A tantalum-doped ruthenium-cobalt electrocatalyst, a preparation method and an electrocatalytic anode oxygen evolution reaction

Abstract

The present application belongs to the technical field of catalytic materials, and particularly relates to a tantalum-doped ruthenium-cobalt electrocatalyst for anode oxygen evolution reaction of a proton exchange membrane electrolytic cell, a preparation method and an electrocatalytic anode oxygen evolution reaction. The tantalum-doped ruthenium-cobalt electrocatalyst Ta@RuCo is composed of three metal elements of tantalum, ruthenium and cobalt, has asymmetric Ru-O-Ta and Co-O-Ta active centers, has a nanocubic morphology and a surface rich in oxygen vacancies, and is an electrocatalytic material with high activity and high stability in an acidic oxygen evolution reaction environment. The present application further provides a preparation method of the catalyst, which first prepares a cobalt-based precursor with a specific morphology, then uniformly mixes the cobalt-based precursor with a ruthenium source, a tantalum source and a molten salt medium through physical grinding, and finally performs one-step low-temperature molten salt heat treatment. The method is simple in process, good in repeatability, low in energy consumption and suitable for large-scale preparation of high-performance acidic OER catalysts.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to an electrocatalytic anodic oxygen evolution reaction catalyst based on a proton exchange membrane electrolyzer, and more particularly to a tantalum-doped ruthenium-cobalt electrocatalyst and its preparation method. Background Technology

[0002] Hydrogen is a core element for the deep decarbonization of the global energy system and has been included in the 2050 carbon neutrality strategy by the International Energy Agency (IEA), the European Union, and the United States, becoming a key pathway to replace fossil fuels. The intermittent nature of renewable energy places higher demands on the flexibility of energy systems, necessitating the development of large-scale, diversified energy conversion and storage methods. Against this backdrop, using renewable energy to electrolyze water for hydrogen production has become an important way to coordinate grid fluctuations and achieve energy transfer across time and space, providing a technological foundation for the large-scale production of green hydrogen. At the application level, green hydrogen produced through water electrolysis not only provides clean fuel for zero-emission transportation (such as heavy trucks, shipping, and aviation), significantly improving urban air quality, but can also be used as a reducing agent in industries with difficult-to-reduce emissions, such as steel and cement, replacing fossil fuels and promoting process decarbonization. At the same time, green hydrogen is also a fundamental raw material for the green transformation of the chemical industry, especially a key source for the production of green ammonia and low-carbon fertilizers. However, global hydrogen production still heavily relies on fossil fuels, with approximately 96% coming from the reforming processes of natural gas, coal, and oil, and only 4% produced through water electrolysis. To truly realize the carbon neutrality vision of hydrogen energy, it is essential to produce "green hydrogen" entirely through the electrolysis of water using renewable energy, ensuring zero carbon emissions throughout its entire lifecycle. Therefore, promoting the large-scale, low-cost production of green hydrogen, centered on water electrolysis technology, has become a crucial path for countries to achieve their climate strategies and energy security goals.

[0003] Currently, water electrolysis technologies mainly include four mainstream routes: alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE), anion exchange membrane water electrolysis (AEMWE), and solid oxide electrolyzers (SOEC). Among them, AWE, as a traditional technology that was commercialized earlier, has the advantage of low cost, but its start-up speed is slow and its dynamic response capability is limited, making it difficult to adapt to the drastic fluctuations in renewable energy power generation. AEMWE, as an emerging technology, attempts to achieve a balance between cost and performance, but it still faces key technical bottlenecks such as insufficient chemical stability of anion exchange membranes and short electrode life. SOEC, on the other hand, shows great potential due to its high energy conversion efficiency under high-temperature conditions, and is particularly suitable for coupling applications with nuclear energy or industrial waste heat, but its material durability and system operation complexity are still problems that need to be solved for large-scale commercialization. PEMWE, due to its excellent operational flexibility, fast start-up and shutdown characteristics, wide load adjustment range, and stability under high current density, is considered the most suitable water electrolysis hydrogen production solution for integration with fluctuating renewable energy sources such as wind and photovoltaic power. PEMWE not only enables real-time matching with grid power fluctuations, but also maintains high-purity hydrogen production, thus becoming a representative technology for the cutting-edge development and commercial application of green hydrogen energy.

[0004] Despite the rapid development of PEMWE technology in recent years, its large-scale industrial application still faces numerous challenges. The key to improving PEMWE efficiency lies in optimizing the catalytic performance of the anodic oxygen evolution reaction (OER). Currently, commonly used anodic catalysts generally suffer from slow OER kinetics and insufficient durability under strongly acidic and high-potential conditions, severely restricting the commercialization of PEMWE technology. Researchers have long been dedicated to exploring OER mechanisms on different metal-based catalysts. Currently, iridium oxide (IrO2) remains the preferred catalyst due to its excellent catalytic stability in acidic environments, but its high cost severely limits the large-scale commercial application of PEMWE. Therefore, developing anodic OER electrocatalysts that combine high activity, high stability, and low cost has become a key challenge in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a highly active, highly stable and low-cost tantalum-doped ruthenium-cobalt electrocatalyst for promoting the oxygen evolution reaction at the anode, and a method for preparing the same.

[0006] To achieve the objectives of this invention, the following technical solution is adopted: The tantalum-doped ruthenium-cobalt electrocatalyst of this invention is composed of three metal elements: tantalum (Ta), ruthenium (Ru), and cobalt (Co). It has asymmetric Ru-O-Ta and Co-O-Ta active centers, and has a nanocubic morphology with oxygen vacancies on its surface. It is an electrocatalytic material that exhibits high activity and high stability in an acidic oxygen evolution reaction (OER) environment, and is named Ta@RuCo.

[0007] The doping of trace amounts of tantalum (Ta) in the tantalum-doped ruthenium-cobalt electrocatalyst of this invention can induce electrons to escape from the high-valence Ta. 5+ Transfer to ruthenium (Ru) and cobalt (Co) sites, characterized by X-ray diffraction (XRD) and Raman spectroscopy. Figure 4 , 5 This indicates that its main crystalline phase is cobalt tetroxide (Co3O4), combined with its regular cubic morphology ( Figure 2 The abundance of oxygen vacancies on the surface and the presence of these vacancies contribute to the material's highly active and stable multi-site catalytic properties. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis... Figure 6 This process effectively reduced the valence states of Ru and Co, thereby optimizing the electronic structure of the metal active sites and enhancing their activity and stability in the acidic oxygen evolution reaction (OER).

[0008] This invention also provides a method for preparing the above-mentioned tantalum-doped ruthenium-cobalt electrocatalyst Ta@RuCo. The method first includes: Step A: Morphology control of cobalt precursor powder to prepare a cobalt precursor with a nanocubic structure; Step B: A uniform solid powder mixture is obtained by uniformly combining the cobalt precursor with a nanocubic structure, a ruthenium source, a tantalum source, and a molten salt medium through a stepwise grinding method. Step C: The obtained solid powder mixture is subjected to low-temperature molten salt heat treatment under a reducing atmosphere; Step D: The heat-treated product is washed and dried to obtain the final product Ta@RuCo.

[0009] In some embodiments, the preparation method further includes pretreatment of the cobalt precursor powder, wherein the pretreatment step involves mixing and reacting a solution containing cobalt nitrate hexahydrate and hexadecyltrimethylammonium bromide with a solution containing 2-methylimidazole, and the reaction product is centrifuged, washed and dried to obtain the cobalt precursor powder.

[0010] Furthermore, in some embodiments, the molar ratio of cobalt nitrate hexahydrate, hexadecyltrimethylammonium bromide, and 2-methylimidazole is (0.8~1.2): (0.016~0.024): (48~72).

[0011] Furthermore, in some embodiments, the volume ratio of the two mixed solutions is (0.8~1.2):(2.5~3.5).

[0012] Furthermore, in some embodiments, the pretreatment centrifugation process is centrifugation at 10,000 rpm for 5 minutes; the drying process is at 60°C. o The test was conducted for 6 hours in a vacuum environment at C.

[0013] In some implementations, step A, which involves morphologically controlling the cobalt precursor powder to prepare a cobalt precursor with a nanocubic structure, specifically involves mixing the cobalt precursor powder with a tannic acid solution, and after it is fully dissolved, centrifuging, washing, and drying to obtain the cobalt precursor with a nanocubic structure.

[0014] Furthermore, the mixing of cobalt precursor powder and tannic acid solution specifically involves dispersing the cobalt precursor powder in anhydrous ethanol, dispersing the tannic acid in a mixed solution composed of deionized water and anhydrous ethanol, and then mixing the two dispersion solutions.

[0015] Further, in some embodiments, the mass ratio of the cobalt precursor to tannic acid is (0.8~1.2):(0.24~0.36). The two are ultrasonically dispersed separately: the cobalt precursor is dispersed in anhydrous ethanol, and the tannic acid is dispersed in a mixed solvent of deionized water and anhydrous ethanol at a volume ratio of 1:(0.8~1.2). The two dispersions are then mixed at a volume ratio of (0.8~1.2):(1.6~2.4) and subjected to ultrasonic treatment again.

[0016] Furthermore, in some embodiments, the ultrasonic dispersion time is 20 to 30 minutes.

[0017] Furthermore, in some embodiments, the centrifugation process in the step of preparing the cobalt precursor with a nanocubic structure is centrifugation at 10,000 rpm for 5 minutes, and the drying process is carried out in a vacuum environment at 60°C for 6 hours.

[0018] In some implementations, the stepwise grinding method described in step B specifically involves first mixing and grinding ruthenium chloride hydrate with a cobalt precursor having a nanocubic structure, then adding tantalum pentachloride and continuing grinding, and finally adding sodium chloride and mixing and grinding to obtain a uniform solid powder.

[0019] Furthermore, in some embodiments, the mass ratio of ruthenium chloride hydrate, Co cube, tantalum pentachloride, and sodium chloride is (21~39): (70~130): (7~13): (350~650).

[0020] Furthermore, in some embodiments, the grinding time is 10 minutes, followed by a second grinding session of 10 minutes, and a final grinding session of 20 minutes.

[0021] In some implementations, the low-temperature molten salt heat treatment in step C is specifically carried out in a tube furnace, first by introducing a reducing gas to eliminate oxygen interference, followed by... o The temperature is programmed to rise at a rate of C / min to 350~850. o The gas was kept at room temperature for 3 hours, with the gas flow rate maintained at 100 mL / min, until the temperature dropped to room temperature.

[0022] In some embodiments, the molten salt treatment temperature is 350°C. o C; In some embodiments, the molten salt treatment temperature is 550°C. o C; In some embodiments, the molten salt treatment temperature is 850°C. o C.

[0023] Furthermore, in some embodiments, the reducing atmosphere is an H2 / Ar mixture, wherein the volume fraction of H2 is 5%.

[0024] In some implementations, step D, washing and drying, involves alternating centrifugal washing with anhydrous ethanol and deionized water five times.

[0025] Furthermore, in some embodiments, the washing involves alternating centrifugal washing with anhydrous ethanol and deionized water five times, with each centrifugation lasting five minutes at a speed of 10,000 rpm.

[0026] Furthermore, in some embodiments, the drying process involves drying the centrifuged and washed sample at 60°C. o Vacuum drying at C.

[0027] The present invention also provides an electrocatalytic anodic oxygen evolution reaction, wherein the above-mentioned tantalum-doped ruthenium-cobalt catalyst Ta@RuCo is used as the anodic electrocatalyst in the anodic oxygen evolution reaction of a proton exchange membrane electrolyzer to catalyze the electrolysis of water.

[0028] The tantalum-doped ruthenium-cobalt electrocatalyst material Ta@RuCo with asymmetric metal-oxygen-metal active sites described in this invention enables highly efficient water electrolysis in a proton exchange membrane electrolyzer, and is suitable for electrocatalysis on the anode side of water electrolysis under acidic conditions.

[0029] Furthermore, the electrolyte for the electrolysis of water is a 0.1 M HClO4 solution.

[0030] As can be seen from the above technical solution, this invention discloses a tantalum-doped ruthenium-cobalt electrocatalyst and its preparation method. This electrocatalyst is composed of three metallic elements: tantalum, ruthenium, and cobalt, and is presented as a nano-cubic powder. Figure 2 As shown, the obtained catalyst exhibits a regular nanocubic morphology. X-ray diffraction (XRD) and Raman spectroscopy patterns (XRD and Raman spectroscopy are also presented.) Figure 4 , 5 The results indicate that its crystal structure is mainly cobalt tetroxide. X-ray photoelectron spectroscopy (XPS) analysis results ( Figure 6 This further reveals that high-priced Ta 5+ By transferring electrons to Ru and Co sites through bridging oxygen, the oxidation state of Ru / Co is effectively controlled, thereby endowing the material with excellent oxygen evolution reaction (OER) electrocatalytic performance. The preparation method first pretreats the cobalt precursor to obtain a nanocubic structure, then uniformly mixes metallic ruthenium and tantalum through a stepwise grinding physical method, followed by low-temperature molten salt treatment, centrifugation, washing and drying to finally obtain the target product.

[0031] Compared with the prior art, the tantalum-doped ruthenium-cobalt electrocatalyst and its preparation method provided by the present invention have at least one of the following advantages: 1. This invention constructs a composite catalytic material with asymmetric Ru-O-Ta and Co-O-Ta active centers, prepared via a low-temperature molten salt method. The catalyst surface is rich in oxygen vacancies. This "asymmetric active center-oxygen vacancy" relationship effectively optimizes the adsorption energy of reaction intermediates, significantly improving the catalytic activity and long-term stability of the acidic oxygen evolution reaction. XRD and XPS characterization results ( Figure 4 , Figure 6 This fully demonstrates the unique advantages of its crystal structure and chemical state; 2. This invention innovatively employs a preparation strategy of first constructing a nanocubic structure and then building active centers via a low-temperature molten salt method. Unlike traditional high-temperature synthesis or simple loading techniques, this method first pretreats the cobalt precursor to obtain a regular nanocubic structure, providing an ideal structural substrate for the introduction of ruthenium and tantalum. Subsequently, stepwise grinding is used to achieve uniform mixing of the metal components, followed by low-temperature molten salt heat treatment to achieve controllable construction of active centers. This method effectively avoids the segregation and aggregation of active components, ensures the formation of asymmetric active centers and the regulation of oxygen vacancies, and overcomes the defects of uncontrollable structure and uneven distribution of active sites in existing technologies. 3. The preparation method described herein is simple, employing a combination of stepwise grinding and low-temperature heat treatment. It eliminates the need for complex and demanding synthesis equipment, features low reaction temperatures and low energy consumption, and utilizes readily available and cost-effective raw materials, demonstrating significant technical and economic advantages. The entire process exhibits good repeatability, is easy to scale up for production, and can stably yield high-quality catalyst products with uniform elemental distribution and regular morphology. This characteristic provides a practical technical solution to the challenge of large-scale preparation of high-performance electrocatalysts under acidic conditions, facilitating their transition from laboratory to practical application, and lays the foundation for developing efficient and stable PEMWE anode materials. Attached Figure Description

[0032] To clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments are briefly described below. It should be noted that the drawings described below are only schematic diagrams of some embodiments. Those skilled in the art can derive other related drawings based on these drawings without any creative effort.

[0033] Figure 1 This is a schematic diagram of the synthesis process of the tantalum-doped ruthenium-cobalt oxygen evolution electrocatalyst (Ta@RuCo) in Example 1; Figure 2 Transmission electron microscope (TEM) image of Ta@RuCo prepared in Example 1 ( Figure 2 A, 2B); Figure 3 The elemental distribution of Ta@RuCo prepared in Example 1 is shown in the energy dispersive X-ray spectroscopy (EDS) spectrum. Figure 4 The XRD comparison spectra of Ta@RuCo in Example 1 with those of Comparative Example 1 Ta@Co, Comparative Example 2 RuO2 and Comparative Example 3 Co3O4 are shown below. Figure 5 The Raman spectrum of Ta@RuCo in Example 1; Figure 6 The Ru3 in Example 1 (Ta@RuCo) and Comparative Example 2 (RuO2) and Comparative Example 3 (Co3O4) is... p and Co 2 p XPS spectrum ( Figure 6 A, 6B); Figure 7 The polarization test (LSV) curves are for Ta@RuCo in Example 1, Ta@Co in Comparative Example 1, and Co3O4 in Comparative Example 3. Detailed Implementation

[0034] To make the objectives, technical solutions, and beneficial effects of this invention clearer, specific examples are provided for further explanation. The listed embodiments are intended to illustrate the technical content of this invention in detail and do not constitute any limitation on the scope of protection of this invention. Any non-essential modifications or substitutions made by those skilled in the art based on the concept of this invention and in conjunction with existing technology should be covered within the scope of protection of this invention.

[0035] Unless otherwise specified, all instruments and equipment mentioned are conventional instruments and equipment; All raw materials involved are commercially available conventional industrial raw materials or raw materials that are available to those skilled in the art; The processing and manufacturing methods involved are all conventional methods or methods mastered by those skilled in the art; The technical and scientific terms described are as understood by those skilled in the art.

[0036] Specifically, this invention provides a tantalum-doped ruthenium-cobalt electrocatalyst material, Ta@RuCo, with asymmetric metal-oxygen-metal active sites. The oxygen evolution electrocatalyst Ta@RuCo of this invention is based on tantalum, ruthenium, and cobalt, and is a composite catalytic material with asymmetric Ru-O-Ta and Co-O-Ta active centers. The catalyst of this invention utilizes the synergistic effect between its components to significantly improve the performance of the oxygen evolution reaction at the anode of water electrolysis under acidic conditions. This is mainly attributed to the following effects: First, the high valence of Ta... 5+ By transferring electrons to Ru and Co sites through bridging oxygen, the oxidation state of Ru / Co is effectively regulated, weakening the covalent nature of the Ru-O bond. This shifts the dominant reaction pathway from the structurally destructive lattice oxygen oxidation (LOM) mechanism to the more stable adsorbed oxygen oxidation (AEM) mechanism, thereby inhibiting the peroxidation and dissolution of the active metal and enhancing the catalyst's structural stability. On the other hand, the incorporation of Ta stabilizes cobalt species, mitigating their dissolution in acidic media, and synergistically optimizes the adsorption energy for oxygen intermediates with cobalt, thus lowering the adsorption energy barrier for oxygen evolution reaction intermediates and significantly improving catalytic activity. Furthermore, the catalyst surface is rich in oxygen vacancies, which can strongly interact with Ru / Co species, providing abundant and stable adsorption sites and further optimizing reaction kinetics, thus improving the oxygen evolution performance of the anode in water electrolysis under acidic conditions.

[0037] This invention utilizes tantalum (Ta), ruthenium (Ru), and cobalt (Co) as key components, and successfully constructs a composite electrocatalyst with asymmetric Ru-O-Ta and Co-O-Ta active centers via a low-temperature molten salt method. This invention achieves uniform dispersion and structural control of multiple components through the low-temperature molten salt process. Based on Ta... 5+Through electron transfer from bridging oxygen to Ru and Co sites, this catalyst effectively modulates the oxidation state of Ru / Co, weakens the covalent nature of the Ru-O bond, and shifts the dominant reaction pathway from the structurally destructive LOM to the more stable AEM, thereby inhibiting the peroxidation and dissolution of the active metal in the acidic oxygen evolution reaction and solving the key problem of poor stability of traditional ruthenium-based catalysts. Simultaneously, the abundant oxygen vacancies on the catalyst surface can strongly interact with Ru / Co species, providing rich and stable adsorption sites and further optimizing the adsorption energy for oxygen intermediates, significantly improving its catalytic activity and durability in acidic media. The preparation method of this invention embodies a material optimization strategy of structural design, component regulation, and defect engineering, providing a new material system and technical path for promoting the development of high-performance, low-cost anode catalysts for water electrolysis, achieving a highly efficient balance between catalyst activity and stability.

[0038] Specifically, this invention first prepares a cobalt-based zeolite imidazole ester framework precursor via a room-temperature coordination reaction using cobalt salt as a raw material and organic ligands as structure directing agents, assisted by a surfactant. Subsequently, the precursor is surface-etched and coordinated using organic acids, inducing its topological transformation into a well-formed nanocubic support. After washing and drying, a Co cubic material is obtained. This method effectively constructs a well-formed cubic morphology through the regulatory effect of organic acids, providing an ideal support substrate for the subsequent introduction of multi-metal components. During the introduction of multi-metal components, a stepwise grinding method is used to sequentially mix and grind tantalum and ruthenium sources with the Co cubic support and molten salt medium, achieving uniform dispersion of dopant elements on the support surface. The resulting solid powder is then subjected to low-temperature molten salt treatment under a reducing atmosphere. This process not only promotes the crystallization of the support to form a stable oxide framework but also induces in-situ doping of tantalum and ruthenium elements into the crystal lattice through the synergistic effect of ion migration in the molten salt medium and the reducing atmosphere, successfully constructing asymmetric Ru-O-Ta and Co-O-Ta active centers. Furthermore, the heat treatment process generates abundant surface oxygen vacancies, further optimizing the electronic structure and reaction adsorption sites of the material. The resulting Ta@RuCo catalyst exhibits excellent acidic oxygen evolution performance in a proton exchange membrane electrolyzer: at 100 mA / cm²... 2 After operating continuously for 100 hours at the specified current density, the performance degradation is negligible. These results demonstrate that the Ta@RuCo sample prepared in this invention, through the regulation of asymmetric metal-oxygen active sites and defect engineering, possesses both excellent electrochemical catalytic activity and long-term operational stability.

[0039] The preparation method described in this invention specifically includes the following steps: 1. Synthesis of Co precursor: First, cobalt nitrate hexahydrate, serving as the metal source, and hexadecyltrimethylammonium bromide, serving as the surfactant, were dissolved together in deionized water to form solution A. The surfactant's role is to regulate the morphology of the subsequently generated material. Simultaneously, 2-methylimidazole, an organic ligand, was dissolved in another portion of deionized water to form solution B. Then, solution A was slowly poured into solution B, and the two solutions rapidly underwent a coordination reaction at room temperature with stirring. The solution color changed from dark blue to purple, indicating successful formation of the Co precursor crystals. After the reaction was complete, the resulting purple precipitate was collected by centrifugation for 5 minutes and washed five times alternately with ethanol and deionized water to remove residual reactants and byproducts. Finally, the precipitate was subjected to a 60°C test. o Vacuum drying with C yielded pure Co precursor powder.

[0040] 2. Morphology control of Co cubes: First, the dried Co precursor powder was redispersed in anhydrous ethanol to form a homogeneous solution C. Tannic acid was dissolved in a mixed solvent of ethanol and water to obtain solution D. Tannic acid, as a weak acid and complexing agent, can selectively regulate the Co precursor crystals. When solutions C and D were mixed, a reaction occurred under the combined action of stirring and sonication for 20–30 minutes. The solution color deepened, indicating a change in the structure and composition of the material. After the reaction was complete, the final Co cubic material was obtained through centrifugation, washing, and drying.

[0041] 3. Stepwise grinding and mixing with molten salt medium: A stepwise grinding method was used to uniformly combine the metal source with the molten salt medium: first, ruthenium chloride hydrate and Co cubic material were ground and mixed for 10 minutes, then tantalum pentachloride was added and grinding was continued for 10 minutes, and finally sodium chloride was added as the molten salt medium and ground for 20 minutes to obtain a uniform solid powder mixture.

[0042] 4. Low-temperature molten salt treatment: The ground powder was placed in a tube furnace and subjected to programmed temperature rise heat treatment under a reducing atmosphere (H2 / Ar mixture, H2 volume fraction 5%): at 2... o Heating rate increased to 350 °C / min o The mixture was heated to C for 3 hours, followed by natural cooling, during which the gas flow rate was maintained at 100 mL / min. This process induces Ta doping into the crystal lattice through ion migration in the molten salt medium and the effect of the reducing atmosphere, successfully constructing asymmetric Ru-O-Ta and Co-O-Ta active centers, while generating abundant surface oxygen vacancies.

[0043] 5. Post-processing and product collection: The heat-treated product was centrifuged at 10,000 rpm for 5 minutes, washed alternately with anhydrous ethanol and deionized water 5 times, and finally centrifuged at 60 °C.o Vacuum drying at C yields the final target product, the Ta@RuCo catalyst.

[0044] The preparation method of the tantalum-doped ruthenium-cobalt electrocatalyst Ta@RuCo described in this invention has the following advantages compared with the prior art: (1) The construction of a well-organized nanocube support provides an ideal template for achieving high dispersion and stable anchoring of multi-metal components. The synthesized Co cubic material has a uniform morphology and well-organized structure, which provides an ideal substrate for the uniform loading of tantalum and ruthenium metal components. It effectively prevents the migration and aggregation of active components during heat treatment and gives full play to the utilization rate and catalytic performance advantages of precious metals. (2) The tannic acid coordination and template steps precisely controlled the morphology and surface chemical properties of the support. Compared with other direct loading methods, this invention successfully constructed a regular cubic structure by controllably adjusting the Co precursor with tannic acid. This not only increased the specific surface area of ​​the material and exposed more active sites, but also the abundant functional groups on its surface were more conducive to the subsequent complexation and fixation of tantalum and ruthenium species. (3) The synergistic effect of stepwise grinding and molten salt medium achieves uniform doping of multi-metal components. Compared with the traditional impregnation method, the present invention uses stepwise grinding to mix ruthenium source, tantalum source and molten salt medium in sequence, and promotes uniform dispersion of each component on the surface of the carrier through mechanochemical action; in the subsequent low temperature molten salt treatment, the ion migration effect of molten salt medium further induces Ta element to be doped into the lattice in situ, and successfully constructs asymmetric Ru-O-Ta and Co-O-Ta active centers; (4) Low-temperature molten salt treatment under a reducing atmosphere effectively modulates the electronic structure and active center configuration of the material. The effect of the H2 / Ar reducing atmosphere and the molten salt medium, on the one hand, promotes the high-valence Ta 5+ By transferring electrons to Ru and Co sites through bridging oxygen, the oxidation state of Ru / Co is optimized, and the covalent nature of the Ru-O bond is weakened; on the other hand, it induces the generation of abundant surface oxygen vacancies, providing stable and efficient reaction adsorption sites; (5) A gentle one-step heat treatment process enables the controllable transformation of the material structure. The 350°C heat treatment process used in this invention... o The C low-temperature molten salt treatment process integrates multiple key steps such as carrier crystallization, heterogeneous element doping, oxygen vacancy construction and active site formation into one, realizing a stable and controllable transformation from precursor to target product, avoiding structural collapse or loss of active sites that may be caused by traditional multi-step high-temperature treatment. (6) The final Ta@RuCo composite structure improves the oxygen evolution reaction performance through asymmetric active sites and defect engineering. The Co cubic framework provides stable structural support, the doping of Ta effectively modulates the electronic state of Ru / Co and shifts the reaction pathway from the lattice oxygen oxidation mechanism (LOM) which is prone to structural destruction to the more stable adsorbed oxygen oxidation mechanism (AEM), while the abundant surface oxygen vacancies optimize the adsorption energy for oxygen intermediates. Together, they endow the material with excellent catalytic activity, fast reaction kinetics and long-term durability.

[0045] In summary, the preparation method provided by this invention has a clear process route, mild and controllable conditions, and good reproducibility. The prepared Ta@RuCo catalyst has low noble metal loading, high activity, and strong stability, and has broad application prospects in fields such as water electrolysis.

[0046] Example 1: Preparation of Ta@RuCo A method for preparing Ta@RuCo, a tantalum-doped ruthenium-cobalt electrocatalyst material with asymmetric Ru-O-Ta and Co-O-Ta active sites.

[0047] The specific method is as follows: (1) Synthesis of Co precursor: 1.0 mM cobalt nitrate hexahydrate and 0.02 mM hexadecyltrimethylammonium bromide were dissolved together in 20 mL of deionized water. 0.06 M 2-methylimidazole was dissolved in another 60 mL of deionized water. The two solutions were then mixed and stirred at room temperature to rapidly induce a coordination reaction. The resulting purple precipitate was collected by centrifugation at 10,000 rpm for 5 minutes and washed five times alternately with ethanol and deionized water to remove residual reactants and byproducts. Finally, the precipitate was centrifuged at 60 °C. o Vacuum drying with C yielded pure Co precursor powder.

[0048] (2) Morphology control of Co cubes: 100 mg of dried Co precursor powder was dispersed in 20 mL of anhydrous ethanol, while 30 mg of tannic acid was dissolved in a mixed solvent of 15 mL of ethanol and 15 mL of water. The two solutions were mixed and stirred and sonicated for 20–30 minutes, resulting in a darker color. After the reaction was complete, the final Co cubic material was obtained by the same centrifugation, washing, and drying steps described above.

[0049] (3) Stepwise grinding and mixing with molten salt medium: A stepwise grinding strategy was adopted to achieve uniform compounding of the metal source and the molten salt medium. First, ruthenium chloride hydrate and Co cubic material were ground together for 10 minutes. Then, tantalum pentachloride was added and grinding was continued for 10 minutes. Finally, sodium chloride molten salt medium was introduced and the whole process was ground for 20 minutes until a uniform solid powder mixture was obtained.

[0050] (4) Low-temperature molten salt treatment: The ground solid powder was placed in a tube furnace and subjected to programmed temperature rise heat treatment under a reducing atmosphere (H2 / Ar mixture, H2 volume fraction 5%): at 2 oC Heating to 350°C at a rate of / min oC After being kept at this temperature for 3 hours, the mixture was allowed to cool naturally, with the gas flow rate maintained at 100 mL / min throughout the process. During this process, the ion migration of the molten salt medium and the reducing atmosphere worked synergistically to induce Ta doping into the crystal lattice, successfully constructing asymmetric Ru-O-Ta and Co-O-Ta active centers, and simultaneously generating abundant surface oxygen vacancies.

[0051] (5) Post-processing and product collection: The heat-treated product was centrifuged at 10,000 rpm for 5 minutes, then washed 5 times alternately with anhydrous ethanol and deionized water, and finally centrifuged at 60 °C. o Vacuum drying at C yields the target product, Ta@RuCo catalyst.

[0052] Comparative Example 1: Ta@Co This comparative example provides a catalyst that does not contain ruthenium for comparison.

[0053] The specific method is as follows: (1) Synthesis of Co precursor: Cobalt nitrate hexahydrate and hexadecyltrimethylammonium bromide were dissolved in water and reacted with a 2-methylimidazole solution, resulting in a purple solution. After centrifugation, washing, and drying, a Co precursor powder was obtained.

[0054] (2) Morphology control of Co cubes: Co precursor was dispersed in ethanol, mixed with tannic acid solution, stirred and sonicated, and then centrifuged, washed and dried to obtain Co cubic material. (3) Stepwise grinding and mixing with molten salt medium: Tantalum pentachloride and Co cubic material were ground together for 10 minutes, and then molten salt medium sodium chloride was introduced and ground together for 20 minutes until a uniform solid powder mixture was obtained.

[0055] (4) Low-temperature molten salt treatment: The ground solid powder was placed in a tube furnace and subjected to programmed temperature rise heat treatment under a reducing atmosphere (H2 / Ar mixture, H2 volume fraction 5%): at 2 oC Heating to 350°C at a rate of / min oCAfter being kept at this temperature for 3 hours, the mixture was allowed to cool naturally, with the gas flow rate maintained at 100 mL / min throughout the process. During this process, the ion migration in the molten salt medium and the reducing atmosphere worked synergistically to induce Ta doping into the Co lattice.

[0056] (5) Post-processing and product collection: The heat-treated product was centrifuged at 10,000 rpm for 5 minutes, then washed 5 times alternately with anhydrous ethanol and deionized water, and finally centrifuged at 60 °C. o Vacuum drying at C yields the target product, Ta@Co catalyst.

[0057] Comparative Example 2: RuO2 This comparative example provides a commercial ruthenium dioxide for comparison.

[0058] Comparative Example 3: Co3O4 This comparative example provides a catalyst that does not contain tantalum or ruthenium for comparison.

[0059] The specific method is as follows: (1) Synthesis of Co precursor: Cobalt nitrate hexahydrate was dissolved in water with a surfactant and then reacted with a 2-methylimidazole solution, turning the solution purple. After centrifugation, washing, and drying, a Co precursor powder was obtained.

[0060] (2) Morphology control of Co cubes: The Co precursor was dispersed in ethanol, mixed with tannic acid solution, stirred and sonicated, and then centrifuged, washed and dried to obtain Co cubic material.

[0061] (3) High-temperature calcination oxidation: The powder in the air atmosphere at 2 o Temperature rises to 350°C / minute oC The mixture was kept at a constant temperature for 3 hours, and then washed and dried to obtain the Co3O4 catalyst.

[0062] Experimental Example: Characterization and Performance Testing 1. Transmission electron microscopy (TEM) analysis The morphology and elemental composition of the Ta@RuCo catalyst prepared in Example 1 were analyzed using a JEM-2100F, 200 kV transmission electron microscope (TEM) and an Oxford X-Max energy dispersive spectrometer (EDS).

[0063] TEM images ( Figure 2 (A, B) shows that the material successfully maintains its nanocubic structure, which is beneficial for providing a high specific surface area and exposing abundant active sites. The corresponding EDS surface distribution diagram ( Figure 3This further indicates that Ta, Ru, and Co elements are evenly distributed, and Ta modulates the electronic interactions between Ru and Co, which may promote electron transport during the reaction process.

[0064] 2. X-ray diffraction (XRD) characterization The crystal structure of the catalyst was characterized using a Haoyuan DX-2700BH X-ray diffractometer (XRD). The test conditions were: Cu target (Cu Kα radiation), operating voltage 40 kV, current 30 mA, scanning range 10°–90° (2θ), and scanning speed 5° / min.

[0065] Figure 4 The XRD patterns of Example 1 Ta@RuCo, Comparative Example 1 Ta@Co, Comparative Example 2 RuO2, and Comparative Example 3 Co3O4 are shown. For Example 1 Ta@RuCo, diffraction peaks appeared at 2θ = 31.15°, 36.75°, 59.23°, and 65.12°, corresponding to the (220), (311), (511), and (440) crystal planes of the Co3O4 standard card (PDF#42-1467), respectively. Compared with the standard card, the diffraction peaks of Ta@RuCo are shifted to lower angles, indicating that the Co3O4 support was successfully formed and that the lattice was distorted due to the doping of other metal elements.

[0066] 3. Raman characterization The molecular structure and defect characteristics of the catalyst were characterized by Raman spectroscopy using a HORIBA Jobin Yvon LabRAM HR Evolution spectrometer (Japan). The test conditions were: laser wavelength 532 nm, laser power 5 mW, and spectral scanning range 100–1000 cm⁻¹. -1 Resolution better than 1 cm -1 The integration time is 30 seconds. Before testing, the single-crystal silicon standard was used at the primary silicon peak (520.7 cm⁻¹). -1 Peak position calibration is performed at ( ).

[0067] Figure 5 The Raman spectrum of Ta@RuCo from Example 1 is shown. The image shows the spectrum at approximately 477 cm⁻¹. -1 517 cm -1 615 cm -1 and 680 cm -1 Four distinct characteristic peaks appear at this point, corresponding to the E values ​​of Co3O4, respectively. g F 2g -1 F 2g -2 and A 1gThe vibrational modes indicate the presence of the Co3O4 phase in the catalyst. Compared to pure Co3O4, the A phase of Ta@RuCo... 1g The characteristic peaks broadened to a certain extent and shifted slightly to lower wavenumbers. This is attributed to the doping of Ta and Ru elements, which caused lattice distortion and oxygen vacancy defects in Co3O4. This further confirms the successful introduction of metal atoms into the carrier lattice and their modulation effect on the local coordination environment.

[0068] 4. X-ray photoelectron spectroscopy (XPS) characterization The surface elemental composition and chemical state of the samples were analyzed using a Thermo Fisher Scientific ESCALAB 250Xi X-ray photoelectron spectroscopy (XPS). The testing conditions were: Al target X-ray source, 500 μm beam spot, energy step 0.05 eV, and test pressure below 10... -7 Pa.

[0069] Example 1: Ta@RuCo and Comparative Example 2 (RuO2) with Ru 3 p XPS spectrum comparison shows that Ru3 in Ta@RuCo p The binding energy shifted by 0.4 eV towards lower binding energies compared to RuO2, indicating that the synergistic effect of Ta doping and the Co cubic support led to a decrease in the valence state of Ru. Figure 6 B illustrates the comparison between Example 1 (Ta@RuCo) and Comparative Example 3 (Co3O4) with Co2. p XPS spectrum comparison shows that Ta@RuCo's Co 2 p The binding energy shifted by 0.5 eV towards lower binding energies compared to Co3O4, confirming that Ta doping also induced a decrease in the valence state of Co. This result demonstrates that the introduction of Ta effectively modulates the electronic structure of the active sites of Ru and Co, reducing the oxidation state of the metal elements through charge transfer, which is beneficial for optimizing the adsorption energy of the reaction intermediates and thus improving the performance of the oxygen evolution reaction.

[0070] 5. Electrochemical testing The oxygen evolution reaction (OER) performance of each catalyst was evaluated using a Gamry Reference 3000 (USA) electrochemical workstation in a three-electrode system. The working electrode was the one used in the corresponding examples and comparative examples; the counter electrode was a platinum sheet; the reference electrode was a saturated calomel electrode (SCE); and the electrolyte was a 0.1 M HClO4 aqueous solution. All measured potentials were expressed using the formula... E RHE = E SCE +0.243 + 0.059pH is converted to the potential relative to the reversible hydrogen electrode.

[0071] The catalyst working electrode is prepared by the following steps: First, 5 mg of catalyst powder is dispersed in 1 mL of mixed solvent (V 去离子水 V 乙醇混合液 A homogeneous catalyst ink was formed by ultrasonic treatment for 30 minutes in a 1:1 mixture of ethanol (containing 5 vol% Nafion). Subsequently, 5 μL of this ink was drop-coated onto the surface of a pre-polished glassy carbon electrode (geometric area: 0.1256 cm²). 2 This results in a catalyst loading of approximately 200 μg cm⁻¹. -2 Finally, the modified electrode was dried under an infrared lamp for electrochemical testing.

[0072] To evaluate the oxygen evolution reaction performance of the catalysts, linear sweep voltammetry (LSV) tests were performed on Example 1 Ta@RuCo, Comparative Example 1 Ta@Co, and Comparative Example 3Co3O4. Figure 7 At a current density of 10 mA cm⁻¹ -2 At that time, the potential values ​​of Example 1, Comparative Example 1 (Ta@Co) and Comparative Example 3 (Co3O4) were 1.48 V, 1.68 V and 1.72 V, respectively, indicating that Example 1 had the best catalytic activity.

[0073] In addition to its high activity, Example 1 also exhibited excellent stability in a proton exchange membrane electrolyzer. At 100 mAcm -2 After 100 hours of continuous testing using the chronopotential method at current density, no significant decay of its operating voltage was observed, indicating that the catalyst still possesses excellent durability under harsh operating conditions.

[0074] In summary, this invention successfully prepared a Ta@RuCo nanocube electrocatalyst with asymmetric Ru-O-Ta and Co-O-Ta active centers and abundant oxygen vacancies via a low-temperature molten salt synthesis route. The material first uses a cobalt-based zeolite imidazole ester framework as a precursor, constructing a nanocube support with a regular morphology through a tannic acid-induced topological transformation under mild conditions. Then, a stepwise grinding method is used to uniformly composite ruthenium and tantalum sources with the molten salt medium, achieving dispersion of multi-metal components on the support surface through the grinding strategy. Finally, during the low-temperature molten salt treatment under a reducing atmosphere, the ion migration of the molten salt medium and the effect of the reducing atmosphere induce in-situ doping of Ta into the Co3O4 lattice, successfully constructing asymmetric Ru-O-Ta and Co-O-Ta active centers, and simultaneously introducing a large number of surface oxygen vacancies. Based on Ta... 5+Through electron transfer to Ru and Co sites via bridging oxygen, this catalyst effectively modulates the oxidation state of Ru / Co, weakens the covalent nature of the Ru-O bond, and shifts the dominant reaction pathway from the structurally destructive lattice oxygen oxidation (LOM) mechanism to the more stable adsorbed oxygen oxidation (AEM) mechanism, thereby inhibiting the peroxidation and dissolution of the active metal in the acidic oxygen evolution reaction. System electrochemical tests show that the obtained Ta@RuCo catalyst exhibits excellent catalytic activity and durability in the acidic oxygen evolution reaction, achieving a maximum catalytic activity of 100 mA / cm² in a proton exchange membrane electrolyzer. 2 It can operate stably for more than 100 hours at current density without significant degradation. This study provides a new, controllable preparation pathway and structural regulation approach for the rational design of highly active and stable multi-metal electrocatalysts.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A tantalum-doped ruthenium-cobalt electrocatalyst Ta@RuCo, characterized in that, Composed of three metallic elements, tantalum (Ta), ruthenium (Ru), and cobalt (Co), it has asymmetric Ru-O-Ta and Co-O-Ta active centers; it has a nanocubic morphology and its surface is rich in oxygen vacancies, exhibiting high activity and high stability in the acidic oxygen evolution reaction (OER) environment; its crystal structure has the X-ray diffraction pattern shown in Figure 4.

2. The method of making the tantalum-doped ruthenium-cobalt electrocatalyst of claim 1, wherein, include: Step A: Morphology control of cobalt precursor powder to prepare a cobalt precursor with a nanocubic structure; Step B: A uniform solid powder mixture is obtained by uniformly combining the cobalt precursor with a nanocubic structure, a ruthenium source, a tantalum source, and a molten salt medium through a stepwise grinding method. Step C: The obtained solid powder mixture is subjected to low-temperature molten salt heat treatment under a reducing atmosphere; Step D: The heat-treated product is washed and dried to obtain the final product Ta@RuCo.

3. The preparation method according to claim 2, characterized in that, Before step A, there is also a step of pretreatment of the cobalt precursor powder, specifically, mixing and reacting a solution containing cobalt nitrate hexahydrate and hexadecyltrimethylammonium bromide with a solution containing 2-methylimidazole, and centrifuging, washing and drying the reaction product to obtain cobalt precursor powder.

4. The preparation method according to claim 2 or 3, characterized in that, Step A, which describes the morphology control of the cobalt precursor powder, involves mixing the cobalt precursor powder with a tannic acid solution. After the solution is fully dissolved, the mixture is centrifuged, washed, and dried to obtain a Co material with a nanocubic structure.

5. The preparation method according to claim 4, characterized in that, The mixing of cobalt precursor powder and tannic acid solution specifically involves dispersing the cobalt precursor powder in anhydrous ethanol, dispersing the tannic acid in a mixed solution of deionized water and anhydrous ethanol, and then mixing the two dispersion solutions.

6. The preparation method according to any one of claims 2-5, characterized in that, The stepwise grinding method described in step B involves first grinding ruthenium chloride hydrate with a cobalt precursor having a nano-cubic structure, then adding tantalum pentachloride and grinding, and finally adding sodium chloride and grinding to obtain a uniform solid powder mixture.

7. The preparation method according to any one of claims 2-6, characterized in that, The low-temperature molten salt heat treatment of step C is specifically to first introduce a reducing gas into a tube furnace to remove the interference of oxygen, and then to program the temperature to 350-850 o at a rate of 2 oC C / min, and to keep the temperature for 3 hours, during which the gas flow rate is kept at 100 mL / min until the temperature drops to room temperature.

8. The preparation method according to claim 7, characterized in that, The reducing atmosphere is an H2 / Ar mixture, wherein the volume fraction of H2 is 5%.

9. The preparation method according to any one of claims 2-8, characterized in that, The washing in Step D is by centrifugation 5 times with absolute ethanol and deionized water; the centrifugation is at 10,000 rpm for 5 minutes; and the drying is at 60 oC under vacuum.

10. An electrocatalytic anodic oxygen evolution reaction, characterized in that, In the oxygen evolution reaction at the anode of a proton exchange membrane electrolyzer, the tantalum-doped ruthenium-cobalt catalyst as described in claim 1 is used as the anode electrocatalyst to catalyze the electrolysis of water.

Images