Preparation process of high-efficiency stable iridium oxide electrocatalyst

Abstract

The application discloses a preparation process of a high-efficiency stable iridium oxide electrocatalyst and relates to the technical field of iridium oxide-based catalyst preparation. 3+ The application comprises the following steps: preparing a copper salt solution A; preparing an alkaline solution B, which contains hydroxyl groups and carbonate groups; preparing an anionic surfactant solution C; preparing an Ir 3+ salt solution D; adding porous carbon material with a layered structure as a template agent into the solution A, and ultrasonic dispersion is performed to form a uniform suspension; under the condition of a constant-temperature water bath, the solution B is added into the suspension of the solution A drop by drop, and is subjected to mixing, incubation reaction, suction filtration separation and pure water washing; the obtained black solid is immersed in the solution C, and is subjected to normal-temperature stirring and suction filtration separation; the obtained solid after suction filtration is immersed in the solution D, and is subjected to water bath reaction, suction filtration separation and pure water washing; the obtained solid is subjected to heat treatment under an air atmosphere, so as to prepare an iridium-copper nanonet catalyst with a three-dimensional network structure.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of iridium oxide-based catalyst preparation, in particular to a preparation process of a high-efficiency stable iridium oxide electrocatalyst. BACKGROUND

[0002] With the economic development and social progress, fossil energy is consumed and utilized in large quantities, and the accompanying environmental problems are becoming increasingly serious. In order to build a sustainable social environment, the development and utilization of green renewable energy has become a universal consensus. Among the current clean energy, hydrogen (H2) is considered to be the most potential energy carrier and the key element of the future sustainable energy system due to its high energy density, green and clean, and abundant element reserves. However, as a secondary energy, H2 cannot be directly obtained from nature. At present, the mainstream way to obtain H2 is still through the reforming of fossil energy, which still cannot reduce the use of fossil energy from the root. The water electrolysis hydrogen production technology can directly decompose water into H2 and O2 by using electric energy, and the required electric energy can be provided by intermittent green energy (such as solar energy, wind energy, tidal energy, etc.). This technology route of water electrolysis hydrogen production avoids the use of fossil energy and the emission of greenhouse gases throughout the process, and is an ideal green hydrogen production technology.

[0003] The water electrolysis process is accompanied by the occurrence of two electrode half-reactions, namely the cathode hydrogen evolution reaction and the anode oxygen evolution reaction. The ideal catalyst for the cathode hydrogen evolution reaction (HER) in water electrolysis is platinum (Pt), which has negligible overpotential in acidic conditions, but the catalytic activity in alkaline environment still has a large space for improvement. The anode oxygen evolution reaction (OER) is limited by the problems of high energy consumption, slow reaction kinetics, high cost of electrocatalysts, etc., which restricts the further development of water electrolysis hydrogen production. The ideal catalyst for the oxygen evolution reaction is iridium oxide (IrO2) or ruthenium oxide (RuO2), among which although RuO2 has more active advantages, IrO2 has higher stability under acidic high potential conditions, making it the best choice for anode catalysts in acidic commercial devices (such as proton exchange membrane (PEM) electrolysis cells). However, since Ir is one of the most rare elements, the high price and scarce production have become a bottleneck for its large-scale application, therefore, how to reasonably design high-efficiency and stable Ir-based catalysts has significant meaning for the development and promotion of green hydrogen energy.

[0004] At present, there are five main preparation routes for Ir-based catalysts, and the specific routes and advantages and disadvantages are as follows:

[0005] (1) Precipitation method: For example, the invention patent application with the title of "Preparation method of proton exchange membrane water electrolysis oxygen evolution catalyst" with the publication number CN116926614A, in the process of preparing iridium oxide catalyst, takes iridium chloride, chloroiridic acid, etc. as precursor, adopts carbonate or oxalate as coprecipitation agent, after reacting for several hours at 30-95℃, adds acidic substance to control the pH value of the solution to 7-10, then sequentially carries out heating concentration and washing and drying, finally calcines the obtained powder at 300-600℃ to prepare oxygen evolution catalyst iridium oxide;

[0006] This method is simple and easy to operate in preparation process, and one or more transition metals can be introduced in the preparation process, which can effectively reduce the load of noble metal iridium and save cost, but the generated precursor precipitate particles are relatively large, and the catalyst morphology particle size is not easy to control;

[0007] (2) Mechanical chemical method: For example, the invention patent application with the title of "Ruthenium monatomic doped metastable iridium oxide catalyst and its preparation method and application" with the publication number CN116695140A, which discloses mixing and grinding lithium carbonate, iridium powder and ruthenium powder with a certain mass ratio, heat treating at 900-1000℃ for 20-24h in air atmosphere, and obtaining the precursor product, lithium intercalated iridium oxide containing ruthenium, after natural cooling to room temperature, then pouring the precursor product into dilute sulfuric acid and stirring at 25-30℃ for 5-8h, centrifuging, ultrasonic washing, vacuum drying and grinding to obtain iridium oxide catalyst;

[0008] This method generally adopts ball milling method for catalyst preparation, and the preparation process is relatively simple and can be prepared in batches, but the uniformity of doped ions is lower than that of liquid phase reaction, and the preparation process needs high temperature heat treatment above 900℃, which requires high equipment and large energy consumption;

[0009] (3) Sol-gel method: For example, the invention patent application with the title of "Vanadium doped iridium dioxide electrocatalyst and its preparation method and application" with the publication number CN114921808A, which discloses first adding iridium chloride and vanadium chloride into pure water in a molar ratio of 3:1 to form a uniform aqueous solution, then adding citric acid and ethylene glycol, and stirring at 100-150℃ until gel microbubbles are formed. Then transfer to a muffle furnace and heat decompose at 300-700℃, finally obtain powder-like vanadium doped iridium oxide catalyst;

[0010] This method adopts complexation of complex and metal ions, and further pyrolysis to obtain the target product, and the obtained catalyst has high activity, but there may be metal ion migration problem in the process of sol-gel thermal decomposition, and the catalyst morphology is not easy to control;

[0011] (4) Molten salt method: For example, the invention patent application with the title of "Metastable phase porous iridium oxide catalyst, preparation method and application in proton exchange membrane water electrolysis technology" with the publication number CN116377481A, which is to use hydroxide as a molten salt, cetyltrimethylammonium bromide as a morphology directing agent, and iridium trichloride as an iridium source. The three raw materials are dissolved in water to obtain a uniform solution, then the solution is transferred to an oven for drying at 140-160℃ for 5-20h, the obtained precursor is transferred to a muffle furnace for programmed temperature calcination, and after cooling to room temperature, further washing and drying are carried out to obtain porous iridium oxide;

[0012] The molten salt method can controllably synthesize metastable phase porous iridium oxide catalyst, which is beneficial to improve the intrinsic activity and catalytic stability of the iridium oxide catalyst. However, strong alkaline and highly toxic substances such as sodium hydroxide and cetyltrimethylammonium bromide are used in the preparation process, and the preparation process is complex, which is not conducive to batch production of the catalyst;

[0013] (5) Microemulsion method: For example, the invention patent with the title of "Method for preparing platinum-iridium-ruthenium composite nanoparticles by microemulsion method" with the publication number CN109382097B, which is to add cetyltrimethylammonium bromide to toluene under vigorous stirring to obtain a milky white suspension, then add the precursor solution of H2PtCl6 to the suspension and stir overnight to obtain an orange yellow solution. Then add a mixed precursor solution containing RuCl3 and IrCl3 to the orange yellow solution and stir, then add alkali solution to the above reaction mixture under stirring to obtain a black microemulsion, which is centrifuged and washed with solvent to remove the surfactant, and dried overnight to obtain an iridium oxide catalyst.

[0014] The microemulsion method uses microemulsion to prepare nanoparticles, which has low energy consumption, simple operation, can effectively control the distribution of active components, simple process, and is conducive to industrialized batch production. However, the product contains many impurities due to the use of many kinds of additives in large quantities, and the product physical properties will be affected if the impurities cannot be removed by washing, which requires a higher post-treatment process.

[0015] In summary, in the existing technical routes, the preparation methods such as precipitation method are simple and easy to operate, but it is difficult to effectively control the catalyst morphology size. Although the molten salt method and the microemulsion method can effectively improve the catalytic activity, the process is complex and requires high equipment, which is not conducive to large-scale production. Therefore, there is an urgent need for a preparation process of high-efficiency and stable iridium oxide electrocatalyst to solve this problem. SUMMARY

[0016] The purpose of the present application is to provide a preparation process of high-efficiency and stable iridium oxide electrocatalyst to solve the problems mentioned in the background art.

[0017] To achieve the above object, the application provides the following technical scheme: a preparation process of high-efficiency stable iridium oxide electrocatalyst, comprising the following specific steps:

[0018] S1: four solutions are prepared, and the sequence is not distinguished in advance:

[0019] A copper salt solution is prepared, which is recorded as solution A, the solvent is pure water, and the solute is a divalent inorganic copper salt dissolved in water;

[0020] A basic solution is prepared, which is recorded as solution B, the solvent is pure water, and the solution B contains hydroxyl and carbonate at the same time, and is used to obtain basic copper carbonate after reacting with the solution A;

[0021] A surfactant emulsion is prepared, which is recorded as solution C, the solvent is pure water, and the surfactant is an anionic surfactant;

[0022] An iridium oxide precursor salt is prepared, which is recorded as solution D, the solvent is pure water, and the solute is an iridium salt dissolved in water and capable of hydrolyzing Ir 3+ ;

[0023] S2: the porous carbon material with a layered structure is added to the solution A as a template agent, and ultrasonic dispersion is performed to form a uniform suspension;

[0024] S3: the solution B is added dropwise to the suspension of the solution A under the condition of constant temperature water bath, and after mixing, heat preservation reaction is performed to obtain a basic copper carbonate carrier with a layered distribution, and after reaction, filtration separation is performed, and pure water is used for washing to remove excess impurity ions;

[0025] S4: the black solid obtained in S3 is immersed in the solution C, and stirring is performed at room temperature for a period of time to form negative charges on the surface of the carrier, and after stirring, filtration separation is performed;

[0026] S5: the solid obtained by filtration in S4 is immersed in the solution D, and water bath reaction is performed for a period of time to load iridium on the surface of the carrier, and after filtration separation, pure water is used for washing to remove excess impurity ions;

[0027] S6: the solid obtained in S5 is heat treated under an air atmosphere to decompose the basic copper carbonate to form holes, and an iridium-copper nanonet catalyst with a three-dimensional network structure is prepared.

[0028] Preferably, in the above step S3, the water bath temperature is 30-80 DEG C, the flow rate of the solution B added dropwise is 1-10 mL / min, and heat preservation is performed for 2-6 h until the reaction is sufficient.

[0029] Preferably, in the above step S4, magnetic stirring is adopted, the stirring speed is 300-600 r / min, and the stirring time is 4-10 h until the mixture is uniform.

[0030] Preferably, in the above step S5, the water bath temperature is 60-80 DEG C, and the reaction time is 1-3 h.

[0031] Preferably, in the step S6, the heat treatment is performed in a muffle furnace, the heat treatment temperature is 300-800℃, the heat treatment time is 4h, and the heating rate is 5℃ / min.

[0032] Preferably, in the step S1, the concentration of copper ions in the solution A is 0.05-0.5 mol / L; the solute of the solution B includes ammonia and carbonate, the concentration of ammonia in the solution B is 1-10%, and the concentration of carbonate is 0.1-1 mol / L; the concentration of the surfactant in the solution C is 0.01-0.1 mol / L; and the concentration of iridium in the solution D is 0.01-0.1 mol / L.

[0033] Optionally, the copper salt is selected from copper chloride, copper sulfate and copper acetate; the carbonate is selected from sodium carbonate, potassium carbonate and ammonium carbonate; the surfactant is selected from dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate and sodium fatty alcohol ether sulfate; and the iridium salt is selected from iridium trichloride, hydrated iridium trichloride and chloroiridic acid.

[0034] Preferably, in the step S2, the porous carbon material is activated carbon, graphite carbon or graphene, and the mass fraction of the porous carbon material in the suspension is 0.1-1%.

[0035] Another technical solution provided by the application is an iridium oxide electrocatalyst prepared by the above preparation process, which is an iridium-copper nanonet catalyst with a three-dimensional network structure, and has a specific surface area greater than 180 m 2 / g, preferably 200-250 m 2 / g; a pore volume not less than 0.15 cm 3 / g, preferably 0.15-0.2 cm 3 / g.

[0036] Preferably, the OER polarization curve test is performed by using a three-electrode system, the reference electrode is an Ag / AgCl electrode, the counter electrode is a graphite rod electrode, the working electrode is a glassy carbon electrode coated with the catalyst prepared by the application, the loading amount of the catalyst is 0.25 mg / cm 2 , and the electrolyte solution is a 0.5 mol / L sulfuric acid aqueous solution; when the current density reaches 10 mA / cm 2 , the oxygen evolution overpotential is not more than 285 mV.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] 1、The preparation process of the high-efficiency stable iridium oxide electrocatalyst uses inexpensive and easily available porous carbon with a layered structure as a template agent to prepare the precursor of the catalyst carrier, basic copper carbonate. The template agent can promote the growth of basic copper carbonate crystals on its surface, tending to form a layered structure. The porous carbon material with a layered structure can play a role in steric hindrance, preventing the crystal nuclei of basic copper carbonate from contacting each other too much and avoiding their contact and agglomeration to form larger particle sizes. Subsequent heat treatment can decompose the basic copper carbonate, and a large amount of H2O and CO2 will escape in the form of gas to form a large number of pores on the surface of the basic copper carbonate, thereby promoting the copper precursor to finally form a three-dimensional network structure without the need for additional introduction of a new pore-forming agent. The three-dimensional network structure can effectively enhance the stability of the catalyst.

[0039] 2、The preparation process of the high-efficiency stable iridium oxide electrocatalyst introduces an anionic surfactant after obtaining the basic copper carbonate. The surfactant can form a negative charge on the surface of the basic copper carbonate. After the addition of an Ir 3+ solution, the Ir 3+ can be effectively loaded on the surface of the basic copper carbonate through simple charge adsorption without obvious agglomeration, which can effectively enhance the catalytic activity.

[0040] 3、The preparation process of the high-efficiency stable iridium oxide electrocatalyst has a simple catalyst preparation process, no special equipment requirements, a small amount of added Ir, low cost, and a high electrocatalytic oxygen evolution activity of the prepared iridium-copper nanometer network catalyst with a three-dimensional network structure, which is suitable for industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A scanning electron microscope (SEM) image of the sample IrO2-1 prepared in Example 1;

[0042] Figure 2 A comparison chart of electrocatalytic oxygen evolution reaction polarization curves of the samples prepared in the example and the comparative example. DETAILED DESCRIPTION

[0043] A preparation process of a high-efficiency stable iridium oxide electrocatalyst, comprising the following specific steps:

[0044] S1 Four solutions are prepared in any order:

[0045] A copper salt solution is prepared, denoted as solution A, with pure water as the solvent and a divalent inorganic copper salt dissolved in water as the solute;

[0046] An alkaline solution is prepared, denoted as solution B, with pure water as the solvent. Solution B contains both hydroxyl and carbonate ions and is used to obtain basic copper carbonate after reacting with solution A;

[0047] Prepare a surfactant emulsion, denoted as solution C, with pure water as solvent and an anionic surfactant as the surfactant;

[0048] Prepare an iridium oxide precursor salt, denoted as solution D, with pure water as solvent and an iridium salt dissolved in water that can be hydrolyzed to generate Ir 3+ ;

[0049] S2: Add a porous carbon material with a layered structure as a template agent to solution A, and ultrasonically disperse it to form a uniform suspension; for reference, the porous carbon material can be activated carbon, graphite carbon, or graphene, and the mass fraction of the porous carbon material in the suspension can be 0.1-1%; the range given here is only a reference range that can be implemented, and the specific selection can be adjusted. The purpose of this step is to add a template agent to solution A to promote the growth of basic copper carbonate crystals on its surface, tending to form a layered structure. The porous carbon material with a layered structure can have a steric hindrance effect, preventing the crystal nuclei of basic copper carbonate from contacting each other too much, avoiding their contact and agglomeration to form larger particle sizes. For reference, if carbon nanotubes are used, the effect is not good, and they cannot have a steric hindrance effect. The basic copper carbonate crystals will still grow too large;

[0050] S3: Under constant temperature water bath conditions, add solution B dropwise to the suspension of solution A, and after mixing, perform a heat preservation reaction to obtain a basic copper carbonate carrier with a layered distribution. After the reaction, perform suction filtration separation and wash with pure water to remove excess impurity ions; the specific water bath temperature, solution B dropwise flow rate, and heat preservation reaction time can be adjusted according to the purpose of obtaining the basic copper carbonate carrier; for reference, the water bath temperature can be 30-80°C, the solution B dropwise flow rate can be 1-10 mL / min, and the heat preservation time can be 2-6 h until the reaction is complete. However, these are only reference optimal conditions, and the desired product can also be obtained under other conditions that are not significantly different, such as a 25°C water bath, a 0.8 mL / min flow rate, and 8 h of heat preservation.

[0051] S4: Dip the black solid obtained in S3 in solution C, and stir at room temperature for a period of time to form a negative charge on the surface of the carrier, and then perform suction filtration separation after stirring; specifically, the main purpose of stirring is to mix well, but the layered structure of the carrier should not be destroyed. Generally, stirring should be below 3000 r / min, and preferably, a magnetic stirrer can be used at a speed of 300-600 r / min for 4-10 h until the mixture is uniform. Of course, these are only reference optimal conditions, and the desired product can also be obtained under other conditions that are not significantly different, such as a 1000 r / min electric stirrer, a stirring paddle, and 3 h of stirring.

[0052] S5: The solid obtained by S4 is immersed in solution D, and the iridium is loaded on the surface of the carrier by water bath reaction for a period of time. After separation by suction filtration, the solid is washed with pure water to remove excess impurity ions. The purpose of this step is to load iridium. The water bath temperature can be controlled at 60-80℃, and the reaction time can be controlled at 1-3h for reference. It is foreseeable that the product of the present application can also be obtained within a range close to the reference range, and there may be differences in performance, yield, etc.

[0053] S6: The solid obtained by S5 is heat treated in an air atmosphere to decompose the basic copper carbonate to form pores, thereby preparing an iridium-copper nanonet catalyst with a three-dimensional network structure. The heat treatment can be carried out using a muffle furnace, etc. For reference, the heat treatment temperature is 300-800℃, the heat treatment time is 4h, and the heating rate is 5℃ / min. It can be understood that the purpose of heat treatment is only to decompose the basic copper carbonate to release gaseous water and carbon dioxide, and the initial decomposition temperature of the basic copper carbonate is 220℃. Therefore, the specific temperature, time, and heating rate can also be adjusted. The values given here are only reference values that can be implemented and should not be considered as absolute limits, such as 3℃ / min to 280℃ for 8h.

[0054] In a more preferred embodiment, in step S1:

[0055] The concentration of copper ions in solution A is 0.05-0.5 mol / L. Further optionally, the copper salt used can be selected from copper chloride, copper sulfate, copper acetate, etc.

[0056] The solutes of solution B include ammonia and carbonate. The concentration of ammonia in solution B is 1-10%, and the concentration of carbonate is 0.1-1 mol / L. Further optionally, the carbonate used can be selected from sodium carbonate, potassium carbonate, ammonium carbonate, etc.

[0057] The concentration of surfactant in solution C is 0.01-0.1 mol / L. Further optionally, the surfactant used can be selected from dodecylbenzenesulfonic acid, sodium dodecylbenzenesulfonate, sodium fatty alcohol ether sulfate, etc.

[0058] The concentration of iridium in solution D is 0.01-0.1 mol / L. Further optionally, the iridium salt used can be selected from iridium trichloride, hydrated iridium trichloride, or chloroiridic acid (such as iridium nitrate and iridium sulfate, which are rarely seen on the market).

[0059] The iridium oxide electrocatalyst prepared by the above preparation process is an iridium-copper nanonet catalyst with a three-dimensional network structure, which has a specific surface area greater than 180 m 2 / g and a pore volume not less than 0.15 cm 3 / g, and if the above preferred parameter conditions are used, the specific surface area can be controlled in the range of 200-250 m 2 / g; and the pore volume is generally 0.15-0.2 cm 3 / g.

[0060] In addition, the OER polarization curve test is carried out by using a three-electrode system, the reference electrode is an Ag / AgCl electrode, the counter electrode is a graphite rod electrode, the working electrode is an iridium-copper nanometer network catalyst coated glassy carbon electrode, the loading amount of the catalyst is 0.25 mg / cm 2 , and the electrolyte solution is a 0.5 mol / L sulfuric acid aqueous solution; when the current density reaches 10 mA / cm 2 , the oxygen evolution overpotential is not more than 285 mV.

[0061] Example 1:

[0062] 2.1 g of copper chloride is dissolved in 200 mL of pure water, denoted as solution A. 4.2 g of sodium carbonate is dissolved in 200 mL of pure water, and 2% ammonia water is added, denoted as solution B. 1.9 g of dodecylbenzenesulfonic acid is dissolved in 300 mL of pure water, denoted as solution C. 0.6 g of iridium trichloride is dissolved in 100 mL of pure water, denoted as solution D. First, 0.6 g of activated carbon is added to solution A, and ultrasonic dispersion is used to form a uniform suspension. Then, solution B is added dropwise to solution A under constant temperature water bath conditions, the dropwise addition rate is 2 mL / min, the water bath temperature is 30°C, and after mixing, it is kept for 2 h, and then it is separated by suction filtration and washed with pure water to remove excess impurity ions. Next, the black solid obtained is immersed in solution C, stirred at room temperature for 4 h, and then separated by suction filtration. The solid obtained by suction filtration is immersed in solution D, and the reaction is carried out at a water bath temperature of 60°C for 1 h. After the reaction is completed, it is separated by suction filtration, and then it is washed with pure water to remove excess impurity ions. Finally, the obtained solid is transferred to a muffle furnace, and high-temperature heat treatment is carried out in an air atmosphere for 4 h, the heat treatment temperature is 300°C, and the heating rate is 5°C / min. An iridium-copper nanometer network catalyst is obtained, denoted as IrO2-1.

[0063] The scanning electron microscope (SEM) image of the sample IrO2-1 prepared in Example 1 is shown in Figure 1 From the figure, it can be seen that the catalyst sample presents a porous three-dimensional network topological structure. This structure can significantly increase the contact area of the active sites (IrO2) loaded on the network surface and the electrolyte, and the pores formed by the network structure can ensure efficient mass transfer process, improve the catalytic activity, and at the same time inhibit the agglomeration of nanoparticles, thereby effectively enhancing the stability and service life of the catalyst.

[0064] Example 2:

[0065] Take 6.4 g of copper sulfate and dissolve it in 200 mL of pure water, marked as solution A. Take 16.6 g of potassium carbonate and dissolve it in 200 mL of pure water, then add 6% ammonia water, marked as solution B. Take 5.2 g of sodium dodecyl benzene sulfonate and dissolve it in 300 mL of pure water, marked as solution C. Take 1.5 g of iridium trichloride and dissolve it in 100 mL of pure water, marked as solution D. First, add 1.0 g of graphite carbon to solution A and disperse it uniformly by ultrasonic dispersion to form a suspension. Then, under constant temperature water bath conditions, solution B is added dropwise to solution A at a flow rate of 5 mL / min, and the water bath temperature is 50°C. After mixing, keep it for 4 hours, then separate by suction filtration and wash with pure water to remove excess impurity ions. Next, the black solid obtained is immersed in solution C, stirred at room temperature for 8 hours, then separated by suction filtration. The solid obtained by suction filtration is immersed in solution D, and the reaction is carried out at a water bath temperature of 70°C for 2 hours. After the reaction is completed, it is separated by suction filtration and washed with pure water to remove excess impurity ions. Finally, the obtained solid is transferred to a muffle furnace and subjected to high temperature heat treatment in an air atmosphere for 4 hours, with a heat treatment temperature of 500°C and a heating rate of 5°C / min, to obtain an iridium-copper nanonet catalyst, marked as IrO2-2.

[0066] Example 3:

[0067] Take 7.9 g of copper acetate and dissolve it in 200 mL of pure water, marked as solution A. Take 18.2 g of ammonium carbonate and dissolve it in 200 mL of pure water, then add 10% ammonia water, marked as solution B. Take 8 g of fatty alcohol ether sodium sulfate and dissolve it in 300 mL of pure water, marked as solution C. Take 2.5 g of hydrated iridium trichloride and dissolve it in 100 mL of pure water, marked as solution D. First, add 2.0 g of graphene to solution A and disperse it uniformly by ultrasonic dispersion to form a suspension. Then, under constant temperature water bath conditions, solution B is added dropwise to solution A at a flow rate of 10 mL / min, and the water bath temperature is 80°C. After mixing, keep it for 6 hours, then separate by suction filtration and wash with pure water to remove excess impurity ions. Next, the black solid obtained is immersed in solution C, stirred at room temperature for 10 hours, then separated by suction filtration. The solid obtained by suction filtration is immersed in solution D, and the reaction is carried out at a water bath temperature of 80°C for 3 hours. After the reaction is completed, it is separated by suction filtration and washed with pure water to remove excess impurity ions. Finally, the obtained solid is transferred to a muffle furnace and subjected to high temperature heat treatment in an air atmosphere for 4 hours, with a heat treatment temperature of 800°C and a heating rate of 5°C / min, to obtain an iridium-copper nanonet catalyst, marked as IrO2-3.

[0068] Comparative Example 1:

[0069] 5 g of chloroiridic acid was weighed and dissolved in 200 mL of ultrapure water; 10 g of sodium carbonate was weighed and dissolved in 100 mL of ultrapure water for standby. The chloroiridic acid solution and the sodium carbonate solution were heated to 80℃, and then the chloroiridic acid solution was added dropwise into the sodium carbonate solution while stirring continuously to obtain a blue colloidal solution. Next, nitric acid was added to the blue colloidal solution to adjust the pH value of the solution to 7, and then heating and concentration and drying were performed in sequence to obtain a blue-black powder. Finally, the obtained blue-black powder was placed in a porcelain boat and was put into a tube furnace for high-temperature heat treatment, the heat treatment time was 0.5 h, the heat treatment temperature was 420℃, and the heating rate was 5℃ / min, to obtain the target product, an iridium oxide catalyst, denoted as IrO2-4.

[0070] The four samples prepared above were subjected to N2adsorption-desorption test and OER polarization curve test respectively; the N2adsorption-desorption test results are shown in Table 1 below:

[0071] Table 1 N2adsorption-desorption test results of examples and comparative examples

[0072] Catalyst Specific surface area (m 2 / g)]]> Pore volume (cm 3 / g)]]> [IrO2-1] 235.6 0.17 [IrO2-2] 248.5 0.18 [IrO2-3] 221.3 0.16 [IrO2-4] 57.1 0.05

[0073] The test results show that the specific surface areas of the three example samples are in the range of 200-250 m 2 / g, and the pore volumes are in the range of 0.15-0.2 cm 3 / g, which are significantly higher than those of the comparative example samples, which is consistent with the characterization results shown. Figure 1

[0074] The OER polarization curve test method is as follows: a three-electrode system was used, and the glassy carbon working electrode was coated with the catalyst prepared in Examples 1-3 and Comparative Example 1 respectively; the reference electrode was an Ag / AgCl electrode; and the counter electrode was a graphite rod electrode. The catalyst to be tested was uniformly dispersed in a mixed solution of isopropanol, water and Nafion by ultrasonic treatment, and was dropped onto the surface of the glassy carbon electrode, and then the working electrode was obtained after natural drying, and the loading amount of the catalyst was 0.25 mg / cm 2 . The electrolyte solution was a 0.5 mol / L sulfuric acid aqueous solution. The polarization curve test was performed on each anode, and the overpotential at a current density of 10 mA / cm 2 indicates the electrocatalytic performance, and the less the loading amount of the catalyst and the smaller the overpotential, the better the performance of the catalyst.

[0075] The test results of OER are shown in Figure 2 From the figure, it can be seen that the catalyst electrode prepared in Example 1 has excellent oxygen evolution electrocatalytic activity, and the overpotential at a current density of 10 mA / cm 2 ​The overpotential required for the catalytic current density of the catalyst prepared by the method of the present application is only 279 mV, while the overpotentials required for the catalysts prepared in Examples 2 and 3 are 283 mV and 285 mV respectively, and the performances of the three samples are basically the same. The overpotential required for the catalyst prepared in Comparative Example 1 is 334 mV, which is significantly higher than that of the catalyst prepared by the method of the present application. This result is also verified by the SEM and N2 adsorption-desorption test results.

[0076] In the invention patent application with the publication number CN115849469A and the name of nano iridium oxide catalyst, its preparation method and application, the specific surface area of the prepared nano iridium oxide catalyst is 130-180 m 2 / g. The oxygen evolution overpotential of the catalyst is less than 280 mV when the catalyst loading is about 0.5 mg / cm 2 . Parallel comparison shows that the performance of the catalyst prepared by the method of the present application is comparable to that of the catalyst prepared in the application, and the catalyst prepared by the method of the present application also contains copper, which only provides a three-dimensional network structure, and the actual iridium loading is lower. Since iridium is expensive and rare, it can be predicted that the present application has good economic value.

[0077] The above is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be defined by the protection scope defined in the claims.

[0078] The details not described in the present application are known technologies of those skilled in the art.

Claims

1. A process for preparing an efficient and stable iridium oxide electrocatalyst, characterized in that: The specific steps include: S1 prepares four solutions in no particular order: Prepare a copper salt solution, denoted as solution A, with pure water as the solvent and a divalent inorganic copper salt soluble in water as the solute; An alkaline solution, referred to as solution B, is prepared. The solvent is pure water. Solution B contains both hydroxide and carbonate, which react with solution A to obtain basic copper carbonate. Prepare a surfactant emulsion, denoted as solution C, with pure water as the solvent and an anionic surfactant as the surfactant; Prepare iridium oxide precursor salt, denoted as solution D, with pure water as the solvent and the solute being soluble in water and capable of hydrolyzing to produce Ir 3+ Iridium salts; S2: adding a porous carbon material with a layered structure as a template to solution A and ultrasonically dispersing it to form a uniform suspension; S3: Add solution B dropwise to the suspension of solution A in a constant temperature water bath. After mixing, keep the mixture warm to react to obtain a basic copper carbonate carrier with a layered distribution. After the reaction, filter and separate the carrier, and wash with pure water to remove excess impurity ions. S4: Immerse the black solid obtained in S3 in solution C, stir at room temperature for a period of time to form a negative charge on the support surface, and then filter and separate; S5: The solid obtained by filtration in S4 is immersed in solution D, and reacted in a water bath for a period of time to load iridium on the surface of the carrier. After filtration and separation, the solid is washed with pure water to remove excess impurity ions; S6: heat-treating the solid obtained in S5 under air atmosphere to decompose basic copper carbonate to form pores, thereby preparing an iridium-copper nano-mesh catalyst with a three-dimensional network structure.

2. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In step S3, the water bath temperature is 30-80° C., the flow rate of solution B is 1-10 mL / min, and the water bath is kept warm for 2-6 hours until the reaction is complete.

3. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In the step S4, magnetic stirring is used to stir at 300-600 r / min for 4-10 hours until the mixture is uniformly mixed.

4. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In step S5, the water bath temperature is 60-80° C., and the reaction time is 1-3 hours.

5. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In step S6, the heat treatment is performed in a muffle furnace at a temperature of 300-800° C., for a time of 4 hours, and at a heating rate of 5° C. / min.

6. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In step S1, the copper ion concentration in solution A is 0.05-0.5 mol / L; the solute in solution B includes ammonia and carbonate, the ammonia concentration in solution B is 1-10%, and the carbonate concentration is 0.1-1 mol / L; the surfactant concentration in solution C is 0.01-0.1 mol / L; and the iridium concentration in solution D is 0.01-0.1 mol / L.

7. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 6, characterized in that: The copper salt is selected from copper chloride, copper sulfate or copper acetate; the carbonate is selected from sodium carbonate, potassium carbonate or ammonium carbonate; the surfactant is selected from dodecylbenzenesulfonic acid, sodium dodecylbenzenesulfonate or sodium fatty alcohol ether sulfate; the iridium salt is selected from iridium trichloride, hydrated iridium trichloride or chloroiridic acid.

8. The process for preparing a highly efficient and stable iridium oxide electrocatalyst according to claim 1, wherein: In step S2, the porous carbon material is activated carbon, graphite carbon or graphene, and the mass fraction of the porous carbon material in the suspension is 0.1-1%.

9. An iridium oxide electrocatalyst prepared by the preparation process according to any one of claims 1 to 8, characterized in that: The iridium oxide electrocatalyst is an iridium-copper nano-net catalyst with a three-dimensional network structure, and its specific surface area is greater than 180m 2 / g, pore volume not less than 0.15 cm 3 / g.

10. The iridium oxide electrocatalyst according to claim 9, characterized in that: The specific surface area of ​​the iridium oxide electrocatalyst is 200 to 250 m 2 / g, pore volume of 0.15~0.2 cm 3 / g.

11. The iridium oxide electrocatalyst according to claim 9, characterized in that: The OER polarization curve test was carried out using a three-electrode system, with the reference electrode being an Ag / AgCl electrode, the counter electrode being a graphite rod electrode, and the working electrode being a glassy carbon electrode coated with the catalyst. The catalyst loading was 0.25 mg / cm 2 , the electrolyte solution is 0.5 mol / L sulfuric acid aqueous solution; reach 10 mA / cm 2 At the current density, the oxygen evolution overpotential does not exceed 285mV.

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