Amorphous iridium hafnium oxide hollow nanospheres, and preparation method and application thereof

Abstract

The present application relates to the technical field of proton exchange membrane water electrolysis, and specifically discloses an amorphous iridium hafnium oxide hollow nanosphere, a preparation method and application thereof, the method comprising the following steps: (1) taking monodisperse SiO2 nanoparticles as a template, introducing a Hf precursor to perform a hydrothermal reaction, and obtaining an amorphous hafnium oxide coated SiO2 nanosphere; (2) removing the SiO2 core of the amorphous hafnium oxide coated SiO2 nanosphere through etching with an alkaline solution, and obtaining an amorphous hafnium oxide hollow microsphere; (3) performing a hydrothermal reaction on the amorphous hafnium oxide hollow microsphere and an Ir precursor, and obtaining an amorphous iridium hafnium oxide hollow nanosphere. The present application has the advantages of simple operation, mild conditions, and can significantly reduce the amount of noble metal Ir, while greatly improving the catalytic activity and stability of the catalyst in the anode oxygen evolution reaction. The material of the present application is suitable for PEMWE, and provides a new solution for developing low-cost and high-stability water electrolysis hydrogen production technology.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane water electrolysis technology, specifically to an amorphous iridium hafnium oxide hollow nanosphere, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane electrolysis (PEMWE) technology is considered an important technological approach for large-scale production of high-purity hydrogen due to its advantages such as high hydrogen purity, high current density, and fast response speed. However, the oxygen evolution reaction on the anode side involves a four-electron transfer process, which suffers from complex reaction pathways and slow kinetics, leading to increased overall energy consumption. Under acidic and highly oxidizing working environments, catalysts are prone to chemical dissolution and electrochemical oxidation, thus affecting their stability.

[0003] Iridium (Ir)-based catalysts have attracted widespread attention due to their ability to balance activity and stability. However, the high price of Ir and the insufficient stability of commercial IrO2 during long-term operation severely restrict the large-scale application of PEMWE. Recent studies have shown that chemically stable metal oxides as supports are an effective means to reduce Ir loading and improve atom utilization. Developing a simple and mild method to achieve in-situ anchoring of Ir species on stable supports (such as hafnium (Hf)) and maintain stability under acidic high potentials remains a core technical challenge that urgently needs to be addressed in this field.

[0004] Therefore, there is an urgent need to provide a simple and efficient preparation method to synthesize nanomaterials with low Ir loading and ensure that the material has high activity to meet the application requirements of PEMWE in commercial water electrolysis for hydrogen production. Summary of the Invention

[0005] The purpose of this invention is to provide amorphous iridium hafnium oxide hollow nanospheres, their preparation method, and applications. This invention utilizes amorphous hafnium oxide (HfO) x Hollow microspheres were used as carriers to uniformly anchor Ir species onto the surface and pores of an amorphous hafnium oxide framework via a hydrothermal method. This effectively improves the Ir catalytic efficiency of PEMWE anodes and reduces the Ir loading, providing a new strategy for efficient and low-cost PEMWE anode catalysts.

[0006] In one aspect of the present invention, a method for preparing amorphous iridium hafnium oxide hollow nanospheres is provided. According to an embodiment of the present invention, the method includes the following steps:

[0007] (1) Using monodisperse SiO2 nanoparticles as templates, Hf precursors were introduced to carry out hydrothermal reactions to obtain amorphous hafnium oxide-coated SiO2 nanospheres;

[0008] (2) The SiO2 core of the amorphous hafnium oxide-coated SiO2 nanospheres was removed by etching with an alkaline solution to obtain amorphous hafnium oxide hollow microspheres;

[0009] (3) The amorphous hafnium oxide hollow microspheres are subjected to hydrothermal reaction with the Ir precursor to obtain amorphous iridium hafnium oxide hollow nanospheres.

[0010] In addition, the method for preparing amorphous iridium hafnium oxide hollow nanospheres according to the above embodiments of the present invention may also have the following additional technical features:

[0011] In some embodiments of the present invention, in step (1), the monodisperse SiO2 nanoparticles are prepared using the Stöber process, specifically including the following steps: ammonia water is added to ethanol and stirred evenly, then preheated, followed by the addition of deionized water and tetraethoxysilane, and reacted at 35-45 °C for 2-4 h. After centrifugation, washing, and drying, monodisperse SiO2 nanoparticles are obtained. Under the alkaline environment provided by ammonia water, tetraethoxysilane undergoes hydrolysis and condensation reactions in an ethanol-water mixed solvent. Tetraethoxysilane first hydrolyzes to generate silicic acid monomers, then the silicic acid monomers condense to form Si-O-Si bonds, and finally, through a nucleation-growth process, uniformly sized spherical SiO2 particles are formed.

[0012] Monodisperse SiO2 nanoparticles are used in this invention because their particle size is highly uniform, making them an ideal hard template for amorphous iridium hafnium oxide hollow nanospheres in subsequent hydrothermal reactions. This facilitates the acquisition of amorphous iridium hafnium oxide hollow nanospheres with regular morphology and uniform shell thickness, thereby improving the specific surface area and active site exposure of the catalyst.

[0013] In some embodiments of the present invention, the volume ratio of ammonia, ethanol, deionized water, and tetraethoxysilane is (25~35):(700~780):(40~60):(15~25). In this ratio, ammonia acts as a catalyst, ethanol as a dispersion medium, deionized water provides the water source required for hydrolysis, and tetraethoxysilane acts as a silicon source. This ratio range can effectively control the hydrolysis rate and the degree of condensation, ensuring the acquisition of monodisperse particles with uniform particle size.

[0014] In some embodiments of the present invention, step (1) is specifically as follows: monodisperse SiO2 nanoparticles are dispersed in ethanol, urea and hafnium acetylacetonate are added, and after stirring evenly, the mixture is transferred to a polytetrafluoroethylene-lined reactor and subjected to hydrothermal reaction at 150-180 °C for 12-24 h. After the reaction is completed, the nanoparticles are washed and dried to obtain amorphous hafnium oxide-coated SiO2 nanospheres. Under hydrothermal conditions, urea slowly decomposes to release ammonia, causing the pH value of the reaction system to gradually increase. Hafnium acetylacetonate then hydrolyzes to generate hafnium ion reaction intermediates. These intermediates undergo heterogeneous nucleation and growth on the surface of the monodisperse SiO2 nanoparticles, ultimately forming a uniformly coated amorphous hafnium oxide shell.

[0015] In some embodiments of the present invention, the mass ratio of the monodisperse SiO2 nanoparticles, urea, and hafnium acetylacetone is (0.08~0.12):(0.7~0.8):(0.02~0.04), and the stirring time is 30-50 min. In this ratio, the monodisperse SiO2 nanoparticles serve as a hard template, urea acts as a precipitant to slowly adjust the pH, and hafnium acetylacetone serves as an Hf source to provide Hf. 4+ This ratio allows for precise control of the thickness and uniformity of the amorphous hafnium oxide shell. Excessive SiO2 content leads to an overly thin shell, while excessive Hf source content easily forms free amorphous hafnium oxide particles. A moderate urea content ensures slow pH changes, avoiding agglomeration or uneven shell formation caused by rapid precipitation. After optimization, this range yields structurally stable, catalytically excellent amorphous hafnium oxide-coated SiO2 nanospheres.

[0016] In some embodiments of the present invention, step (2) is specifically as follows: Amorphous hafnium oxide-coated SiO2 nanospheres are placed in a 1.2~1.8 mol / L NaOH solution and treated at 60~80 ℃ for 50~70 min. After etching, the nanospheres are repeatedly washed with deionized water until the washing solution is neutral, resulting in amorphous hafnium oxide hollow microspheres. Under alkaline conditions, the SiO2 core reacts with NaOH to generate soluble sodium silicate, which is then etched away. The amorphous hafnium oxide shell has high chemical stability in an alkaline environment and is not easily dissolved, thus achieving selective etching away the SiO2 core and retaining only the amorphous hafnium oxide hollow shell structure.

[0017] In some embodiments of the present invention, step (3) is specifically as follows: amorphous hafnium oxide hollow microspheres are added to a mixed system composed of formamide and water and stirred evenly. An iridium source is added, and the mixture is continuously stirred at 25-35 °C to form a uniform precursor solution. The solution is then transferred to an autoclave and reacted at 90-160 °C for 18-24 h. After washing and drying, amorphous iridium hafnium oxide hollow nanospheres are obtained. In the formamide-water mixed solvent, the iridium source slowly hydrolyzes, and heterogeneous nucleation and growth occur on the surface of the amorphous hafnium oxide hollow microspheres. By controlling a lower reaction temperature and a longer reaction time, iridium species are uniformly deposited in an amorphous form on the inner and outer surfaces of the amorphous hafnium oxide shell, ultimately forming amorphous iridium hafnium oxide hollow nanospheres.

[0018] In some embodiments of the present invention, the iridium source is hydrated iridium chloride; the volume ratio of formamide to water is 1:(4~6); and the mass ratio of the amorphous hafnium oxide hollow microspheres to the molar amount of hydrated iridium chloride is 10 mg:0.1 mmol. In this system, formamide acts as a reducing agent and solvent to synergistically control the reaction rate, water acts as a co-solvent to adjust the polarity of the system, and hydrated iridium chloride acts as the iridium source to provide Ir. 3+ Amorphous hafnium oxide hollow microspheres serve as a carrier to provide a deposition substrate. By using the above ratio, iridium species can be uniformly and amorphously deposited on the surface of amorphous hafnium oxide.

[0019] In another aspect of the present invention, the present invention provides a method for preparing amorphous iridium hafnium oxide hollow nanospheres to obtain amorphous iridium hafnium oxide hollow nanospheres.

[0020] In another aspect of the invention, the invention proposes the application of amorphous iridium hafnium oxide hollow nanospheres in proton exchange membrane water electrolysis.

[0021] Furthermore, the application of amorphous iridium hafnium oxide hollow nanospheres according to the above embodiments of the present invention in proton exchange membrane water electrolysis may also have the following additional technical features:

[0022] In some embodiments of the present invention, the amorphous iridium hafnium oxide hollow nanospheres are used to prepare anode materials.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention provides a method for preparing amorphous iridium-hafnium oxide hollow nanospheres. Through simple hydrothermal treatment, Ir species are in situ anchored to the amorphous hafnium oxide framework. This method has the advantages of simple operation, low cost, good reproducibility, and uniform product structure. The obtained product has a hollow spherical morphology, which significantly increases the exposed area of ​​active sites and improves the utilization rate of noble metals.

[0025] 2. The amorphous iridium-hafnium oxide hollow nanospheres synthesized in this invention significantly increase the specific surface area and the degree of exposure of active sites of the catalyst. At the same time, the amorphous hafnium oxide shell has extremely high chemical stability under strong acid (pH less than 1) and high oxidation potential conditions, and is not prone to dissolution, phase transformation or structural collapse. This effectively inhibits the dissolution and loss of Ir, maintains the long-term stability of active sites, and ultimately enables the catalyst to have both high activity and high durability in OER (oxygen evolution reaction).

[0026] 3. The amorphous iridium hafnium oxide hollow nanospheres prepared by this invention exhibit amorphous characteristics. Compared with crystalline materials, their abundant surface defects and flexible coordination environment are conducive to reducing the reaction energy barrier, thereby accelerating the oxygen evolution reaction and showing excellent reaction kinetics characteristics. Attached Figure Description

[0027] Figure 1 This is a transmission electron microscope image of the monodisperse spherical SiO2 nanoparticles obtained in step (1) of Example 1 of the present invention;

[0028] Figure 2 This is a transmission electron microscope image of the amorphous hafnium oxide-coated SiO2 nanospheres obtained in step (2) of Example 1 of the present invention;

[0029] Figure 3 The images shown are transmission electron microscope (a), high-resolution electron microscope (b), and EDS (energy-dispersive X-ray spectroscopy) elemental mapping (c) of the amorphous iridium hafnium oxide hollow nanospheres obtained in step (4) of Example 1 of the present invention. In the c image, from left to right, the high-angle annular dark field image of the sample, the EDS surface distribution map of Ir element, the EDS surface distribution map of Hf element, the EDS surface distribution map of O element, and the overall EDS surface distribution map are shown.

[0030] Figure 4 The amorphous Ir / Hf in Embodiment 1 of the present invention 2.60 O x Comparative Example 1: Amorphous HfO x X-ray diffraction patterns of commercial IrO2 in Comparative Example 5, where JCPDS 43-1019 indicates Joint Committee on Powder Diffraction Standards (JCPDS) card number 43-1019;

[0031] Figure 5 The amorphous Ir / Hf in Embodiment 1 of the present invention 2.60 O x Amorphous HfO prepared in Comparative Example 1 x Ir / Hf prepared in Comparative Example 2 1.34 O x Ir / Hf prepared in Comparative Example 3 5.87 O xIr / Hf prepared in Comparative Example 4 8.16 O x Comparison of electrochemical performance of commercial IrO2 in Comparative Example 5;

[0032] Figure 6 In Application Example 1 of this invention, the amorphous Ir / Hf prepared in Example 1 is used. 2.60 O x PEMWE activity test of commercial IrO2 in Comparative Example 5;

[0033] Figure 7 In Application Example 1 of this invention, the amorphous Ir / Hf prepared in Example 1 is used. 2.60 O x PEMWE performance stability test. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] The electric thermostatic drying oven used in the following examples and comparative examples is the DHG (electric thermostatic forced-air drying oven)-9011A oven manufactured by Shanghai Jinghong, the transmission electron microscope is the JEOL (Japan Electronics Corporation)-F2010 manufactured in Japan, and the centrifuge is the Anke (Anting) TGL (tabletop high-speed refrigerated centrifuge)-10B manufactured by Shanghai Anting Scientific Instrument Factory, and PEMWE Automatic Measurement Green Energy Co., Ltd.

[0036] The medicines used in the following examples were purchased and used directly without any treatment.

[0037] Example 1

[0038] A method for preparing amorphous iridium hafnium oxide hollow nanospheres includes the following steps:

[0039] (1) 30 mL of ammonia solution was added to 740 mL of ethanol and magnetically stirred at 400 rpm for 10 min at room temperature to ensure uniform distribution of ammonia solution. The mixture was then preheated at 40 °C for 30 min. 54 mL of deionized water and 20 mL of tetraethoxysilane were quickly added to the preheated solution and stirred continuously at 400 rpm for 3 h at 40 °C to ensure complete reaction. After the reaction was completed, the product was washed multiple times with ethanol and deionized water, centrifuged (12000 rpm for 10 min), and dried at 70 °C to finally obtain monodisperse spherical SiO2 nanoparticles with an average diameter of approximately 140 nm.

[0040] Depend on Figure 1 As shown, the SiO2 nanoparticles are uniformly distributed.

[0041] (2) Weigh 0.1 g of the SiO2 nanoparticles obtained in step (1), disperse them in 25 mL of ethanol, add 0.75 g of urea and 0.03 g of hafnium acetylacetonate, and stir at 400 rpm for 40 min at room temperature to form a homogeneous precursor solution. Then transfer this solution to a hydrothermal reactor lined with polytetrafluoroethylene and react at 170 ℃ for 24 h. After the reaction is complete, wash the product repeatedly with anhydrous ethanol, centrifuge (12000 rpm, 10 min), and dry at 50 ℃ to obtain amorphous hafnium oxide-coated SiO2 nanospheres.

[0042] Depend on Figure 2 As shown, HfO x Uniform growth on the SiO2 surface.

[0043] (3) Weigh an appropriate amount of the amorphous hafnium oxide-coated SiO2 nanospheres obtained in step (2), place them in a 1.5 mol / L NaOH solution (pH 14), and treat them at 70 °C for 60 min to chemically etch away the SiO2 cores. After etching is complete, wash repeatedly with deionized water until the washing solution is neutral, and then centrifuge (12000 rpm, 10 min) to obtain amorphous hafnium oxide hollow microspheres.

[0044] (4) Weigh 10 mg of the amorphous hafnium oxide hollow microspheres obtained in step (3) and add them to a mixture of 1 mL formamide and 5 mL water. Stir at 400 rpm for 40 min at room temperature to ensure uniform dispersion. Then add 0.1 mmol of hydrated iridium chloride and stir continuously at 400 rpm at 30 °C until a homogeneous precursor solution is formed. The solution is then transferred to a polytetrafluoroethylene (PTFE) lined autoclave with a stainless steel shell and reacted at 100 °C for 20 h. After the reaction is completed, allow it to cool naturally to room temperature, wash the precipitate with deionized water, centrifuge (12000 rpm, 10 min), and dry overnight at 60 °C to obtain amorphous iridium hafnium oxide hollow nanospheres.

[0045] Depend on Figure 3 As shown, EDS mapping analysis of the amorphous iridium-hafnium oxide hollow nanosphere catalyst revealed that Ir and Hf are uniformly distributed on the nanospheres. The composition of the amorphous iridium-hafnium oxide hollow nanospheres was confirmed as Ir / Hf by EDS analysis. 2.60 O x .

[0046] Example 2

[0047] A method for preparing amorphous iridium hafnium oxide hollow nanospheres differs from Example 1 only in that: in step (4), the temperature at which the solution is transferred to a polytetrafluoroethylene-lined autoclave with a stainless steel shell is set to 150°C; all other steps and parameters are the same as in Example 1, yielding Ir / Hf 2.60 O x Hollow microspheres.

[0048] Example 3

[0049] A method for preparing amorphous iridium hafnium oxide hollow nanospheres differs from Example 1 only in that the temperature in step (3) is set to 90 °C, while the other steps and parameters are the same as in Example 1, yielding Ir / Hf 2.60 O x Hollow microspheres.

[0050] Comparative Example 1

[0051] A method for preparing an Ir-free amorphous hafnium oxide hollow microsphere catalyst, differing from Example 1 only in that hydrated iridium chloride is not added in step (4), while the other steps and parameters are the same as in Example 1, yielding amorphous hafnium oxide (HfO). x Hollow microspheres.

[0052] Depend on Figure 4 As shown, Example 1 prepared amorphous Ir / Hf 2.60 Ox The amorphous hafnium oxide hollow microspheres prepared in Comparative Example 1 did not exhibit obvious crystal diffraction peaks in their X-ray diffraction patterns, indicating that the materials have an amorphous structure. This signifies that the amorphous hafnium oxide hollow microspheres and amorphous Ir / Hf 2.60 O x Successful synthesis.

[0053] Comparative Example 2

[0054] A type of Ir / Hf 1.34 O x The preparation method differs from Example 1 only in that 45 mg of hydrated iridium chloride is added in step (4), and the other steps and parameters are the same as in Example 1.

[0055] Comparative Example 3

[0056] A type of Ir / Hf 5.87 O x The preparation method differs from Example 1 only in that 20 mg of hydrated iridium chloride is added in step (4), and the other steps and parameters are the same as in Example 1.

[0057] Comparative Example 4

[0058] A type of Ir / Hf 8.16 O x The preparation method differs from Example 1 only in that 10 mg of hydrated iridium chloride is added in step (4), and the other steps and parameters are the same as in Example 1.

[0059] Comparative Example 5

[0060] Commercial IrO2 was used directly.

[0061] Weigh out 4 mg of the amorphous iridium hafnium oxide hollow nanospheres prepared in Example 1, the amorphous hafnium oxide hollow microspheres prepared in Comparative Example 1, and the Ir / Hf nanospheres prepared in Comparative Example 2. 1.34 O x Ir / Hf prepared in Comparative Example 3 5.87 O x Ir / Hf prepared in Comparative Example 4 8.16 O x In Comparative Example 5, 490 μL of isopropanol and 10 μL of Nafion (perfluorosulfonic acid resin solution) were added to commercially available IrO2, respectively, and the solutions were sonicated for at least 30 min to ensure uniform dispersion, resulting in different dispersions. Then, 10 μL of each dispersion was dropped onto a glassy carbon electrode. After drying, the dispersion was used as the working electrode for oxygen evolution reaction performance testing. The reference electrode was an Ag / AgCl electrode, and the counter electrode was a graphite carbon electrode. The reaction was carried out in 0.1 mol / L O2 saturated atmosphere. -1Electrochemical tests were conducted in an HClO4 electrolyte.

[0062] like Figure 5 As shown, amorphous Ir / Hf 2.60 O x The activity is significantly higher than that of HfO. x 、Ir / Hf 1.34 O x 、Ir / Hf 5.87 O x 、Ir / Hf 8.16 O x And commercial IrO2, at a current density of 10 mA / cm 2 At that time, the overpotential was only 227 mV.

[0063] Application Example 1

[0064] The proton exchange membrane water electrolysis method includes the following steps:

[0065] The amorphous iridium-hafnium oxide hollow nanospheres prepared in Example 1 were sprayed onto the anode side of a proton exchange membrane (PEM) as anolyte oxygen evolution material, with the Ir noble metal loading controlled at 0.5 mg / cm³. -2 The cathode was prepared by spraying a commercially available Pt black catalyst onto the PEM cathode side, with a Pt loading of 1.25 mg / cm³. -2 The PEM used was Nafion (perfluorosulfonic acid proton exchange membrane) 212. The double-sided coated membrane, the anode porous transport layer (PTL, 0.23 mm thick platinum-titanium fiber felt), the cathode gas diffusion layer (Toray carbon paper TGP-H-060), the PTFE gasket, and the bipolar plate were assembled into a membrane electrode assembly. The assembled membrane electrode assembly was subjected to PEMWE performance testing. Before testing, at 1 A cm⁻¹... -2 Activation was completed after running at the current density for 1 hour.

[0066] like Figure 6 As shown, the amorphous iridium hafnium oxide hollow nanospheres prepared in Example 1 were observed at 1 A cm⁻¹. -2 At the given current density, the voltage is only 1.52 V, significantly lower than the commercial IrO2 in Comparative Example 5. Figure 7 The stability test showed almost no degradation after more than 3,000 hours, demonstrating extremely high stability.

[0067] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the present invention, and all such modifications or additions should fall within the protection scope of the present invention.

Claims

1. A method for preparing amorphous iridium hafnium oxide hollow nanospheres, characterized in that, Includes the following steps: (1) Using monodisperse SiO2 nanoparticles as templates, Hf precursors were introduced to carry out hydrothermal reactions to obtain amorphous hafnium oxide-coated SiO2 nanospheres; (2) The SiO2 core of the amorphous hafnium oxide-coated SiO2 nanospheres was removed by etching with an alkaline solution to obtain amorphous hafnium oxide hollow microspheres; (3) The amorphous hafnium oxide hollow microspheres are subjected to a hydrothermal reaction with the Ir precursor to obtain amorphous iridium hafnium oxide hollow nanospheres; Specifically, step (1) is as follows: Monodisperse SiO2 nanoparticles are dispersed in ethanol, urea and hafnium acetylacetonate are added, and after stirring evenly, they are transferred to a polytetrafluoroethylene-lined reactor and hydrothermally reacted at 150~180 ℃ for 12~24 h. After the reaction is completed, the nanoparticles are washed and dried to obtain amorphous hafnium oxide-coated SiO2 nanospheres. The mass ratio of the monodisperse SiO2 nanoparticles, urea and hafnium acetylacetonate is (0.08~0.12):(0.7~0.8):(0.02~0.04), and the stirring time is 30-50 min. Step (3) is as follows: Amorphous hafnium oxide hollow microspheres are added to a mixed system composed of formamide and water and stirred evenly. An iridium source is added and stirred continuously at 25~35 °C to form a uniform precursor solution. Then, the solution is transferred to an autoclave and reacted at 90~160 °C for 18~24 h. After washing and drying, amorphous iridium hafnium oxide hollow nanospheres are obtained. The volume ratio of formamide to water is 1:(4~6).

2. The method for preparing amorphous iridium hafnium oxide hollow nanospheres according to claim 1, characterized in that, In step (1), the preparation method of the monodisperse SiO2 nanoparticles is as follows: ammonia water is added to ethanol and stirred evenly, then preheated, followed by the addition of deionized water and tetraethoxysilane, and reacted at 35~45 ℃ for 2~4 h. After centrifugation, washing and drying, monodisperse SiO2 nanoparticles are obtained.

3. The method for preparing amorphous iridium hafnium oxide hollow nanospheres according to claim 2, characterized in that: The volume ratio of ammonia, ethanol, deionized water and tetraethoxysilane is (25~35):(700~780):(40~60):(15~25).

4. The method for preparing amorphous iridium hafnium oxide hollow nanospheres according to claim 1, characterized in that: Step (2) is as follows: the amorphous hafnium oxide-coated SiO2 nanospheres are placed in a 1.2~1.8 mol / L NaOH solution and treated at 60~80 ℃ for 50~70 min. After etching is completed, the nanospheres are repeatedly washed with deionized water until the washing solution is neutral to obtain amorphous hafnium oxide hollow microspheres.

5. The method for preparing amorphous iridium hafnium oxide hollow nanospheres according to claim 1, characterized in that: The iridium source is hydrated iridium chloride; the mass ratio of the amorphous hafnium oxide hollow microspheres to the molar amount of hydrated iridium chloride is 10 mg : 0.1 mmol.

6. Amorphous iridium hafnium oxide hollow nanospheres prepared by the method described in any one of claims 1 to 5.

7. The application of the amorphous iridium hafnium oxide hollow nanospheres as described in claim 6 in proton exchange membrane water electrolysis.

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