A doped tin oxide-cobalt oxide composite electrocatalytic material, a preparation method and application thereof

Abstract

The application discloses a kind of doped tin oxide-cobalt oxide composite electrocatalytic materials and its preparation method and application.The preparation method includes: substrate is immersed in the first mixed solution including tin salt, doped metal salt and solvent, after drying, first annealing treatment is carried out in air, and the substrate coated with doped tin oxide is prepared;Again, it is immersed in the second mixed solution including cobalt salt, reducing agent, inducing agent and solvent, then second annealing treatment is carried out, and the doped tin oxide-cobalt oxide composite electrocatalytic material is prepared.The preparation method of the application uses the substrate coated with doped tin oxide as support electrode, by controlling the concentration of cobalt salt, reducing agent and inducing agent, hydrothermal reaction temperature and time, annealing temperature and time, the composite electrocatalytic material with controllable morphology is obtained, and the preparation method of the application is simple, and the doped tin oxide-cobalt oxide composite electrocatalytic material prepared has excellent performance in acidic water oxidation electrocatalytic reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to a cobalt oxide material, in particular to a doped tin oxide-cobalt oxide composite electrocatalytic material and a preparation method and application thereof, and belongs to the technical field of cobalt oxide materials and water electrolysis. BACKGROUND

[0002] The overexploitation and consumption of traditional fossil fuels have caused a series of problems such as ecological environment destruction and global climate warming. Using renewable energy such as wind energy, solar energy, and biomass energy to convert into electric energy to meet the needs of industrial production and human activities is considered an effective solution to the current environmental crisis and reduction of dependence on carbonaceous fossil fuels. However, these renewable energy power generation is easily affected by light and seasonal factors and is difficult to be connected to the grid for large-scale application. Hydrogen as an energy carrier has the characteristics of clean, non-polluting, and zero carbon emission, and can convert renewable energy in nature into hydrogen energy for use. Compared with traditional industrial hydrogen production, water electrolysis driven by renewable energy is considered as a clean and efficient alternative technology. Among them, the acid proton exchange membrane water electrolysis technology has the advantages of large working current density, high energy efficiency, high hydrogen purity, and compact device, and has broad commercial application prospects. At present, the acid water electrolysis oxygen evolution half-reaction mainly uses iridium-based and ruthenium-based noble metal catalysts, but their resources are limited and expensive, which limits the development of the technology. The development of non-noble metal acid oxygen evolution electrocatalysts with high activity and high stability has attracted the attention of academia and industry. Cobalt oxide catalyst is predicted as a potential alternative to noble metal materials, and has been verified in alkaline water electrolysis technology. However, cobalt oxide has poor intrinsic stability in acid medium and is prone to electrochemical corrosion under anodic oxidation conditions, and new preparation technologies need to be explored to realize the application of cobalt oxide materials in acid water electrolysis technology. SUMMARY

[0003] The main purpose of the present application is to provide a doped tin oxide-cobalt oxide composite electrocatalytic material and a preparation method thereof to overcome the deficiencies in the prior art.

[0004] Another purpose of the present application is to provide the application of the doped tin oxide-cobalt oxide composite electrocatalytic material.

[0005] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:

[0006] The present application provides a preparation method of a doped tin oxide-cobalt oxide composite electrocatalytic material, which comprises:

[0007] Mixing the tin salt, the doped metal salt and the solvent uniformly to form a first mixed solution;

[0008] immersing the substrate in the first mixed solution, taking out and drying, and then performing a first annealing treatment in air to obtain a substrate coated with doped tin oxide;

[0009] uniformly mixing the cobalt salt, the reducing agent, the inducing agent and the solvent to form a second mixed solution;

[0010] immersing the substrate coated with doped tin oxide in the second mixed solution to react, and then performing a second annealing treatment in air to obtain a doped tin oxide-cobalt oxide composite electrocatalytic material.

[0011] The embodiment of the present application also provides a doped tin oxide-cobalt oxide composite electrocatalytic material, which is prepared by the preparation method.

[0012] In some embodiments, the doped tin oxide-cobalt oxide composite electrocatalytic material comprises a doped tin oxide film layer and cobalt oxide nanomaterials uniformly distributed on the doped tin oxide film layer.

[0013] The embodiment of the present application also provides an application of the aforementioned doped tin oxide-cobalt oxide composite electrocatalytic material in an acidic electrocatalytic oxygen evolution reaction.

[0014] Compared with the prior art, the embodiment of the present application has the following beneficial effects.

[0015] The preparation method of the doped tin oxide-cobalt oxide composite electrocatalytic material provided by the present application uses a substrate coated with doped tin oxide as a support electrode, and by controlling the concentrations of the cobalt salt, the reducing agent and the inducing agent, the hydrothermal reaction temperature and time, and the annealing temperature and time, a composite electrocatalytic material with controllable morphology is obtained. Moreover, the preparation method is simple, and the doped tin oxide-cobalt oxide composite electrocatalytic material prepared by the method has excellent performance in an acidic water oxidation electrocatalytic reaction. The method has universality, is easy to scale up, and is expected to replace noble metals and be applied to industrial scale production. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0017] Figure 1 X-ray diffraction (XRD) pattern of the doped tin oxide-cobalt oxide composite electrocatalytic material prepared in Embodiment 1 of the present application;

[0018] Figures 2a-2cThe X-ray photoelectron spectroscopy (XPS) diagram of the doped tin oxide-cobalt oxide composite electrocatalytic material prepared for the embodiment 2 of the present application;

[0019] Figure 3 The scanning electron microscope (SEM) diagram of the doped tin oxide-cobalt oxide composite electrocatalytic material prepared for the embodiment 3 of the present application;

[0020] Figure 4 The transmission electron microscope (TEM) diagram of the doped tin oxide-cobalt oxide composite electrocatalytic material prepared for the embodiment 4 of the present application;

[0021] Figure 5 The acid oxygen evolution activity diagram of the doped tin oxide-cobalt oxide composite electrocatalytic material in the application example 1 of the present application;

[0022] Figure 6 The acid oxygen evolution stability diagram of the doped tin oxide-cobalt oxide composite electrocatalytic material in the application example 2 of the present application. DETAILED DESCRIPTION

[0023] In view of the deficiencies of the prior art, after long-term research and a large number of experiments, the present inventors have proposed the technical solution, which mainly develops a method that is simple to operate, easy to scale up, and has strong compatibility, grows cobalt oxide catalyst on the surface of a doped tin oxide-coated substrate, and provides a high-efficiency and stable electrocatalyst to achieve a high-efficiency acid water oxidation electrocatalysis process. The specific scheme is to use a doped tin oxide-coated substrate as a support electrode, control the concentrations of cobalt salt, reducing agent, and inducing agent, the hydrothermal reaction temperature and time, and the annealing temperature and time to obtain a composite electrocatalytic material with controllable morphology.

[0024] The technical solution, its implementation process, and principles will be further explained and described as follows.

[0025] As an aspect of the technical solution of the present application, a preparation method of a doped tin oxide-cobalt oxide composite electrocatalytic material (which can also be referred to as "a preparation method of growing cobalt oxide catalyst on the surface of a doped tin oxide-coated substrate") includes the following steps:

[0026] Mixing tin salt, doped metal salt, and solvent uniformly to form a first mixed solution;

[0027] Immersing the substrate in the first mixed solution, taking it out, drying, and then performing first annealing treatment in air to obtain a substrate coated with doped tin oxide;

[0028] Mixing cobalt salt, reducing agent, inducing agent, and solvent uniformly to form a second mixed solution;

[0029] reacting the substrate coated with doped tin oxide in the second mixed solution, and then performing a second annealing treatment in air to obtain a doped tin oxide-cobalt oxide composite electrocatalytic material.

[0030] In some embodiments, the preparation method specifically comprises: immersing the substrate in the first mixed solution, drying at 60-180°C for 5-120 min after taking out, repeating the above operation for multiple times, and then performing a first annealing treatment in air to obtain a substrate coated with doped tin oxide.

[0031] In some embodiments, the preparation method can further comprise: before immersing the substrate in the first mixed solution, immersing the substrate in a dilute aqueous acid solution, heating in a constant temperature water bath at a temperature of 60-90°C for 20-60 min, and then ultrasonically cleaning the substrate with acetone, ethanol and water in sequence and drying. The present application uses a dilute aqueous acid solution to treat the substrate, which makes the surface of the substrate more roughened, and is beneficial to the growth of the surface catalytic material.

[0032] In some embodiments, the reaction temperature is 100-250°C, and the reaction time is 2-24 h.

[0033] In some more specific embodiments, the preparation method of the doped tin oxide-cobalt oxide composite electrocatalytic material specifically comprises the following steps:

[0034] (1) immersing the substrate in a dilute aqueous acid solution, heating in a constant temperature water bath at a temperature of 60-90°C for 20-60 min, and then ultrasonically cleaning the substrate with acetone, ethanol and deionized water in sequence and drying;

[0035] (2) dissolving tin salt and doped metal salt in a solvent in a certain proportion, stirring uniformly at room temperature to form a first mixed solution;

[0036] (3) immersing the substrate obtained in step (1) in the first mixed solution obtained in step (2) for a certain time, taking out and drying at 60-180°C for 5-120 min. After repeating the above operation for a certain number of times, the obtained sample is subjected to a first annealing treatment in air to obtain a substrate coated with doped tin oxide;

[0037] (4) dissolving cobalt salt, reducing agent and inducing agent in a solvent in a certain proportion, stirring uniformly at room temperature to form a second mixed solution;

[0038] (5) The sample obtained in step (3) is placed in the second mixed solution obtained in step (4) and reacted at 100-250°C for 2-24 hours. The obtained sample is washed with deionized water and dried. Then the obtained sample is subjected to a second annealing treatment in air to obtain a cobalt oxide catalyst grown on the surface of the substrate coated with the doped tin oxide, i.e. the aforementioned doped tin oxide-cobalt oxide composite electrocatalytic material.

[0039] In some embodiments, in step (1), the substrate can be at least any one of carbon paper, carbon cloth, nickel mesh, copper mesh, tantalum sheet, stainless steel felt, titanium felt, and the like, but is not limited thereto.

[0040] In some embodiments, in step (1), the dilute aqueous acid can be any one or a combination of two or more of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, dilute phosphoric acid, dilute hydrofluoric acid, and the like, but is not limited thereto.

[0041] Further, in step (1), the concentration of the dilute aqueous acid is 0.5-10 mol / L.

[0042] In some embodiments, in step (2), the tin salt can be any one or a combination of two or more of stannous sulfate, stannous chloride, tin chloride pentahydrate, tin methane sulfonate, tin ethane sulfonate, tin propane sulfonate, tin hydroxymethane sulfonate, tin 2-hydroxyethyl-1-sulfonate, tin 2-hydroxybutyl-1-sulfonate, and the like, but is not limited thereto.

[0043] In some embodiments, in step (2), the doped metal element contained in the doped metal salt can be any one or a combination of two or more of tantalum, antimony, niobium, titanium, molybdenum, tungsten, nickel, and the like, but is not limited thereto. Specifically, the doped metal salt can be any one or a combination of two or more of tantalum chloride, antimony chloride, niobium chloride, titanium chloride, molybdenum chloride, tungsten chloride, and nickel chloride, and the like, but is not limited thereto. The preparation method of the present application has the characteristics of universality, and the source of the doped metal salt used is wide and the price is low.

[0044] In some embodiments, in step (2), the solvent can be any one or a combination of two or more of water (such as deionized water), methanol, ethanol, propanol, and isopropanol, and the like, but is not limited thereto.

[0045] In some embodiments, in step (2), the concentration of the tin salt in the first mixed solution is 0.1-5 mol / L.

[0046] Further, the concentration of the doped metal salt in the first mixed solution is 0.1-1 mol / L.

[0047] In some embodiments, in step (3), the substrate is immersed in the first mixed solution obtained in step (2) for 10-300 seconds. The immersion does not cause chemical reaction, and the purpose is to immerse the substrate in the liquid-phase tin salt and dopant metal mixed solution, so as to form a coating layer containing the dopant metal and tin element on the surface of the substrate.

[0048] In some embodiments, in step (3), the drying temperature is 60-180°C, and the drying time is 5-120 min. Further, the drying temperature is 60-120°C, and the drying time is 60-120 min, or the drying temperature is 120-180°C, and the drying time is 5-60 min.

[0049] In some embodiments, in step (3), the number of repeated operations is 1-20.

[0050] In some embodiments, in step (3), the first annealing temperature is 200-900°C, and the first annealing time is 0.5-12 h.

[0051] In some embodiments, in step (4), the cobalt salt can be any one or a combination of two or more of cobalt nitrate, cobalt chloride, cobalt perchlorate, cobalt iodide, cobalt sulfate, and cobalt acetate, but is not limited thereto. The cobalt salt used in the present application has a wide source and is relatively inexpensive compared with noble metals.

[0052] In some embodiments, in step (4), the reducing agent can be any one or a combination of two or more of ammonia, hydrazine hydrate, sodium borohydride, acetaldehyde, urea, and glucose, but is not limited thereto.

[0053] In some embodiments, in step (4), the inducing agent can be any one or a combination of two or more of sodium fluoride, ammonium fluoride, potassium fluoride, and calcium fluoride, but is not limited thereto. The inducing agent used in the present application has the effect of: in the growth process, the F ions in the inducing agent are adsorbed on some crystal faces of the cobalt oxide, so as to change the crystal dynamics behavior of the crystal faces, and further cause the difference in the morphology and periodic crystal structure of the material.

[0054] In some embodiments, in step (4), the solvent can be any one or a combination of two or more of water (such as deionized water), methanol, ethanol, propanol, and isopropanol, but is not limited thereto.

[0055] In some embodiments, in step (4), the concentration of the cobalt salt in the second mixed solution is 0.5-5 mol / L.

[0056] Further, the concentration of the reducing agent in the second mixed solution is 0.5-5 mol / L.

[0057] Further, the concentration of the inducing agent in the second mixed solution is 0.5-5 mol / L.

[0058] In some embodiments, in step (5), the temperature of the reaction is 100-250℃, and the reaction time is 2-24 h. Further, the temperature of the reaction is 100-150℃, and the reaction time is 12-24 h, or the temperature of the reaction is 150-250℃, and the reaction time is 2-12 h.

[0059] In some embodiments, in step (5), the temperature of the second annealing treatment is 300-800℃, and the time is 1-10 h.

[0060] In summary, the preparation method of the present application has the characteristics of simple synthesis process, easy control of conditions, and easy amplification.

[0061] As another aspect of the technical solution of the present application, it further relates to a doped tin oxide-cobalt oxide composite electrocatalytic material prepared by the aforementioned preparation method.

[0062] In some embodiments, the doped tin oxide-cobalt oxide composite electrocatalytic material comprises a doped tin oxide film layer and cobalt oxide nanomaterials uniformly distributed on the doped tin oxide film layer. The thickness of the doped tin oxide film layer ranges from 50 to 1000 nm.

[0063] Further, the content of the doped tin oxide film layer in the doped tin oxide-cobalt oxide composite electrocatalytic material ranges from 55 to 80 wt%, and the content of the cobalt oxide nanomaterials ranges from 20 to 45 wt%.

[0064] In some more preferred embodiments, the cobalt oxide nanomaterials comprise cobalt oxide nanowires formed by assembly of a plurality of cobalt oxide nanoparticles. The diameter of the cobalt oxide nanowires ranges from 100 to 200 nm, and the diameter of the nanoparticles constituting the cobalt oxide nanowires ranges from 15 to 50 nm. The cobalt oxide nanoparticles in the present application self-assemble into nanowire structures, which have more excellent charge transport properties than disordered nanoparticles, and are beneficial to the improvement of electrocatalytic performance.

[0065] The cobalt oxide nanomaterials prepared in the present application can be stabilized by the corrosion-resistant and high-conductivity doped tin oxide, and at the same time, strong interaction can occur at their interfaces to regulate the catalyst activity. The doped tin oxide-cobalt oxide composite electrocatalytic material has high activity and long-term stability for acid electrolytic water oxygen evolution reaction.

[0066] Further, the doped tin oxide-cobalt oxide composite electrocatalytic material obtained in the present application can be directly used as an electrode material in an electrochemical system device without additional carriers and current collectors.

[0067] Correspondingly, as another aspect of the technical scheme of the present application, it also relates to the application of the aforementioned doped tin oxide-cobalt oxide composite electrocatalytic material. Specifically, the cobalt oxide nanomaterial grown on the doped tin oxide prepared by the present application has excellent performance in the acidic water oxidation electrocatalytic reaction.

[0068] By the above technical scheme, the present application directly prepares cobalt oxide nanomaterial in situ on the corrosion-resistant doped tin oxide, and then applies it to the acidic electrocatalytic oxygen evolution reaction. The method has universality, is easy to scale up, simple and easy to control, and is expected to replace noble metals for industrial scale production.

[0069] The entire process will be described in detail below through several embodiments and drawings, but the scope of the claims of the present application is not limited by these embodiments. Meanwhile, the embodiments only give some conditions for achieving the purpose, but do not mean that these conditions must be met to achieve the purpose. All modifications derived from the disclosed content of the present application are considered to be within the protection scope of the present application.

[0070] Example 1

[0071] (1) Put the titanium felt into a 0.5 mol / L dilute sulfuric acid aqueous solution, heat in a constant temperature water bath at 70℃ for 60 minutes. Then ultrasonically clean the substrate with acetone, ethanol and deionized water in sequence, and dry;

[0072] (2) Dissolve 1 mol / L tin chloride pentahydrate, 0.2 mol / L antimony chloride in ethanol, and stir uniformly at room temperature to form a first mixed solution;

[0073] (3) Put the substrate obtained in step (1) into the first mixed solution obtained in step (2), soak for 10 seconds, and then take out and dry at 120℃ for 60 minutes. Repeat the above operation 3 times, and then perform first annealing treatment on the obtained sample in air at 500℃ for 6h, to obtain a doped tin oxide coated substrate;

[0074] (4) Dissolve 1 mol / L cobalt nitrate, 1 mol / L urea and 1 mol / L ammonium fluoride in deionized water, and stir uniformly at room temperature to form a second mixed solution;

[0075] (5) Put the sample obtained in step (3) into the second mixed solution obtained in step (4), and react at 100℃ for 24 hours. The obtained sample is washed with deionized water and dried. Then perform second annealing treatment on the obtained sample in air at 300℃ for 10h, to obtain a cobalt oxide catalyst grown on the surface of the doped tin oxide coated substrate (i.e. a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0076] AsFigure 1 Figure 2 shows the XRD pattern of the catalyst (i.e., the doped tin oxide-cobalt oxide composite electrocatalytic material) prepared in Example 1, which shows diffraction peaks of tin oxide and cobalt oxide in addition to the titanium metal diffraction peak, proving that the cobalt oxide catalyst is grown on the surface of the doped tin oxide-coated titanium substrate.

[0077] Example 2

[0078] (1) The carbon paper was placed in a 1 mol / L dilute hydrochloric acid aqueous solution and heated in a constant-temperature water bath at 80°C for 40 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0079] (2) 2 mol / L stannous sulfate, 0.4 mol / L antimony chloride were dissolved in methanol and stirred uniformly at room temperature to form a first mixed solution;

[0080] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2) and soaked for 60 seconds, and then taken out and dried at 130°C for 45 minutes. After repeating the above operation 6 times, the obtained sample was subjected to a first annealing treatment in air at 500°C for 6h, thereby obtaining a doped tin oxide-coated substrate;

[0081] (4) 2 mol / L cobalt sulfate, 1 mol / L ammonia water and 2 mol / L sodium fluoride were dissolved in methanol and stirred uniformly at room temperature to form a second mixed solution;

[0082] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 120°C for 18 hours. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment in air at 400°C for 7h, thereby obtaining a cobalt oxide catalyst grown on the surface of the doped tin oxide-coated substrate (i.e., the doped tin oxide-cobalt oxide composite electrocatalytic material).

[0083] As shown in Figure 3, the XPS pattern of the catalyst (i.e., the doped tin oxide-cobalt oxide composite electrocatalytic material) prepared in Example 2 shows the presence of cobalt-oxygen bonds, tin-oxygen bonds and antimony-oxygen bonds, proving that the cobalt oxide catalyst is grown on the surface of the doped tin oxide-coated carbon paper substrate. Figure 2a 、 Figure 2b 、 Figure 2c As shown in Figure 3, the XPS pattern of the catalyst (i.e., the doped tin oxide-cobalt oxide composite electrocatalytic material) prepared in Example 2 shows the presence of cobalt-oxygen bonds, tin-oxygen bonds and antimony-oxygen bonds, proving that the cobalt oxide catalyst is grown on the surface of the doped tin oxide-coated carbon paper substrate.

[0084] Example 3

[0085] (1) The stainless steel felt was placed in a 3 mol / L dilute nitric acid aqueous solution and heated in a constant-temperature water bath at 80°C for 30 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0086] (2) dissolving 3 mol / L stannous chloride and 0.6 mol / L niobium chloride in deionized water and stirring the mixture at room temperature to form a first mixed solution;

[0087] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), soaked for 120 seconds, and then taken out and dried at 140°C for 30 minutes. After repeating the above operation 10 times, the obtained sample was subjected to a first annealing treatment at 600°C in air for 4 hours to obtain a doped tin oxide-coated substrate;

[0088] (4) dissolving 3 mol / L cobalt chloride, 2 mol / L hydrazine hydrate, and 3 mol / L potassium fluoride in ethanol and stirring the mixture at room temperature to form a second mixed solution;

[0089] (5) The sample obtained in step (3) is placed in the second mixed solution obtained in step (4), and the mixture is reacted at 150° C. for 12 hours. The obtained sample is washed with deionized water and dried. The obtained sample is then subjected to a second annealing treatment at 500° C. in air for 5 hours to obtain a cobalt oxide catalyst grown on the surface of a substrate coated with doped tin oxide (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0090] like Figure 3 , which is an SEM image of the catalyst prepared in Example 3 (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material), shows that the cobalt oxide nanowires are evenly distributed on the doped tin oxide, proving that the cobalt oxide catalyst is grown on the surface of the stainless steel substrate coated with the doped tin oxide.

[0091] Example 4

[0092] (1) The carbon substrate was placed in a 5 mol / L dilute phosphoric acid aqueous solution and heated in a constant temperature water bath at 90°C for 30 minutes. The substrate was then ultrasonicated with acetone, ethanol, and deionized water in sequence and dried.

[0093] (2) dissolving 4 mol / L tin methanesulfonate and 0.8 mol / L titanium chloride in propanol and stirring uniformly at room temperature to form a first mixed solution;

[0094] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), soaked for 150 seconds, and then taken out and dried at 160°C for 15 minutes. After repeating the above operation 15 times, the obtained sample was subjected to a first annealing treatment at 700°C in air for 2 hours to obtain a doped tin oxide-coated substrate;

[0095] (4) dissolving 4 mol / L of cobalt acetate, 3 mol / L of sodium hydrogen borate, and 4 mol / L of calcium fluoride in propanol and stirring the mixture at room temperature to form a second mixed solution;

[0096] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 130°C for 16 hours. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 600°C in air for 4h, to obtain a doped tin oxide-coated substrate surface-grown cobalt oxide catalyst (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0097] As shown in FIG. 6, a TEM image of the catalyst (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material) prepared in Example 4 shows that the cobalt oxide nanowires are assembled from nanoparticles, proving that the cobalt oxide catalyst is grown on the surface of the doped tin oxide-coated carbon cloth substrate. Figure 4

[0098] Example 5

[0099] (1) The tantalum sheet was placed in a 10 mol / L dilute nitric acid aqueous solution and heated in a constant temperature water bath at 80°C for 30 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0100] (2) 5 mol / L tin hydroxymethane sulfonate, 1 mol / L tungsten chloride were dissolved in isopropanol and stirred uniformly at room temperature to form a first mixed solution;

[0101] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), soaked for 180 seconds, and then taken out and dried at 180°C for 5 minutes. After repeating the above operation 20 times, the obtained sample was subjected to a first annealing treatment at 900°C in air for 0.5h, to obtain a doped tin oxide-coated substrate;

[0102] (4) 5 mol / L cobalt perchlorate, 4 mol / L glucose and 5 mol / L ammonium fluoride were dissolved in isopropanol and stirred uniformly at room temperature to form a second mixed solution;

[0103] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 140°C for 14 hours. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 800°C in air for 1h, to obtain a doped tin oxide-coated substrate surface-grown cobalt oxide catalyst (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0104] Example 6

[0105] (1) The titanium felt was placed in a 1 mol / L dilute hydrofluoric acid aqueous solution and heated in a constant temperature water bath at 90°C for 20 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0106] ​(2) Dissolve 0.5 mol / L tin ethanesulfonate and 0.1 mol / L tantalum chloride in ethanol, and stir uniformly at room temperature to form a first mixed solution;

[0107] (3) Put the substrate obtained in step (1) into the first mixed solution obtained in step (2), soak for 200 seconds, and then take out and dry at 120°C for 60 minutes. Repeat the above operation 15 times, and then perform first annealing treatment on the obtained sample in air at 300°C for 9h to obtain a substrate coated with doped tin oxide;

[0108] (4) Dissolve 0.5 mol / L cobalt nitrate, 0.5 mol / L urea, and 0.5 mol / L ammonium fluoride in deionized water, and stir uniformly at room temperature to form a second mixed solution;

[0109] (5) Put the sample obtained in step (3) into the second mixed solution obtained in step (4), and react at 150°C for 12 hours. The obtained sample is washed with deionized water and dried. Then perform second annealing treatment on the obtained sample in air at 400°C for 7h to obtain a substrate coated with doped tin oxide with cobalt oxide catalyst (i.e., doped tin oxide-cobalt oxide composite electrocatalytic material) grown on the surface of the substrate.

[0110] Example 7

[0111] (1) Put a nickel mesh into a 2 mol / L dilute phosphoric acid aqueous solution, heat in a constant-temperature water bath at 60°C for 60 minutes. Then ultrasonically clean the substrate with acetone, ethanol, and deionized water in sequence, and dry;

[0112] (2) Dissolve 0.1 mol / L tin propanesulfonate and 0.1 mol / L molybdenum chloride in propanol, and stir uniformly at room temperature to form a first mixed solution;

[0113] (3) Put the substrate obtained in step (1) into the first mixed solution obtained in step (2), soak for 240 seconds, and then take out and dry at 60°C for 120 minutes. Repeat the above operation 10 times, and then perform first annealing treatment on the obtained sample in air at 300°C for 9h to obtain a substrate coated with doped tin oxide;

[0114] (4) Dissolve 0.5 mol / L cobalt chloride, 5 mol / L acetaldehyde, and 0.5 mol / L sodium fluoride in ethanol, and stir uniformly at room temperature to form a second mixed solution;

[0115] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 180°C for 9 hours. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 500°C in air for 5h, to obtain a doped tin oxide coated substrate surface grown cobalt oxide catalyst (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0116] Example 8

[0117] (1) The copper mesh was placed in 1 mol / L dilute hydrochloric acid aqueous solution, heated in a constant temperature water bath at 70°C for 50 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0118] (2) 5 mol / L 2-hydroxyethyl-1-sulfonic acid tin and 1 mol / L nickel chloride were dissolved in isopropanol, stirred uniformly at room temperature to form a first mixed solution;

[0119] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), soaked for 270 seconds, and then taken out and dried at 70°C for 100 minutes. After repeating the above operation 5 times, the obtained sample was subjected to a first annealing treatment at 200°C in air for 12h, to obtain a doped tin oxide coated substrate;

[0120] (4) 5 mol / L cobalt sulfate, 5 mol / L glucose and 5 mol / L potassium fluoride were dissolved in propyl alcohol, stirred uniformly at room temperature to form a second mixed solution;

[0121] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 200°C for 6 hours. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 300°C in air for 10h, to obtain a doped tin oxide coated substrate surface grown cobalt oxide catalyst (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0122] Example 9

[0123] (1) The carbon paper was placed in 5 mol / L dilute hydrochloric acid aqueous solution, heated in a constant temperature water bath at 80°C for 30 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0124] (2) 5 mol / L 2-hydroxybutyl-1-sulfonic acid tin and 1 mol / L tantalum chloride were dissolved in ethanol, stirred uniformly at room temperature to form a first mixed solution;

[0125] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2) and soaked for 300 seconds, and then taken out and dried at 80°C for 90 minutes. After the above operation was performed once, the obtained sample was subjected to a first annealing treatment at 900°C in air for 0.5 h, thereby obtaining a substrate coated with doped tin oxide;

[0126] (4) Cobalt chloride 5 mol / L, hydrazine hydrate 0.5 mol / L and ammonium fluoride 5 mol / L were dissolved in isopropyl alcohol and stirred uniformly at room temperature to form a second mixed solution;

[0127] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 250°C for 2 h. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 800°C in air for 1 h, thereby obtaining a substrate coated with doped tin oxide with cobalt oxide catalyst grown on the surface (i.e., a doped tin oxide-cobalt oxide composite electrocatalytic material).

[0128] Comparative Example 1

[0129] (1) The titanium felt was placed in 1 mol / L dilute sulfuric acid aqueous solution and heated in a constant temperature water bath at 80°C for 30 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in sequence and dried;

[0130] (2) Tin chloride pentahydrate 0.1 mol / L was dissolved in ethanol and stirred uniformly at room temperature to form a first mixed solution;

[0131] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2) and soaked for 30 seconds, and then taken out and dried at 60°C for 120 minutes. After the above operation was repeated for 10 times, the obtained sample was subjected to a first annealing treatment at 400°C in air for 8 h, thereby obtaining a substrate coated with doped tin oxide;

[0132] (4) Cobalt chloride 0.5 mol / L, glucose 5 mol / L and sodium fluoride 1 mol / L were dissolved in deionized water and stirred uniformly at room temperature to form a second mixed solution;

[0133] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4) and reacted at 100°C for 24 h. The obtained sample was washed with deionized water and dried. Then the obtained sample was subjected to a second annealing treatment at 400°C in air for 7 h, thereby obtaining a substrate coated with pure tin oxide with cobalt oxide catalyst grown on the surface (i.e., a tin oxide-cobalt oxide composite electrocatalytic material).

[0134] Comparative Example 2

[0135] (1) The carbon cloth was placed in 1 mol / L dilute hydrochloric acid aqueous solution, heated in a constant temperature water bath at 80°C for 30 minutes. Then the substrate was ultrasonically cleaned with acetone, ethanol and deionized water in turn, and dried;

[0136] (2) 5 mol / L stannous chloride and 1 mol / L niobium chloride were dissolved in deionized water, stirred uniformly at room temperature to form a first mixed solution;

[0137] (3) The substrate obtained in step (1) was placed in the first mixed solution obtained in step (2), soaked for 60 seconds, and then taken out and dried at 120°C for 60 minutes. After repeating the above operation for 10 times, the obtained sample was subjected to a first annealing treatment in air at 400°C for 8h, to obtain a substrate coated with doped tin oxide;

[0138] (4) 5 mol / L cobalt sulfate and 5 mol / L ammonia water were dissolved in deionized water, stirred uniformly at room temperature to form a second mixed solution;

[0139] (5) The sample obtained in step (3) was placed in the second mixed solution obtained in step (4), and reacted at 150°C for 12 hours. The obtained sample was washed with deionized water and dried. Then the sample was subjected to a second annealing treatment in air at 400°C for 7h, to obtain a substrate coated with doped tin oxide, and cobalt oxide catalyst was grown on the surface of the substrate, but the cobalt oxide catalyst failed to form nanowire structure.

[0140] Application Example 1

[0141] The cobalt oxide catalyst grown on the substrate coated with doped tin oxide obtained in Example 1 (i.e. doped tin oxide-cobalt oxide composite electrocatalytic material) was used as a working electrode to catalyze the acidic oxygen evolution reaction, and activity test was performed.

[0142] (1) The electrochemical oxygen evolution performance of the composite electrocatalytic material was tested on an electrochemical workstation in a three-electrode mode. A 0.5 mol / L sulfuric acid aqueous solution was used as electrolyte, the prepared catalyst was used as working electrode, silver / silver chloride was used as reference electrode, and high-purity platinum wire was used as counter electrode, and polarization curve test was performed in a potential range of 1-2V.

[0143] (2) Test conditions: test temperature was room temperature 25°C, linear scanning speed: 2mV / s.

[0144] (3) As shown in Figure 5 , the composite electrocatalytic material exhibited excellent electrocatalytic oxygen evolution activity in acidic environment, and the overpotential of current density 10mA / cm 2 was 238mV, which was significantly lower than the overpotential of cobalt-based non-noble metal in the current field.

[0145] Application Example 2

[0146] The cobalt oxide catalyst grown on the surface of the doped tin oxide coated substrate obtained from Example 1 (i.e., doped tin oxide-cobalt oxide composite electrocatalytic material) was used as the working electrode to catalyze the acidic oxygen evolution reaction and was subjected to stability testing.

[0147] (1) The electrochemical oxygen evolution performance of the composite electrocatalytic material was tested on an electrochemical workstation in a three-electrode mode. A 0.5 mol / L aqueous sulfuric acid solution was used as the electrolyte, the prepared catalyst was used as the working electrode, silver / silver chloride was used as the reference electrode, and high-purity platinum wire was used as the counter electrode, and a potential-time curve test was performed in a constant current mode.

[0148] (2) Test conditions: the test temperature was room temperature 25°C.

[0149] (3) As shown in FIG. 1, the composite electrocatalytic material exhibited excellent oxygen evolution stability in an acidic environment, and was stably operated for more than 100 hours at a current density of 100 mA / cm 2 Figure 6 , which was significantly better than the stability of cobalt-based non-noble metals in the current field.

[0150] In addition, the inventors of the present case also tested other raw materials and conditions listed in the specification in the manner of the foregoing examples, and also prepared a doped tin oxide-cobalt oxide composite electrocatalytic material with excellent performance in acidic water oxidation electrocatalytic reactions.

[0151] Aspects, embodiments, features, and examples of the present application should be considered illustrative in all aspects and are not intended to limit the present application, the scope of which is defined only by the claims. Those skilled in the art will appreciate other embodiments, modifications, and uses without departing from the spirit and scope of the claimed application.

[0152] Although the present application has been described with reference to illustrative embodiments, those skilled in the art will appreciate that various other changes, omissions, and / or additions can be made and elements of the described embodiments can be substituted with substantial equivalents without departing from the spirit and scope of the present application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from the scope thereof. Therefore, the present application is not intended to be limited to the disclosed embodiments for carrying out the present application, but rather is intended to encompass all embodiments falling within the scope of the claims.​

Claims

1. A method for preparing a doped tin oxide-cobalt oxide composite electrocatalytic material, characterized in that: include: Uniformly mixing the tin salt, the doping metal salt, and the solvent to form a first mixed solution, wherein the doping metal salt contains a doping metal element selected from any one or a combination of two or more of tantalum, antimony, niobium, titanium, molybdenum, tungsten, and nickel, and the concentration of the doping metal salt in the first mixed solution is 0.1 to 1 mol / L; immersing the substrate in the first mixed solution, taking it out, drying it, and then performing a first annealing treatment in air to obtain a substrate coated with doped tin oxide; uniformly mixing a cobalt salt, a reducing agent, an inducer, and a solvent to form a second mixed solution, wherein the cobalt salt is selected from any one or a combination of two or more of cobalt nitrate, cobalt chloride, cobalt perchlorate, cobalt iodide, cobalt sulfate, and cobalt acetate; the reducing agent is selected from any one or a combination of two or more of ammonia water, hydrazine hydrate, sodium hydrogen borate, acetaldehyde, urea, and glucose; and the inducer is selected from any one or a combination of two or more of sodium fluoride, ammonium fluoride, potassium fluoride, and calcium fluoride; and the concentration of the cobalt salt in the second mixed solution is 0.5 to 5 mol / L, the concentration of the reducing agent is 0.5 to 5 mol / L, and the concentration of the inducer is 0.5 to 5 mol / L; The substrate coated with doped tin oxide is immersed in the second mixed solution for reaction, and then a second annealing treatment is performed in air to obtain a doped tin oxide-cobalt oxide composite electrocatalytic material. The reaction temperature is 100-250°C, the reaction time is 2-24 hours, and the second annealing treatment temperature is 300-800°C, and the time is 1-10 hours.

2. The preparation method according to claim 1, wherein: The tin salt includes any one or a combination of two or more of stannous sulfate, stannous chloride, stannous chloride pentahydrate, stannous methanesulfonate, stannous ethanesulfonate, stannous propanesulfonate, hydroxy stannous methanesulfonate, 2-hydroxyethyl-1-stannous sulfonate, and 2-hydroxybutyl-1-stannous sulfonate.

3. The preparation method according to claim 1, wherein: The doping metal salt includes any one or a combination of two or more of tantalum chloride, antimony chloride, niobium chloride, titanium chloride, molybdenum chloride, tungsten chloride and nickel chloride.

4. The preparation method according to claim 1, wherein: The solvent includes any one of water, methanol, ethanol, propanol and isopropanol, or a combination of two or more thereof.

5. The preparation method according to claim 1, wherein: The concentration of the tin salt in the first mixed solution is 0.1-5 mol / L.

6. The preparation method according to claim 1, wherein: The substrate is immersed in the first mixed solution for 10 to 300 seconds.

7. The preparation method according to claim 1, wherein: The drying temperature is 60-180° C. and the drying time is 5-120 min.

8. The preparation method according to claim 7, wherein: The drying temperature is 60-120° C. and the drying time is 60-120 min, or the drying temperature is 120-180° C. and the drying time is 5-60 min.

9. The preparation method according to claim 1, wherein Specifically include: The substrate is immersed in the first mixed solution for 10-300 seconds, taken out and dried at 60-180°C for 5-120 minutes, and the above operation is repeated multiple times. Thereafter, a first annealing treatment is performed in air to obtain a substrate coated with doped tin oxide.

10. The preparation method according to claim 9, characterized in that: Repeat the operation 1 to 20 times.

11. The preparation method according to claim 1, wherein: The temperature of the first annealing treatment is 200-900°C, and the time is 0.5-12 h.

12. The preparation method according to claim 1, wherein: The reaction temperature is 100-150° C., and the reaction time is 12-24 h. Alternatively, the reaction temperature is 150-250° C., and the reaction time is 2-12 h.

13. The preparation method according to claim 1, wherein Also includes: Before immersing the substrate in the first mixed solution, the substrate is first placed in a dilute acid aqueous solution and heated in a constant temperature water bath at a temperature of 60-90°C for 20-60 minutes. The substrate is then ultrasonically cleaned with acetone, ethanol, and water in sequence and dried.

14. The preparation method according to claim 13, characterized in that: The dilute acid aqueous solution includes any one or a combination of two or more of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, dilute phosphoric acid and dilute hydrofluoric acid.

15. The preparation method according to claim 13, wherein: The concentration of the dilute acid aqueous solution is 0.5-10 mol / L.

16. The preparation method according to claim 1, characterized in that: The substrate includes at least any one of carbon paper, carbon cloth, nickel mesh, copper mesh, tantalum sheet, stainless steel felt and titanium felt.

17. A doped tin oxide-cobalt oxide composite electrocatalytic material prepared by the preparation method according to any one of claims 1 to 16, comprising a doped tin oxide film layer and a cobalt oxide nanomaterial uniformly distributed on the doped tin oxide film layer, wherein the cobalt oxide nanomaterial comprises cobalt oxide nanowires, and the cobalt oxide nanowires are assembled from a plurality of cobalt oxide nanoparticles.

18. The doped tin oxide-cobalt oxide composite electrocatalytic material according to claim 17, characterized in that: The thickness of the doped tin oxide film is 50-1000 nm.

19. The doped tin oxide-cobalt oxide composite electrocatalytic material according to claim 17, wherein: The content of the doped tin oxide film layer in the doped tin oxide-cobalt oxide composite electrocatalytic material is 55-80 wt %, and the content of the cobalt oxide nanomaterial is 20-45 wt %.

20. The doped tin oxide-cobalt oxide composite electrocatalytic material according to claim 17, wherein: The diameter of the cobalt oxide nanowires is 100-200 nm, and the diameter of the cobalt oxide nanoparticles constituting the cobalt oxide nanowires is 15-50 nm.

21. Use of the doped tin oxide-cobalt oxide composite electrocatalytic material according to any one of claims 17 to 20 in an acidic electrocatalytic oxygen evolution reaction.

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