A method for preparing an iridium oxide or doped iridium oxide catalyst and the catalyst

Abstract

This invention discloses a method for preparing iridium oxide or iridium oxide-doped catalysts and the catalyst itself. The method includes: S100, mixing a water-soluble iridium or iridium-ruthenium precursor with carbon powder, reducing to obtain an iridium-carbon or iridium-ruthenium-carbon precursor with a noble metal loading of 35-45 wt%; S200, filtering, washing, drying, and grinding to obtain precursor powder; S300, mixing the precursor powder with a water-soluble inorganic salt with a thermal decomposition temperature greater than 450℃; S400, heat-treating in air or oxygen at 350-420℃; S500, washing with water to remove the inorganic salt, thus obtaining a core-shell structured catalyst. In this invention, CO2 is generated by the combustion of carbon powder and localized exothermic reaction, while the inorganic salt provides physical isolation to prevent agglomeration. This allows for the acquisition of a core-shell structure with a metal core and an oxide shell at a relatively low temperature. This method effectively inhibits the agglomeration and sintering of catalyst particles, thereby obtaining a catalyst with high specific surface area and uniform dispersion.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, specifically to a method for preparing iridium oxide or doped iridium oxide catalysts and the catalyst itself. Background Technology

[0002] Electrolysis of water is one of the main methods for producing green hydrogen. Proton exchange membrane electrolysis is an important implementation method within this process. However, the oxygen evolution reaction at the anolyte is kineticly slow and operates in an acidic and high-potential environment, thus relying on noble metal catalysts, which is a key factor limiting hydrogen production efficiency. Currently, commercially available noble metal catalysts are mainly iridium-based catalysts, such as iridium oxide and doped iridium oxide.

[0003] The main methods for synthesizing this type of catalyst include the melt method (Adams process) and the impregnation-calcination method, both of which generally require high temperatures (usually above 400℃). At high temperatures, the catalyst is prone to sintering, reducing the number of active centers and decreasing the catalyst activity. Furthermore, since catalysts such as iridium oxide and ruthenium oxide are semiconductor oxides with poor conductivity, maintaining both catalyst activity and the conductivity of the metal is a challenge in their preparation.

[0004] Therefore, developing a method for preparing core-shell structured or doped iridium oxide catalysts with high specific surface area, high conductivity, and high catalytic activity at lower temperatures is of significant industrial value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as high heat treatment temperature, easy sintering of catalysts, and poor conductivity, and to provide a method for preparing iridium oxide or iridium oxide-doped catalysts, as well as the catalyst obtained by this method. This method employs a sacrificial template method, which can obtain a core-shell structured catalyst at a relatively low temperature, exhibiting both high conductivity and high catalytic activity.

[0006] To achieve the above objectives, the present invention provides a method for preparing iridium oxide or iridium oxide-doped catalysts, the method comprising the following steps: S100. The water-soluble iridium or iridium-ruthenium precursor solution and carbon powder are stirred and dispersed evenly in deionized water. Then, a reducing agent is added under stirring conditions to reduce the mixture and obtain a suspension. The total amount of carbon powder added is such that the noble metal loading in the final iridium-carbon or iridium-ruthenium-carbon precursor is 35-45 wt%. In this step, iridium (or iridium-ruthenium) metal nanoparticles are loaded onto the surface of carbon powder using a liquid-phase reduction method. The carbon powder serves as a sacrificial template and support for subsequent heat treatment. The amount of carbon powder added determines the degree of dispersion and particle size of the precious metal on the carbon surface. When the precious metal loading is too low (<35%), the gas generated by the conversion of carbon into carbon dioxide is too large, the catalyst is blown away by the gas flow, and the yield is low. Moreover, there is excessive local heat release, resulting in excessive emissions of the greenhouse gas carbon dioxide. When the precious metal loading is too high (>45%), the metal particles are prone to agglomeration, resulting in uneven core-shell structure in the subsequent process.

[0007] S200: The suspension obtained in step S100 is filtered, washed, dried and ground to obtain iridium carbon or iridium ruthenium carbon precursor powder; In this step, filtration and washing remove unreacted ions and byproducts, while drying and grinding yield a uniform, flowable powder that is easy to mix with inorganic salts later.

[0008] S300. Grind and mix the precursor powder obtained in step S200 with water-soluble inorganic salt to obtain a mixed powder, wherein the thermal decomposition temperature of the water-soluble inorganic salt is greater than 450°C. In this step, water-soluble inorganic salt serves as the second sacrificial template. Its thermal decomposition temperature is greater than 450℃, which means that the inorganic salt remains solid throughout the subsequent heat treatment process. It physically isolates adjacent iridium-carbon particles at the nanoscale, effectively preventing particle agglomeration and sintering during carbon combustion and metal conversion. At the same time, the inorganic salt acts as a uniform heat conduction medium, making the local temperature distribution more uniform.

[0009] S400. The mixed powder obtained in step S300 is heat-treated in an air or oxygen atmosphere and then naturally cooled to room temperature. In this step, in an air or oxygen atmosphere, the carbon powder gradually oxidizes and burns to generate CO2 gas, which escapes, generates local heat and forms pores. Since the heat treatment temperature is lower than the complete oxidation temperature of iridium (>450℃), the iridium nanoparticles only undergo partial surface oxidation, thus forming a core-shell structure of a metal core and an oxide shell.

[0010] S500: Thoroughly clean the material after heat treatment in step S400 with deionized water to remove water-soluble inorganic salts, then dry and grind to obtain the core-shell structured catalyst.

[0011] In this step, the complete removal of inorganic salts avoids interference from impurities with catalytic performance.

[0012] Furthermore, in step S100, the toner is a composite toner, composed of amorphous carbon and graphitized carbon mixed in a mass ratio of 1:3-5. Compared to single toner, this composite toner can more effectively achieve the gradient oxidation effect of "low-temperature ignition and pore formation, and high-temperature partial retention," reducing carbon residue and increasing specific surface area.

[0013] Further, in step S100, a reducing agent is added for reduction under stirring conditions at a temperature of 40-60℃, wherein the reducing agent is sodium borohydride or potassium borohydride. This temperature range is mild and does not damage the toner structure. Sodium / potassium borohydride is a strong reducing agent and can efficiently reduce Ir. 3+ / Ru 3+ It is reduced to a metallic state.

[0014] Furthermore, in step S100, the water-soluble iridium precursor is iridium chloride, and the water-soluble ruthenium precursor is ruthenium chloride. Chloride salts have high solubility in water, easily forming a homogeneous solution, and chloride ions are removed by water washing, having no adverse effect on subsequent reduction reactions.

[0015] Furthermore, in step S200, the drying temperature of the suspension is 80-100℃. This temperature range allows for rapid removal of moisture without causing significant oxidation or sintering of the metal nanoparticles in air.

[0016] Further, in step S300, the water-soluble inorganic salt is a binary composite inorganic salt, composed of sodium chloride and sodium sulfate in a mass ratio of 2-5:1, and the mass ratio of the water-soluble inorganic salt to the precursor powder is 1:15-25. Since sodium chloride is solid at the heat treatment temperature, it mainly serves as a physical barrier to prevent agglomeration; while sodium sulfate undergoes a crystal transformation during cooling, shrinking in volume by approximately 5-7%, thereby introducing microcracks or rough surfaces into the product, increasing electrolyte accessibility and specific surface area.

[0017] Further, in step S400, the heat treatment specifically involves heating to 350-420℃ at a heating rate of 5-20℃ / min and holding at that temperature for 50-120 minutes. Choosing a suitable heating rate avoids localized overheating. Simultaneously, below 350℃, carbon combustion is incomplete; above 420℃, iridium is completely oxidized and the particles sinter. The holding time ensures complete carbon combustion and oxidation; too short a time results in insufficient reaction, while too long a time increases energy consumption and may lead to complete oxidation without a metal core.

[0018] The present invention also provides an iridium oxide or doped iridium oxide catalyst prepared according to any of the above preparation methods. The catalyst prepared by the above methods has a unique core-shell structure, with metallic iridium or an iridium-ruthenium alloy as the core and iridium oxide or doped iridium oxide as the shell. This structure combines the high conductivity of the metal core and the high catalytic activity of the oxide shell, while also having a high specific surface area and a good lattice-matched interface, exhibiting low overpotential and high-quality activity in the acidic oxygen evolution reaction.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects: (1) In this invention, carbon powder is used as a sacrificial template. During the heat treatment process, the carbon powder is burned to generate CO2 gas that escapes. The local exothermic reaction is used to assist the oxidation of iridium or ruthenium, so that the heat treatment temperature can be as low as 350-420℃, which is much lower than the traditional method. This effectively inhibits the agglomeration and sintering of catalyst particles, thereby obtaining a catalyst with high specific surface area and uniform dispersion. At the same time, at this heat treatment temperature, only the surface of iridium nanoparticles or ruthenium nanoparticles is partially oxidized, thereby forming a core-shell structure with metallic iridium or iridium-ruthenium alloy as the core and iridium oxide or doped iridium oxide as the shell. The metallic core ensures good conductivity, and the oxide shell provides abundant catalytic active sites, thereby significantly improving the overall oxygen evolution reaction performance of the catalyst.

[0020] (2) The present invention uses water-soluble inorganic salt as the second sacrificial template. The water-soluble inorganic salt remains solid at the heat treatment temperature, which can physically isolate adjacent particles at the nanoscale, effectively preventing agglomeration during carbon combustion and metal oxidation, and making the product particle size uniform. At the same time, the inorganic salt can be completely removed by water washing without introducing impurities. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 A flowchart of a method for preparing an iridium oxide or doped iridium oxide catalyst according to the present invention is shown; Figure 2 The image shows a transmission electron microscope (TEM) image of the iridium oxide catalyst prepared in Example 1 of the present invention; Figure 3 The TEM image of the ruthenium-doped iridium oxide catalyst prepared in Example 2 of the present invention is shown. Figure 4 A TEM image of the catalyst prepared in Example 3 of the present invention is shown; Figure 5 A TEM image of the catalyst prepared in Example 4 of this invention is shown; Figure 6 A TEM image of the catalyst prepared in Comparative Example 1 of the present invention is shown; Figure 7 A TEM image of the catalyst prepared in Comparative Example 2 of the present invention is shown; Figure 8 A TEM image of the catalyst prepared in Comparative Example 3 of the present invention is shown; Figure 9A TEM image of the catalyst prepared in Comparative Example 4 of the present invention is shown; Figure 10 A TEM image of the catalyst prepared in Comparative Example 5 of the present invention is shown; Figure 11 A TEM image of the catalyst prepared in Comparative Example 6 of the present invention is shown; Figure 12 A TEM image of the catalyst prepared in Comparative Example 7 of the present invention is shown; Figure 13 A TEM image of the catalyst prepared in Comparative Example 8 of the present invention is shown; Figure 14 A TEM image of the catalyst prepared in Comparative Example 9 of the present invention is shown. Detailed Implementation

[0023] To make the objectives, technical solutions, and technical effects of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings, multiple embodiments, and comparative examples.

[0024] like Figure 1 As shown, the present invention provides a method for preparing iridium oxide or iridium oxide-doped catalyst, the method comprising steps S100 to S500, which have been described in detail in the summary of the invention section and will not be repeated here.

[0025] The technical solution of the present invention is verified below through Examples 1-4 and Comparative Examples 1-9. Unless otherwise specified, the following basic parameters are used: iridium chloride concentration 0.05 mol / L, sodium borohydride concentration 2.5 mol / L, reduction temperature 40℃, reduction time 2h, drying temperature 100℃, heat treatment heating rate 5℃ / min, holding temperature 350℃, holding time 120min, and precursor powder to inorganic salt mass ratio 1:20. Examples 2-4 are adjusted accordingly based on the basic parameters.

[0026] Example 1 This embodiment provides a method for preparing iridium oxide or iridium oxide-doped catalysts, specifically including the following steps: S100. Place 100 mL of iridium chloride solution in a beaker, add 0.96 g of carbon black (Vulcan XC-72R, single graphitized carbon), and disperse ultrasonically; then add 20 mL of sodium borohydride solution dropwise in a 40℃ water bath, stir and reduce for 2 h to obtain a suspension. The noble metal loading was found to be 40 wt%. S200, filter, wash, dry at 100℃, grind to obtain iridium carbon precursor powder; S300. Grind and mix 2g of iridium-carbon precursor powder with 40g of sodium chloride (NaCl); S400: In air atmosphere, heat to 350℃ at 5℃ / min, hold for 120min, and then cool naturally to room temperature; After washing with S500 and deionized water four times, the catalyst with a core-shell structure can be obtained by drying and grinding.

[0027] Example 2 The difference from Example 1 is that in step S300, the inorganic salt is a binary composite inorganic salt, composed of NaCl and Na2SO4 in a mass ratio of 3:1, and the amount used is still 40g, and the rest is the same as in Example 1.

[0028] Example 3 The difference from Example 1 is as follows: In step S100, the toner is a composite toner, which is composed of amorphous carbon (Regal 400) and graphitized carbon (Vulcan XC-72R) mixed in a mass ratio of 1:4, with a total mass of 0.96g. The rest is the same as in Example 1.

[0029] Example 4 The difference from Example 1 is as follows: In step S100, the toner used is composite toner (amorphous carbon: graphitized carbon = 1:4), with a total mass of 0.96g; In step S300, the inorganic salt used is a binary composite inorganic salt (NaCl:Na2SO4=3:1), and the amount used is 40g; The rest is the same as in Example 1.

[0030] Example 5 The difference from Example 1 is as follows: In step S100, the amount of toner added was adjusted to 1.14 grams, and the water bath temperature was set to 50°C. Testing revealed that the noble metal loading in the precursor was 35 wt%. In step S200, the drying temperature is set to 80°C; In step S300, the mass of sodium chloride is adjusted to 30g; In step S400, the temperature is increased to 350℃ at a rate of 12℃ / min and held for 50 minutes; It is the same as in Example 1.

[0031] Example 6 The difference from Example 1 is as follows: In step S100, the amount of toner added was adjusted to 0.85 grams, and the water bath temperature was set to 60°C. Testing revealed that the noble metal loading in the precursor was 45 wt%. In step S200, the drying temperature is set to 100℃; In step S300, the mass of sodium chloride is adjusted to 50g; In step S400, the temperature is increased to 420℃ at a rate of 20℃ / min and held for 120min; The rest is the same as in Example 1.

[0032] Comparative Example 1 In step S100, no toner is added; otherwise, it is the same as in Example 1.

[0033] Comparative Example 2 In step S300, no inorganic salt is added; otherwise, it is the same as in Example 1.

[0034] Comparative Example 3 In step S100, the amount of toner was increased to 6.0g. After testing, the noble metal loading in the precursor was 15%, and the rest was the same as in Example 1.

[0035] Comparative Example 4 In step S100, the amount of toner was reduced to 0.5g. After testing, the noble metal loading in the precursor was 70%, and the rest was the same as in Example 1.

[0036] Comparative Example 5 In step S400, the heat treatment holding temperature is 300℃, and the rest is the same as in Example 1.

[0037] Comparative Example 6 In step S400, the heat treatment holding temperature is 500℃, and the rest is the same as in Example 1.

[0038] Comparative Example 7 Iridium oxide was prepared using the typical Adams process: 0.3 g iridium trichloride, 1.2 g sodium nitrate, and 10 g sodium citrate were dissolved in 20 ml of deionized water at 85 °C, stirred and dried to a sol state, and dried at 120 °C to obtain precursor powder. After grinding, the powder was calcined at 450 °C for 1 hour, washed, and dried.

[0039] Comparative Example 8 The difference from Example 2 is that the ratio of NaCl to Na2SO4 in the binary composite inorganic salt is 1:1.

[0040] Comparative Example 9 The difference from Example 3 is that the ratio of amorphous carbon to graphitized carbon in the composite toner is 1:1.

[0041] To verify the effectiveness and inventiveness of the technical solution of this invention, performance tests were conducted on the catalysts prepared in Examples 1-4 and Comparative Examples 1-9. The test results are shown in Table 1 and... Figures 2-14 As shown.

[0042]

[0043] As shown in Table 1, the catalysts prepared in Examples 1-6 all had overpotentials ≤320mV and mass activities ≥1.05A / mg, while the catalyst prepared in Comparative Example 7 had an overpotential as high as 365mV and a mass activity of only 0.6A / mg. Therefore, the sacrificial template method (Examples 1-6) provided by this invention can successfully prepare iridium oxide or doped iridium oxide catalysts with core-shell structures at a relatively low temperature of 350-420℃. Compared with the traditional Adams method (Comparative Example 7), the overpotential and mass activity of the products are significantly improved, which proves the advanced nature of the technical solution of this invention.

[0044] As shown in Table 1, the product of Comparative Example 1 (without carbon template) is a large agglomerate with a BET of only 15 m² / g and an overpotential as high as 450 mV; the product of Comparative Example 2 (without inorganic salt template) is severely sintered with a BET of only 40 m² / g. This indicates that carbon powder and inorganic salt are indispensable as dual sacrificial templates. Carbon powder creates pores and provides local heat during combustion, while inorganic salt provides physical isolation to prevent agglomeration. Only through their synergy can a core-shell structure catalyst with high specific surface area and uniform dispersion be obtained.

[0045] As shown in Table 1, when the precious metal loading is below 35% (e.g., Comparative Example 3), the BET is only 60 m² / g, and the overpotential is 370 mV; when the precious metal loading is above 45% (e.g., Comparative Example 4), the BET is only 45 m² / g, and the overpotential is 385 mV. However, in Examples 1-6 (precious metal loading between 35-45%) within the scope of this invention, the BET is ≥88 m² / g, and the overpotential is ≤340 mV. In particular, Examples 5 (35% loading) and 6 (45% loading) respectively verified the feasibility of the lower and upper limits, and their performance (overpotentials of 335 mV and 340 mV, respectively) is still significantly better than Comparative Example 3 and Comparative Example 4. This proves that a precious metal loading of 35-45 wt% is the key critical range for obtaining excellent performance.

[0046] As shown in Table 1, when the heat treatment temperature is below 350℃ (Comparative Example 5), the carbon powder burns incompletely, and carbon residue leads to experimental failure; when the temperature is above 420℃ (Comparative Example 6), the catalyst sintersulates, and the overpotential rises to 365mV. However, Examples 1-6 within the scope of this invention (heat treatment temperature controlled between 350-420℃) all successfully obtained pure core-shell structured catalysts. In particular, Examples 5 (350℃) and 6 (420℃) respectively verified the feasibility of the lower and upper limits, proving that 350-420℃ is the critical temperature window of this invention.

[0047] As shown in Table 1, compared with Example 1, Example 3 replaced single graphitized carbon with composite carbon powder (amorphous carbon: graphitized carbon = 1:4). Under the same inorganic salt (single NaCl) conditions, the BET increased from 105 m² / g to 130 m² / g, representing a 24% improvement in BET performance; the overpotential decreased from 320 mV to 300 mV, a reduction of 20 mV. This is because amorphous carbon preferentially burns to create pores and provides localized auxiliary heating, while graphitized carbon is partially retained as a conductive framework. The two work synergistically to achieve a gradient oxidation effect of "low-temperature ignition and pore creation, high-temperature partial retention".

[0048] As shown in Table 1, compared with Example 1, Example 2 replaced single NaCl with a binary composite inorganic salt (NaCl:Na2SO4 = 3:1). Under the same carbon powder (single graphitized carbon) conditions, the BET increased from 105 m² / g to 125 m² / g, representing a 19% improvement in BET performance. The overpotential decreased from 320 mV to 305 mV, a reduction of 15 mV. This is because the crystal transformation of Na2SO4 during cooling generates microcracks or a rough surface, increasing electrolyte accessibility and specific surface area.

[0049] As shown in Table 1, Example 4, which uses both composite carbon powder and binary composite inorganic salt, achieves a BET of 145 m² / g, an overpotential as low as 285 mV, and a mass activity as high as 1.52 A / mg. Its performance surpasses the simple superposition of Example 2 (binary composite inorganic salt only) and Example 3 (composite carbon powder only). This demonstrates a significant synergistic effect between composite carbon powder and binary salt. The gradient oxidation of composite carbon powder provides an ideal precursor morphology for the core-shell structure, while the phase change pore formation of the binary composite inorganic salt further increases the specific surface area. Both work together to improve the catalyst's microstructure and electrochemical performance.

[0050] As shown in Table 1, in Comparative Example 8, the ratio of the binary composite inorganic salt deviated from the range of the present invention by 2-5:1, resulting in a BET of the prepared catalyst decreasing to 100 m² / g and an overpotential increasing to 335 mV. In Comparative Example 9, the ratio of the composite carbon powder deviated from the range of the present invention by 1:3-5, resulting in a carbon residue of 8% and an overpotential increasing to 345 mV. Examples 2-4, within the range of the present invention, all showed significantly better performance than Comparative Examples 8-9. This demonstrates that a composite carbon powder ratio of 1:3-5 and a binary salt ratio of 2-5:1 have a criticality and are key to achieving optimal performance.

[0051] In summary, this invention utilizes the synergistic effect of carbon powder and water-soluble inorganic salt as dual templates to successfully prepare iridium oxide or doped iridium oxide catalysts with a core-shell structure of a metal core and an oxide shell at relatively low temperatures (350-420℃). This method is simple and inexpensive, and the resulting catalysts exhibit both high conductivity and high catalytic activity, demonstrating excellent electrochemical performance (overpotential ≤320mV, mass activity ≥1.05A / mg) in the acidic water electrolysis oxygen evolution reaction. In particular, the catalyst prepared using composite carbon powder (amorphous carbon: graphitized carbon = 1:3-5) and binary composite inorganic salt (NaCl:Na2SO4 = 2-5:1) exhibits the best performance, with an overpotential as low as 285mV and a mass activity as high as 1.52A / mg. Therefore, the preparation method provided by this invention has good industrial application value.

[0052] The preparation method of iridium oxide or iridium oxide-doped catalyst and the catalyst provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for preparing iridium oxide or iridium oxide-doped catalyst, characterized in that, Includes the following steps: S100. The water-soluble iridium or iridium-ruthenium precursor solution and carbon powder are stirred and dispersed evenly in deionized water. Then, a reducing agent is added under stirring conditions to reduce the mixture and obtain a suspension. The total amount of carbon powder added is such that the noble metal loading in the final iridium-carbon or iridium-ruthenium-carbon precursor is 35-45 wt%. S200: The suspension obtained in step S100 is filtered, washed, dried and ground to obtain iridium carbon or iridium ruthenium carbon precursor powder. S300. Grind and mix the precursor powder obtained in step S200 with water-soluble inorganic salt to obtain a mixed powder, wherein the thermal decomposition temperature of the water-soluble inorganic salt is greater than 450°C. S400. The mixed powder obtained in step S300 is heat-treated in an air or oxygen atmosphere and then naturally cooled to room temperature. S500: Thoroughly clean the material after heat treatment in step S500 with deionized water to remove water-soluble inorganic salts, then dry and grind to obtain the core-shell structured catalyst.

2. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S100, the toner is a composite toner, which is composed of amorphous carbon and graphitized carbon mixed in a mass ratio of 1:3-5.

3. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S100, a reducing agent is added for reduction under stirring conditions at a temperature of 40-60℃, wherein the reducing agent is sodium borohydride or potassium borohydride.

4. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S100, the water-soluble iridium precursor is iridium chloride, and the water-soluble ruthenium precursor is ruthenium chloride.

5. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S200, the drying temperature of the suspension is 80-100℃.

6. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S300, the water-soluble inorganic salt is a binary composite inorganic salt composed of sodium chloride and sodium sulfate in a mass ratio of 2-5:1, and the mass ratio of the water-soluble inorganic salt to the precursor powder is 1:15-25.

7. The method for preparing iridium oxide or doped iridium oxide catalyst according to claim 1, characterized in that, In step S400, the heat treatment specifically involves heating to 350-420℃ at a heating rate of 5-20℃ / min and holding at that temperature for 50-120 minutes.

8. An iridium oxide or doped iridium oxide catalyst prepared by the preparation method according to any one of claims 1-7.

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