Preparation method of Au-doped iridium-based supported catalyst

Abstract

The application belongs to the field of hydrogen production by water electrolysis, and relates to a preparation method of an Au-doped iridium-based supported catalyst. The carrier of the Au-doped iridium-based supported catalyst is anatase TiO2 with a mesoporous sheet structure with a high specific surface area, and the iridium and gold nanoclusters are uniformly covered on the carrier. The preparation method comprises the following steps: reducing titanium ions by an ethylene glycol solvothermal method to generate a mesoporous sheet-shaped titanium oxide carrier with a high specific surface area; and generating the Au-doped iridium-based supported catalyst by using an improved co-precipitation method. The catalyst prepared by the application has high OER catalytic performance, and the overpotential can be as low as 230 mV under a current density of 10 mA·cm ‑2 . The catalyst can be stably operated for 500 h under a current density of 1 A·cm ‑2 , and the attenuation rate is only 0.19 mV·h ‑1 . The production process is simple, the preparation time is short, the repeatability is high, and the catalyst is beneficial to the large-scale production of OER electrodes in the field of hydrogen production by water electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production by water electrolysis, and specifically relates to a method for preparing an Au-doped iridium-based supported catalyst. Background Technology

[0002] In recent years, humanity's over-reliance on and excessive consumption of fossil fuels have led to numerous serious environmental problems. In light of this, hydrogen energy, due to its unique advantages of being clean and pollution-free, is widely considered one of the most promising renewable energy sources of the 21st century. Compared to "gray hydrogen" and "blue hydrogen" technologies, "green hydrogen" technology, which produces hydrogen through water electrolysis using renewable energy, represents the most promising solution for achieving a sustainable hydrogen economy.

[0003] Currently, the main technical routes for "green hydrogen" include alkaline (ALK) water electrolysis, proton exchange membrane (PEM) water electrolysis, high-temperature solid oxide (SOEC) water electrolysis, and anion exchange membrane (AEM) water electrolysis. Among them, PEM water electrolysis has attracted much attention due to its advantages such as good gas separation effect, high hydrogen purity, and high current density. However, the oxygen evolution reaction (OER) at the anolyte of PEM water electrolysis must undergo a four-electron coupling reaction, which is slow and energy-intensive. Therefore, it is urgent to design a highly efficient OER electrocatalyst to reduce its overpotential. In addition, the proton exchange membrane in PEM water electrolysis will generate a local high acid environment, which will make the OER catalyst prone to severe degradation and peroxidation under long-term operation, affecting its sustainable application [Advanced Materials, 2023, 35(22), 2210565]. Considering the OER activity and corrosion resistance of the material, the anode material that can be used for hydrogen production by PEM water electrolysis should first be a noble metal iridium (Ir) based catalyst. Ir is one of the rarest elements in the Earth's crust and is very expensive. To improve the utilization rate of Ir active sites, Ir is supported on a carrier with a suitable specific surface area to enhance its dispersion and thus improve its OER quality activity. This patent specifies the preparation of an Ir-based supported catalyst (Ir@TiO2) using self-made titanium dioxide (TiO2). A suitable specific surface area and pore distribution can provide a large number of growth sites and sufficient internal diffusion channels for the metal element.

[0004] With in-depth research on OER catalysts for PEM water electrolysis to produce hydrogen, Ir@TiO2 with a second metal component has shown great potential in improving the stability of OER catalysts. Studies have shown that by introducing a second metal component, the electronic structure of the catalyst can be tuned, thereby improving both the intrinsic activity and the stability of the catalyst in PEM water electrolysis. Currently, transition metals such as tungsten, molybdenum, chromium, vanadium, and manganese are often used to dope TiO2 supports; however, these metal elements are easily lost in highly acidic environments, leading to corrosion of PEM electrolyzer components. There are still many challenges in second metal doping. On the one hand, the interaction mechanisms between different metal elements and Ir are complex, making it difficult to precisely control their electronic structure to achieve optimal stability; on the other hand, in actual operation, the long-term stability of the catalyst is still affected by the localized highly acidic environment of the proton exchange membrane, resulting in a limited selection of suitable second metal components.

[0005] Against this backdrop, the introduction of Au offers a new approach to solving the aforementioned problems. Au possesses a unique electronic structure and excellent antioxidant properties, enabling the continuous adjustment of the catalyst's electronic structure to effectively enhance its stability. Specifically, Au exhibits extremely high electronegativity and a low work function; Au doping can optimize the electron cloud distribution of Ir and enhance the interaction between Ir and the TiO2 support, thereby improving Ir dispersion and stability. Furthermore, Au demonstrates superior stability under highly acidic environments compared to many other metal elements, effectively mitigating catalyst degradation during PEM water electrolysis. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a method for preparing an Au-doped iridium-based supported catalyst. The support is anatase TiO2 with a lamellar structure and a specific surface area of ​​up to 144.11 m². 2 The catalyst, with a pore size distribution primarily mesoporous (6.2 nm), exhibits Ir and Au nanoclusters uniformly covering the support, demonstrating high oxygen evolution electrochemical activity and stability, making it suitable for use as an anode in PEM water electrolysis. This invention aims to develop a highly efficient and stable OER catalyst to promote the development of PEM water electrolysis for hydrogen production. The advantages of this invention are: the use of an improved co-precipitation ethylene glycol reduction method, where the ethylene glycol solvent possesses certain reducing properties and viscosity, allowing control over the reduction rate of the metal complex, thereby controlling the nucleation rate of Ir and Au nanoclusters, as well as their deposition rate and dispersion on the support. The prepared OER catalyst exhibits high OER reactivity and stability at 10 mA·cm⁻¹. -2 The overpotential can be as low as 230mV, at 1A·cm -2 It can operate stably for 500 hours with a decay rate of only 0.19 mV·h. -1The production process is simple, the preparation time is short, and the repeatability is high, which is conducive to the batch preparation of OER electrodes in the field of water electrolysis for hydrogen production.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing an Au-doped iridium-based supported catalyst, comprising the following steps:

[0009] (1) Ethylene glycol reduction of metal ions: Iridium salt is dissolved in ethylene glycol to prepare solution A; gold salt is dissolved in ethylene glycol to prepare solution B; after stirring evenly, a certain amount of solution A and solution B are mixed and stirred evenly to prepare metal precursor solution C;

[0010] (2) Ethylene glycol reduction of titanium ions: Titanium salt is dissolved in ethylene glycol, then water is added to prepare solution D, and then a solvothermal reaction is carried out. After maintaining a certain temperature and time, the temperature is lowered to obtain the precipitate. After washing and drying, TiO2 support is obtained.

[0011] (3) Preparation process of Au-doped iridium-based supported catalyst: The TiO2 support obtained in step (2) is uniformly dispersed in ethylene glycol to prepare dispersion E; the alkaline substance is dissolved in ethylene glycol to prepare solution F; then the pH of solution E is adjusted to alkaline by solution F to obtain support dispersion G; solution C in step (1) is slowly added dropwise to dispersion G to prepare dispersion H with a certain metal loading; the uniformly dispersed dispersion H is heated to a certain temperature and kept at that temperature for a certain time, and then cooled to a certain temperature before separation, washing and drying to obtain Au-doped iridium-based supported catalyst.

[0012] Furthermore, in step (1), the iridium salt in solution A is one or a mixture of two or more of the following: iridium chloroiridic acid, hydrated iridium chloroiridic acid, iridium trichloride, iridium tetrachloride, iridium acetate, ammonium chloroiridate, potassium hexachloroiridate, and iridium acetylacetonate. The molar concentration of the iridium salt in solution A is 0.1–20 mmol·L⁻¹. -1 The gold salt in solution B is one or a mixture of two or more of the following: gold chloride, hydrated gold chloride, chloroauric acid, potassium chloroaurate, gold nitrate, sodium gold sulfite, and gold iodide. The molar concentration of the gold salt in solution B is 0.01–20 mmol·L⁻¹. -1 The molar ratio of iridium salt to gold salt in solution C is 14:1 to 3:2.

[0013] Furthermore, in step (2), the titanium salt in solution D is one or more of titanium tetrachloride, titanium trichloride, tetrabutyl titanate, and titanium butoxide, and the molar concentration of the titanium salt in solution D is 0.01–20 mol·L⁻¹. -1The molar ratio of titanium salt, ethylene glycol, and deionized water is 1:(5–500):(1–200). The solvothermal reaction temperature is 100–400℃, and the holding time is 0.5–48 h. The drying method is one or a combination of two or more of the following: forced air drying, freeze drying, and vacuum drying, and the drying time is 1–48 h. The drying atmosphere is an inert gas.

[0014] Furthermore, in step (3), the molar concentration of TiO2 in the dispersion E is 0.01–20 mmol·L⁻¹. -1 The alkaline substance in solution F is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, and ammonia water, and the molar concentration of the alkaline substance in solution F is 0.1–5 mol·L⁻¹. -1 The pH of solution G is 7–14. The dropping rate of solution C is 0.01–50 mL / min. -1 The heating temperature of dispersion H is 100–300℃, and the holding time is 0.5–24 h. After the reaction is complete, the mixed solution is cooled to 20–90℃. The separation method is one or a combination of centrifugation, vacuum filtration, and rotary evaporation. The drying method is one or a combination of vacuum drying, forced air drying, spray drying, and freeze drying, and the drying time is 3–48 h.

[0015] The Au-doped iridium-based supported catalyst prepared by the method of this invention has the morphology of iridium and gold nanoclusters uniformly covering a self-made TiO2 support. The nanoclusters have a particle size of approximately 1 nm. XRD patterns show broad diffraction peaks at 2θ = 25.3° and 2θ = 38.18°, corresponding to the (101) crystal plane of the anatase TiO2 nanocrystals and the (111) crystal plane of the Au nanocrystals, respectively. The Ir element exhibits an amorphous morphology. Only a 230 mV overpotential is required in the OER to achieve a 10 mA cm⁻¹ ionization potential. -2 The current density and mass activity are 690 A / g Ir @275mV. Electrolyzing water with PEM at 1Acm -2 The current density can operate stably for 500 hours, with a decay rate of only 0.19 mV·h. -1 .

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) In the preparation process of this invention, ethylene glycol is used instead of the organic surfactants that must be used in other technologies, and the raw materials are simple. Ethylene glycol is used as a solvent and dispersant, and its viscosity acts as a spatial barrier to a certain extent, which controls the growth of iridium nanoclusters on the carrier, resulting in stable anti-flocculation performance and good shape uniformity.

[0018] (2) The titanium oxide support prepared by the present invention forms a mesoporous sheet structure, which is conducive to the formation of continuous electron network channels on the surface and provides sufficient diffusion and conduction channels within the material.

[0019] (3) The titanium oxide support prepared by the present invention has a high specific surface area, which is conducive to the high dispersion and high loading of the active component Ir on the support, providing sufficient reaction sites for intermediates, thereby improving its electrocatalytic performance.

[0020] (4) The titanium oxide carrier prepared by the present invention has excellent corrosion resistance, which is beneficial to the practical application of PEM electrolysis of water.

[0021] (5) The Au-doped iridium-based supported catalyst prepared in this invention uses ethylene glycol as a reducing agent and dispersant, which is beneficial to the uniform adsorption of Ir and Au nanoclusters on the support surface. The anchoring effect of the support on metal atoms strongly reduces the aggregation tendency of atomic-level metal nanoparticles in the OER process, and achieves high dispersion of Ir and Au on the support surface.

[0022] (6) This invention selects Au as the dopant element, which has strong resistance to acid corrosion, high electronegativity, and low work function. It can optimize the electron cloud distribution of Ir and enhance the interaction between Ir and TiO2 support, thereby improving the dispersion and stability of Ir.

[0023] (7) The Au-doped iridium-based supported catalyst prepared in this invention uses a co-precipitation method to support Ir and Au, and utilizes the interaction between Ir and Au to effectively achieve cluster-level uniform dispersion.

[0024] (8) The interaction between the metal and the support is conducive to spontaneously adjusting the electronic structure of the active component, thereby improving the mass activity of iridium.

[0025] (9) This method does not require calcination, thus avoiding the collapse of carrier pores and aggregation of active sites caused by calcination.

[0026] (10) The synthesis process of the Au-doped iridium-based supported catalyst prepared by this method is simple, the preparation time is short and the repeatability is high, which is beneficial to the batch preparation of OER electrodes in the field of water electrolysis for hydrogen production. Attached Figure Description

[0027] Figure 1 This is a TEM image of the TiO2 carrier in Embodiment 1 of the present invention.

[0028] Figure 2 These are BET images and pore size distribution images of the TiO2 carrier in Embodiment 1 of the present invention.

[0029] Figure 3This is an XRD image of the TiO2 carrier in Embodiment 1 of the present invention.

[0030] Figure 4 This is a TEM image of the Au-doped iridium-based supported catalyst in Example 1 of this invention.

[0031] Figure 5 This is a mapping image of Ir, Au, Ti, and O elements in the Au-doped iridium-based supported catalyst in Example 1 of this invention.

[0032] Figure 6 This is an XRD image of the Au-doped iridium-based supported catalyst in Example 1 of this invention.

[0033] Figure 7 This is a comparison diagram of the OER polarization curves of Embodiment 1 and Embodiment 4 of the present invention.

[0034] Figure 8 This is a comparison diagram of the OER polarization curves of Embodiment 1 and the comparative example of the present invention.

[0035] Figure 9 This is a comparison chart of the durability test curves of Embodiment 1 and the comparative example in the PEM electrolyzer. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0037] Example 1:

[0038] (1) Ethylene glycol reduction of metal ions: Iridium tetrachloride was dissolved in ethylene glycol to prepare a solution with a molar concentration of 5.8 mmol·L⁻¹. -1 Solution A: Gold chloride was dissolved in ethylene glycol to prepare a solution with a molar concentration of 9.2 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 7:1;

[0039] (2) Ethylene glycol reduction of titanium ions: 9.2 mmol of titanium tetrachloride was dissolved in ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 19.8 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:197:63, was transferred to an autoclave for a solvothermal reaction at 200°C for 24 hours. The solution was then cooled to obtain a precipitate, which was continuously washed with water and ethanol before being dried in a 60°C vacuum drying oven for 12 hours to obtain the TiO2 support.

[0040] (3) Preparation process of Au-doped iridium-based supported catalyst: The TiO2 support obtained in step (2) was uniformly dispersed in ethylene glycol to prepare a TiO2 molar concentration of 6.2 mmol·L⁻¹. -1 Dispersion E; sodium hydroxide was dissolved in ethylene glycol to prepare a concentration of 0.7 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 8 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 0.5 mL / min. -1 Dispersion G was added dropwise to prepare dispersion H, which was then heated to 170°C and kept at that temperature for 3 hours. After cooling to room temperature, the catalyst was separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst, named Ir7Au1@TiO2.

[0041] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 230mV@10mA·cm. -2 .

[0042] Figure 1 This is a TEM image of the TiO2 carrier in Example 1 of the present invention; the morphology is nanosheets.

[0043] Figure 2 This is a BET image of the TiO2 carrier in Embodiment 1 of the present invention; the specific surface area can reach 144.11 m². 2 / g, the pore size distribution is mainly mesoporous (6.2nm).

[0044] Figure 3 This is an XRD image of the carrier TiO2 in Example 1 of the present invention; its diffraction peaks correspond to those of anatase TiO2 (PDF#21-1272).

[0045] Figure 4 This is a TEM image of the Au-doped iridium-based supported catalyst in Example 1 of the present invention; the morphology is that Ir and Au nanoclusters are uniformly covered on a high specific surface area of ​​sheet-like TiO2.

[0046] Figure 5 This is a mapping image of Ir, Au, Ti, and O elements in the Au-doped supported iridium-based catalyst in Example 1 of the present invention; it shows that Ir, Au, Ti, and O elements are uniformly dispersed.

[0047] Figure 6This is an XRD image of the Au-doped iridium-based supported catalyst in Example 1 of this invention; it shows broad diffraction peaks at 2θ = 25.3° and 2θ = 38.18°, corresponding to the (101) crystal plane of the anatase TiO2 nanoparticles and the (111) crystal plane of the Au nanoparticles, respectively. The Ir element is in an amorphous state. Due to the high loading of metal elements, the originally weak peaks of the anatase TiO2 support are masked by the recombination between substances.

[0048] Example 2:

[0049] (1) Ethylene glycol reduction of metal ions: Ammonium chloroiridate is dissolved in ethylene glycol to prepare a solution with a molar concentration of 0.6 mmol·L⁻¹. -1 Solution A; dissolve gold chloride hydrate in ethylene glycol to prepare solution B with a molar concentration of 1.2 mmol·L⁻¹; after stirring each solution thoroughly, mix solution A and solution B and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 14:3.

[0050] (2) Ethylene glycol reduction of titanium ions: 7.9 mmol of tetrabutyl titanate was dissolved in ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 6.3 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:407:52, was transferred to an autoclave for a solvothermal reaction at 230°C for 32 hours. The solution was then cooled to obtain a precipitate, which was continuously washed with water and ethanol before being dried in a 70°C vacuum drying oven for 12 hours to obtain the TiO2 support.

[0051] (3) Preparation process of Au-doped iridium-based supported catalyst: TiO2 obtained in step (2) is uniformly dispersed in ethylene glycol to prepare a titanium dioxide molar concentration of 17.4 mmol·L⁻¹. -1 Dispersion E; ammonia water was dissolved in ethylene glycol to prepare a molar concentration of 0.5 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 11 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 0.02 mL / min. -1 Dispersion G was added dropwise to prepare dispersion H, which was then heated to 170°C and kept at that temperature for 5 hours. The mixture was then cooled to room temperature, rotary evaporated, washed, and dried by forced air for 45 hours to obtain an Au-doped iridium-based supported catalyst.

[0052] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 233mV@10mA·cm. -2 .

[0053] Example 3:

[0054] (1) Ethylene glycol reduction of metal ions: Iridium acetate was dissolved in ethylene glycol to prepare a solution with a molar concentration of 17.5 mmol·L⁻¹. -1 Solution A: Chloroauric acid was dissolved in ethylene glycol to prepare a solution with a molar concentration of 9.9 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 14:1;

[0055] (2) Ethylene glycol reduction of titanium ions: 9.1 mmol of titanium trichloride was dissolved in an ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 10.8 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:200:62, was transferred to an autoclave for a solvothermal reaction at 190°C for 38 hours. After cooling, a precipitate was obtained, which was continuously washed with water and ethanol and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a titanium oxide support.

[0056] (3) Preparation process of Au-doped iridium-based supported catalyst: The titanium dioxide obtained in step (2) is uniformly dispersed in ethylene glycol to prepare a titanium dioxide molar concentration of 0.08 mmol·L⁻¹. -1 Dispersion E; Lithium hydroxide and sodium hydroxide were dissolved in ethylene glycol to prepare a concentration of 4.7 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 13 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 28 mL / min. -1 Dispersion G was added dropwise, then heated to 300℃ and kept at that temperature for 0.5h. The mixture was then cooled to room temperature, separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst.

[0057] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 242mV@10mA·cm. -2 .

[0058] Example 4:

[0059] (1) Ethylene glycol reduction of metal ions: Potassium hexachloroiridate was dissolved in ethylene glycol to prepare a solution with a molar concentration of 19.6 mmol·L⁻¹. -1 Solution A: Potassium chloroaurate was dissolved in ethylene glycol to prepare a solution with a molar concentration of 19.2 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 6:1;

[0060] (2) Ethylene glycol reduction of titanium ions: 11.8 mmol of titanium butoxide was dissolved in an ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 0.1 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:106:10, was transferred to an autoclave for a solvothermal reaction at 120°C for 48 hours. After cooling, a precipitate was obtained, which was continuously washed with water and ethanol and then freeze-dried for 24 hours to obtain the TiO2 support.

[0061] (3) Preparation process of Au-doped iridium-based supported catalyst: The TiO2 obtained in step (1) was uniformly dispersed in ethylene glycol to prepare a TiO2 molar concentration of 6.8 mmol·L⁻¹. -1 Dispersion E; sodium hydroxide was dissolved in ethylene glycol to prepare a concentration of 0.1 mol·L⁻¹. -1 Solution F; then adjust the pH of solution G to 12 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 48 mL / min. -1 Dispersion G was added dropwise to prepare dispersion H, which was then heated to 110°C and kept at that temperature for 24 hours. After cooling to room temperature, the catalyst was separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst, named Ir6Au1@TiO2.

[0062] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 256mV@10mA·cm. -2 .

[0063] Figure 7 This is a comparison of the OER polarization curves of Embodiments 1 and 4 of the present invention. At 10 mA cm⁻¹ -2 At the given current density, the potential of Ir7Au1@TiO2 is 1.46V and the overpotential is 230mV; the potential of Ir6Au1@TiO2 is 1.48V and the overpotential is 256mV.

[0064] Example 5:

[0065] (1) Ethylene glycol reduction of metal ions: hydrated chloroiridic acid was dissolved in ethylene glycol to prepare a solution with a molar concentration of 5.9 mmol·L⁻¹. -1 Solution A: Gold nitrate was dissolved in ethylene glycol to prepare a solution with a molar concentration of 6.2 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B together and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 7:2.

[0066] (2) Ethylene glycol reduction of titanium ions: 4.1 mmol of tetrabutyl titanate and titanium butoxide were dissolved in ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 0.07 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:500:194, was transferred to an autoclave for a solvothermal reaction at 165°C for 12 hours. After cooling, a precipitate was obtained, which was continuously washed with water and ethanol and then dried in a vacuum drying oven for 24 hours to obtain the TiO2 support.

[0067] (3) Preparation process of Au-doped iridium-based supported catalyst: The TiO2 obtained in step (2) was uniformly dispersed in ethylene glycol to prepare a TiO2 molar concentration of 4.2 mmol·L⁻¹. -1 Dispersion E; sodium hydroxide was dissolved in ethylene glycol to prepare a concentration of 0.7 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 10 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 1 mL·min -1Dispersion G was added dropwise to prepare dispersion H, which was then heated to 175°C and kept at that temperature for 3 hours. The temperature was then lowered to 90°C, and the catalyst was separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst.

[0068] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 235mV@10mA·cm. -2 .

[0069] Example 6:

[0070] (1) Ethylene glycol reduction of metal ions: Hydrated chloroiridic acid and ammonium chloroiridate are dissolved in ethylene glycol to prepare a solution with a molar concentration of 11.9 mmol·L⁻¹. -1 Solution A: Dissolve sodium gold sulfite in ethylene glycol to prepare a solution with a molar concentration of 0.12 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 3:2;

[0071] (2) Ethylene glycol reduction of titanium ions: 9.3 mmol of titanium trichloride was dissolved in ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 0.08 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:400:62, was transferred to an autoclave for a solvothermal reaction at 150°C for 12 hours. After cooling, a precipitate was obtained, which was continuously washed with water and ethanol and then dried in a vacuum drying oven at 60°C for 24 hours to obtain the TiO2 support.

[0072] (3) Preparation process of Au-doped iridium-supported catalyst: The TiO2 obtained in step (2) was uniformly dispersed in ethylene glycol to prepare a TiO2 molar concentration of 8.2 mmol·L⁻¹. -1 Dispersion E; sodium hydroxide was dissolved in ethylene glycol to prepare a concentration of 2.5 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 11 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 20 mL / min. -1 Dispersion G was added dropwise to prepare dispersion H, which was then heated to 200°C and kept at that temperature for 7 hours. After cooling to room temperature, the catalyst was separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst.

[0073] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. A suitable amount of the catalyst obtained in (2) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode as the counter electrode. 0.5 M H₂SO₄ was used as the acidic electrolyte, the test temperature was 25 °C, and a linear scan was performed at a scan rate of 1 mV / s. Under these preparation conditions, the catalyst had an overpotential of only 233 mV@10 mA·cm⁻¹. -2 .

[0074] Example 7:

[0075] (1) Ethylene glycol reduction of metal ions: Iridium tetrachloride was dissolved in ethylene glycol to prepare a solution with a molar concentration of 5.9 mmol·L⁻¹. -1 Solution A: Gold iodide was dissolved in ethylene glycol to prepare a solution with a molar concentration of 15.2 mmol·L⁻¹. -1 Solution B; after stirring each solution thoroughly, mix solutions A and B together and stir thoroughly to prepare metal precursor solution C, in which the molar ratio of iridium salt to gold salt is 14:5;

[0076] (2) Ethylene glycol reduction of titanium ions: 8.1 mmol of titanium tetrachloride was dissolved in ethylene glycol solution, and then a certain amount of water was added to prepare a solution with a Ti molar concentration of 0.02 mol·L⁻¹. -1 Solution D, with a molar ratio of titanium salt, ethylene glycol, and deionized water of 1:196:62, was transferred to an autoclave for a solvothermal reaction at 380°C for 0.5 h. After cooling, a precipitate was obtained, which was continuously washed with water and ethanol and then dried in a vacuum drying oven at 60°C for 24 h to obtain a titanium oxide support.

[0077] (3) Preparation process of Au-doped iridium-supported catalyst: The titanium oxide obtained in step (2) was uniformly dispersed in ethylene glycol to prepare a titanium oxide molar concentration of 11.1 mmol·L⁻¹. -1 Dispersion E; sodium hydroxide was dissolved in ethylene glycol to prepare a concentration of 1.7 mol·L⁻¹. -1 Solution F; then adjust the pH of solution E to 13 using solution F to obtain carrier dispersion G; dissolve solution C from step (1) at a rate of 40 mL / min. -1 Dispersion G was added dropwise to prepare dispersion H, which was then heated to 180°C and kept at that temperature for 13 hours. The mixture was then cooled to room temperature, separated, washed, and dried to obtain an Au-doped iridium-based supported catalyst.

[0078] (4) Performance testing: An RDE rotating disk electrode apparatus was used for electrochemical testing in a three-electrode system. An appropriate amount of the catalyst obtained in (3) was prepared as a slurry and drop-coated onto a platinum-carbon electrode to obtain the working electrode. A mercurous sulfate electrode was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. 0.5M H2SO4 was used as the acidic electrolyte, the test temperature was 25℃, and a linear scan was performed at a scan rate of 1mV / s. Under these preparation conditions, the overpotential of the catalyst was only 239mV@10mA·cm. -2 .

[0079] Comparative example:

[0080] (1) Comparative catalysts: commercial Heraeus IrO@TiO2 and Ir7Au1@TiO2 prepared in Example 1.

[0081] (2) Performance testing: Linear voltammetry tests were performed on the catalyst (1). The test conditions were as follows: a three-electrode system was used for electrochemical testing, with mercurous sulfate electrode as reference electrode and platinum electrode as electrode. 0.5M H2SO4 was used as acidic electrolyte, the test temperature was 25℃, and linear scan was performed at a scan rate of 1mV / s.

[0082] Figure 8 This is a comparison chart of the OER polarization curves of Embodiment 1 and the comparative example of the present invention. At 10 mA cm⁻¹ -2 At the given current density, the potential of commercial Heraeus IrO@TiO2 is 1.55V and the overpotential is 298mV; the potential of Au-doped supported iridium catalyst is 1.46V and the overpotential is 230mV.

[0083] Figure 9 This is a comparison of the durability test curves of Example 1 and the comparative example in a PEM electrolyzer; showing that the Au-doped supported iridium-based catalyst in the PEM electrolyzer was subjected to a reaction at 1 A cm⁻¹. -2 The current density can operate stably for 500 hours, with an initial potential of only 1.71V and a decay rate of only 0.19mV·h. -1 .

[0084] In summary, through characterization methods such as TEM, XRD, BET, and electrochemical testing, the Au-doped iridium-based supported catalyst support prepared in this invention is anatase TiO2 with a plate-like structure and a specific surface area of ​​up to 144.11 m². 2 / g, the pore size distribution is mainly mesoporous, showing Ir and Au nanoclusters uniformly covering high specific surface area plate-like titanium oxide, with the (101) crystal plane of anatase TiO2 and the (111) crystal plane of nanocrystal Au, and the Ir element is in an amorphous form. It has high oxygen evolution electrochemical activity, at 10 mA·cm -2The overpotential can be as low as 230mV and as high as 256mV, which is achieved in PEM electrolysis of water at 1A cm⁻¹. -2 The current density can operate stably for 500 hours, with an initial potential of only 1.71V and a decay rate of only 0.19mV·h. -1 Its oxygen evolution electrochemical performance is far superior to that of commercial samples.

Claims

1. A method for preparing an Au-doped iridium-based supported catalyst, characterized in that, It comprises the following steps: (1) Glycol reduction of metal ions process: dissolve iridium salt in glycol to configure solution A; dissolve gold salt in glycol to configure solution B; after stirring uniformly respectively, mix a certain amount of solution A and solution B to configure metal precursor solution C; (2) Glycol reduction of titanium ions process: dissolve titanium salt in glycol solution, then add water to configure solution D, then carry out solvothermal reaction, keep a certain temperature and time, then reduce the temperature to obtain precipitate product, wash and dry to obtain TiO2 carrier; (3) Preparation process of Au-doped iridium-based supported catalyst: uniformly disperse TiO2 carrier obtained in step (2) in glycol to configure dispersion liquid E; dissolve alkaline substance in glycol to configure solution F; then adjust the pH of solution E to alkaline with solution F to obtain carrier dispersion liquid G; slowly drop solution C in step (1) into dispersion liquid G to configure dispersion liquid H with a certain metal loading, heat the uniformly dispersed dispersion liquid H to a certain temperature and keep it for a certain time, then separate, wash and dry after reducing to a certain temperature to obtain Au-doped iridium-based supported catalyst; In step (2), the temperature of solvothermal reaction is 100-400℃, and the holding time is 0.5-48 h; the drying atmosphere is inert gas; In step (3), the heating temperature is 100-300℃, and the holding time is 0.5-24 h; after the reaction is completed, the mixed solution is reduced to 20-90℃; In step (1), the iridium salt in solution A is one or more than two kinds of mixture of chloroiridic acid, hydrated chloroiridic acid, iridium chloride, iridium tetrachloride, iridium acetate, ammonium chloroiridate, potassium hexachloroiridate, and acetylacetone iridium; the gold salt in solution B is one or more than two kinds of mixture of gold chloride, hydrated gold chloride, chloroauric acid, potassium chloroaurate, gold nitrate, sodium gold sulfite, and gold iodide; In step (2), the titanium salt in solution D is one or more than two kinds of mixture of titanium tetrachloride, titanium trichloride, tetrabutyl titanate, and titanium butoxide.

2. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1, characterized in that, In the step (1), the molar concentration of the iridium salt in the solution A is 0.1-20 mmol·L -1 ; the molar concentration of the gold salt in the solution B is 0.01-20 mol·L -1 ; and the molar ratio of the iridium salt to the gold salt in the solution C is 14:1-3:

2.

3. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1 or 2, characterized in that, In the step (2), the molar concentration of the titanium salt in the solution D is 0.01-20 mol·L -1 ; the molar ratio of the titanium salt, ethylene glycol, and deionized water is 1:(5-500):(1-200).

4. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1 or 2, characterized in that, In step (2), the drying method is one or more than two kinds of combination of air drying, freeze drying, and vacuum drying, and the drying time is 1-48 h.

5. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1 or 2, characterized in that, The molar concentration of titanium oxide in the dispersion E in the step (3) is 0.01 to 20 mmol L -1 ; the basic substance in the solution F is one of sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, ammonia water or a mixture of two or more thereof; and the dropping speed of the solution C is 0.01 to 50 mL min -1 .

6. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1 or 2, characterized in that, In step (3), the pH of solution G is 7-14.

7. The method for preparing an Au-doped iridium-based supported catalyst according to claim 1 or 2, characterized in that, In step (3), the drying method is one or more than two kinds of combination of vacuum drying, air drying, spray drying, and freeze drying, and the drying time is 3-48 h.

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