Composite oxygen evolution catalyst and preparation method thereof

Abstract

The invention provides a composite oxygen evolution catalyst and a preparation method thereof. The chemical formula of the composite oxygen evolution catalyst is BaIrxTi (1-x) O3, and x is more than or equal to 0.1 and less than or equal to 1. The composite oxygen evolution catalyst has optimized electron cloud distribution, lower oxygen evolution reaction overpotential and more active sites, the reaction kinetics process is accelerated, and the doping amount of iridium is reduced by introducing barium and titanium, so that the problems of low activity, poor stability and high preparation cost of the oxygen evolution catalyst in the prior art are solved. Besides, the catalyst disclosed by the invention has chemical adaptability with an adjustable structure, specifically, comprehensive optimization of activity, stability, cost and adaptability of the BaIrxTi (1-x) O3 composite oxygen evolution catalyst can be realized by adjusting the value of x, and a high-performance and economic catalytic material is provided for oxygen evolution reaction processes such as hydrogen production by electrolysis of water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oxygen evolution catalysts, in particular to a composite oxygen evolution catalyst and a preparation method thereof. BACKGROUND

[0002] With the global emphasis on environmental protection and sustainable development, the energy structure is gradually transformed to clean energy. Hydrogen energy, as a clean, low-carbon, green, environmentally friendly and efficient secondary energy, is of great importance to the technology of water electrolysis for hydrogen production. However, the oxygen evolution reaction (OER) of the anode of water electrolysis is slow in kinetics due to the four-electron transfer process, and requires a large overpotential, resulting in low efficiency and high energy consumption of water electrolysis. The current commercial noble metal catalysts (such as iridium dioxide) have problems of resource scarcity and high price, which cannot meet the development needs of large-scale water electrolysis for hydrogen production. Reducing the content of noble metals in the catalyst and improving the phase stability of the catalyst crystal structure are among the research directions in this field.

[0003] As the core link of the key process of water splitting, the performance of the oxygen evolution reaction directly determines the large-scale application of clean energy. However, the current catalysts for the oxygen evolution reaction cannot meet the demand of large-scale application of clean energy. Non-noble metal catalysts have low activity, high overpotential and large energy consumption for the oxygen evolution reaction, resulting in high cost of hydrogen production. Although iridium-based catalysts have high activity, they are scarce in resources and expensive in price, which cannot meet the demand of large-scale production. In addition, the preparation process of the catalyst also seriously hinders its large-scale development. For example, the high-temperature solid-phase synthesis method has huge energy consumption for long-time high-temperature calcination, and it is difficult to accurately control the particle size distribution and crystal structure of the product, resulting in uneven product quality. This process usually has a long process flow and complex operation, which not only consumes a large amount of time and energy, requires high equipment, greatly increases the production cost, but also easily introduces impurities, affecting the consistency and stability of the catalyst performance.

[0004] Therefore, it is urgent to develop a new type of oxygen evolution catalyst and a preparation method thereof to achieve a balance between high activity, high stability and low cost of the oxygen evolution catalyst, so as to meet the development needs of large-scale water electrolysis for hydrogen production. SUMMARY

[0005] The main purpose of the present application is to provide a composite oxygen evolution catalyst and a preparation method thereof, so as to solve the problems of low activity, poor stability and high preparation cost of the oxygen evolution catalyst in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a composite oxygen evolution catalyst is provided, which has a chemical formula of BaIr x Ti (1-x) O3, wherein 0.1≤x≤1.

[0007] Further, the above x is 0.5≤x≤1, and / or the composite oxygen evolution catalyst is selected from BaIr 0.18 Ti 0.82 O3, BaIr 0.35 Ti 0.65 O3, BaIr 0.5 Ti 0.5 O3, BaIr 0.55 Ti 0.45 O3, BaIr 0.58 Ti 0.42 O3, BaIr 0.6 Ti 0.4 O3, BaIr 0.63 Ti 0.37 O3, BaIr 0.66 Ti 0.34 O3, BaIr 0.7 Ti 0.3 O3, BaIr 0.77 Ti 0.23 O3, BaIr 0.8 Ti 0.2 O3, BaIr 0.89 Ti 0.11 O3, BaIr 0.9 Ti 0.1 O3, and any one or more of BaIrO3.

[0008] Further, the specific surface area of the above composite oxygen evolution catalyst is 30-50m 2 / g; and / or the average particle size of the composite oxygen evolution catalyst is 20-200nm.

[0009] Further, in the electrolytic water oxygen evolution reaction of a three-electrode system, the Tafel slope of the above composite oxygen evolution catalyst is 53-95mV·dec -1 tested in a 0.5mol / L H2SO4 solution environment; and / or the overpotential η -2 required for the composite oxygen evolution catalyst to reach a current density of 10mA·cm 10 in an acidic environment with pH=0.3 is 256-295mV; and / or the attenuation rate of the overpotential η 10 of the composite oxygen evolution catalyst is 35-55μV·h -1 when the stable operation time reaches 350h at a current density of 1A·cm -2 .

[0010] According to another aspect of the present application, there is provided a method for preparing the composite oxygen evolution catalyst as described above, the method comprising: step S1, dispersing raw materials comprising an iridium source, a titanium source, a barium salt and an organic polyacid in a mixed solvent of a polyol and water to obtain a mixed solution; step S2, performing solvent evaporation drying treatment on the mixed solution and then performing calcination under an air atmosphere to obtain a primary product; and step S3, performing protonation on the primary product with an inorganic acid and then sequentially performing washing and filtering to obtain the composite oxygen evolution catalyst.

[0011] Further, in the step S1, the iridium source is an iridium-containing compound and / or a hydrate corresponding to the iridium-containing compound, and the iridium-containing compound is selected from any one or more of iridium trichloride, chloro iridic acid, potassium chloro iridic acid, sodium chloro iridic acid, ammonium chloro iridic acid, iridium acetate and acetylacetone iridium; and / or, the barium salt is a barium-containing compound and / or a hydrate corresponding to the barium-containing compound, and the barium-containing compound is selected from any one or more of barium chloride, barium hydroxide and barium nitrate; and / or, the titanium source is isopropyl titanate.

[0012] Further, the organic polyacid is selected from any one or more of citric acid, oxalic acid, tartaric acid, malic acid and succinic acid.

[0013] Further, in the step S1, the volume ratio of the polyol to water is 1-3:2-2.5, and / or the polyol is selected from any one or more of ethylene glycol, propylene glycol, glycerol, polyethylene glycol 200 and polypropylene glycol 200.

[0014] Further, in the step S2, the temperature of the solvent evaporation drying treatment is 90-150℃, and the time of the solvent evaporation drying treatment is 5-11h; and / or, the temperature of the calcination is 450-800℃, and the time of the calcination is 2-8h.

[0015] Further, in the step S3, the inorganic acid is selected from any one or more of hydrochloric acid, sulfuric acid and glacial acetic acid; and / or, the concentration of the inorganic acid is 0.5-1 mol / L.

[0016] According to the technical solution of the application, the composite oxygen evolution catalyst with stable and efficient crystal structure framework is constructed by accurately controlling the synergistic proportion of each element. Specifically, from the perspective of ions, barium ions and iridium ions are bridged by oxygen ions to construct a stable three-dimensional network structure. This structure can effectively maintain the integrity of the composite oxygen evolution catalyst lattice under harsh reaction conditions such as strong oxidation and high potential, and exhibits good structural stability. At the same time, it creates abundant active sites for the oxygen evolution reaction and provides a fast ion transmission channel. The specific oxygen coordination environment around the iridium ion can effectively adjust its electronic structure, prompting the iridium ion to have appropriate adsorption and activation ability to the oxygen species generated in the catalytic reaction process, thereby greatly accelerating the oxygen evolution reaction process; from the perspective of electronic structure, the presence of barium ions can effectively regulate the electron cloud density and energy level distribution of iridium ions, prompting the formation of stronger interaction between the d-orbital electrons of iridium ions and the 2p-orbital electrons of oxygen species generated in the catalytic reaction process, significantly enhancing the adsorption and activation ability of oxygen species. This synergistic effect can also promote the rapid transmission of electrons within the catalyst, improving the electrical conductivity of the catalyst and further accelerating the kinetics of the oxygen evolution reaction; through the synergistic effect of the above two aspects, the composite oxygen evolution catalyst of the application has optimized electron cloud distribution, lower oxygen evolution reaction overpotential and more active sites, which accelerates the reaction kinetics, and the introduction of barium and titanium reduces the doping amount of iridium, thereby solving the problems of low activity, poor stability and high preparation cost of the existing oxygen evolution catalyst. In addition, the catalyst of the application has a structure-adjustable chemical adaptability, specifically, by adjusting the value of x, the activity, stability, cost and adaptability of the BaIr x Ti (1-x) O3 composite oxygen evolution catalyst can be optimized, providing a high-performance and economical catalytic material for the oxygen evolution reaction process such as water electrolysis to produce hydrogen. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application given below, make an explanation of the application, and do not constitute an improper limitation on the application. In the drawings:

[0018] Figure 1 A stability test diagram of a composite oxygen evolution catalyst according to embodiment 1 of the application in a PEM electrolytic cell is shown;

[0019] Figure 2 A polarization curve diagram of a composite oxygen evolution catalyst according to embodiment 1 of the application in an acidic environment is shown;

[0020] Figure 3 A diagram of the overpotential of a composite oxygen evolution catalyst according to embodiment 1 of the application is shown;

[0021] Figure 4 A Tafel curve diagram of a composite oxygen evolution catalyst according to Embodiment 1 of the present application is shown. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0023] As described in the background section, the prior art oxygen evolution catalyst has the problems of low activity, poor stability and high preparation cost. In order to solve the above problems, the present application provides a composite oxygen evolution catalyst and a preparation method thereof.

[0024] In a typical embodiment of the present application, a composite oxygen evolution catalyst is provided, which has a chemical formula of BaIr x Ti (1-x) O3, wherein 0.1≤x≤1.

[0025] The present application constructs a composite oxygen evolution catalyst with stable and efficient crystal structure framework by precisely controlling the synergistic ratio of each element. Specifically, from the perspective of ions, barium ions and iridium ions are bridged by oxygen ions to construct a stable three-dimensional network structure. This structure can effectively maintain the integrity of the composite oxygen evolution catalyst lattice under harsh reaction conditions such as strong oxidation and high potential, and exhibits good structural stability. At the same time, it creates abundant active sites for the oxygen evolution reaction and provides a fast ion transport channel. The specific oxygen coordination environment around the iridium ion can effectively adjust its electronic structure, prompting the iridium ion to have appropriate adsorption and activation ability for the oxygen species generated in the catalytic reaction process, thereby greatly accelerating the oxygen evolution reaction process. From the perspective of electronic structure, the presence of barium ions can effectively regulate the electron cloud density and energy level distribution of iridium ions, prompting the formation of stronger interaction between the d-orbital electrons of iridium ions and the 2p-orbital electrons of oxygen species generated in the catalytic reaction process, significantly enhancing the adsorption and activation ability of oxygen species. This synergistic effect can also promote the rapid transmission of electrons within the catalyst, improving the electrical conductivity of the catalyst and further accelerating the kinetics of the oxygen evolution reaction. Through the synergistic effect of the above two aspects, the composite oxygen evolution catalyst of the present application has optimized electron cloud distribution, lower oxygen evolution reaction overpotential and more active sites, which accelerates the reaction kinetics process, and the introduction of barium and titanium reduces the doping amount of iridium, thereby solving the problems of low activity, poor stability and high preparation cost of the prior art oxygen evolution catalyst. In addition, the catalyst of the present application has a structure-adjustable chemical adaptability. Specifically, by adjusting the value of x, BaIr x Ti (1-x)The comprehensive optimization of the activity, stability, cost and adaptability of the O3 composite oxygen evolution catalyst provides high-performance and economical catalytic materials for the oxygen evolution reaction process such as water electrolysis hydrogen production.

[0026] In an embodiment of the present application, 0.5≤x≤1, and / or, the composite oxygen evolution catalyst is selected from BaIr 0.18 Ti 0.82 O3, BaIr 0.35 Ti 0.65 O3, BaIr 0.5 Ti 0.5 O3, BaIr 0.55 Ti 0.45 O3, BaIr 0.58 Ti 0.42 O3, BaIr 0.6 Ti 0.4 O3, BaIr 0.63 Ti 0.37 O3, BaIr 0.66 Ti 0.34 O3, BaIr 0.7 Ti 0.3 O3, BaIr 0.77 Ti 0.23 O3, BaIr 0.8 Ti 0.2 O3, BaIr 0.89 Ti 0.11 O3, BaIr 0.9 Ti 0.1 O3, and any one or more of BaIrO3.

[0027] On the one hand, increasing the iridium content generally improves catalyst activity, but excessive iridium content not only increases cost but may also reduce stability due to lattice distortion. Conversely, increasing the titanium content is beneficial for cost control and improved structural stability, but may also reduce activity. Therefore, the synergistic effect of titanium and iridium in the catalyst can optimize electron transport pathways, enhance the adsorption and desorption capabilities of intermediates (oxygen species), and accelerate the reaction rate. Furthermore, controlling the x value within the above range not only balances the activity and stability of the composite oxygen evolution catalyst, but also produces a catalyst with a better Tafel slope and lower overpotential, thereby accelerating the kinetics of the oxygen evolution reaction and improving energy conversion efficiency. On the other hand, specific composite oxygen evolution catalysts corresponding to some of the above-mentioned x values ​​may be more suitable for operation in environments with high temperature, high pressure, or specific pH values, while other composite oxygen evolution catalysts may exhibit excellent performance under mild conditions. Therefore, by controlling the range of x and selecting specific composite oxygen evolution catalysts within the above range, it is beneficial to achieve fine-tuning of catalyst performance, including the comprehensive optimization of activity, stability, cost, and application flexibility, providing more efficient, economical, and sustainable solutions for clean energy technologies such as water electrolysis to produce hydrogen.

[0028] In addition, it is preferred that the composite oxygen evolution catalyst is selected from BaIr 0.5 Ti 0.5 O3、BaIr 0.55 Ti 0.45 O3、BaIr 0.58 Ti 0.42 O3、BaIr 0.6 Ti 0.4 O3、BaIr 0.63 Ti 0.37 O3、BaIr 0.66 Ti 0.34 O3、BaIr 0.7 Ti 0.3 O3、BaIr 0.77 Ti 0.23 O3、BaIr 0.8 Ti 0.2 O3、BaIr 0.89 Ti 0.11 O3、BaIr 0.9 Ti 0.1 Any one or more of O3 and BaIrO3.

[0029] In one embodiment of the present application, the specific surface area of ​​the composite oxygen evolution catalyst is 30 to 50 m 2 / g; and / or the average particle size of the composite oxygen evolution catalyst is 20 to 200 nm.

[0030] On one hand, a higher specific surface area can provide more surface active sites for the composite oxygen evolution catalyst, which is beneficial for the catalytic reaction, especially in the oxygen evolution reaction, more active sites mean higher catalytic activity and reaction rate. Increasing the specific surface area not only facilitates the transfer of species in the electrolyte to the surface of the catalyst, thereby accelerating the reaction kinetics, but also facilitates the more efficient use of catalyst materials, reduces the amount of noble metal used, and reduces costs. On the other hand, reducing the particle size of the catalyst can increase the density of its surface active sites, thereby improving catalytic efficiency. The smaller the particle size, the greater the surface area per unit mass of catalyst, and the more active sites. However, too small a particle size can lead to the catalyst being easily dissolved at high potentials, while too large a particle size can reduce the active sites and reduce the catalytic efficiency. By controlling the average particle size of the composite oxygen evolution catalyst within the above range, the risk of too small or too large particle size affecting the stability of the catalyst can be reduced. Therefore, by synergistically controlling the specific surface area and average particle size of the composite oxygen evolution catalyst within the above range, the catalytic activity, stability and resource utilization efficiency of the composite oxygen evolution catalyst in the oxygen evolution reaction can be significantly improved.

[0031] In an embodiment of the present application, in the electrolytic water oxygen evolution reaction of a three-electrode system, the Tafel slope of the composite oxygen evolution catalyst is 53-95 mV·dec -1 ; and / or the overpotential η -2 required for the composite oxygen evolution catalyst to reach a current density of 10 mA·cm 10 in an acidic environment with pH=0.3 is 256-295 mV; and / or the decay rate of the overpotential η -2 of the composite oxygen evolution catalyst is 35-55 μV·h 10 when the composite oxygen evolution catalyst is stably operated for 350 h at a current density of 1 A·cm -1 .

[0032] On one hand, a lower Tafel slope means that the catalyst accelerates the kinetic process of the electrochemical reaction. In the present application, controlling the Tafel slope within the above range indicates that the catalyst significantly promotes the oxygen evolution reaction, which can effectively reduce the potential required in the oxygen evolution process, thereby reducing energy consumption and improving the energy conversion efficiency of water electrolysis to produce hydrogen. On the other hand, a lower overpotential means that the voltage required to achieve the same current density is smaller, thereby reducing the energy consumption of the electrochemical reaction and reducing the cost of hydrogen production. On the other hand, a low decay rate ensures that the catalyst can still maintain high catalytic activity over a long period of time, which is crucial for industrial applications such as water electrolysis to produce hydrogen that require long-term continuous operation, and helps to reduce catalyst replacement frequency and reduce operation and maintenance costs. In summary, by controlling the Tafel slope, overpotential η 10And the decay rate is in the above range, not only helps to improve the catalytic efficiency and stability of the catalyst, reduces the energy consumption cost, also helps to improve the reliability and consistency of the catalytic reaction.

[0033] In another typical embodiment of the present application, a preparation method of the composite oxygen evolution catalyst is provided, which comprises: step S1, dispersing raw materials including an iridium source, a titanium source, a barium salt and an organic polyacid in a mixed solvent of a polyol and water to obtain a mixed solution; step S2, performing solvent evaporation drying treatment on the mixed solution, and then performing calcination under an air atmosphere to obtain a primary product; and step S3, performing protonation on the primary product with an inorganic acid, and then performing washing and filtering in sequence to obtain the composite oxygen evolution catalyst.

[0034] In another typical embodiment of the present application, a preparation method of the composite oxygen evolution catalyst is provided, which comprises: step S1, dispersing raw materials including an iridium source, a titanium source, a barium salt and an organic polyacid in a mixed solvent of a polyol and water to obtain a mixed solution; step S2, performing solvent evaporation drying treatment on the mixed solution, and then performing calcination under an air atmosphere to obtain a primary product; and step S3, performing protonation on the primary product with an inorganic acid, and then performing washing and filtering in sequence to obtain the composite oxygen evolution catalyst.

[0035] In another typical embodiment of the present application, a preparation method of the composite oxygen evolution catalyst is provided, which comprises: step S1, dispersing raw materials including an iridium source, a titanium source, a barium salt and an organic polyacid in a mixed solvent of a polyol and water to obtain a mixed solution; step S2, performing solvent evaporation drying treatment on the mixed solution, and then performing calcination under an air atmosphere to obtain a primary product; and step S3, performing protonation on the primary product with an inorganic acid, and then performing washing and filtering in sequence to obtain the composite oxygen evolution catalyst.

[0036] The different iridium sources, titanium sources and barium salts have different activities in chemical reactions, thereby affecting the formation rate and uniformity of the precursor. The different iridium-containing compounds, titanium sources and barium-containing compounds can have different sizes, shapes and charge states of ions or molecules, which will directly affect the structure formation of the final composite material. Therefore, controlling the specific types of iridium sources, titanium sources and barium salts within the above ranges helps to effectively regulate the preparation process of the composite oxygen evolution catalyst, including reaction activity, crystal structure, purity, cost and adaptability to preparation conditions, thereby improving the excellent performance of the final composite oxygen evolution catalyst.

[0037] In an embodiment of the present application, in the step S1, the organic polyacid is selected from any one or more of citric acid, oxalic acid, tartaric acid, malic acid and succinic acid.

[0038] The organic polyacid can form stable complexes with metal ions (such as iridium, barium and titanium), promoting the uniform dispersion of metal ions in the precursor solution. This stable coordination is conducive to the ordered deposition of metal ions in subsequent reactions, forming a more uniform catalyst structure, thereby improving the activity and stability of the catalyst. On the one hand, different organic polyacids have different regulatory effects on crystal growth during preparation. On the other hand, selecting the above types of organic acids is also beneficial to optimizing the active sites on the surface of the catalyst, reducing the overpotential of the oxygen evolution reaction, while enhancing its stability at high potentials, prolonging the service life of the catalyst.

[0039] In an embodiment of the present application, in the step S1, the volume ratio of the polyol to water is 1-3:2-2.5, and / or the polyol is selected from any one or more of ethylene glycol, propylene glycol, glycerol, polyethylene glycol 200 and polypropylene glycol 200.

[0040] The volume ratio of the polyol to water affects the polarity, viscosity and surface tension of the solution, thereby affecting the coordination environment of metal ions and the crystal growth conditions. A higher volume ratio of the polyol to water can reduce the solution viscosity, promoting crystal growth, while a lower volume ratio of the polyol to water can help to form more stable complexes, inhibiting crystal growth, maintaining small particle size and high specific surface area. Therefore, by controlling the volume ratio of the polyol to water within the above range, the present application helps to provide a more favorable solvent environment for the formation and stabilization of the composite oxygen evolution catalyst, promoting the uniform dispersion and ordered deposition of metal ions, forming a composite oxygen evolution catalyst crystal with high activity and stability.

[0041] In addition, by controlling the type of polyol within the above range, on the one hand, the polyol of the above type has good solubility and gelation ability, thereby helping to promote the gelation process of the precursor solution and form a gel with rich pore structure. The pore structure not only can increase the specific surface area of the catalyst to provide more active sites, but also can improve the penetration of the electrolyte and accelerate the transport of the reactants to improve the efficiency of the oxygen evolution reaction. On the other hand, the polyol of the above type has good thermal stability, which is conducive to playing a protective role in the subsequent high-temperature calcination step, thereby reducing the volatilization and aggregation of metal ions and helping to maintain the structural integrity of the composite oxygen evolution catalyst. At the same time, the thermal decomposition products of the polyol can form a porous structure during the calcination process, thereby helping to improve the porosity of the composite oxygen evolution catalyst and enhance its catalytic performance and long-term stability.

[0042] In an embodiment of the present application, in the step S2, the temperature of the solvent evaporation treatment is 90-150°C, and the time of the solvent evaporation treatment is 5-11h; and / or, the temperature of the calcination is 450-800°C, and the time of the calcination is 2-8h.

[0043] The lower temperature is conducive to slow evaporation of the solvent and promotes the formation of a more ordered and uniform-porosity gel structure, which helps to form a catalyst with high specific surface area and rich active sites in the subsequent calcination process. The higher temperature can accelerate the evaporation of the solvent and shorten the preparation time, but needs to be carefully controlled to reduce the risk of uneven gel structure caused by too fast evaporation, which affects the performance consistency of the catalyst. The longer evaporation treatment is conducive to ensuring complete removal of the solvent and reducing the risk of bubbles generated by residual solvent during the calcination process, which can damage the structure of the catalyst. However, too long a treatment time can increase energy consumption. A lower calcination temperature can not completely convert the precursor, thereby affecting the activity and stability of the catalyst. A higher calcination temperature can cause damage to the structure of the catalyst and reduce the active sites. A shorter calcination time can not be sufficient to complete the structural conversion, which in turn affects the activity of the catalyst; a longer calcination time, although conducive to more complete structural conversion, can also increase energy consumption and production cost. Therefore, the present application precisely controls the temperature and time of the solvent evaporation treatment and calcination within the above range, which helps to make the composite oxygen evolution catalyst exhibit high and stable catalytic performance in the water electrolysis oxygen evolution reaction, while reducing energy consumption and production cost in the preparation process.

[0044] In an embodiment of the present application, in the step S3, the inorganic acid is selected from any one or more of hydrochloric acid, sulfuric acid and glacial acetic acid; and / or, the concentration of the inorganic acid is 0.5-1 mol / L.

[0045] Different kinds of inorganic acids have different solubility and selectivity to metal oxides. The above kinds of inorganic acids can effectively clean the surface of the catalyst without excessive erosion of the structure. The concentration of the inorganic acid affects the cleaning effect of the catalyst surface and the generation of active sites. Lower acid concentration may not effectively remove surface impurities, while too high acid concentration may damage the structure of the catalyst and reduce the number of active sites. Therefore, by controlling the type and concentration of inorganic acid within the above range, not only can the surface inorganic salt residue be removed, the catalyst surface structure can be optimized, and the number of active sites can be increased, but also the catalyst surface can be cleaned gently, and the formation of specific active sites can be promoted.

[0046] The application will be further described in detail below in conjunction with specific examples, which cannot be understood as limiting the scope of the application claimed.

[0047] Example 1

[0048] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 3.66 g of iridium chloride were dissolved in 50 mL of deionized water to obtain solution A;

[0049] (2) After stirring solution A for 12 h, a water bath was used to heat and keep the temperature at 70°C for 3 h, and a mixed solution was obtained after sufficient reaction;

[0050] (3) The mixed solution in step (2) was placed in an oven and kept at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0051] (4) The solid polymer obtained in step (3) was placed in a porcelain boat and then placed in a muffle furnace, and heated to 600°C at a heating rate of 5°C / min in an air atmosphere, and kept for 6 h for calcination. After calcination, it was cooled to room temperature to obtain a primary product;

[0052] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, and then washed with water and ethanol, and vacuum dried to obtain a barium iridium titanium perovskite oxygen evolution catalyst BaIr 0.99 Ti 0.01 O3.

[0053] Example 2

[0054] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 3.66 g of iridium chloride were dissolved in 50 mL of deionized water to obtain solution A; 4.936 g of isopropyl titanate was dissolved in 20 mL of ethylene glycol to obtain solution B, wherein the volume ratio of ethylene glycol to water was 1:1;

[0055] (2) Solution A was added drop by drop into solution B, stirred for 12 h, and then heated in a water bath at 70°C for 3 h, to obtain a mixed solution after full reaction;

[0056] (3) The mixed solution in step (2) was placed in an oven and kept at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0057] (4) The solid polymer obtained in step (3) was placed in a porcelain boat and then placed in a muffle furnace, heated to 600°C at a heating rate of 5°C / min in an air atmosphere, and then kept at 600°C for 6 h for calcination. After calcination, the product was cooled to room temperature to obtain a primary product;

[0058] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, and then washed with water and ethanol, and vacuum dried to obtain a composite oxygen evolution catalyst BaIr 0.5 Ti 0.5 O3.

[0059] Example 3

[0060] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 2.14 g of iridium chloride were dissolved in 50 mL of deionized water to obtain solution A; 4.0246 g of isopropyl titanate was dissolved in 20 mL of ethylene glycol to obtain solution B, wherein the volume ratio of ethylene glycol to water was 1:1;

[0061] (2) Solution A was added drop by drop into solution B, stirred for 12 h, and then heated in a water bath at 70°C for 3 h, to obtain a mixed solution after full reaction;

[0062] (3) The mixed solution in step (2) was placed in an oven and kept at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0063] (4) The solid polymer obtained in step (3) was placed in a porcelain boat and then placed in a muffle furnace, heated to 600°C at a heating rate of 5°C / min in an air atmosphere, and then kept at 600°C for 6 h for calcination. After calcination, the product was cooled to room temperature to obtain a primary product;

[0064] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, and then washed with water and ethanol, and vacuum dried to obtain a composite oxygen evolution catalyst BaIr 0.58 Ti 0.42 O3.

[0065] Example 4

[0066] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 3.68 g of chloroiridic acid were weighed into 50 mL of deionized water to obtain solution A; 3.146 g of isopropyl titanate was weighed into 20 mL of ethylene glycol to obtain solution B, wherein the volume ratio of ethylene glycol to water was 1:1;

[0067] (2) Solution A was added dropwise into solution B, and after stirring for 12 h, a water bath was used for heating at 70°C for 3 h, and after full reaction, a mixed solution was obtained;

[0068] (3) The mixed solution in step (2) was placed in an oven and kept at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0069] (4) The solid polymer obtained in step (3) was placed in a porcelain boat and then placed in a muffle furnace, and heating was performed at a heating rate of 5°C / min under an air atmosphere, heating to 600°C and keeping for 6 h for calcination, and after calcination was completed, cooling to room temperature to obtain a primary product;

[0070] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, and then washed with water and ethanol, and vacuum dried to obtain a composite oxygen evolution catalyst BaIr 0.7 Ti 0.3 O3.

[0071] Example 5

[0072] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 3.68 g of chloroiridic acid were weighed into 50 mL of deionized water to obtain solution A; 3.146 g of isopropyl titanate was weighed into 20 mL of ethylene glycol to obtain solution B, wherein the volume ratio of ethylene glycol to water was 1:1;

[0073] (2) Solution A was added dropwise into solution B, and after stirring for 12 h, a water bath was used for heating at 70°C for 3 h, and after full reaction, a mixed solution was obtained;

[0074] (3) The mixed solution in step (2) was placed in an oven and kept at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0075] (4) The solid polymer obtained in step (3) was placed in a porcelain boat and then placed in a muffle furnace, and heating was performed at a heating rate of 5°C / min under an air atmosphere, heating to 600°C and keeping for 6 h for calcination, and after calcination was completed, cooling to room temperature to obtain a primary product;

[0076] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, and then washed with water and ethanol, and vacuum dried to obtain a composite oxygen evolution catalyst BaIr0.9 Ti 0.1 O3.

[0077] Example 6

[0078] (1) 6.4252 g of barium chloride, 3.28 g of citric acid, and 3.66 g of chloroiridic acid were weighed and dissolved in 50 mL of deionized water to form solution A;

[0079] (2) After solution A was stirred for 12 h, it was heated using a water bath at 70°C for 3 h, and B was obtained after sufficient reaction, wherein the volume ratio of ethylene glycol to water was 1:1;

[0080] (3) B in step (2) was kept in an oven at 150°C for 3 h, and the solvent was dried to obtain a solid polymer;

[0081] (4) The solid polymer obtained in step (3) was placed in a porcelain boat in a muffle furnace, heated to 600°C at a heating rate of 5°C / min in an air atmosphere, and kept for 6 h, and then cooled to room temperature after calcination was completed; -1

[0082] (5) The product after calcination in step (4) was washed with 1M hydrochloric acid, and finally washed with water and ethanol, and then vacuum dried to obtain the composite oxygen evolution catalyst BaIrO3.

[0083] Example 7

[0084] The difference from Example 1 is that in step (1), the volume ratio of ethylene glycol to water is 1.5:1, and finally the composite oxygen evolution catalyst BaIr 0.55 Ti 0.45 O3.

[0085] Example 8

[0086] The difference from Example 1 is that in step (1), the volume ratio of ethylene glycol to water is 1:1.5, and finally the composite oxygen evolution catalyst BaIr 0.35 Ti 0.65 O3.

[0087] Example 9

[0088] The difference from Example 1 is that in step (3), the mixed solution is placed in an oven at 90°C for 3 h, the solvent is dried to obtain a solid polymer, and finally the composite oxygen evolution catalyst BaIr 0.77 Ti 0.23 O3.

[0089] Example 10

[0090] ​The difference from Example 1 is that in step (3), the mixed solution is placed in an oven at 120℃ for 3h, and the solvent is dried to obtain a solid polymer, and finally a composite oxygen evolution catalyst BaIr 0.8 Ti 0.2 O3.

[0091] Example 11

[0092] The difference from Example 1 is that in step (4), the solid polymer is placed in a porcelain boat and then placed in a muffle furnace, heated to 800℃ in an air atmosphere, and then held for 6h to perform calcination to obtain a primary product, and finally a composite oxygen evolution catalyst BaIr 0.66 Ti 0.34 O3.

[0093] Example 12

[0094] The difference from Example 1 is that in step (4), the solid polymer is placed in a porcelain boat and then placed in a muffle furnace, heated to 400℃ in an air atmosphere, and then held for 6h to perform calcination to obtain a primary product, and finally a composite oxygen evolution catalyst BaIr 0.89 Ti 0.11 O3.

[0095] Example 13

[0096] The difference from Example 1 is that in step (5), the inorganic acid is 0.5mol / L glacial acetic acid, and finally a composite oxygen evolution catalyst BaIr 0.63 Ti 0.37 O3.

[0097] Example 14

[0098] The difference from Example 1 is that in step (1), the iridium source is sodium chloroiridate, and finally a composite oxygen evolution catalyst BaIr 0.18 Ti 0.82 O3.

[0099] Comparative Example 1

[0100] The difference from Example 1 is that in step (1), the barium salt is barium nitrate, and finally a composite oxygen evolution catalyst BaIr 0.09 Ti 0.91 O3.

[0101] Comparative Example 2

[0102] (1) 6.4252g of barium chloride, 3.28g of citric acid, and 1.08g of chloroiridic acid were weighed and dissolved in 50mL of deionized water to obtain solution A; 5.113g of isopropyl titanate was weighed and dissolved in 20mL of ethylene glycol to obtain solution B, wherein the volume ratio of ethylene glycol to water is 1:1;

[0103] (2) Solution A was added dropwise to solution B, stirred for 12 h, and then heated in a water bath at 70 °C for 3 h to obtain a mixed solution after sufficient reaction;

[0104] (3) placing the mixed solution in step (2) in an oven at 150° C. for 3 h to dry the solvent to obtain a solid polymer;

[0105] (4) placing the solid polymer obtained in step (3) in a porcelain boat and then placing it in a muffle furnace, heating it at a heating rate of 5°C / min in an air atmosphere, heating it to 600°C, keeping it at that temperature for 6 hours, and calcining it. After calcination, cooling it to room temperature to obtain a primary product;

[0106] (5) The primary product in step (4) was protonated with 1M hydrochloric acid, then washed with water and ethanol, and dried under vacuum to obtain the composite oxygen evolution catalyst BaIr 0.02 Ti 0.98 O3.

[0107] Comparative Example 3

[0108] The difference from Example 1 is that the catalyst is IrO2.

[0109] Performance testing:

[0110] Specific surface area of ​​composite oxygen evolution catalyst: Take 100-200mg of catalyst sample (adjust according to the specific surface area to ensure the adsorption amount is ≥0.1mL / g), place it in a sample tube, and record the sample mass m (accurate to 0.1mg). Connect the sample tube to the surface area analyzer degassing station for heating and degassing. Use high-purity nitrogen as the adsorbent and helium as the carrier gas to calibrate the surface area analyzer. Then measure the adsorption-desorption curve of the catalyst sample. Finally, calculate the specific surface area of ​​the catalyst sample based on the adsorption-desorption curve and the BJH model. This method also complies with the international standard ISO9277:2010 and is suitable for quantitative characterization of catalyst specific surface area. The reliability of the results can be ensured by repeated testing (parallel samples ≤3 times, relative deviation ≤5%).

[0111] Average particle size of the composite oxygen evolution catalyst: 5-10 mg of catalyst powder (concentration 0.1-1.0 mg / mL) was placed in a 50 mL centrifuge tube. 20 mL of ethanol was then added as the dispersion medium and ultrasonically dispersed at room temperature for at least 60 minutes. Finally, the particle size distribution of the catalyst sample was measured using a laser particle size analyzer.

[0112] The specific surface area and average particle size of the composite oxygen evolution catalysts obtained in the above examples and comparative examples were tested, and the test data and the chemical formula of the composite oxygen evolution catalysts are listed in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] The catalysts obtained in the above examples and comparative examples were prepared into catalyst ink for testing. In the electrolysis of water and oxygen evolution reaction in a three-electrode system, the Tafel slope of the composite oxygen evolution catalyst was obtained by testing in a 0.5 mol / L H2SO4 solution environment. The composite oxygen evolution catalyst reached 10 mA·cm in an acidic environment of pH = 0.3. -2 The overpotential η required for current density 10 ; Composite oxygen evolution catalyst at 1A·cm -2 When the stable operation time reaches 350h under the current density, the overpotential η 10 The test results are listed in Table 2.

[0117] Table 2

[0118] Examples / Comparative Examples Tafel slope (mV dec -1 )]]> Overshoot η 10 (mV) Overpotential η 10 Decay rate (μV·h -1 )]]> Example 1 55 260 36 Example 2 89 293 54 Example 3 74 292 50 Example 4 67 281 45 Example 5 58 263 39 Example 6 53 256 35 Example 7 77 281 39 Example 8 93 293 53 Example 9 65 280 43 Example 10 62 270 41 Example 11 69 285 46 Example 12 60 267 40 Example 13 72 289 48 Example 14 95 295 55 Comparative Example 1 102 315 60 Comparative Example 2 105 324 65 Comparative Example 3 53 280 35

[0119] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0120] The present application constructs a composite oxygen evolution catalyst with stable and efficient crystal structure framework by precisely controlling the synergistic proportion of each element. Specifically, from the perspective of ions, barium ions and iridium ions are bridged by oxygen ions to form a stable three-dimensional network structure. This structure can effectively maintain the integrity of the composite oxygen evolution catalyst lattice under harsh reaction conditions such as strong oxidation and high potential, and exhibits good structural stability. At the same time, it creates abundant active sites for the oxygen evolution reaction and provides a fast ion transport channel. The specific oxygen coordination environment around the iridium ion can effectively adjust its electronic structure, prompting the iridium ion to have appropriate adsorption and activation ability for the oxygen species generated in the catalytic reaction process, thereby greatly accelerating the oxygen evolution reaction process; from the perspective of electronic structure, the presence of barium ions can effectively regulate the electron cloud density and energy level distribution of iridium ions, prompting the formation of stronger interaction between the d-orbital electrons of iridium ions and the 2p-orbital electrons of oxygen species generated in the catalytic reaction process, significantly enhancing the adsorption and activation ability of oxygen species. This synergistic effect can also promote the rapid transmission of electrons within the catalyst, improving the electrical conductivity of the catalyst and further accelerating the kinetics of the oxygen evolution reaction; through the synergistic effect of the above two aspects, the composite oxygen evolution catalyst of the present application has optimized electron cloud distribution, lower oxygen evolution reaction overpotential and more active sites, accelerating the reaction kinetics, and by introducing barium and titanium, the amount of iridium doping is reduced, thereby solving the problems of low activity, poor stability and high preparation cost of the existing oxygen evolution catalyst. In addition, the catalyst of the present application has a structure-adjustable chemical adaptability, specifically, by adjusting the value of x, the activity, stability, cost and adaptability of the BaIr x Ti (1-x) O3 composite oxygen evolution catalyst can be optimized, providing a high-performance and economical catalytic material for the oxygen evolution reaction process such as water electrolysis to produce hydrogen.

[0121] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A composite oxygen evolution catalyst, characterized in that The chemical formula of the composite oxygen evolution catalyst is BaIr x Ti (1-x) O3, where 0.1≤x≤1.

2. The composite oxygen evolution catalyst according to claim 1, characterized in that 0.5≤x≤1, and / or, the composite oxygen evolution catalyst is selected from BaIr 0.18 Ti 0.82 O3、BaIr 0.35 Ti 0.65 O3、BaIr 0.5 Ti 0.5 O3、BaIr 0.55 Ti 0.45 O3、BaIr 0.58 Ti 0.42 O3、BaIr 0.6 Ti 0.4 O3、BaIr 0.63 Ti 0.37 O3、BaIr 0.66 Ti 0.34 O3、BaIr 0.7 Ti 0.3 O3、BaIr 0.77 Ti 0.23 O3、BaIr 0.8 Ti 0.2 O3、BaIr 0.89 Ti 0.11 O3、BaIr 0.9 Ti 0.1 Any one or more of O3 and BaIrO3.

3. The composite oxygen evolution catalyst according to claim 1 or 2, characterized in that The specific surface area of ​​the composite oxygen evolution catalyst is 30 to 50 m 2 / g; and / or the average particle size of the composite oxygen evolution catalyst is 20 to 200 nm.

4. The composite oxygen evolution catalyst according to any one of claims 1 to 3, characterized in that In the oxygen evolution reaction of water electrolysis in a three-electrode system, the Tafel slope of the composite oxygen evolution catalyst tested in a 0.5 mol / L H2SO4 solution environment was 53-95 mV·dec. -1 and / or the composite oxygen evolution catalyst reaches 10 mA cm in an acidic environment of pH = 0.3 -2 The overpotential η required for current density 10 is 256-295mV; and / or the composite oxygen evolution catalyst is at 1A·cm -2 When the stable operation time reaches 350h under the current density, the overpotential η 10 The decay rate is 35~55μV·h -1 .

5. A method for preparing the composite oxygen evolution catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Step S1, dispersing raw materials including an iridium source, a titanium source, a barium salt, and an organic polyacid in a mixed solvent of a polyol and water to obtain a mixed solution; Step S2, evaporating the solvent from the mixed solution and then calcining the mixed solution under air atmosphere to obtain a primary product; Step S3, protonating the primary product with an inorganic acid, and then washing and filtering the product in sequence to obtain the composite oxygen evolution catalyst.

6. The method for preparing the composite oxygen evolution catalyst according to claim 5, characterized in that: In step S1, the iridium source is an iridium-containing compound and / or a hydrate corresponding to the iridium-containing compound, and the iridium-containing compound is selected from any one or more of iridium trichloride, chloroiridic acid, potassium chloroiridate, sodium chloroiridate, ammonium chloroiridate, iridium acetate and iridium acetylacetonate; and / or, the barium salt is a barium-containing compound and / or a hydrate corresponding to the barium-containing compound, and the barium-containing compound is selected from any one or more of barium chloride, barium hydroxide and barium nitrate; and / or, the titanium source is isopropyl titanate.

7. The method for preparing the composite oxygen evolution catalyst according to claim 5 or 6, characterized in that: In step S1, the organic polyacid is selected from any one or more of citric acid, oxalic acid, tartaric acid, malic acid and succinic acid.

8. The method for preparing the composite oxygen evolution catalyst according to any one of claims 5 to 7, characterized in that: In step S1, the volume ratio of the polyol to the water is 1-3:2-2.5, and / or the polyol is selected from any one or more of ethylene glycol, propylene glycol, glycerol, polyethylene glycol 200, and polypropylene glycol 200.

9. The method for preparing the composite oxygen evolution catalyst according to any one of claims 5 to 8, characterized in that: In the step S2, the temperature of the solvent evaporation treatment is 90-150° C., and the time of the solvent evaporation treatment is 5-11 hours; and / or the temperature of the calcination is 450-800° C., and the time of the calcination is 2-8 hours.

10. The method for preparing the composite oxygen evolution catalyst according to any one of claims 5 to 9, characterized in that: In step S3, the inorganic acid is selected from any one or more of hydrochloric acid, sulfuric acid and glacial acetic acid; and / or the concentration of the inorganic acid is 0.5 to 1 mol / L.

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