide appear outside the diffraction peaks of the titanium metal substrate, proving that a cobalt oxide catalyst has grown on the surface of the tin oxide film-coated titanium substrate.

[0088] As Figure 4 shown, it is the SEM image of the integrated electrode of cobalt oxide modified tin oxide film prepared in Comparative Example 1, showing that cobalt oxide nanosheets are uniformly distributed on the tin oxide film, proving that a cobalt oxide catalyst has grown on the surface of the tin oxide-coated titanium felt substrate.

[0089] Comparative Example 2 (1) Place the titanium felt in a 0.5 mol / L dilute sulfuric acid aqueous solution and heat it in a constant temperature water bath at 90 °C for 60 minutes. Then ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; (2) Dissolve 10 mmol / L of stannous chloride pentahydrate and 2 mmol / L of antimony chloride in 1 mol / L dilute hydrochloric acid, and stir evenly at room temperature to form a first mixed solution; (3) Place the substrate obtained in step (1) into the first mixed solution obtained in step (2), with a deposition potential of -1.7 V, and perform electrochemical deposition for 150 s. After taking it out, dry it at 80 °C for 12 h, and then perform a first annealing treatment in air at an annealing temperature of 400 °C for 5 h to obtain a substrate coated with antimony-doped tin oxide film.

[0090] As Figure 5 shown, it is the XRD pattern of the antimony-doped tin oxide film prepared in Comparative Example 2, showing that obvious diffraction peaks of antimony-doped tin oxide appear outside the diffraction peaks of the titanium metal substrate, proving that the antimony-doped tin oxide film is coated on the titanium substrate.

[0091] As Figure 6 shown, it is the SEM image of the antimony-doped tin oxide film prepared in Comparative Example 2, showing that the antimony-doped tin oxide film is composed of uniform nanoparticles.

[0092] Comparative Example 3 (1) Place the stainless steel felt in a 0.1 mol / L dilute hydrochloric acid aqueous solution and heat it in a constant temperature water bath at 40 °C for 90 minutes. Then ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; (2) Dissolve 200 mmol / L of stannous chloride pentahydrate and 40 mmol / L of antimony chloride in water, and stir evenly at room temperature. It is very difficult to form a first mixed solution; Step (3) cannot be carried out, and a stainless steel substrate coated with antimony-doped tin oxide cannot be prepared.

[0093] Comparative Example 4 (1) Place the titanium felt in a 0.5 mol / L dilute sulfuric acid aqueous solution and heat it in a constant temperature water bath at 90 °C for 60 minutes. Then ultrasonically clean the substrate successively with acetone, ethanol, and deionized water, and dry it; (2) Dissolve 10 mmol / L of stannous chloride pentahydrate and 2 mmol / L of antimony chloride in 1 mol / L dilute hydrochloric acid, and stir evenly at room temperature to form a first mixed solution; (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), with a deposition potential of -0.3 V, and electrochemically deposited for 150 s. After taking it out, it was dried at 80 °C for 12 h, and then subjected to a first annealing treatment in air at an annealing temperature of 400 °C for 5 h. However, a substrate coated with antimony-doped tin oxide thin film could not be obtained.

[0094] Application Example 1 Using the substrate surface-modified cobalt oxide catalyst coated with the antimony-doped tin oxide thin film obtained in Example 1 (i.e., the cobalt oxide-modified antimony-doped tin oxide thin film monolithic electrode) as the working electrode to catalyze the acidic oxygen evolution reaction, an activity test was carried out.

[0095] (1) The electrocatalytic oxygen evolution performance of the composite electrocatalytic material was tested on an electrochemical workstation using a three-electrode mode. Using a 0.5 mol / L sulfuric acid aqueous solution as the electrolyte, the prepared catalyst was used as the working electrode, silver / silver chloride as the reference electrode, and a high-purity platinum wire as the counter electrode. Polarization curve tests were carried out in the potential range of 1 - 2 V.

[0096] Test conditions: The test temperature was room temperature 25 °C, and the linear sweep rate was 5 mV / s.

[0097] (3) As Figure 7 shown, the composite electrocatalytic material exhibited excellent electrocatalytic oxygen evolution activity in an acidic environment. The overpotential at a current density of 10 mA / cm 2 was 326.9 mV, and the measured catalytic activity was comparable to that of the better non-noble metal activities in current acidic electrolytic water hydrogen evolution research.

[0098] Application Example 2 Using the substrate surface-modified cobalt oxide catalyst coated with the antimony-doped tin oxide thin film obtained in Example 1 (i.e., the cobalt oxide-modified antimony-doped tin oxide thin film monolithic electrode) as the working electrode to catalyze the acidic oxygen evolution reaction, a stability test was carried out.

[0099] (1) The electrocatalytic oxygen evolution performance of the composite electrocatalytic material was tested on an electrochemical workstation using a three-electrode mode. Using a 0.5 mol / L sulfuric acid aqueous solution as the electrolyte, the prepared catalyst was used as the working electrode, silver / silver chloride as the reference electrode, and a high-purity platinum wire as the counter electrode. Potential-time curve tests were carried out in the constant current mode.

[0100] (2) Test conditions: The test temperature was room temperature 25 °C.

[0101] (3) As Figure 8 shown, the composite electrocatalytic material exhibited excellent oxygen evolution stability in an acidic environment. At a current density of 10 mA / cm 2It can stably operate for more than 500 hours, and the measured catalytic stability leads that of the common non-precious metals in the current acidic electrolytic water hydrogen evolution research.

[0102] Application Example 3 Using the cobalt oxide catalyst modified on the surface of the substrate coated with the tin oxide film obtained in Comparative Example 1 (i.e., the cobalt oxide-modified tin oxide film monolithic electrode) as the working electrode to catalyze the acidic oxygen evolution reaction, and conduct an activity test.

[0103] (1) The electrochemical oxygen evolution performance of the composite electrocatalytic material was tested on an electrochemical workstation using a three-electrode mode. Using a 0.5 mol / L sulfuric acid aqueous solution as the electrolyte, the prepared catalyst was used as the working electrode, silver / silver chloride as the reference electrode, and a high-purity platinum wire as the counter electrode, and a polarization curve test was conducted in the potential range of 1 - 2 V.

[0104] (2) Test conditions: The test temperature was room temperature 25 °C, and the linear scanning rate was 5 mV / s.

[0105] (3) The overpotential of the composite electrocatalytic material at a current density of 10 mA / cm 2 was 402.9 mV, and the measured catalytic activity was poor.

[0106] Application Example 4 Using the substrate coated with the antimony-doped tin oxide film obtained in Comparative Example 2 as the working electrode to catalyze the acidic oxygen evolution reaction, and conduct an activity test.

[0107] (1) The electrochemical oxygen evolution performance of the material was tested on an electrochemical workstation using a three-electrode mode. Using a 0.5 mol / L sulfuric acid aqueous solution as the electrolyte, the prepared substrate was used as the working electrode, silver / silver chloride as the reference electrode, and a high-purity platinum wire as the counter electrode, and a polarization curve test was conducted in the potential range of 1 - 2 V.

[0108] (2) Test conditions: The test temperature was room temperature 25 °C, and the linear scanning rate was 5 mV / s.

[0109] (3) The overpotential of the material at a current density of 10 mA / cm 2 was 825.9 mV, and the measured catalytic activity was very poor.

[0110] In addition, the inventor of this case also conducted experiments in the manner of the foregoing embodiments with other raw materials and conditions listed in this specification, and also prepared a metal oxide-modified doped tin oxide film monolithic electrode with excellent performance in the acidic water oxidation electrocatalytic reaction.

[0111] It should be understood that the technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention without departing from the purpose of the present invention and the scope protected by the claims falls within the protection scope of the present invention.

Claims

1. A method for preparing a metal oxide modified doped tin oxide thin film monolithic electrode, characterized in that: include: Placing the substrate in a solution containing at least tin salt and doped metal salt for electrochemical deposition, and then subjecting the substrate to a first annealing treatment to obtain a substrate coated with a doped tin oxide film; Furthermore, the substrate coated with the doped tin oxide film is immersed in a metal salt solution, and then subjected to a second annealing treatment to obtain a metal oxide-modified doped tin oxide film integral electrode.

2. The preparation method according to claim 1, characterized in that: Specifically include: uniformly mixing the tin salt, the doped metal salt and the first solvent to form a first mixed solution; And, placing the substrate in the first mixed solution for electrochemical deposition, and then drying and performing a first annealing treatment in air to obtain a substrate coated with a doped tin oxide film.

3. The preparation method according to claim 2, characterized in that: The tin salt includes any one or a combination of two or more of tin chloride pentahydrate, stannous sulfate, stannous chloride, tin propane sulfonate, tin ethane sulfonate, and tin methane sulfonate; And / or, the doped metal element contained in the doped metal salt includes any one or a combination of two or more of titanium, niobium, tantalum, molybdenum, tungsten, copper, bismuth, germanium, antimony, and tellurium; preferably, the doped metal salt includes any one or a combination of two or more of titanium sulfate, niobium chloride, tantalum chloride, ammonium molybdate, ammonium metatungstate, copper nitrate, bismuth nitrate, ammonium hexafluorogermanate, antimony chloride, and sodium tellurite; And / or, the first solvent includes any one or a combination of two or more of dilute hydrochloric acid, dilute sulfuric acid, and dilute nitric acid; And / or, the concentration of the tin salt in the first mixed solution is 1-100 mmol / L; And / or, the concentration of the doped metal salt in the first mixed solution is 0.2-20 mmol / L; And / or, the concentration of the dilute acid in the first mixed solution is 0.5~3 mol / L.

4. The preparation method according to claim 2, characterized in that: The electrochemical deposition potential used in the electrochemical deposition is -1.3 to -2.3 V, and the time is 50 to 500 s; preferably, the electrochemical deposition potential is -1.3 to -2 V, and the time is 100 to 300 s; And / or, the drying temperature is 60-200°C, and the time is 3-24 h; preferably, the drying temperature is 60-180°C, and the time is 3-12 h; And / or, the temperature of the first annealing treatment is 300-800°C, and the time is 2-10 h; preferably, the temperature of the first annealing treatment is 300-600°C, and the time is 3-6 h.

5. The preparation method according to claim 1, characterized in that: Specifically include: uniformly mixing the metal salt and the second solvent to form a second mixed solution; And, placing the substrate coated with the doped tin oxide film in a second mixed solution, taking it out after dip coating and drying it, repeating the dip coating and drying operation, and then performing a second annealing treatment in air to obtain a metal oxide modified doped tin oxide film integral electrode.

6. The preparation method according to claim 5, characterized in that: The metal salt includes any one or a combination of two or more of magnesium nitrate, aluminum nitrate, manganese sulfate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, and zinc nitrate; And / or, the second solvent includes any one of water, methanol, ethanol, propanol, isopropanol, or a combination of two or more thereof; And / or, the concentration of the metal salt in the second mixed solution is 0.1-5 mol / L.

7. The preparation method according to claim 5, characterized in that: Specifically include: The substrate coated with the doped tin oxide film is dip-coated in the second mixed solution, taken out and dried at 60-180° C. for 5-60 min, the above operation is repeated several times, and then a second annealing treatment is performed in air to obtain a metal oxide modified doped tin oxide film integral electrode; preferably, the above operation is repeated 1-10 times; And / or, the temperature of the second annealing treatment is 300-800°C, preferably 300-600°C; And / or, the second annealing treatment time is 2 to 10 hours, preferably 3 to 6 hours.

8. The preparation method according to claim 1, characterized in that: Also includes: Before the electrochemical deposition treatment, the substrate is placed in a dilute acid aqueous solution and heated at 40-90°C for 20-90 min, and then the substrate is ultrasonically cleaned with acetone, ethanol, and water in sequence and dried; preferably, the dilute acid aqueous solution includes any one of dilute sulfuric acid, dilute nitric acid, dilute hydrochloric acid, and dilute phosphoric acid, or a combination of two or more thereof; preferably, the concentration of the dilute acid aqueous solution is 0.1-5 mol / L; And / or, the substrate includes any one of stainless steel felt, titanium felt, foam copper, foam nickel, and carbon cloth.

9. The metal oxide modified doped tin oxide thin film monolithic electrode prepared by the preparation method according to any one of claims 1 to 8, characterized in that: include: A substrate, a doped tin oxide thin film layer coated on the surface of the substrate, and a metal oxide nanomaterial uniformly distributed on the doped tin oxide thin film layer; Preferably, the thickness of the doped tin oxide film layer is 50-800 nm; preferably, the mass ratio of the doped tin oxide film layer to the metal oxide nanomaterial is 20-40:60-80; Preferably, the metal oxide nanomaterial comprises metal oxide nanosheets; the diameter of the metal oxide nanosheets is 100-500 nm.

10. Use of the metal oxide modified doped tin oxide thin film monolithic electrode according to claim 9 in acidic electrocatalytic oxygen evolution reaction.

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