Iridium oxide cluster assembly catalyst for acidic water electrolysis to produce hydrogen and preparation method thereof

Abstract

The present invention relates to an iridium oxide cluster assembly catalyst [(IrO x ) n ], is composed of amorphous iridium oxide nanoclusters [(IrO x ) n0 ] spontaneously aggregated into iridium oxide cluster assemblies [(IrO x ) n ], the amorphous nanoclusters [(IrO x ) n0 ] size is 1-1.8nm, and the iridium oxide cluster assembly [(IrO x ) n The monomer size is 3-5 nm. The iridium oxide cluster assembly catalyst provided by the present invention has both catalytic activity and stability, and is a promising anode catalyst material for PEM water electrolysis hydrogen production.

Description

Technical Field

[0001] The invention belongs to the field of water electrolysis catalyst materials, and particularly relates to an iridium oxide cluster assembly catalyst for producing hydrogen by acidic water electrolysis and a preparation method thereof. Background Art

[0002] In recent years, energy shortages have become increasingly prominent, and the economy, which relies primarily on traditional fossil energy, has increasingly exposed more environmental problems. These include dust, haze, air pollution, water pollution, and ozone depletion. Clean energy sources are urgently needed to replace traditional fossil fuels. The hydrogen economy, powered by hydrogen, is an energy-saving, environmentally friendly, and highly efficient emerging energy economy. With the development of the hydrogen energy industry, hydrogen can be categorized by its source: gray hydrogen, blue hydrogen, and green hydrogen. Gray hydrogen is produced through coal chemical processing, but this process produces a large amount of carbide impurities. Further decarbonization can yield blue hydrogen with a purity exceeding 95%. Green hydrogen is produced through the electrolysis of renewable energy-based water, also producing water. This technology is not only pollution-free but also produces extremely high-purity hydrogen. Water electrolysis is one of the main technologies for producing green hydrogen. It involves two half-reactions: the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). Because the OER involves four electrons and the HER involves two electrons, the anodic reaction is the primary kinetic constraint on water electrolysis. Developing higher-performing anodic catalysts is currently a major research focus in acidic water electrolysis.

[0003] Currently, there are three types of water electrolysis hydrogen production technologies: high-temperature solid oxide water electrolysis (SOEC), alkaline water electrolysis, and solid polymer water electrolysis (also known as PEM / acidic water electrolysis). High-temperature SOEC technology is still in the research stage due to its high operating temperature (600°C to 1000°C) and stringent material requirements. Alkaline and PEM water electrolysis, also known as low-temperature water electrolysis technologies, operate at lower temperatures (generally less than 90°C) and have achieved commercial application. Compared to the mature alkaline water electrolysis technology, PEM water electrolysis offers advantages such as higher hydrogen purity (up to 99.99%), higher current density, differential pressure operation, smaller footprint, and the fact that the entire reaction system involves only water, which prevents alkaline corrosion. Therefore, PEM water electrolysis has excellent development prospects.

[0004] Although PEM water electrolysis hydrogen production technology has developed rapidly, it faces the problem of developing low-cost, efficient and stable anode catalysts, and is still in its infancy for large-scale industrial applications. The commercial catalysts for PEM water electrolysis hydrogen production are IrO2 and RuO2. However, IrO2 faces two problems: small reserves, high price and limited activity. Although RuO2 is cheaper and more active than IrO2, its stability is far inferior to commercial IrO2. To this end, researchers have made many efforts. However, emerging catalysts often undergo unfavorable structural evolutions such as cation leaching, irreversible oxidation and surface reconstruction, which will cause the crystal structure to collapse and then degrade the catalyst. In addition, due to the great differences between the three-electrode test system and the PEM water electrolysis test system in the experimental test, the excellent activity and stability of the anode catalyst in the three-electrode test system cannot be transferred to the high performance of the PEM electrolyzer. For example, Professor Zhao Dongyuan of Fudan University synthesized an ultra-thin Ir-IrO with ordered interlayer space. x / C nanosheets (Journal of the American Chemical Society, 2022, 144(5): 2208-17.), and enhanced OER through a nanoconfined self-assembly strategy, using block copolymers to form stable terminal fused lamellar micelles to obtain Ir-IrO x Evenly distributed within the nanosheets. Importantly, the fabricated Ir-IrO x / C electrocatalyst in acidic medium with a current density of 10 mA cm -2 The low overpotential (η) of 198 mV was shown, and the activity was greatly improved, but it can only be used at low current density (10 mA cm -2 ) can not be used for industrial-scale PEM water electrolysis to produce hydrogen.

[0005] Based on the fact that Ir is more stable than Ru in acidic electrolysis, it is a feasible strategy to prepare highly active IrO2PEM electrolysis anode catalyst based on its stability. Many studies have shown that compared with commercial rutile IrO2, amorphous IrO2 has higher electrocatalytic activity, but its Ir ions are easily leached and its stability is greatly challenged. In addition, since catalysis is a surface reaction, the surface atoms of metal-based catalysts are far more important than the bulk atoms, and the size of the metal limits the content of surface atoms in the component. In order to improve the utilization efficiency of precious metals, it is very important to develop precious metal-based catalysts with high dispersion and a large proportion of surface atoms. Due to their rich and unique physical and chemical properties, metal clusters have both metallic properties and a high surface atom content, and also have an amorphous structure. They show broad application prospects in the fields of materials, energy, and environment. Therefore, metal cluster catalysts can be selected as active components. Compared with the method of Yan Haibo et al. to prepare iridium oxide clusters (size: tens to hundreds of nanometers) by high temperature and high pressure hydrothermal method in a reactor (publication number: CN113620358A), the amorphous IrO x The synthesis conditions of nanoclusters (~1.4nm) are room temperature and normal pressure, and the preparation process is simple and safe. Summary of the Invention

[0006] In order to solve the problem of low catalytic activity and high dosage of IrO2 in the anode OER reaction of commercial acidic water electrolysis hydrogen production (PEM) in the prior art, the present invention prepares amorphous [(IrO x ) n0 ] nanoclusters (1-2nm), which spontaneously transform into [(IrO x ) n ] cluster assembly, avoiding [(IrO x ) n0 ] quickly dissolves in water, maintains excellent stability while improving its activity, and is a promising anode catalyst material for PEM electrolysis of water to produce hydrogen due to its low loading and stability. The present invention spontaneously converts [(IrO x ) n ] cluster assemblies (in this process, the size of 1.2-1.7 nm clusters slightly increased to 3-4 nm cluster assemblies), which maintained excellent stability while improving activity, which has not been reported before.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] The first object of the present invention is to provide an iridium oxide cluster assembly catalyst [(IrO x ) n], is composed of amorphous iridium oxide nanoclusters [(IrO x ) n0 ] spontaneously aggregated into iridium oxide cluster assemblies [(IrO x ) n ], the amorphous nanoclusters [(IrO x ) n0 ] size is 1-1.8 nm, and the iridium oxide cluster assembly [(IrO x ) n ]The monomer size is 3-5nm.

[0009] x = 1.5-2, preferably, x = 1.7-2. The chemical formula of iridium oxide is IrO2, but due to the calcination process in a joule furnace under a nitrogen atmosphere, slight reduction of iridium oxide is inevitable, so the valence of Ir is between 3 and 4, so x is between 1.5-2.

[0010] The inventor estimated that n0 is 2-3, n is 3-5, and n>n0 based on the size of electron microscope. x ) n0 ] in a Joule furnace through several rapid heating and cooling pulse heating processes, spontaneous aggregation into [(IrO x ) n ] cluster assembly, in the process of spontaneous aggregation, due to the rapid heating and cooling process, the nanoclusters have no time to crystallize and remain in an amorphous state. However, during the heating process, as [(IrO x ) n0 ]Surface hydrophilic groups OH - The detachment and subsequent [(IrO x ) n0 ] self-assembly, iridium oxide cluster assembly [(IrO x ) n ] The phenomenon of Ir dissolution due to dissolution in water no longer occurs. The obtained iridium oxide cluster assembly retains the high activity of the amorphous state and gives the cluster assembly good stability, that is, it has both the catalytic activity of the amorphous iridium oxide catalyst and the stability of the crystalline iridium oxide.

[0011] Preferably, the amorphous [(IrO x ) n0 ] nanocluster size is 1.2-1.7nm, such as 1.3nn, 1.4nm, 1.5nm, 1.6nm; the iridium oxide cluster assembly [(IrO x ) n]The monomer size is 3-4nm, such as 3.1nm, 3.2nm, 3.3nm, 34nm, 3.5nm, 3.6nm, 3.7nm, 3.8nm, and 3.9nm.

[0012] The condition for the spontaneous aggregation of the amorphous iridium oxide nanoclusters into iridium oxide cluster assemblies is that the amorphous iridium oxide nanoclusters are placed in a heater of a joule furnace under an inert atmosphere and heated under 250-400°C pulse heating conditions; the pulse heating refers to the heater rapidly heating to 250-400°C within 1-2s, then rapidly cooling to room temperature within 1-2s, and maintaining room temperature for 10-20s, and this process is one cycle; thereafter, this process is cycled for a total of 2-20 times, preferably 5-15 times, such as 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, and 14 times. Preferably, the inert atmosphere is nitrogen and / or argon. The heater is selected from at least one of carbon paper, carbon plate, carbon felt, tungsten foil, nickel foil, and nickel foam.

[0013] Joule furnace is an ultra-fast high-temperature device that can perform pulse heating on the heater in an ultra-short time, with a heating rate of up to 10 3 ℃ / s, the cooling rate can reach 10 3 ℃ / s.

[0014] Furthermore, compared with commercial rutile-phase IrO2, the acidic electrolysis of water to produce hydrogen (PEM) anode OER catalyst [(IrO x ) n ] is an amorphous structure.

[0015] Since the nanoclusters will form weak agglomerations during the rapid heating-rapid cooling pulse heating process, the iridium oxide cluster assembly of the present invention is composed of multiple amorphous iridium oxide nanoclusters and has a high electrochemical active area. The inventors found that [(IrO x ) n The size of cluster assembly units has an important influence on catalytic activity and stability. x When the catalyst is used, the conventional temperature-programmed calcination conditions will result in the unloaded IrO x Nanoclusters undergo Austenite ripening and then sintering, making it difficult to maintain an amorphous structure and a high specific surface area. It is generally believed that catalysis is a surface reaction, and clusters aggregate to form massive substances, which reduces the utilization rate of surface atoms. While ensuring stability, it is difficult to improve activity. The present invention is based on the fact that amorphous iridium oxide can improve the catalytic activity of the anode OER reaction and has a low overpotential. However, its stability is greatly challenged due to the easy leaching of Ir ions. The present invention aims to regulate the calcination of the obtained nanocluster assembly [(IrO x) n ]While improving the activity, its stability is also guaranteed.

[0016] A second object of the present invention is to provide a method for preparing the iridium oxide cluster assembly, comprising the following steps:

[0017] (S1) dissolving a soluble iridium source in water, adding alkali, and preparing a product by hydrothermal method. The product is allowed to stand in the dark, washed, and dried to obtain dispersed iridium oxide nanoclusters [(IrO x ) n0 ];

[0018] (S2) The obtained iridium oxide nanoclusters [(IrO x ) n0 ] Pulse heating was performed under the protection of an inert atmosphere at a temperature of 250-450°C to obtain an iridium oxide cluster assembly [(IrO x ) n ].

[0019] Furthermore, in step (S1), the soluble iridium source is selected from at least one of chloroiridic acid hexahydrate, potassium hexachloroiridate, and iridium trichloride; and the amount of the soluble iridium source and deionized water is such that the Ir concentration in the solution is 2 to 4 mmol / L.

[0020] Furthermore, in step (S1), the base is NaOH and / or KOH, and the amount of the base is such that the pH of the system is adjusted to 12-14.

[0021] Furthermore, in step (S1), the hydrothermal method is to continuously stir at 80-98°C for 10-30 minutes and stand in the dark for 20-30 hours.

[0022] Furthermore, in step (S2), the pulse heating is performed in a Joule furnace, and the sample is placed in the heater of the Joule furnace. The pulse heating is performed by heating the heater in the Joule furnace to 250-450°C within 1-2 seconds, then cooling to room temperature within 1-2 seconds, and maintaining room temperature for 10-15 seconds as one cycle, and performing the above cycles 5-15 times in total. Using a Joule furnace for calcination can avoid the aggregation of clusters caused by long-term high temperature in ordinary programmed temperature calcination (such as a tubular furnace or muffle furnace), which can increase the activity of the catalyst. Figure 9 This is a physical diagram of a Joule furnace and its heating plate.

[0023] In this state, the iridium oxide nanoclusters will spontaneously transform into iridium oxide cluster assemblies with an increased size. The pulse heating temperature should not be too high, and the pulse heating time should not be too long, otherwise [(IrO x ) n0] nanoclusters will further mature and it will be difficult to maintain the amorphous structure, thus forming large particles. The purpose of pulse heating is to avoid the assembly of too small [(IrO x ) n0 ] nanoclusters dissolve in water, which is beneficial for enhancing the x While maintaining activity, it also ensures good stability.

[0024] Furthermore, in step (S2), the washing is performed with an alcohol-water mixed solvent, the alcohol is selected from at least one of methanol, ethanol, and isopropanol, and the mass ratio of alcohol to water is 4-6:1; the drying is not particularly limited, such as oven drying and vacuum drying.

[0025] The inventors found that the [(IrO x ) n ] cluster assembly has the highest catalytic activity for the OER reaction in the PEM electrolysis of water to produce hydrogen. [(IrO x ) n0 ] When nanoclusters are calcined in a common muffle furnace, the large rutile IrO2 particles formed due to agglomeration cannot achieve the catalytic effect of the catalyst. Possible reasons [(IrO x ) n0 ] clusters aggregate, resulting in low surface atomic utilization of the catalyst and increased crystallinity, which will reduce the activity. x ) n ] high OER activity of the cluster assembly (10 mA cm -2 When the overpotential is 220mV, in PEM, [(IrO x ) n ] loading of 1.25 mg cm -2 , the current density is 1.25Acm -2 When the voltage is low to 1.78V, the stability can be guaranteed for 300h with almost no voltage attenuation).

[0026] The third object of the present invention is to provide the iridium oxide cluster assembly catalyst [(IrO x ) n ] as an acidic water electrolysis catalyst. The iridium oxide cluster assembly provided by the present invention [(IrO x ) n ], with the advantages of high Ir utilization efficiency, high catalytic activity, long-term catalyst stability, and long service life. It can catalyze the anodic oxygen precipitation reaction at room temperature, and the product is non-toxic and harmless, causing no secondary pollution.

[0027] The fourth object of the present invention is to provide a method for acidic water electrolysis, wherein the oxygen electrode adopts the above-mentioned iridium oxide cluster assembly catalyst [(IrOx ) n ]. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 [(IrO x ) n0 ]High-resolution transmission electron microscopy (HRTEM) image of nanoclusters.

[0029] Figure 2 [(IrO x ) n0 ] Statistical histogram of nanocluster size distribution.

[0030] Figure 3 [(IrO x ) n0 ]Diagram of the nanocluster pulse heating process.

[0031] Figure 4 [(IrO x ) n ]Spherical aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) images of cluster assemblies.

[0032] Figure 5 [(IrO x ) n ]X-ray diffraction (XRD) pattern of cluster assembly.

[0033] Figure 6 The iridium oxide cluster assembly [(IrO x ) n ]Monomer particle size distribution diagram.

[0034] Figure 7 IrO obtained in Comparative Example 2 x Transmission electron microscopy (TEM) images of particle aggregates.

[0035] Figure 8 IrO obtained in Comparative Example 2 x XRD diffraction patterns of particle aggregates.

[0036] Figure 9 This is a diagram of the actual Joule furnace setup. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. The following examples are convenient for better understanding of the present invention, but are not intended to limit the present invention. The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0038] Unless otherwise specified, the "parts" in the examples of the present invention are parts by mass, and the "%" in the examples of the present invention are percentages by mass unless otherwise specified.

[0039] Joule furnace equipment model: HTS-1510D; specifications: 150-1100°C (Sanya Kechuang Future Technology Co., Ltd.)

[0040] Example 1

[0041] (S1) Preparation of [(IrO x ) n0 ] nanoclusters: 1.686 mL of 80 mg / mL H2IrCl6·6H2O solution was dissolved in 100 mL of deionized water in a conical flask; 25 wt% NaOH was quickly added thereto while stirring to adjust the pH of the system to 13, and the conical flask was quickly placed in a 90°C preheated oil bath for 20 minutes. The reaction was then removed and allowed to stand in the dark for 24 hours. The resulting blue-purple solution without precipitation was precipitated and washed three times in a mixed solution of anhydrous ethanol and water in a mass ratio of 4:1. The obtained solid was dried in a vacuum freeze drying oven to obtain [(IrO x ) n0 ]Nanocluster solids.

[0042] Figure 1 [(IrO x ) n0 ] high-resolution transmission electron microscopy (HRTEM) images of nanoclusters. It can be seen that [(IrO x ) n0 ] nanoclusters, with a size of about 1.4 nm, are not aggregated and are evenly dispersed.

[0043] Figure 2 [(IrO x ) n0 ] Statistical histogram of nanocluster size distribution.

[0044] (S2)[(IrO x ) n0 ] nanoclusters: the [(IrO x ) n0 The nanoclusters were placed on the carbon cloth of the Joule furnace heater and pulse heated: the temperature was raised to 350 ° C within 1 second, then cooled to room temperature within 1 second, and then maintained at room temperature for 15 seconds. The above process was a pulse heating cycle. A total of 10 pulse heating cycles were performed to obtain the iridium oxide cluster assembly [(IrO x ) n ].

[0045] Figure 3 [(IrO x ) n0 ]Diagram of the nanocluster pulse heating process. Figure 3 Medium cooling is cooling to room temperature, but since the instrument diagram can only display a minimum of 150°C, Figure 3 The end point of the intermediate cooling is actually room temperature.

[0046] Figure 4 The iridium oxide cluster assembly [(IrO x ) n ] is aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) image. During the calcination process, [(IrO x ) n0 ] inevitably grows up. As can be seen from the figure, [(IrO x ) n ]The cluster assembly is composed of units with a size of 3 to 4 nm.

[0047] Figure 5 The iridium oxide cluster assembly [(IrO x ) n ], it can be seen from the X-ray diffraction pattern (XRD) that compared with commercial IrO2, the iridium oxide cluster assembly [(IrO x ) n ] still maintains an amorphous structure.

[0048] Figure 6 The [(IrO x ) n ] From the particle size distribution diagram of the cluster assembly monomer, it can be seen that the particle size of the iridium oxide cluster assembly monomer is 3-4nm.

[0049] Example 2

[0050] Other conditions and operations were the same as those in Example 1, except that in step (S1), the oil bath temperature was 80°C.

[0051] Example 3

[0052] Other conditions and operations were the same as those in Example 1, except that in step (S1), the oil bath temperature was 98°C.

[0053] Example 4

[0054] Other conditions and operations were the same as those in Example 1, except that in step (S1), the amount of NaOH added was adjusted to adjust the pH of the system to 12.

[0055] Example 5

[0056] Other conditions and operations were the same as those in Example 1, except that in step (S1), the amount of NaOH added was adjusted to adjust the pH of the system to 14.

[0057] Example 6

[0058] Other conditions and operations are the same as those in Example 1, except that in step (S2), the temperature of pulse heating is 250°C.

[0059] Example 7

[0060] Other conditions and operations are the same as those in Example 1, except that in step (S2), the temperature of pulse heating is 450°C.

[0061] Example 8

[0062] Other conditions and operations are the same as those in Example 1, except that in step (S2), the pulse heating cycle is performed a total of 5 times.

[0063] Example 9

[0064] Other conditions and operations are the same as those in Example 1, except that in step (S2), the pulse heating cycle is performed 15 times in total.

[0065] Comparative Example 1

[0066] The catalyst is [(IrO x ) n0 ] nanoclusters without undergoing the pulse heating treatment of step (S2).

[0067] Comparative Example 2

[0068] Step (S1) is the same as that in Example 1, and step (S2) is modified as follows: calcining at 350°C for 1 hour in a muffle furnace, and then naturally cooling to room temperature. Figure 7 IrO obtained in Comparative Example 2 x Transmission electron microscopy images of particle aggregates. Figure 8 IrO obtained in Comparative Example 2 x The XRD diffraction pattern of the particle aggregate shows that the structure is similar to [(IrO x ) n ]The structures of cluster assemblies are obviously different.

[0069] Comparative Example 3

[0070] Commercial IrO2 was used as a comparative catalyst.

[0071] Comparative Example 4

[0072] Commercial Ir / C with a mass fraction of 5 wt% was used as a comparative catalyst.

[0073] Application Examples

[0074] The catalyst performances of the above examples and comparative examples were tested under two specific test conditions: a standard three-electrode system test and a PEM device test.

[0075] The standard three-electrode system test conditions are as follows: a carbon rod is used as the counter electrode, a saturated calomel electrode (SCE) is used as the reference electrode, and the prepared [(IrO x ) n ]The cluster assembly was used as the working electrode (the material was dropped on hydrophilic carbon paper), all data were calibrated to the standard hydrogen electrode (RHE) potential, and the electrolyte test results were corrected by 95% IR to reduce the impedance of the solution during the test.

[0076] The calibration formula is:

[0077] E (RHE) =E (SCE) +0.0591*pH+0.24-0.95*I*R

[0078] Overpotential η 10 At a current density of 10 mA cm -2 When , the magnitude of the overpotential.

[0079] PEM device test: The cathode used commercial 40% Pt / C catalyst, and the anode used the catalysts of the embodiment and comparative example. The catalysts were sprayed on both sides of the N117 proton exchange membrane by ultrasonic spraying using the CCM method. x ) n The loading amount of ] was 1.25 mg cm -2 , the loading of 40% Pt / C is 1 mg cm -2 ), and then the cathode and anode gas diffusion layers (GDL) are attached to the catalyst layers (CL) on both sides by hot pressing to obtain a membrane electrode (MEA), which is then installed in a PEM water electrolysis device. The test conditions are: current density 1.25A cm -2 , the test area is 4cm 2 , the temperature is 80℃.

[0080] Table 1 Catalyst performance indicators

[0081]

[0082] In terms of the synthesis method of the catalyst, the alkali thermal synthesis temperature is too high or too low, which is not conducive to the uniform size of [(IrO x ) n0] nanoclusters, and during the synthesis process, the alkali concentration has a greater impact on the Ir intermediates. When the alkali concentration is too low, the OH - The concentration is low, and the Cl ions coordinated with Ir ions cannot be well - Replacement is not conducive to the formation of [Ir(OH)6] 2- Active intermediate; when the base concentration is high, the intermediate product [Ir(OH)6] 2- Maintaining a stable state is not conducive to IrO x nucleation, so in the synthesis of IrO x In the process, temperature and alkali concentration are very important. In addition, due to the synthesis of IrO x It is a water-soluble product. Therefore, a mixed solution of ethanol and water is required for centrifugal washing. The solid product obtained has a very poor stability due to the inevitable dissolution even if it has high activity at the beginning. To solve this problem, we used a rapid heating and cooling device to make the obtained [(IrO x ) n0 ] nanoclusters were dehydrated and assembled to a certain extent, and the obtained [(IrO x ) n ] cluster assembly can reduce its water solubility and improve its stability. During the calcination process, the temperature is too high and the time is too long, which will cause [(IrO x ) n0 ] nanoclusters form rutile IrO with high crystallinity x If the temperature is too low, it will be detrimental to the [(IrO x ) n0 ] self-assembly, the catalyst still dissolves in water. Comparison of Example 1 with Examples 8 and 9 shows that too low a number of pulse heating times leads to incomplete assembly and the catalyst still dissolves in water; too high a number of pulse heating times leads to a certain amount of crystallization due to the long calcination time, resulting in reduced activity.

[0083] It can be found from Example 1 and Comparative Example 2 that, compared with the long annealing process of the muffle furnace, the rapid heating and cooling reduction of the Joule furnace can avoid the [(IrO x ) n0 ] nanoclusters form rutile IrO with high crystallinity x , while ensuring high activity, it can also maintain good stability.

Claims

1. A method for preparing an iridium oxide cluster assembly catalyst for producing hydrogen by acidic water electrolysis, characterized in that: The following steps are involved: (S1) dissolving a soluble iridium source in water, adding alkali, and preparing a product by an alkaline thermal method. The product is allowed to stand in the dark, washed, and dried to obtain dispersed iridium oxide nanoclusters with a size of 1-1.8 nm; (S2) pulse heating the obtained iridium oxide nanoclusters under the protection of an inert atmosphere at a pulse heating temperature of 250-450° C. to obtain an iridium oxide cluster assembly; the pulse heating is performed in a Joule furnace, and the sample is placed in a heater of the Joule furnace. The pulse heating is performed by heating the heater in the Joule furnace to 250-450° C. within 1-2 seconds, then cooling to room temperature within 1-2 seconds, and maintaining room temperature for 10-15 seconds as one cycle, and performing the above cycles 5-15 times in total; The iridium oxide cluster assembly catalyst is formed by spontaneous aggregation of amorphous iridium oxide nanoclusters into iridium oxide cluster assemblies, and the size of the iridium oxide cluster assembly is 3-5 nm.

2. The preparation method according to claim 1, characterized in that The size of the amorphous iridium oxide nanoclusters is 1.2-1.7 nm; the size of the iridium oxide cluster assembly is 3-4 nm.

3. The preparation method according to claim 1, characterized in that In step (S1), the soluble iridium source is selected from at least one of chloroiridic acid hexahydrate, potassium hexachloroiridate, and iridium trichloride; the amount of the soluble iridium source and deionized water is such that the Ir concentration in the solution is 2-4 mmol / L; the base is NaOH and / or KOH, and the amount of the base is such that the pH of the system is adjusted to 12-14; the alkaline thermal method is performed by continuously stirring at 80-98°C for 10-30 minutes; and the standing time in the dark is 20-30 hours.

4. The preparation method according to claim 1, characterized in that In step (S2), the washing is performed with a mixed solvent of alcohol and water, the alcohol is selected from at least one of methanol, ethanol, and isopropanol, and the mass ratio of alcohol to water is 4-6:

1.

5. Use of the iridium oxide cluster assembly catalyst prepared by the preparation method according to any one of claims 1 to 4 as an acidic water electrolysis catalyst.

6. A method for electrolyzing acidic water, characterized in that: The oxygen electrode is an iridium oxide cluster assembly catalyst prepared by the preparation method according to any one of claims 1 to 4.

Images