High-stability supported acidic OER catalyst and its preparation method and application

Abstract

The present invention provides a method for preparing a highly stable supported acidic OER catalyst, comprising: preparing a carbon nanotube dispersion containing hexadecyltrimethylammonium bromide; adding an alkali solution and a hydrolyzable silicon source, titanium source, niobium source, tantalum source, or zirconium source solution to the carbon nanotube dispersion for reaction to obtain a composite support of nano-oxides and carbon nanotubes; dispersing the composite support in an ethanol solution to obtain a support dispersion; adding an iridium salt and a ruthenium salt to the support dispersion, stirring, and then performing a reflux reaction. The reflux reaction product is subjected to solid-liquid separation, washing, and drying to obtain a supported iridium-based alloy catalyst. The supported acidic OER catalyst prepared by this method has high stability, an adjustable active catalyst loading, a uniform dispersion of the active catalyst on the support, a large specific surface area, and numerous active sites, resulting in ultrahigh catalytic activity and being suitable for water electrolysis.

Description

Technical Field

[0001] The present invention relates to the field of water electrolysis, and specifically to the preparation of acidic OER catalysts. Background Art

[0002] Hydrogen energy is a clean, efficient, and renewable energy source with broad application prospects. Water electrolysis is one of the important ways to produce hydrogen. Among them, proton exchange membrane (PEM) water electrolysis technology has attracted widespread attention due to its advantages such as high efficiency, high purity, and low pollution. However, PEM water electrolysis technology faces some challenges, mainly the slow kinetics of the anodic oxygen evolution reaction (OER), which requires high-performance catalysts to increase the reaction rate and reduce the overpotential. At present, iridium-based catalysts are the most effective OER catalysts in PEM water electrolysis, but their high price and scarce resources limit the commercial application of PEM water electrolysis technology.

[0003] To reduce the usage and cost of iridium-based catalysts, iridium nanoparticles are typically supported on oxide supports with large surface areas to improve their dispersion and utilization. The advantages of supported iridium alloy catalysts include improved dispersion and utilization of the precious metal, reduced catalyst usage and cost, and the ability to prevent nanoparticle aggregation, maintaining high OER activity and stability. However, due to the extreme environment of PEM water electrolysis, such as high proton concentrations and high oxidation potentials, few supports are stable under these conditions. Currently, only a few, such as silica, titania, niobium oxide, tantalum oxide, and zirconium oxide, are available. While these oxides are stable, their small surface areas and poor electrical conductivity significantly impact their performance. While carbon supports offer high surface areas and excellent electrical conductivity, they are highly susceptible to corrosion at high oxidation potentials, resulting in reduced catalyst stability. Currently, no support possesses the combination of high conductivity, high surface area, and high stability. Therefore, the search for stable, high-performance supports with excellent electrical conductivity and the development of supported iridium-based OER catalysts are of great practical significance. Summary of the Invention

[0004] In response to the above technical problems, the present application provides a highly stable supported acidic OER catalyst and its preparation method and application.

[0005] To achieve the above objectives, this application proposes the following solutions:

[0006] To address the problems of poor conductivity and poor stability of carbon supports of traditional oxides such as silica, titania, niobium oxide, tantalum oxide, and zirconium oxide, this application achieves a simultaneous improvement in the conductivity and stability of the support material by in situ coating the carbon support with nano-oxides such as nano-silica, titania, niobium oxide, tantalum oxide, and zirconium oxide, providing theoretical guidance for the development of supported OER catalysts.

[0007] In a first aspect, a method for preparing a highly stable supported acidic OER catalyst is provided, comprising:

[0008] (1) preparing a carbon nanotube dispersion containing hexadecyltrimethylammonium bromide;

[0009] (2) adding an alkali solution and a hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source solution to the carbon nanotube dispersion to react and obtain a composite support of nano-oxide and carbon nanotubes;

[0010] (3) dispersing the composite carrier in an ethanol solution to obtain a carrier dispersion;

[0011] (4) Adding iridium salt and ruthenium salt to the carrier dispersion, stirring, and then performing a reflux reaction. The reflux reaction product is subjected to solid-liquid separation, washing, and drying to obtain a supported iridium-based alloy acidic OER catalyst.

[0012] Preferably, after step (2), the method further comprises the step of continuously adding excess concentrated sulfuric acid to the reaction system for aging treatment to sulfonate the oxides in the composite support.

[0013] Preferably, the aging treatment time is 6 to 18 hours, and the aging treatment temperature is 40 to 80°C.

[0014] Preferably, the concentration of cetyltrimethylammonium bromide in the carbon nanotube dispersion is 0.05-2 g / 10 mL.

[0015] Preferably, the carbon nanotubes are acid-treated multi-walled carbon nanotubes.

[0016] Preferably, the hydrolyzable silicon source is ethyl silicate; the hydrolyzable titanium source is titanium tetrachloride or tetrabutyl titanate; the niobium source is niobium chloride; the tantalum source is tantalum chloride; and the zirconium source is zirconium chloride or zirconium oxychloride octahydrate.

[0017] Preferably, the amount of the hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source is determined so that the mass proportion of the oxide in the composite support is 20-99%.

[0018] Preferably, the iridium salt is any one or more of chloroiridic acid and iridium chloride; and the ruthenium salt is any one or more of ruthenium chloride and ruthenium acetylacetonate.

[0019] Preferably, the iridium salt and the ruthenium salt are prepared in a mass ratio of iridium to ruthenium of 1:0.2~2.

[0020] Preferably, the amount of the iridium salt and the ruthenium salt added is determined so that the total mass proportion of the iridium and ruthenium elements in the synthesized supported iridium-based alloy catalyst is 20-99%.

[0021] Preferably, in step (4), the total concentration of the iridium element and the ruthenium element in the ethanol solution is 0.01-2 g / L.

[0022] Preferably, in step (2), the amount of the alkali solution added is determined by adjusting the initial pH of the reaction system to 11-13.

[0023] Preferably, in step (2), the reaction temperature is 40-80° C.; and the reaction time is 1-12 h.

[0024] Preferably, in step (4), the temperature of the reflux reaction is 80-140° C.; and the time of the reflux reaction is 0.5-4 h.

[0025] In a second aspect, an acidic OER catalyst is also provided, which is prepared using the aforementioned preparation method.

[0026] In a third aspect, the application of the aforementioned acidic OER catalyst in water electrolysis is also provided.

[0027] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0028] The present application prepares a dispersion of carbon nanotubes containing hexadecyltrimethylammonium bromide, adds a hydrolyzable silicon source, titanium source or zirconium source solution thereto, and conducts an in-situ reaction after adjusting the pH to in-situ cover the carbon nanotubes with one or more porous layers of nano-oxide particles. The composite carrier is used as a catalyst carrier, and an iridium-based alloy catalyst is in-situ loaded on the catalyst carrier through an ethanol reflux reaction. The composite carrier has good conductivity and good stability. The loading of nano-scale oxides increases the specific surface area of ​​the carbon nanotubes, and there are many catalytic active sites. The active sites and proton transport channels greatly improve the catalytic activity and stability of the catalyst. In the finally formed OER catalyst, the active catalyst has a small particle size and is evenly distributed on the carrier and has ultra-high catalytic activity.

[0029] The introduction of hexadecyltrimethylammonium bromide not only allows the nano-oxides to adhere stably to the carbon nanotubes, but also cleans and removes CTAB after the reaction, forming numerous nano-pore structures on the composite carrier of carbon nanotubes and nano-oxides, increasing the specific surface area of ​​the material, facilitating the attachment of precious metal catalysts, and significantly improving the activity of the catalyst.

[0030] This application introduces a large number of sulfonic acid and hydroxyl groups through surface modification, making the support material hydrophilic, acidic, and highly surface active. This provides attachment anchors for the subsequent reduction of iridium and ruthenium metal ions, facilitating uniform adsorption of the metal ions onto the nano-oxide carbon tube support. Furthermore, the sulfonic acid groups act as electron donors in charge transfer, facilitating the electrocatalytic reaction of the iridium-based alloy. The surface-modified supported iridium-based catalyst exhibits enhanced electrocatalytic performance.

[0031] By coating carbon nanotubes with nano-oxide particles, the carbon nanotubes can be protected from corrosion in acidic electrolytes and high-voltage environments to a great extent, greatly improving the stability of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is the SEM characterization picture of Example 1.

[0034] Figure 2 This is the TEM characterization image of Example 2.

[0035] Figure 3 This is the TEM characterization image of Example 3.

[0036] Figure 4 The OER activity curves are obtained by linear sweep voltammetry of the supported iridium-based catalysts prepared in Examples 1 to 7 and Comparative Example 1 and the commercial IrO2 catalyst in a 0.5 mol / L sulfuric acid solution.

[0037] Figure 5 The supported catalysts prepared in Examples 1, 2, and 7 and the commercial IrO2 catalyst were assembled into a full electrolytic cell and the electrolytic cell was heated at 100 mA / cm 2 Stability curve tested under constant current. DETAILED DESCRIPTION

[0038] Some embodiments provide a method for preparing a highly stable supported acidic OER catalyst, comprising:

[0039] (1) preparing a carbon nanotube dispersion containing hexadecyltrimethylammonium bromide;

[0040] (2) adding an alkali solution and a hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source solution to the carbon nanotube dispersion to react and obtain a composite support of nano-oxide and carbon nanotubes;

[0041] (3) dispersing the composite carrier in an ethanol solution to obtain a carrier dispersion;

[0042] (4) Adding iridium salt and ruthenium salt to the carrier dispersion, stirring, and then performing a reflux reaction. The reflux reaction product is subjected to solid-liquid separation, washing, and drying to obtain a supported iridium-based alloy acidic OER catalyst.

[0043] In the above technical solution, in step (2), nano-oxide particles such as titanium dioxide, zirconium dioxide, and silicon dioxide, which are chemically inert and highly stable, are formed in situ and combined with carbon nanotubes as iridium-based alloy catalyst carriers to synergistically enhance the conductivity and stability of the OER catalyst material, thereby solving the problem of the difficulty in achieving both stability and conductivity of the OER catalyst carrier. The catalyst has excellent ability to regulate surface properties. Although the chemical properties of the nano-oxide particles used to modify carbon nanotubes are different, the properties of the catalyst can be easily adjusted by controlling the functionalization of the surface. For example, titanium dioxide particles themselves contain more hydrophilic surface hydroxyl groups, zirconium dioxide particles have more oxygen vacancies that are beneficial to catalytic reactions, and silicon dioxide particles can be sulfonated to regulate active sites, thereby improving the activity of the catalyst.

[0044] Compared with traditional composites, in-situ reactions are not only easier to control the size and morphology of oxides, but also the particle size of nano-oxides, the thickness of growth points on carbon nanotubes, etc. can be controlled by controlling the time, temperature and duration of the reaction, making it easier to adjust the morphology of the composite material. Moreover, the interface bonding strength between oxides and carbon materials in in-situ synthesized composite materials is higher, and stronger chemical bonds can be formed between nanoparticles and matrix materials, which helps to improve the mechanical strength and durability of the composite material. Moreover, the product uniformity of in-situ synthesis is better. Since the oxide precursor is water-soluble, it is evenly distributed in the solution at the beginning of the reaction, and will be evenly deposited and loaded on the carbon nanotubes as the reaction time progresses.

[0045] The in-situ coated nano-oxide porous layer has a higher specific surface area than conventional particle-sized oxides due to its small size. Therefore, it can provide more active sites during the subsequent iridium and ruthenium reduction loading, while preventing the subsequent loaded catalyst active materials from agglomerating, improving the dispersion uniformity of the subsequent catalyst active materials, and thus enhancing the catalytic performance of the material. In addition, nano-oxide-coated carbon tubes solve the problem of poor conductivity of traditional oxides. Since traditional large-sized oxides have poor conductivity, nano-scale oxide-coated carbon tubes can fully utilize the conductivity of carbon tubes compared to traditional oxides. At the same time, the nano-scale porous layered structure will not completely wrap the carbon tubes to make them insulated. The synthesized composite carrier can still have excellent electron transport performance. In addition, the nano-scale oxide is more tightly combined with the carbon tubes, which can significantly reduce the contact resistance and improve the catalytic efficiency.

[0046] This technical solution employs a simple solvothermal method to prepare carbon nanotube supports with varying nanooxide loadings by varying the amount of nanooxide precursor added to accommodate varying amounts of iridium and ruthenium. By leveraging the synergistic effect between the carbon nanotubes and the iridium and ruthenium alloy, the catalyst's catalytic performance is further enhanced, resulting in exceptionally high catalytic activity and stability in PEM water electrolysis for hydrogen production.

[0047] In some preferred embodiments, after step (2), the step of continuously adding excess concentrated sulfuric acid to the reaction system for aging treatment is further included to sulfonate the oxides in the composite support.

[0048] In some preferred embodiments, the aging treatment time is 6 to 18 hours, and the aging treatment temperature is 40 to 80°C.

[0049] In some preferred embodiments, the concentration of cetyltrimethylammonium bromide in the carbon nanotube dispersion is 0.05-2 g / 10 mL, more preferably 0.2-1.5 g / 10 mL.

[0050] In some preferred embodiments, the carbon nanotubes are acid-treated carbon nanotubes. The acid used for the acid treatment may be concentrated nitric acid, for example, the carbon nanotubes are refluxed in concentrated nitric acid at 140° C. for 4 hours to obtain acid-treated carbon nanotubes.

[0051] In some preferred embodiments, the hydrolyzable silicon source is ethyl silicate; the hydrolyzable titanium source is titanium tetrachloride or tetrabutyl titanate; the hydrolyzable niobium source is niobium chloride; the hydrolyzable tantalum source is tantalum chloride; the hydrolyzable zirconium source is zirconium chloride or zirconium oxychloride octahydrate.

[0052] In some preferred embodiments, the amount of the hydrolyzable silicon source, titanium source or zirconium source is determined so that the mass proportion of the oxide in the composite support is 20-99%, more preferably 60-90%.

[0053] In some preferred embodiments, the iridium salt and the ruthenium salt are prepared in a mass ratio of iridium to ruthenium of 1:0.2~2.

[0054] In some preferred embodiments, the amount of the iridium salt and the ruthenium salt added is determined so that the total mass proportion of the iridium and ruthenium elements in the synthesized supported iridium-based alloy catalyst is 20-99%, and more preferably 40-60%.

[0055] In some preferred embodiments, in step (4), the total concentration of the iridium and ruthenium elements in the ethanol solution is 0.01-2 g / L.

[0056] In some preferred embodiments, in step (2), the amount of alkali solution added is to adjust the initial pH of the reaction system to 11-13.

[0057] In some preferred embodiments, in step (2), the reaction temperature is 40-80° C.; and the reaction time is 1-12 h.

[0058] In some preferred embodiments, in step (4), the reflux reaction temperature is 80-140°C, more preferably 100-130°C, and the reflux reaction time is 0.5-4 hours. Controlling the reflux reaction temperature at 80-140°C allows the ethanol solution to remain boiling, at which point ethanol has the strongest reducing power for the iridium-ruthenium compound.

[0059] In some preferred embodiments, the solvent of the hydrolyzable silicon source, titanium source or zirconium source solution is any solvent that can dissolve the hydrolyzable silicon source, titanium source or zirconium source into a solution, such as ethanol, water or the like.

[0060] In some preferred embodiments, dispersing the composite carrier in the ethanol solution specifically includes: adding the composite carrier to the ethanol solution, and fully dispersing it evenly through an ultrasonic machine or a cell disruptor to obtain a carrier material dispersion.

[0061] Some embodiments provide acidic OER catalysts prepared using the aforementioned preparation method. The catalysts have the characteristics of high specific surface area, high porosity, high dispersibility, high stability, high catalytic activity, and high selectivity.

[0062] Some embodiments also provide use of the aforementioned acidic OER catalyst in water electrolysis.

[0063] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0064] Example 1:

[0065] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0066] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 371 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0067] Step S3, centrifugation, washing, and drying to obtain a 40 wt% SiO2-loaded carbon nanotube carrier, recorded as 40% SiO2 / CNTs;

[0068] Step S4, taking 16 mg of the synthesized 40% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0069] In step S5, iridium chloride and ruthenium chloride precursor salts were added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt was 4:6, and the total amount of iridium (9.6 mg) and ruthenium (14.4 mg) accounted for 60 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours. The mixture was then refluxed at 120°C for 2 hours using a reflux device. After the reaction, the mixture was cooled to room temperature to obtain a supported iridium-ruthenium catalyst, designated as 60% IrRu (mass ratio 4:6) @ 40% SiO2 / CNTs.

[0070] Example 2:

[0071] The only difference between this example and Example 1 is that the amount of TEOS diluent reagent added in Example 1 is 835 μL. Other operations are referred to Example 1 to prepare a supported iridium ruthenium catalyst, which is recorded as 60% IrRu (mass ratio 4:6) @ 60% SiO2 / CNTs.

[0072] Example 3:

[0073] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0074] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 300 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0075] Step S3, centrifugation, washing, and drying to obtain a 35 wt% SiO2-loaded carbon nanotube support, recorded as 35% SiO2 / CNTs;

[0076] Step S4, taking 4 mg of the synthesized 35% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0077] In step S5, iridium chloride and ruthenium chloride precursor salts were added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt was 4:6, with 14.4 mg of iridium and 21.6 mg of ruthenium. The total amount of iridium-ruthenium alloy elements accounted for 90 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours. Afterwards, the mixture was refluxed at 120°C for 2 hours using a reflux device. After completion of the reaction, the mixture was cooled to room temperature to obtain a supported iridium-ruthenium catalyst, designated as 90% IrRu (mass ratio 4:6) @ 35% SiO2 / CNTs.

[0078] Example 4

[0079] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0080] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 2226 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0081] Step S3, centrifugation, washing, and drying to obtain a carbon nanotube carrier with 80 wt% SiO2 loading, which is recorded as 80% SiO2 / CNTs;

[0082] Step S4, taking 32 mg of the synthesized 80% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0083] In step S5, iridium chloride and ruthenium chloride precursor salts were added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt was 7:3, with 5.6 mg of iridium and 2.4 mg of ruthenium. The total amount of iridium-ruthenium alloy elements accounted for 20 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours. After that, the mixture was refluxed at 120°C for 2 hours using a reflux device. After the reaction, the mixture was cooled to room temperature to obtain a supported iridium-ruthenium catalyst, which was recorded as 20% IrRu (mass ratio 7:3) @ 80% SiO2 / CNTs.

[0084] Example 5:

[0085] The amount of TEOS diluent reagent added in Example 1 was changed to 10573 μL, and the other operations were referred to Example 1 to prepare a supported iridium ruthenium catalyst, which was recorded as 60% IrRu (mass ratio 4:6) @ 95% SiO2 / CNTs.

[0086] Example 6:

[0087] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0088] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 41 μL titanium tetrachloride (analytical grade), and stir to react for 12 hours;

[0089] Step S3, centrifugation, washing, and drying to obtain a 50 wt% TiO2-loaded carbon nanotube carrier, recorded as 50% TiO2 / CNTs;

[0090] Step S4, taking 24 mg of the synthesized 50% TiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0091] In step S5, iridium chloride and ruthenium chloride precursor salts were added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt was 4:6, with 6.4 mg of iridium and 9.6 mg of ruthenium. The total amount of iridium-ruthenium alloy elements accounted for 50 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours. Afterwards, the mixture was refluxed at 120°C for 2 hours using a reflux device. After completion of the reaction, the mixture was cooled to room temperature to obtain a supported iridium-ruthenium catalyst, designated as 40% IrRu (mass ratio 4:6) @ 50% TiO2 / CNTs.

[0092] Example 7

[0093] After step S2 in Example 1, an excess of concentrated sulfuric acid was used to perform a sulfonation operation. Other operations were performed with reference to Example 1 to obtain a supported iridium ruthenium catalyst, which was recorded as 60% IrRu (mass ratio 4:6)@40% sulfonated SiO2 / CNTs.

[0094] Example 8

[0095] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0096] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 371 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0097] Step S3, centrifugation, washing, and drying to obtain a 40 wt% SiO2-loaded carbon nanotube carrier, recorded as 40% SiO2 / CNTs;

[0098] Step S4, taking 16 mg of the synthesized 40% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0099] In step S5, iridium chloride and ruthenium chloride precursor salts are added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt is 4:6, and the total amount of iridium (9.6 mg) and ruthenium (14.4 mg) accounts for 60 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution is stirred and deposited at room temperature for 12 hours. The mixture is then refluxed at 140°C for 1 hour using a reflux device. After the reaction is completed, the mixture is cooled to room temperature to obtain a supported iridium-ruthenium catalyst.

[0100] Example 9

[0101] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0102] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 371 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0103] Step S3, centrifugation, washing, and drying to obtain a 40 wt% SiO2-loaded carbon nanotube carrier, recorded as 40% SiO2 / CNTs;

[0104] Step S4, taking 16 mg of the synthesized 40% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0105] In step S5, iridium chloride and ruthenium chloride precursor salts were added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt was 4:6, and the total amount of iridium (9.6 mg) and ruthenium (14.4 mg) accounted for 60 wt % of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours. The mixture was then refluxed at 90° C. for 4 hours using a reflux device. After completion of the reaction, the mixture was cooled to room temperature to obtain a supported iridium-ruthenium catalyst.

[0106] Example 10

[0107] Step S1, 30 mg of acid-treated carbon nanotubes and 1.5 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0108] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 80°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 371 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir for 6 hours;

[0109] Step S3, centrifugation, washing, and drying to obtain a 40 wt% SiO2-loaded carbon nanotube carrier, recorded as 40% SiO2 / CNTs;

[0110] Step S4, taking 16 mg of the synthesized 40% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0111] In step S5, iridium chloride and ruthenium chloride precursor salts are added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt is 4:6, and the total amount of iridium (9.6 mg) and ruthenium (14.4 mg) accounts for 60 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution is stirred and deposited at room temperature for 12 hours. The mixture is then refluxed at 120°C for 2 hours using a reflux device. After completion of the reaction, the mixture is cooled to room temperature to obtain a supported iridium-ruthenium catalyst.

[0112] Example 11

[0113] Step S1, 30 mg of acid-treated carbon nanotubes and 6 g of (CTAB) reagent were mixed, 30 mL of deionized water was added, and ultrasonic dispersion was performed for 2 h to obtain a carbon nanotube dispersion;

[0114] Step S2: Place the carbon nanotube dispersion in an oil bath controlled at 60°C, add a 2 mol / L NaOH aqueous solution (0.3 mL) and 371 μL of TEOS diluent reagent (the volume ratio of TEOS to ethanol in the diluent is 1:4), and stir to react for 12 hours;

[0115] Step S3, centrifugation, washing, and drying to obtain a 40 wt% SiO2-loaded carbon nanotube carrier, recorded as 40% SiO2 / CNTs;

[0116] Step S4, taking 16 mg of the synthesized 40% SiO2 / CNTs material and adding it to 50 mL of ethanol solution, and fully dispersing it by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0117] In step S5, iridium chloride and ruthenium chloride precursor salts are added to the composite material dispersion. The mass ratio of iridium to ruthenium in the precursor salt is 4:6, and the total amount of iridium (9.6 mg) and ruthenium (14.4 mg) accounts for 60 wt% of the final supported iridium-ruthenium alloy catalyst. The mixed solution is stirred and deposited at room temperature for 12 hours. The mixture is then refluxed at 120°C for 2 hours using a reflux device. After completion of the reaction, the mixture is cooled to room temperature to obtain a supported iridium-ruthenium catalyst.

[0118] Comparative Example 1:

[0119] Step S1, taking 16 mg of acid-treated CNTs and adding them to 50 mL of ethanol solution, and fully dispersing them by ultrasonication for 2 hours to obtain a carrier material dispersion;

[0120] Step S2: Adding iridium chloride and ruthenium chloride precursor salts to the carbon nanotube dispersion, with the iridium to ruthenium mass ratio of the precursor salt being 4:6, 9.6 mg of iridium to 14.4 mg of ruthenium, and the total amount of iridium-ruthenium alloy accounting for 60 wt % of the final supported iridium-ruthenium alloy catalyst. The mixed solution was stirred and deposited at room temperature for 12 hours, then refluxed at 120°C for 2 hours in a reflux apparatus. After completion of the reaction, the mixture was cooled to room temperature to obtain a reaction product.

[0121] In step S3, the reaction product is subjected to solid-liquid separation, washing, and drying to obtain a supported iridium-based alloy catalyst, which is recorded as 60% IrRu (mass ratio 4:6)@CNTs.

[0122] Figure 1 This is a scanning electron microscope image of the supported iridium-based catalyst prepared in Example 1 of the present invention. It can be seen intuitively that the fibrous carbon tubes serve as the basic structure of the catalyst support, and the surface is evenly coated with nano-silicon dioxide and iridium-ruthenium alloy particles.

[0123] Figure 2 and Figure 3 The transmission electron microscope images of the supported iridium-based catalysts prepared in Examples 2 and 3 of the present invention are shown. It can be seen that the iridium-ruthenium alloy particles are uniformly loaded on the surface of the carbon tube silicon dioxide, the grains are small, and the alloy particles are only a few nanometers in diameter. Figure 2 and Figure 3It can be seen that as the amount of iridium-ruthenium alloy added increases, the iridium-ruthenium alloy layer wrapped on the surface of the carbon tube silica support becomes thicker. However, thanks to the large number of active sites provided by the nanoporous silica, the iridium-ruthenium alloy particles can still maintain a particle size of 1 to 2 nanometers and uniform dispersion without agglomeration.

[0124] Figure 4 The OER activity curves of the supported iridium-based catalysts prepared in Examples 1 to 7 and Comparative Example 1 and the commercial IrO2 catalyst tested in 0.5 mol / L sulfuric acid electrolyte are shown in FIG. Figure 4 It can be seen that the OER performance of the supported iridium-based catalyst synthesized by the carbon nanotube carrier loaded with silica is improved compared with the supported catalyst prepared by using carbon nanotubes as the carrier alone, which proves that the nano-oxide-loaded carbon tubes have a certain effect on improving the activity of iridium-ruthenium catalysts. Figure 2 and Figure 3 The TEM image shows that the particles of the iridium-ruthenium active catalyst loaded on the carrier are all alloy particles with a diameter of 1 to 2 nanometers. The reason for this is that the nano-oxides introduced on the carbon tubes can provide more active sites for the reduction of the iridium-ruthenium alloy, while inhibiting the agglomeration of the alloy, allowing the iridium-ruthenium catalyst to be more evenly reduced into finer particles, thereby further improving the activity of the catalyst.

[0125] Figure 5 The supported iridium-based catalyst prepared in Examples 1, 2, and 7 of the present invention and the commercial IrO2 catalyst were assembled into a full electrolytic cell at 100 mA / cm 2 The constant current stability test curve is Figure 5 It can be seen that the stability of the three examples using carbon tube silica as a support is significantly improved compared to commercial IrO2. Example 2 increases the silica content in the carbon tube silica support compared to Example 1, showing that the stability of the catalyst is further improved with the increase in nanosilica loading. Furthermore, Example 7 includes an additional concentrated sulfuric acid sulfonation step compared to Example 1, which doubles the catalyst's stability, demonstrating that the sulfonation step in this invention significantly improves catalyst performance and stability.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a highly stable supported acidic OER catalyst, characterized in that: include: (1) preparing a carbon nanotube dispersion containing hexadecyltrimethylammonium bromide; the carbon nanotube dispersion is a dispersion of carbon nanotubes in deionized water; In the carbon nanotube dispersion, the concentration of cetyltrimethylammonium bromide is 0.2-2 g / 10 mL; (2) adding an alkali solution and a solution of a hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source to the carbon nanotube dispersion to react, centrifugally washing and drying to obtain a composite support of nano-oxides and carbon nanotubes; the alkali solution is a NaOH aqueous solution; the amount of the hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source is determined so that the mass proportion of the oxide in the composite support is 20-90%; (3) dispersing the composite carrier in an ethanol solution to obtain a carrier dispersion; (4) adding iridium salt and ruthenium salt to the carrier dispersion, stirring, and then performing a reflux reaction, wherein the temperature of the reflux reaction is 80-140° C., the time of the reflux reaction is 0.5-4 h, and the reflux reaction product is subjected to solid-liquid separation, washing and drying to obtain a supported iridium-based alloy acidic OER catalyst; the amount of the iridium salt and ruthenium salt added is determined based on the total mass proportion of iridium and ruthenium elements in the synthesized supported iridium-based alloy acidic OER catalyst being 20-90%; the iridium salt and ruthenium salt are prepared according to a mass ratio of iridium to ruthenium of 1:0.2-2.

2. The method for preparing a highly stable supported acidic OER catalyst according to claim 1, wherein: After step (2), the step of continuing to add excess concentrated sulfuric acid to the reaction system for aging treatment to sulfonate the oxide in the composite support is also included; The aging treatment time is 6 to 18 hours, and the aging treatment temperature is 40 to 80°C.

3. The method for preparing a highly stable supported acidic OER catalyst according to claim 1, wherein: In the carbon nanotube dispersion, the concentration of cetyltrimethylammonium bromide is 0.2-1.5 g / 10 mL; The carbon nanotubes are acid-treated carbon nanotubes.

4. The method for preparing a highly stable supported acidic OER catalyst according to claim 1, wherein: The hydrolyzable silicon source is ethyl silicate; the hydrolyzable titanium source is titanium tetrachloride or tetrabutyl titanate; the hydrolyzable niobium source is niobium chloride; the hydrolyzable tantalum source is tantalum chloride; the hydrolyzable titanium source is zirconium chloride or zirconium oxychloride octahydrate; The amount of the hydrolyzable silicon source, titanium source, niobium source, tantalum source or zirconium source is determined so that the mass proportion of the oxide in the composite support is 60-90%.

5. The method for preparing a highly stable supported acidic OER catalyst according to any one of claims 1 to 4, wherein: The iridium salt is any one or more of chloroiridic acid and iridium chloride, and the ruthenium salt is any one or more of ruthenium chloride and ruthenium acetylacetonate.

6. The method for preparing a highly stable supported acidic OER catalyst according to any one of claims 1 to 4, wherein: In step (4), the total concentration of the iridium element and the ruthenium element in the ethanol solution is 0.01-2 g / L.

7. The method for preparing a highly stable supported acidic OER catalyst according to any one of claims 1 to 4, wherein: In step (2), the amount of the alkali solution added is determined by adjusting the initial pH of the reaction system to 11-13; In step (2), the reaction temperature is 40-80° C.; the reaction time is 1-12 h.

8. A highly stable supported acidic OER catalyst, characterized in that: The method is as described in any one of claims 1 to 7.

9. Use of the highly stable supported acidic OER catalyst as claimed in claim 8 in water electrolysis.

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