A rare earth metal and transition metal co-modified mesoporous iridium-based oxygen evolution catalyst, its preparation method and application

Abstract

This invention discloses a mesoporous iridium-based oxygen evolution catalyst co-modified with rare earth metals and transition metals, its preparation method, and its application. Through hydrothermal assembly and sonochemical doping processes, rare earth and transition metals are uniformly distributed within the catalyst, constructing a dual-active center integrating electrothermal conduction sites and electrochemical catalytic sites. This avoids energy loss and significantly improves the synergistic efficiency of electrothermal and electrochemical catalysis, achieving highly efficient oxygen evolution through "electrothermal drive to lower the energy barrier and electrochemical catalysis to accelerate electron transfer." The resulting catalyst has low iridium loading, excellent stability, and a simple and controllable preparation process, enabling large-scale production. Its application to the anode of proton exchange membrane water electrolysis significantly improves the energy conversion efficiency of hydrogen production and reduces hydrogen production costs.

Description

Technical Field

[0001] This invention belongs to the field of interdisciplinary technology of electrolytic hydrogen production and electrothermal catalysis, specifically relating to a mesoporous iridium-based oxygen evolution catalyst co-modified by rare earth metals and transition metals, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean and renewable secondary energy source, is an important carrier for achieving the "dual carbon" goal. Proton exchange membrane electrolysis (PEMWE) has become a core technology for large-scale hydrogen production due to its high current density, high hydrogen purity, and fast response speed. However, the oxygen evolution reaction at the PEMWE anode is a complex process involving four electron transfers, characterized by slow kinetics, high overpotential, and a strongly acidic, highly oxidizing environment at the anode. Only iridium-based materials can be stably used as catalysts, but the scarcity of iridium leads to high catalyst costs. Meanwhile, traditional pure electrochemical catalytic oxygen evolution modes suffer from high energy consumption and low energy conversion efficiency.

[0003] To reduce energy consumption and improve catalytic efficiency, electrothermal coupled catalysis has gradually become a research hotspot for oxygen evolution reaction. It lowers the reaction energy barrier through external electrothermal input, achieving synergistic oxygen evolution through "electrothermal drive + electrochemical catalysis". Compared with pure electrochemical catalysis, it can significantly improve energy utilization efficiency. However, the design of existing iridium-based oxygen evolution catalysts is still based on electrochemical catalysis and lacks targeted design for electrothermal coupling. Specifically, the following key problems exist: (1) The catalyst does not have a continuous electrothermal conduction network. After the electrothermal input, the distribution is uneven. Local overheating leads to the collapse of the catalyst structure, while insufficient local temperature cannot effectively reduce the reaction energy barrier; (2) Existing doping modification only targets electrochemical active sites and does not take into account the optimization of electrothermal conduction efficiency. The doping of rare earth, transition metal and other elements has not achieved the dual function of "electrothermal conduction + catalytic activity"; (3) The catalyst pore structure design is simple and the mass transfer efficiency is low. Electrolyte diffusion and product O2 desorption under electrothermal drive are hindered, further reducing the electrothermal coupling efficiency; (4) The iridium loading is too high, and under the harsh conditions of electrothermal-electrochemical dual environment, the iridium-based lattice is easily dissolved by peroxidation, the catalyst has poor stability and it is difficult to achieve long-term operation.

[0004] Therefore, developing an electrothermal coupled iridium-based oxygen evolution catalyst that combines a continuous electrothermal conduction network, highly active electrothermal coupled catalytic sites, low iridium loading, and high structural stability has become a core technical challenge in solving the high energy consumption and high cost of PEMWE hydrogen production. Summary of the Invention

[0005] To achieve the above objectives, this invention provides a mesoporous iridium-based oxygen evolution catalyst co-modified by rare earth metals and transition metals, its preparation method, and its applications. This invention primarily utilizes electrothermal-driven oxygen evolution reaction (OER), supplemented by electrochemical catalysis. It achieves the dual goals of "optimized electrothermal conduction efficiency + regulated catalytic active sites" by constructing a continuous mesoporous electrothermal conduction network and co-modifying with rare earth metals and transition metals. Simultaneously, it anchors the iridium-based lattice using rare earth-oxygen bonds, and the mesoporous structure enables uniform electrothermal distribution and rapid mass transfer. Ultimately, it achieves a low energy barrier, high activity, high stability, and high energy conversion efficiency for the electrothermally coupled OER under low iridium loading.

[0006] The technical solution adopted in this invention is as follows: A method for preparing a rare earth and transition metal co-doped mesoporous iridium-based oxygen evolution catalyst, specifically including the following steps: (1) Weigh out monodisperse polymer microspheres and anionic surfactants, disperse them in anhydrous alcohol solvent, and sonicate them to obtain a dispersion. The resulting dispersion has both dispersibility and conductive precursor properties, laying the foundation for the subsequent construction of electrothermal structures. (2) Dissolve iridium salt and transition metal salt in deionized water to obtain a mixed solution of metal salts; dissolve organic ligand in deionized water to obtain a structure directing agent solution; add the mixed solution of metal salts dropwise to the structure directing agent solution, then add the dispersion from step (1), stir the reaction to obtain a precursor reaction solution; the resulting reaction solution is a homogeneous emulsion, which has both electrothermal conduction and catalytic precursor properties; (3) Add rare earth metal salts and the precursor reaction solution from step (2) into deionized water containing nonionic surfactants for sonochemical treatment; to achieve uniform doping of rare earth elements and optimization of the electrothermal conduction network. (4) The precursor reaction solution treated with sonochemistry is transferred to a high-pressure reactor for hydrothermal reaction. After the reaction is completed, it is naturally cooled to room temperature. The precipitate is collected by centrifugation. The precipitate is washed and vacuum dried to obtain precursor powder. The template assembly, metal hydroxide crystallization and electrothermal active site preconstruction are realized. (5) The precursor powder from step (4) is calcined in air to obtain a mesoporous iridium-based electrothermal coupled oxygen evolution catalyst. This achieves template removal, iridium oxide crystallization, stabilization of the mesoporous electrothermal structure, and lattice fusion with multi-element doping.

[0007] In preferred step (1), the monodisperse polymer microspheres are at least one of polymethyl methacrylate microspheres and monodisperse polystyrene microspheres; the anionic surfactant is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; the anhydrous alcohol solvent is at least one of anhydrous ethanol and anhydrous methanol; and the mass-volume ratio of polymer microspheres, anionic surfactant, and anhydrous alcohol solvent is (2~6) mg: (1~4) mg: 1 mL.

[0008] In preferred step (2), the iridium salt is at least one of iridium trichloride hydrate, iridium acetate, and chloroiridium acid; the transition metal salt is at least one of the chlorides, nitrates, and sulfates of iron, cobalt, nickel, and manganese; the organic ligand is at least one of urea, ethylenediamine, and methylenebisacrylamide; in the metal salt mixed solution, the molar ratio of transition metal to iridium is (0.01~0.1):1, and the concentration of iridium is (0.02~0.08) mol / L; in the structure-directing agent solution, the concentration of structure-directing agent is (0.5~2.5) mol / L; the mass ratio of iridium to structure-directing agent in the metal salt mixed solution and the structure-directing agent solution is 1:(8~20); the mass ratio of iridium to monodisperse polymer microspheres in the metal salt mixed solution and the dispersion is 1:(0.01~0.F1); the stirring time of the stirring reaction is 0.5~2h, and the stirring speed is 600~1000r / min.

[0009] In preferred step (3), the rare earth metal salt is at least one of the chlorides, nitrates, and sulfates of lanthanum, cerium, samarium, and ytterbium; the nonionic surfactant is at least one of Tween85, polyethylene glycol, and polyvinylpyrrolidone; the molar ratio of rare earth element to iridium is (0.01~0.1):1; the molar ratio of nonionic surfactant to iridium is (0.1~1.2):1; the ultrasonic power of the sonochemical treatment is 30~60kHz, and the ultrasonic time is 1~3h.

[0010] Uniform doping of rare earth elements in mesoporous structures and modification of electrothermal conduction networks are achieved through sonochemical treatment.

[0011] In the preferred step (4), the heating process of the hydrothermal reaction is as follows: the first stage is 80~100℃, and the temperature is kept for 4~8h; the second stage is 140~160℃, and the temperature is kept for 10~14h; the centrifugation parameters are 7000~9000rpm, centrifugation for 4~6min, and the vacuum drying temperature is 50~70℃.

[0012] The first stage achieves the ordered assembly of polymer templates and the pre-distribution of electrothermal conduction sites; the second stage achieves the crystallization of transition metal / iridium hydroxide and the initial formation of mesoporous electrothermal structures.

[0013] In the preferred step (5), the calcination process is as follows: the temperature is raised to 250-300℃ at a heating rate of 0.5-1.5℃ / min and held for 3-5 hours; the temperature is raised to 400-500℃ at a heating rate of 1.5-2.5℃ / min and held for 1.5-3 hours; the temperature is raised to 500-600℃ at a heating rate of 3-6℃ / min and held for 1-3 hours.

[0014] Gradient calcination is used to gently remove the polymer template at low temperatures while preserving a continuous mesoporous electrothermal conductive framework; at high temperatures, rare earth elements and transition metals are co-doped on the surface / lattice to form electrothermal coupled catalytic active centers.

[0015] The rare earth and transition metal co-doped mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared by any of the above preparation methods is a three-dimensional porous structure assembled from mesoporous nanosheets / nanoflowers, with an iridium loading of 0.05~0.1 mg / cm².

[0016] The mesoporous iridium-based electrothermal-coupled oxygen evolution catalyst co-doped with rare earth and transition metals was used to prepare an electrothermal-coupled oxygen evolution electrode for application in the electrothermal-coupled oxygen evolution reaction.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Pioneering electrothermal coupling core design significantly reduces oxygen evolution energy consumption. This invention abandons the traditional pure electrochemical catalysis mode and constructs an oxygen evolution reaction system mainly driven by electrothermal energy. By directly reducing the energy barrier for the adsorption and conversion of oxygen intermediates through external electrothermal input, and combined with the electron transfer assistance of electrochemical catalysis, the prepared catalyst has an overpotential as low as 200~250mV at a high current density of 10mA / cm², thus solving the problem of high energy consumption in the traditional catalysis mode.

[0018] 2. Construct a continuous mesoporous electrothermal conduction network to achieve uniform and efficient utilization of electrothermal energy. Using polymer microspheres as soft templates, a continuous mesoporous three-dimensional electrothermal conductive framework was prepared through hydrothermal assembly and gradient calcination. After electrothermal input, it can be uniformly distributed inside the catalyst, avoiding the problems of local overheating or insufficient temperature. At the same time, the mesoporous structure provides a rapid mass transfer channel, promoting electrolyte diffusion and product O2 desorption under electrothermal drive, thereby achieving efficient utilization of electrothermal energy.

[0019] 3. Synergistic modification of multiple elements Co-doping of rare earth elements with transition metals: rare earth elements f Electron and Iridium d Orbital hybridization breaks the scaling relationship of adsorption energy of oxygen intermediates. At the same time, rare earth-oxygen bonds anchor the iridium-based lattice, improving the structural stability under both electrothermal and electrochemical environments. Rare earth ions can also optimize the electrothermal conduction network and improve the electrothermal conductivity. 4. Integrated electrothermal-catalytic dual-site system By employing hydrothermal assembly and sonochemical doping processes, rare earth elements and transition metals are uniformly distributed within the catalyst, constructing a dual active center that integrates electrothermal conduction sites and electrochemical catalytic sites. This avoids energy loss and significantly improves the synergistic efficiency of electrothermal and electrochemical catalysis, achieving highly efficient oxygen evolution through "electrothermal drive to lower the energy barrier and electrochemical catalysis to accelerate electron transfer."

[0020] 5. Low iridium load The high specific surface area of ​​the mesoporous structure fully exposes the iridium active sites, allowing the iridium loading to be as low as 0.05~0.1 mg / cm², significantly reducing catalyst costs; 6. Suitable for large-scale production This invention uses soft template method, hydrothermal reaction, sonochemical treatment and gradient calcination as the core process. The process is controllable, the product has good repeatability, no complicated post-processing is required, and it can achieve large-scale preparation, laying the foundation for industrial application. Attached Figure Description

[0021] Figure 1 This is a SEM image of the nanoflower electrothermal composite precursor prepared in Example 1.

[0022] Figure 2 The image shows the XRD pattern of the samarium-iron co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 1.

[0023] Figure 3 XPS image of the samarium-iron co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 1.

[0024] Figure 4 The LSV curves at 40°C to 80°C are for the samarium-iron co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 1.

[0025] Figure 5 EIS curves of the samarium-iron co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 1 at 40℃~80℃.

[0026] Figure 6 This is a TEM image of the lanthanum and cobalt co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 2.

[0027] Figure 7 The LSV curve of the lanthanum and cobalt co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 2 is shown at 80 °C.

[0028] Figure 8 The LSV curve of the cerium-manganese co-modified mesoporous iridium-based electrothermal coupled oxygen evolution catalyst prepared in Example 3 at 80°C is shown. Specific implementation methods

[0029] To better understand the present invention, the following embodiments further illustrate its content, but the content of the present invention is not limited to the following embodiments. All raw materials used in the following embodiments are commercially available, and the equipment used is conventional chemical and materials preparation equipment. Example 1

[0030] A samarium-iron co-modified mesoporous iridium-based oxygen evolution nanosheet catalyst is prepared by the following method: (1) Weigh 5.8 mg of PMMA microspheres and 3 mg of sodium dodecyl sulfate (SDS), disperse them in 1.5 mL of anhydrous ethanol, and sonicate for 30 min to form a milky white dispersion.

[0031] (2) Weigh 159.4 mg IrCl3・3H2O (0.45 mmol), dissolve in 15 mL of deionized water, add 200 μL of 0.1 MFeCl3 dilute hydrochloric acid solution (Fe:Ir=0.04:1), stir until clear, and obtain a metal salt mixed solution; then add 1500 mg urea (25 mmol), dissolve in 13 mL of deionized water, stir until dissolved, and obtain a structure directing agent solution; slowly add all the metal salt mixed solution to the structure directing agent solution that is being vigorously stirred, then add all the dispersion from step (1), and continue to stir vigorously for 1 h at a stirring speed of 600 r / min to obtain the precursor reaction solution.

[0032] (3) Weigh 10 mg Sm(NO3)3·6H2O (0.049 mmol, Sm to Ir molar ratio 0.05:1), and add it together with all the precursor reaction solution from step (2) into 50 mL of deionized water containing 0.5 mL LTween85 for sonochemical treatment: ultrasonic power 40 kHz, ultrasonic time 2 h.

[0033] (4) The precursor reaction solution treated with sonochemicals was transferred to a 50 mL high-pressure reactor lined with polytetrafluoroethylene and subjected to a programmed temperature rise hydrothermal reaction: the first stage was held at 90 °C for 6 h, and the second stage was held at 150 °C for 12 h; after the reaction was completed, the mixture was naturally cooled to room temperature, and the precipitate was collected by centrifugation at 8000 rpm for 5 min. The precipitate was then vacuum dried at 60 °C to obtain the precursor powder, the SEM of which is shown in the figure. Figure 1 ,from Figure 1 It can be seen that after sonochemical treatment and hydrothermal reaction, the prepared precursor powder exhibits a porous and loose structure composed of nanoparticles with uniform particle size distribution and no obvious agglomeration, which is beneficial to the uniform diffusion of elements and exposure of active sites during subsequent calcination.

[0034] (5) The precursor powder from step (4) was placed in a muffle furnace and subjected to gradient calcination in an air atmosphere: the temperature was increased to 280℃ at a heating rate of 1℃ / min and held for 4h, then increased to 450℃ at a heating rate of 2℃ / min and held for 2h, and finally increased to 550℃ at a heating rate of 5℃ / min and held for 2h, to obtain a samarium-iron co-doped mesoporous iridium-based electrothermal coupled oxygen evolution catalyst. The XRD and XPS of the obtained catalyst are shown in [reference needed]. Figure 2 and Figure 3 ,from Figure 2It can be seen that the prepared catalyst exhibits typical diffraction peaks characteristic of iridium-based oxides. After doping with samarium and iron, no obvious impurity phases appeared, and some diffraction peaks shifted slightly to lower or higher angles, indicating that samarium and iron ions were successfully incorporated into the iridium-based lattice, forming a uniform solid solution structure. Figure 3 It can be seen that the surface chemical state of the catalyst has changed significantly, and the Ir 4f binding energy has shifted, indicating that the electronic structure has been effectively regulated. At the same time, the characteristic peaks of Fe 2p and Sm 3d are clearly visible, confirming that the samarium and iron co-doped elements have been successfully present on the catalyst surface.

[0035] Performance Testing: 4 mg of the catalyst was weighed and ultrasonically mixed with 20 μL of perfluorosulfonic acid-polytetrafluoroethylene copolymer (Nafion), 400 μL of isopropanol, and 600 μL of water for 1 hour to prepare a catalyst slurry. The slurry was coated onto the electrode surface with an iridium loading of 0.08 mg / cm². LSV and EIS tests were performed in a 0.5 M H₂SO₄ electrolyte at an operating temperature of 40–80 °C. The results are shown below. Figure 4 and Figure 5 ,from Figure 4 and Figure 5 It can be seen that the catalytic activity of the catalyst increases with the increase of electrolyte temperature. This indicates that the diffusion coefficient in the catalyst pores increases with the increase of temperature, making it easier for the reactants to come into contact with the active sites on the catalyst surface. Example 2

[0036] A lanthanum- and cobalt-modified mesoporous iridium-based oxygen evolution catalyst is prepared by the following method: (1) Weigh 4 mg of PS microspheres and 4.5 mg of sodium dodecylbenzenesulfonate, disperse them in 1.5 mL of anhydrous methanol, and sonicate for 25 min to form a milky white dispersion.

[0037] (2) Weigh 200 mg of iridium acetate (Ir(CH3COO)3, 0.67 mmol), dissolve it in 12 mL of deionized water, add 150 μL of 0.1 MCo(NO3)2 solution (Co:Ir=0.03:1), and stir until clear to obtain a mixed metal salt solution; then weigh 1200 mg (20 mmol) of ethylenediamine, dissolve it in 12 mL of deionized water, and stir until dissolved to obtain a structure-directing agent solution. Slowly add the entire mixed metal salt solution to the vigorously stirred structure-directing agent solution, then add the entire dispersion from step (1), and continue vigorous stirring for 0.8 h at a stirring speed of 1000 r / min to obtain the precursor reaction solution.

[0038] (3) Weigh 8 mg of LaCl3・7H2O (0.027 mmol, La to Ir molar ratio 0.04:1) and add it together with all the precursor reaction solution from step (2) into 45 mL of deionized water containing 0.4 g of polyethylene glycol for sonochemical treatment: ultrasonic power 35 kHz, ultrasonic time 2.5 h.

[0039] (4) The precursor reaction solution treated by sonochemistry was transferred to a high-pressure reactor with a 50 mL polytetrafluoroethylene liner and subjected to a programmed temperature rise hydrothermal reaction: the first stage was kept at 85℃ for 7 h, and the second stage was kept at 145℃ for 11 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the precipitate was collected by centrifugation at 7500 rpm for 5 min. The precipitate was then dried under vacuum at 55℃ to obtain the precursor powder.

[0040] (5) The precursor powder from step (4) was placed in a muffle furnace and subjected to gradient calcination in an air atmosphere: the temperature was increased to 260℃ at a heating rate of 0.8℃ / min and held for 4.5h, then increased to 420℃ at a heating rate of 1.5℃ / min and held for 2.5h, and finally increased to 520℃ at a heating rate of 4℃ / min and held for 2.5h, to obtain a lanthanum and cobalt co-doped mesoporous iridium-based electrothermal coupled oxygen evolution catalyst. Its TEM image is shown in [image missing]. Figure 6 .from Figure 6 It can be seen that the nanosheets are uniform in thickness and range in size from tens to hundreds of nanometers. The surface of the sheets is covered with abundant mesoporous channels (pore diameter of about 2–5 nm). The channels are uniformly distributed and interconnected, forming an open structure with a high specific surface area.

[0041] Performance Testing: A catalyst slurry was prepared by ultrasonication for 1 hour with 4 mg of the catalyst, 20 μL of Nafion, 400 μL of isopropanol, and 600 μL of water. The slurry was coated onto the electrode surface with an iridium loading of 0.07 mg / cm². LSV (Laminated Static Value) tests were performed in a 0.5 M H₂SO₄ electrolyte at an operating temperature of 40–80 °C. The results are shown below. Figure 7 ,from Figure 7 As can be seen, the oxygen evolution reaction activity of Example 2 significantly increased with increasing test temperature from 40℃ to 80℃. At the same potential, the current density increased significantly with increasing temperature. This indicates that heating effectively reduced the overpotential of the oxygen evolution reaction and accelerated the reaction kinetics. This temperature dependence conforms to Arrhenius behavior, indicating that the catalyst exhibits good thermally enhanced electrocatalytic activity in the 40~80℃ range, making it suitable for medium- and low-temperature electrothermal coupling applications. Example 3

[0042] A cerium- and manganese co-modified mesoporous iridium-based oxygen evolution catalyst is prepared by the following method: (1) Weigh 5 mg of PMMA microspheres and 4 mg of SDS, disperse them in 1.5 mL of anhydrous ethanol, and sonicate for 35 min to form a milky white dispersion.

[0043] (2) Weigh 250 mg of chloroiridium acid (H2IrCl6・6H2O, 0.49 mmol), dissolve it in 18 mL of deionized water, add 180 μL of 0.1 MnSO4 solution (Mn:Ir=0.04:1, containing 0.018 mmol MnSO4), stir until clear, and obtain a metal salt mixed solution; then weigh 1249 mg (8.33 mmol) of methylenebisacrylamide, dissolve it in 14 mL of deionized water, stir until dissolved, and obtain a structure directing agent solution; slowly add all the metal salt mixed solution to the structure directing agent solution that is being vigorously stirred, then add all the dispersion from step (1), and continue to stir vigorously for 1.5 h at a stirring speed of 800 r / min to obtain the precursor reaction solution.

[0044] (3) Weigh 12 mg Ce(NO3)3・6H2O (0.029 mmol, Ce to Ir molar ratio 0.06:1) and add it together with all the precursor reaction solution from step (2) into 55 mL of deionized water containing 0.7 mL LTween85 for sonochemical treatment: ultrasonic power 50 kHz, ultrasonic time 1.5 h.

[0045] (4) The precursor reaction solution treated by sonochemistry was transferred to a high-pressure reactor with a 50 mL polytetrafluoroethylene liner and subjected to a programmed temperature rise hydrothermal reaction: the first stage was kept at 95 °C for 5 h, and the second stage was kept at 155 °C for 13 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the precipitate was collected by centrifugation at 8500 rpm for 4 min. The precipitate was then dried under vacuum at 65 °C to obtain the precursor powder.

[0046] (5) The precursor powder from step (4) was placed in a muffle furnace and subjected to gradient calcination in an air atmosphere: the temperature was raised to 290℃ at a rate of 1.5℃ / min and held for 3.5h, the temperature was raised to 480℃ at a rate of 2.5℃ / min and held for 1.5h, and the temperature was raised to 580℃ at a rate of 5.5℃ / min and held for 1.5h, to obtain a cerium-manganese co-doped mesoporous iridium-based electrothermal coupled oxygen evolution catalyst.

[0047] Performance Testing: A catalyst slurry was prepared by ultrasonication for 1 hour with 4 mg of the catalyst, 20 μL of Nafion, 400 μL of isopropanol, and 600 μL of water. The slurry was coated onto the electrode surface with an iridium loading of 0.09 mg / cm². The LSV (Laminated Static Value) was tested in a 0.5 M H₂SO₄ electrolyte at an operating temperature of 80 °C. The results are shown below. Figure 8 ,from Figure 8 As can be seen, with the increase of temperature, the starting potential of Example 3 is smaller and the current density is higher. This is due to the optimization of the electronic structure of the iridium-based material by cerium and manganese co-doping, as well as the rich active sites and good mass transfer ability provided by the porous sheet structure.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing mesoporous iridium-based oxygen evolution catalysts co-modified with rare earth metals and transition metals, characterized in that, Includes the following steps: (1) Weigh out monodisperse polymer microspheres and anionic surfactants, disperse them in anhydrous alcohol solvent, and sonicate them to obtain a dispersion; (2) Dissolve iridium salt and transition metal salt in deionized water to obtain a mixed solution of metal salts; dissolve organic ligand in deionized water to obtain a structure directing agent solution; add the mixed solution of metal salts dropwise to the structure directing agent solution, then add the dispersion from step (1), stir the reaction, and obtain the precursor reaction solution; (3) Add the rare earth metal salt and the precursor reaction solution from step (2) into deionized water containing nonionic surfactants for sonochemical treatment; (4) The precursor reaction solution treated with sonochemicals was transferred to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, it was naturally cooled to room temperature. The precipitate was collected by centrifugation. The precipitate was washed and vacuum dried to obtain precursor powder. (5) The precursor powder from step (4) is calcined in an air atmosphere to obtain a mesoporous iridium-based electrothermal coupled oxygen evolution catalyst.

2. The production method according to claim 1, characterized by, In step (1), the monodisperse polymer microspheres are at least one of polymethyl methacrylate microspheres and monodisperse polystyrene microspheres; the anionic surfactant is at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; the anhydrous alcohol solvent is at least one of anhydrous ethanol and anhydrous methanol; the mass-volume ratio of polymer microspheres, anionic surfactant and anhydrous alcohol solvent is (2~6) mg: (1~4) mg: 1 mL.

3. The preparation method according to claim 1, characterized in that, In step (2), the iridium salt is at least one of iridium trichloride hydrate, iridium acetate, and chloroiridium acid; the transition metal salt is at least one of the chlorides, nitrates, and sulfates of iron, cobalt, nickel, and manganese; and the organic ligand is at least one of urea, ethylenediamine, and methylenebisacrylamide.

4. The method of claim 1, wherein, In step (2), in the metal salt mixed solution, the molar ratio of transition metal to iridium is (0.01~0.1):1, and the concentration of iridium is (0.02~0.08) mol / L; in the structure-directing agent solution, the concentration of structure-directing agent is (0.5~2.5) mol / L; the ratio of the metal salt mixed solution to the structure-directing agent solution by mass is 1:(8~20); the ratio of the metal salt mixed solution to the dispersion by mass is 1:(0.01~0.1) by mass of iridium to monodisperse polymer microspheres. The stirring time is 0.5~2h, and the stirring speed is 600~1000r / min.

5. The preparation method according to claim 1, characterized in that, In step (3), the rare earth metal salt is at least one of the chlorides, nitrates, and sulfates of lanthanum, cerium, samarium, and ytterbium, and the nonionic surfactant is at least one of Tween85, polyethylene glycol, and polyvinylpyrrolidone.

6. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of rare earth elements to iridium is (0.01~0.1):1; the molar ratio of nonionic surfactant to iridium is (0.1~1.2):1; the ultrasonic power of the sonochemical treatment is 30~60kHz, and the ultrasonic time is 1~3h.

7. The preparation method according to claim 1, characterized in that, In step (4), the heating process of the hydrothermal reaction is as follows: the first stage is 80~100℃, and the temperature is kept for 4~8h; the second stage is 140~160℃, and the temperature is kept for 10~14h; the centrifugation parameters are 7000~9000rpm, centrifugation for 4~6min, and the vacuum drying temperature is 50~70℃.

8. The preparation method according to claim 1, characterized in that, In step (5), the calcination process is as follows: the temperature is raised to 250-300℃ at a heating rate of 0.5-1.5℃ / min and held for 3-5 hours; the temperature is raised to 400-500℃ at a heating rate of 1.5-2.5℃ / min and held for 1.5-3 hours; the temperature is raised to 500-600℃ at a heating rate of 3-6℃ / min and held for 1-3 hours.

9. The rare earth and transition metal co-doped mesoporous iridium-based oxygen evolution catalyst prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The catalyst is a three-dimensional porous structure assembled from mesoporous nanosheets / nanoflowers, with an iridium loading of 0.05~0.1 mg / cm².

10. The mesoporous iridium-based oxygen evolution catalyst co-doped with rare earth and transition metal as described in claim 9 is prepared into an electrothermal coupled oxygen evolution electrode and applied to the electrothermal coupled oxygen evolution reaction.

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