A method for preparing an iridium oxide thin film electrocatalyst based on chemical vapor deposition and application thereof

Abstract

This invention relates to the field of electrocatalytic materials technology, and provides a method for preparing iridium oxide thin-film electrocatalysts based on chemical vapor deposition (CVD) and its applications. This invention employs CVD to prepare iridium oxide thin films on the surface of nickel foam. By controlling the flow rates of oxygen and inert gases, the oxygen partial pressure is controlled, and the concentration of oxygen vacancies in the iridium oxide film is controlled by adjusting the oxygen partial pressure, thereby significantly improving the electrocatalytic activity of the iridium oxide film. Furthermore, the CVD method used in this invention enables uniform deposition of the iridium oxide film on the complex surface of nickel foam, ensuring the electrochemical stability of the catalyst. The results of the examples show that the iridium oxide thin-film electrocatalyst prepared by this invention exhibits excellent catalytic performance in the OER reaction and demonstrates excellent durability in long-term stability tests, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and in particular to a method for preparing iridium oxide thin film electrocatalysts based on chemical vapor deposition and its application. Background Technology

[0002] Electrolysis of water to produce hydrogen is considered an important pathway for large-scale consumption and storage of renewable energy. However, the oxygen evolution reaction (OER) at the anolyte, due to its slow kinetics caused by multi-electron coupling and oxygen-oxygen bond formation, often becomes a key factor limiting the energy efficiency and stability of electrolyzers. Among existing OER anode catalysts, IrO2 is widely used due to its good stability at high potentials, especially suitable for systems with higher stability requirements. However, the scarcity and high price of Ir resources have prompted research and industry to continuously seek technological routes that improve the activity and durability per unit of iridium while reducing the amount of precious metal used.

[0003] In practical water electrolysis systems, the anode catalyst needs to be supported on a three-dimensional matrix with high conductivity, high specific surface area, and high stability to achieve efficient catalysis and industrial applications. Nickel foam, with its three-dimensional interconnected pore structure, excellent conductivity, good mechanical strength, and low cost, has become one of the ideal supporting matrices for IrO2 catalysts. Effectively combining IrO2 with nickel foam can improve catalyst dispersibility and reduce the amount of Ir required by leveraging the three-dimensional structure of nickel foam, while simultaneously enhancing electron transport between the catalyst and the matrix, further optimizing OER catalytic performance.

[0004] Numerous studies have shown that the electrocatalytic performance of IrO2 is not only related to its crystal phase, crystal facets, and particle size, but also closely related to its surface / near-surface defects. In particular, oxygen vacancies can significantly affect the activity and stability of the OER by altering the Ir-O bond strength, regulating the electronic structure, and influencing the adsorption energy of reaction intermediates. Therefore, achieving the controllable construction and stable existence of oxygen vacancies is one of the effective pathways to improve the electrocatalytic performance of IrO2.

[0005] Existing IrO2 preparation processes include sol-gel, dip-coating pyrolysis, powder loading, magnetron sputtering, and thermal oxidation. However, these methods typically introduce defects through post-treatment (reduction / annealing) or doping, making it difficult to achieve reproducible control with strong coupling to process parameters, and the control of oxygen vacancies is imprecise. Furthermore, nickel foam has complex pores, and solution methods are prone to uneven loading inside and outside the pores, pore blockage, or localized detachment. Linear deposition methods such as sputtering do not adequately cover the complex inner surface of nickel foam.

[0006] In summary, there is an urgent need for a method that can achieve uniform deposition of IrO2 thin films on three-dimensional nickel foam substrates and effectively control oxygen vacancy concentration to improve the electrocatalytic performance of IrO2. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing iridium oxide thin-film electrocatalysts based on chemical vapor deposition and its application. The present invention utilizes chemical vapor deposition to prepare iridium oxide thin-film electrocatalysts. The iridium oxide thin film can be uniformly deposited on a nickel foam substrate, exhibiting good bonding performance with the substrate, and the concentration of oxygen vacancies can be effectively controlled. The resulting iridium oxide thin-film electrocatalyst exhibits high activity and good stability.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for preparing iridium oxide thin film electrocatalysts based on chemical vapor deposition includes the following steps: The iridium oxide thin film electrocatalyst was obtained by chemical vapor deposition of nickel foam using iridium acetylacetone as a reaction precursor. The chemical vapor deposition was carried out under the conditions of a reaction gas and a protective gas, wherein the reaction gas was oxygen and the protective gas was an inert gas. The flow rate of the oxygen was 200~400 mL / min and the flow rate of the inert gas was 100~200 mL / min.

[0009] Preferably, the flow rate ratio of oxygen to inert gas is 1 to 4:1.

[0010] Preferably, the total pressure of the chemical vapor deposition is 0.05~0.1 MPa.

[0011] Preferably, the deposition temperature of the chemical vapor deposition is 400~500℃.

[0012] Preferably, the deposition time of the chemical vapor deposition is 100~200 min.

[0013] Preferably, the chemical vapor deposition includes: placing iridium acetylacetone in the precursor source region and nickel foam in the deposition region; heating and sublimating iridium acetylacetone under inert gas protection, followed by introducing oxygen for chemical vapor deposition; the heating and sublimation temperature is 170~180°C.

[0014] The present invention also provides an iridium oxide thin film electrocatalyst prepared by the method described above, comprising a nickel foam substrate and an iridium oxide thin film supported on the nickel foam substrate.

[0015] Preferably, the thickness of the iridium oxide film is 0.1~5μm.

[0016] The present invention also provides the application of the iridium oxide thin-film electrocatalyst described above in the oxygen evolution reaction of water electrolysis.

[0017] Preferably, the iridium oxide thin-film electrocatalyst operates at 10 mA / cm². 2 The oxygen evolution overpotential at current density is 260~280mV.

[0018] This invention provides a method for preparing iridium oxide thin-film electrocatalysts based on chemical vapor deposition (CVD), comprising the following steps: using iridium acetylacetone (Ir(acac)3) as a reaction precursor to perform CVD on nickel foam (NF) to obtain the iridium oxide thin-film electrocatalyst (denoted as IrO2 / NF catalyst); the CVD is carried out under the conditions of a reaction gas and a protective gas, wherein the reaction gas is oxygen and the protective gas is an inert gas; the flow rate of the oxygen is 200~400 mL / min and the flow rate of the inert gas is 100~200 mL / min. This invention uses CVD to prepare iridium oxide thin films on the surface of nickel foam, and controls the oxygen partial pressure by controlling the flow rates of oxygen and inert gas. By adjusting the oxygen partial pressure, the concentration of oxygen vacancies in the iridium oxide thin film can be controlled, thereby significantly improving the electrocatalytic activity of the iridium oxide thin film. Furthermore, this invention uses CVD to achieve uniform deposition of iridium oxide thin films on the complex surface of nickel foam, ensuring the electrochemical stability of the catalyst, and exhibiting good bonding performance between the film and the nickel foam substrate, resulting in a long service life. The results of the examples show that the iridium oxide thin-film electrocatalyst prepared in this invention exhibits excellent catalytic performance in the OER reaction and demonstrates excellent durability in long-term stability tests. Attached Figure Description

[0019] Figure 1 X-ray diffraction patterns of iridium oxide thin film electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-3; Figure 2 The images show the characterization of the iridium oxide thin film electrocatalyst prepared in Example 1, where the left image is a SEM image, and the middle and right images are energy dispersive spectral mappings of oxygen (O) and iridium (Ir), respectively. Figure 3 These are paramagnetic electron resonance (EPR) images of the iridium oxide thin film electrocatalysts prepared in Examples 1-3; Figure 4 The electrochemical performance and stability test results of the iridium oxide thin film electrocatalysts prepared in Examples 1-3 are shown below, where: (a) is the polarization curve, (b) is the Nyquist plot of electrochemical impedance spectroscopy, (c) is the Tafel curve, and (d) is the long-term stability test curve of the iridium oxide thin film electrocatalyst in Example 1. Detailed Implementation

[0020] This invention provides a method for preparing iridium oxide thin film electrocatalysts based on chemical vapor deposition, comprising the following steps: The iridium oxide thin film electrocatalyst was obtained by chemical vapor deposition of nickel foam using iridium acetylacetone as a reaction precursor. The chemical vapor deposition was carried out under the conditions of a reaction gas and a protective gas, wherein the reaction gas was oxygen and the protective gas was an inert gas. The flow rate of the oxygen was 200~400 mL / min and the flow rate of the inert gas was 100~200 mL / min.

[0021] In this invention, the nickel foam is preferably pretreated before chemical vapor deposition. The pretreatment preferably includes: acid washing, water washing and drying of the nickel foam, followed by ultrasonic treatment, and then water washing and drying again. The reagent used for acid washing is preferably hydrochloric acid solution, and the concentration of the hydrochloric acid solution is preferably 2-4 mol / L, specifically 3 mol / L. The acid washing is preferably carried out under immersion conditions, and the immersion time is preferably 10 min. This invention removes impurities and oxide layers from the surface of the nickel foam by acid washing. The ultrasonic treatment specifically involves ultrasonication in acetone and ethanol for 20 min each.

[0022] In this invention, the oxygen flow rate is preferably 200-400 mL / min, specifically 200, 250, 300, 350, or 400 mL / min; the inert gas flow rate is preferably 100-200 mL / min, specifically 100, 150, or 200 mL / min; the inert gas is preferably argon; and the oxygen to inert gas flow rate ratio is preferably 1-4:1, specifically 1:1, 2:1, or 4:1. In this invention, the formation quality and electrocatalytic performance of the iridium oxide thin film depend on the synergistic matching of oxygen partial pressure and gas flow rate. At the same oxygen partial pressure, a higher oxygen flow rate results in more oxygen molecules being delivered to the substrate surface per unit time, leading to a more sufficient oxygen supply and facilitating the continuous and complete oxidation of the precursor to IrO2. Simultaneously, a higher gas flow rate enhances mass transfer, thins the surface boundary layer, and removes decomposition byproducts more quickly, thereby improving the surface reaction environment. Conversely, a lower oxygen flow rate results in a lower actual oxygen supply rate and byproduct removal efficiency, easily leading to incomplete oxidation or poor film quality. This invention controls the oxygen partial pressure by controlling the flow rates of oxygen and inert gas during chemical vapor deposition, thereby controlling the concentration of oxygen vacancies in the iridium oxide film and forming a high-quality film, thus improving the electrocatalytic activity of iridium oxide.

[0023] In this invention, the total pressure of the chemical vapor deposition is preferably 0.05~0.1MPa, and more specifically, it can be 0.08MPa.

[0024] In this invention, the deposition temperature of the chemical vapor deposition is preferably 400~500℃, specifically 450℃.

[0025] In this invention, the deposition time of the chemical vapor deposition is preferably 100-200 min, specifically 120 min.

[0026] In this invention, the chemical vapor deposition preferably includes: placing iridium acetylacetone in the precursor source region and nickel foam in the deposition region; heating and sublimating iridium acetylacetone under inert gas protection, followed by introducing oxygen for chemical vapor deposition; the heating and sublimation temperature is 170~180℃, specifically 170℃; the temperature of the deposition region is 400~500℃. In a specific embodiment of this invention, it is preferable to place iridium acetylacetone in a quartz boat, and then place the quartz boat in the precursor source region of the chemical vapor deposition apparatus.

[0027] After chemical vapor deposition is completed, the present invention preferably cuts off the precursor, stops the oxygen supply, keeps the flow rate of inert gas constant, cools to room temperature, shuts off the inert gas, and then removes the product.

[0028] The present invention also provides an iridium oxide thin-film electrocatalyst prepared by the method described above, comprising a nickel foam substrate and an iridium oxide thin film supported on the nickel foam substrate; the main component of the iridium oxide thin film is IrO. x It also contains a small amount of metallic Ir; the iridium oxide film contains oxygen vacancies and exhibits excellent electrocatalytic activity.

[0029] In this invention, the thickness of the iridium oxide film is preferably 0.1~5μm, specifically 1μm.

[0030] This invention also provides the application of the iridium oxide thin-film electrocatalyst described above in the oxygen evolution reaction of water electrolysis. In this invention, the iridium oxide thin-film electrocatalyst operates at 10 mA / cm². 2 The oxygen evolution overpotential at current density is 260~280mV.

[0031] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0032] Example 1 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Soak in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h.

[0033] (2) Place Ir(acac)3 in the precursor source region and heat it to the sublimation temperature of 170°C; heat the reactor deposition region to the deposition temperature of 450°C.

[0034] (3) During the heating process of the precursor, the protective carrier gas is Ar, and the Ar flow rate is 200 mL / min. When the precursor is heated to 170 °C, O2 is introduced, and the O2 flow rate is 400 mL / min. The system is deposited for 120 min under a total pressure of P=0.08 MPa.

[0035] (4) After the deposition is completed, the precursor is cut off, the O2 supply is stopped, the Ar atmosphere flow rate is kept constant, the cooling rate is kept slow, the Ar is turned off after the temperature is reduced to room temperature, the sample is taken out, and the foam nickel skeleton continuously covered by the iridium oxide film is obtained, which is the iridium oxide film electrocatalyst.

[0036] Example 2 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Soak in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h.

[0037] (2) Place Ir(acac)3 in the precursor source region and heat it to the sublimation temperature of 170°C; heat the reactor deposition region to the deposition temperature of 450°C.

[0038] (3) During the heating process of the precursor, the protective carrier gas is Ar, and the Ar flow rate is 100 mL / min. When the precursor is heated to 170 °C, O2 is introduced, and the O2 flow rate is 400 mL / min. The system is deposited for 120 min under a total pressure of P=0.08 MPa.

[0039] (4) After the deposition is completed, the precursor is cut off, the O2 supply is stopped, the Ar atmosphere flow rate is kept constant, the cooling rate is kept slow, the Ar is turned off after the temperature is reduced to room temperature, the sample is taken out, and the foam nickel skeleton continuously covered by the iridium oxide film is obtained, which is the iridium oxide film electrocatalyst.

[0040] Example 3 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Soak in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h.

[0041] (2) Place Ir(acac)3 in the precursor source region and heat it to the sublimation temperature of 170°C; heat the reactor deposition region to the deposition temperature of 450°C.

[0042] (3) During the heating process of the precursor, the protective carrier gas is Ar, and the Ar flow rate is 200 mL / min. When the precursor is heated to 170 °C, O2 is introduced, and the O2 flow rate is 200 mL / min. The system is deposited for 120 min under a total pressure of P=0.08 MPa.

[0043] (4) After the deposition is completed, the precursor is cut off, the O2 supply is stopped, the Ar atmosphere flow rate is kept constant, the cooling rate is kept slow, the Ar is turned off after the temperature is reduced to room temperature, the sample is taken out, and the foam nickel skeleton continuously covered by the iridium oxide film is obtained, which is the iridium oxide film electrocatalyst.

[0044] Comparative Example 1 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Soak in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h.

[0045] (2) Place Ir(acac)3 in the precursor source region and heat it to the sublimation temperature of 170°C; heat the reactor deposition region to the deposition temperature of 450°C.

[0046] (3) During the heating process of the precursor, the protective carrier gas is Ar, and the Ar flow rate is 300 mL / min. When the precursor is heated to 170 ℃, O2 is introduced, and the O2 flow rate is 100 mL / min. The system is deposited for 120 min under a total pressure of P=0.08 MPa.

[0047] (4) After the deposition is completed, the precursor is cut off, the O2 supply is stopped, the Ar atmosphere flow rate is kept constant, the cooling rate is kept slow, the Ar is turned off after the temperature is reduced to room temperature, the sample is taken out, and the foam nickel skeleton continuously covered by the iridium oxide film is obtained, which is the iridium oxide film electrocatalyst.

[0048] Comparative Example 2 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Soak in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h.

[0049] (2) Place Ir(acac)3 in the precursor source region and heat it to the sublimation temperature of 170°C; heat the reactor deposition region to the deposition temperature of 450°C.

[0050] (3) No protective carrier gas is introduced during the heating of the precursor (i.e., the Ar flow rate is 0). When the precursor is heated to 170°C, O2 is introduced at a flow rate of 400 mL / min. Deposition is carried out for 120 min at a system pressure of P=0.08 MPa, which is the iridium oxide thin film electrocatalyst. (4) After deposition, the precursor is cut off, the O2 supply is stopped, and a slow cooling rate is maintained. After cooling to room temperature, the sample is taken out, and a foam nickel skeleton continuously covered by iridium oxide thin film is obtained, which is the iridium oxide thin film electrocatalyst.

[0051] Comparative Example 3 (1) Using nickel foam as the substrate, nickel foam (20mm) 20mm (1.5mm) Immerse in 3 M HCl for 10 min to remove surface impurities and oxide layer, then wash with deionized water until neutral and dry. Then sonicate with acetone and ethanol for 20 min each, then rinse with deionized water until neutral and dry at 60℃ for 12 h. (2) Place Ir(acac)3 in the precursor source area and heat to the sublimation temperature of 170℃; heat the reactor deposition area to the deposition temperature of 450℃. (3) During the heating process of the precursor, the protective carrier gas is Ar, and the Ar flow rate is 100 mL / min. When the precursor is heated to 170℃, O2 is introduced, and the O2 flow rate is 200 mL / min. Deposition is carried out for 120 min at a total system pressure of P=0.08 MPa. (4) After the deposition is completed, the precursor is cut off, the O2 supply is stopped, the Ar atmosphere flow rate is kept constant, the cooling rate is kept slow, the Ar is turned off after the temperature is reduced to room temperature, the sample is taken out, and the foam nickel skeleton continuously covered by the iridium oxide film is obtained, which is the iridium oxide film electrocatalyst.

[0052] Test case The iridium oxide thin-film electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-3 were characterized and their performance was tested. The results are as follows: 1. X-ray diffraction test Figure 1 X-ray diffraction patterns of iridium oxide thin film electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-3.

[0053] according to Figure 1It can be seen that the catalysts of Examples 1-3 and Comparative Examples 1-3 all exhibit multiple distinct diffraction peaks in the range of 20° to 80°. According to the standard PDF card comparison, the main phases include iridium oxide (IrO2, PDF#01-086-0330), metallic iridium (Ir, PDF#01-071-4659), and the Ni metal peak (PDF#01-071-3740) that appears in the samples.

[0054] Characteristic IrO2 diffraction peaks ((110), (101), (211) crystal planes, etc.) located at approximately 28.0°, 34.5°, and 54.0° were observed in samples 1-3 and comparative examples 2-3, indicating that iridium oxide structures were successfully deposited. Samples 1-3 showed IrO2 as the main characteristic phase. In comparative examples 2-3, characteristic IrO2 peaks were observed, but accompanied by metallic Ir signals. Comparative example 1, however, mainly showed a metallic Ir phase with indistinct IrO2 peaks. This suggests that under low oxygen partial pressure or reducing conditions, the Ir precursor was not completely oxidized, retaining some metallic Ir. This incomplete oxidation not only weakens the purity of the IrO2 phase but also affects the formation and distribution of oxygen vacancies, thus adversely impacting electrocatalytic activity.

[0055] Further analysis of the intensity and width changes of the diffraction peaks revealed that the main diffraction peak of IrO2 in samples 1-3 was significantly broadened and its intensity decreased compared to the comparative samples, with the most significant change observed in Sample 1. The increased peak width reflects a decrease in grain size and enhanced structural inhomogeneity; the decreased peak intensity indicates a decrease in material crystallinity and an increase in the number of defects. Combined with Scherrer equation analysis, this indicates that the sample from the examples has smaller grain size and a looser structure, exhibiting a higher level of lattice defects, particularly oxygen vacancies. Oxygen vacancies, as lattice point defects, cause local lattice distortion and stress concentration, which manifests as peak broadening and slight positional shifts in the XRD patterns. Combining this with EPR test results, it can be confirmed that Sample 1 had the highest oxygen vacancy concentration, the largest XRD peak width, and the weakest peak intensity, exhibiting typical characteristics of high defect rate and high specific surface area.

[0056] In summary, by appropriately adjusting the CVD process parameters (oxygen partial pressure conditions), Examples 1-3 not only effectively formed a catalytic phase dominated by IrO2, but also introduced a high concentration of oxygen vacancies and nanoscale grain structure, which is beneficial to improving the density of surface active sites and charge transfer ability, thereby significantly enhancing its electrocatalytic performance.

[0057] 2. Scanning electron microscopy and elemental distribution testing Figure 2 The images show the characterization of the iridium oxide thin-film electrocatalyst prepared in Example 1, with the left image being a SEM image, and the middle and right images being energy dispersive spectral mappings of oxygen (O) and iridium (Ir), respectively.

[0058] according to Figure 2 The left image shows that iridium oxide forms a uniformly arranged nanorod / nanofacial structure on the surface of nickel foam, exhibiting vertical growth characteristics, which is beneficial for increasing the specific surface area. According to... Figure 2 As can be seen from the middle and right figures, the two elements are evenly distributed throughout the structure, indicating that IrO2 was successfully deposited on the substrate surface and formed a good capping layer, providing a continuous and uniform active surface for subsequent electrocatalytic reactions.

[0059] 3. EPR test Figure 3 The images show the paramagnetic electronic resonance (EPR) images of the iridium oxide thin film electrocatalysts prepared in Examples 1-3.

[0060] like Figure 3 As shown, the location of a typical oxygen vacancy signal at g ≈ 2.00 in the EPR spectrum. In contrast, under the moderate oxygen partial pressure condition in Example 2, the EPR signal intensity is significantly higher than that under the high oxygen partial pressure condition in Example 1 and the low oxygen partial pressure condition in Example 3, indicating that the sample has the highest concentration of oxygen vacancies under this condition. This result shows that the oxygen vacancy concentration does not change monotonically with oxygen partial pressure during the CVD preparation of iridium oxide. This phenomenon may be attributed to the fact that the iridium oxide structure formed under the moderate oxygen partial pressure in Example 2 is in a non-stoichiometric state (IrO2-δ), allowing stable oxygen vacancies to be embedded in the lattice, especially shallow vacancies on the surface. Under high oxygen partial pressure, the strong oxidizing environment promotes the complete oxidation of Ir to Ir. 4+ This inhibits the formation of oxygen vacancies; however, under low oxygen partial pressure, due to insufficient oxidation of the Ir precursor, it is difficult to form a complete iridium oxide crystal structure, thus limiting the formation and stability of oxygen vacancies.

[0061] 4. Electrochemical performance testing The electrochemical performance of iridium oxide thin-film electrocatalysts was evaluated using a three-electrode system. The three-electrode system consists of a working electrode (WE), a counter electrode (CE), and a reference electrode (RE), which allows for the measurement of the current response during the reaction process under stable electrode potential control, thereby obtaining reliable electrochemical test data.

[0062] In the electrochemical performance testing, the iridium oxide thin-film electrocatalyst sample was used directly as the working electrode. The nickel foam was cut to a size of 1 cm × 1.5 cm, with approximately 0.5 cm used for clamping and conductive connections, resulting in an effective area of ​​1 cm × 1 cm for the actual electrochemical reaction. During testing, the working electrode was fixed with a clamp and connected to the electrochemical workstation. A platinum sheet (Pt sheet) was used as the counter electrode to ensure the stability of current transfer during testing. A 1 M KOH solution was used as the electrolyte, and electrochemical performance testing was conducted under alkaline conditions. A Hg / HgO electrode was used as the reference electrode, and the obtained potentials were uniformly converted to a reversible hydrogen electrode (RHE) during data processing. All electrochemical tests were performed at room temperature. The electrocatalytic performance of iridium oxide electrodes prepared under different deposition conditions was characterized and compared using methods such as polarization curves, electrochemical impedance spectroscopy, and constant current stability testing. Untreated bare nickel foam was used as a control during testing.

[0063] Test results are as follows Figure 4 As shown, Figure 4 In the figure, (a) is the polarization curve; (b) is the Nyquist plot of electrochemical impedance spectroscopy; (c) is the Tafel curve; and (d) is the long-term stability test curve of the iridium oxide thin film electrocatalyst in Example 1.

[0064] Depend on Figure 4 polarization curves in Figure 4 As can be seen in (a) at the same potential, the current response of samples 1-3 is significantly higher than that of comparative samples 1-3, and much higher than that of the bare Ni substrate. Among them, the current density of sample 1 is the highest, indicating that its oxygen evolution reaction activity is superior; Electrochemical impedance spectroscopy Nyquist plot ( Figure 4 In Example 1 (b), the semi-circular radius is the smallest, indicating lower charge transfer resistance and faster interfacial electron transport; Tafel curve ( Figure 4 (c) shows that the Tafel slope of Example 1 is approximately 115 mV·dec. -1 This is lower than that of Example 2 (approximately 143 mV·dec). -1 ) and Example 3 (approximately 119 mV·dec) -1 This indicates that Example 1 has faster reaction kinetics; long-term stability test curves ( Figure 4 The results (d) show that the potential remained basically stable with minimal fluctuations over approximately 200 h, indicating that the catalyst of Example 1 has good operational stability and durability.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing iridium oxide thin film electrocatalysts based on chemical vapor deposition, characterized in that, Includes the following steps: The iridium oxide thin film electrocatalyst was obtained by chemical vapor deposition of nickel foam using iridium acetylacetone as a reaction precursor. The chemical vapor deposition was carried out under the conditions of a reaction gas and a protective gas, wherein the reaction gas was oxygen and the protective gas was an inert gas. The flow rate of the oxygen was 200~400 mL / min and the flow rate of the inert gas was 100~200 mL / min.

2. The method according to claim 1, characterized in that, The flow rate ratio of oxygen to inert gas is 1 to 4:

1.

3. The method according to claim 1, characterized in that, The total pressure of the chemical vapor deposition is 0.05~0.1 MPa.

4. The method according to claim 1, characterized in that, The deposition temperature for the chemical vapor deposition is 400~500℃.

5. The method according to claim 1, characterized in that, The deposition time for the chemical vapor deposition is 100-200 min.

6. The method according to claim 1, characterized in that, The chemical vapor deposition includes: placing iridium acetylacetone in the precursor source region and nickel foam in the deposition region; heating and sublimating iridium acetylacetone under inert gas protection, followed by introducing oxygen for chemical vapor deposition; the heating and sublimation temperature is 170~180℃.

7. The iridium oxide thin-film electrocatalyst prepared by the method according to any one of claims 1 to 6, characterized in that, It includes a nickel foam substrate and an iridium oxide film loaded on the nickel foam substrate.

8. The iridium oxide thin-film electrocatalyst according to claim 7, characterized in that, The thickness of the iridium oxide film is 0.1~5μm.

9. The application of the iridium oxide thin-film electrocatalyst according to claim 7 or 8 in the oxygen evolution reaction of water electrolysis.

10. The application according to claim 9, characterized in that, The iridium oxide thin-film electrocatalyst operates at 10 mA / cm². 2 The oxygen evolution overpotential at current density is 260~280mV.

Images