Ru / Ni-3DONMC catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Ru / Ni-3DONMC catalyst as well as a preparation method and application thereof, and relates to the technical field of new energy materials and electrochemical catalysis. According to the invention, self-designed ordered SiO2 microspheres are self-assembled as a template, a nitrogen-doped carbon carrier with a three-dimensional ordered hierarchical pore structure is constructed, and a composite catalytic system with a multi-stage active center is successfully prepared by combining a bimetallic precursor adsorption impregnation and thermal reduction process. The catalyst disclosed by the invention shows excellent bifunctional catalytic performance in an alkaline medium; only 16 mV overpotential is needed in a hydrogen evolution reaction under the current density of 10 mA cm <-2 >, and the Tafel slope is as low as 40.54 mV / dec; and in a hydroxide reaction, the material has high limiting current density of 2.55 mA cm <-2 > and excellent mass activity. And it is powerfully proved that the intrinsic catalytic activity and long-term operation stability of the hydrogen-electricity reaction can be effectively improved through a monatomic-nanocluster cooperative regulation strategy.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials and electrocatalytic technology, and specifically relates to a Ru / Ni-3DONMC catalyst and a preparation method thereof, as well as the application of the catalyst in the fields of electrochemical hydrogen production and hydrogen energy conversion. Background Art

[0002] The electrochemical generation and conversion of hydrogen, as well as the role it plays as an energy carrier, are the core key elements of almost all future decarbonized energy system solutions. In this context, the economy and feasibility of hydrogen depend on the efficiency of two technologies: one is the electrolytic water hydrogen production technology based on renewable energy power-driven electrolyzers, which realizes the efficient conversion of "green electricity" to "green hydrogen"; the other is fuel cell technology, which completes the reversible conversion of hydrogen energy to electrical energy. Together, they jointly construct the core technology system of the future green hydrogen cycle. Among them, the hydrogen evolution reaction (HER) of electrolytic water hydrogen production and the hydrogen oxidation reaction (HOR) of hydrogen fuel cells are the key steps determining the hydrogen-electricity conversion efficiency. However, the hydrogen-electricity conversion process faces the dual constraints of high overpotential and low reaction kinetics characteristics, which seriously hinder its industrialization process. Therefore, the development of new catalysts with both high catalytic performance, long-term stability and economic feasibility has become the key breakthrough point to break through the existing technical bottlenecks and promote the hydrogen energy industry towards large-scale development.

[0003] Currently, Ru-based materials are one of the most promising candidate materials to replace Pt-based catalysts due to their unique electronic structure, moderate hydrogen adsorption ability and significant cost advantage (about 1 / 5 of the Pt price). However, how to precisely regulate the electronic structure of active sites at the atomic scale to break through its intrinsic activity bottleneck is still the key scientific problem restricting its development. Research shows that strategies such as interface coupling, alloying, strain engineering, defect construction and heterostructure design can significantly improve the catalytic performance while reducing the noble metal loading.

[0004] In supported catalysts, optimizing the interfacial interaction between metals and supports is a feasible regulation strategy, which can significantly enhance the intrinsic activity of metal active sites through electronic structure regulation. The weak interaction between traditional carbon-based supports (activated carbon, graphene, etc.) and metal particles can easily cause Ru migration, Ostwald ripening, or even shedding or dissolution, resulting in loss of active components and attenuation of catalytic performance. Heteroatom doping modification is an effective way to solve the above problems and has become a research hotspot for strengthening the metal-support interface. However, a large number of studies currently focus on non-metallic doping (N, P, S, B, etc.) systems. For example, by introducing nitrogen species with different configurations (graphitic nitrogen / pyrrolic nitrogen / pyridinic nitrogen) or multi-element co-doping regulation, the charge distribution on the carbon surface can be effectively reconstructed and rich defect sites can be constructed, thereby activating the strong electronic coupling effect between Ru nanoclusters and the support interface. It is worth noting that compared with non-metallic doping, transition metal atoms, with their unique d electron orbital characteristics, construct atomically dispersed MN in the carbon skeleton. x -C active sites can produce more significant synergistic effects with the main active components, providing a new idea for regulating the electronic metal-support interaction and electrocatalytic performance of ruthenium-based nanoparticles. However, the precise synthesis of synergistic hydrogen-electric bifunctional catalysts of single atoms and clusters currently requires precise control of synthesis conditions. In addition, the mechanism of hydrogen evolution reaction of synergistic single atoms and clusters is relatively complex, involving multi-step electron transfer and intermediate adsorption and desorption processes, which makes the further optimization and design of catalysts face many challenges and still requires in-depth research and exploration. Summary of the invention

[0005] The object of the present invention is to provide a ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical pore carbon-based composite catalyst (Ru / Ni-3DONMC) and a preparation method thereof.

[0006] The ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst (Ru / Ni-3DONMC) provided by the present invention uses a three-dimensional ordered structure N-doped hierarchical porous carbon material as a carrier, and uses ruthenium and nickel as active components; wherein the Ni species is uniformly embedded in the interior of the carrier in the form of single atoms to form highly dispersed metal sites, and ruthenium is loaded on the surface of the carrier in a cluster state; The size of Ru nanoclusters is between 1 and 2.5 nm.

[0007] The above-mentioned ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst (Ru / Ni-3DONMC) is prepared by a method comprising the following steps: (1) mixing a silicon source, anhydrous ethanol, ammonia water and water to obtain a microemulsion solution, centrifuging, washing, drying and self-assembling to obtain SiO2 nanoparticles with uniform particle size and tight and regular arrangement; (2) Mix the SiO2 nanospheres prepared in step (1), carbon source precursor, nitrogen dopant, and water, impregnate under vacuum, remove the residual liquid on the surface, freeze-dry the bottom solid under vacuum, and calcine and etch to obtain a three-dimensional ordered N-doped hierarchical porous carbon material (3DONMC); (3) Mix soluble ruthenium salt, soluble nickel salt, monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material obtained in step (2), impregnate, dry, and calcine to obtain the Ru / Ni-3DONMC catalyst.

[0008] In step (1) of the above method, the silicon source may be selected from: tetraethyl orthosilicate, sodium silicate, tetramethyl orthosilicate, methyltrimethoxysilane, and specifically may be tetraethyl orthosilicate; The volume ratio of tetraethyl orthosilicate to absolute ethanol is 1:12 - 14, and specifically may be 1:13.3; The volume of tetraethyl orthosilicate used is 20 - 25 mL, and specifically may be 22.5 mL; The volume of ammonia water used is 45 - 55 mL, and specifically may be 50 mL, The volume ratio of ammonia water, absolute ethanol, and water may be 0.5 - 1.5:4 - 8:2 - 3 in sequence, and specifically may be 1:6:2.4; The temperature of the reaction may be 35 - 45 °C, and specifically may be 40 °C; The duration of the reaction is 2 - 6 h, and specifically may be 4 h; The rotation speed of the centrifugation may be 4000 - 8000 r min -1 , and specifically may be 6000 r min -1 ; The duration of the centrifugation may be 5 - 15 min, and specifically may be 10 min; In step (1) of the above method, the drying temperature may be 40 - 50 °C, and specifically may be 45 °C; The drying duration may be 40 - 75 h, and specifically may be 48 h; The particle size of the obtained SiO2 nanospheres is 200 - 300 nm.

[0009] In step (2) of the above method, the carbon source precursor may be glucose; The nitrogen dopant may be monocyanamide; The mass ratio of SiO2 nanospheres, glucose, and monocyanamide may be 0.5 - 1.5:1.5 - 2.5:0.5 - 1.5 in sequence, and specifically may be 1:2:1; Among them, the amount of SiO2 nanospheres used is 2.5 - 3.5 g, and specifically may be 3 g; In step (2) of the above method, the duration of the vacuum impregnation can be 4 - 8 h, specifically 6 h; The duration of the vacuum freeze-drying can be 30 - 40 h, specifically 36 h; In step (2) of the above method, the calcination is carried out under the protection of an inert atmosphere; The heating rate of the calcination can be 1 - 5 °C / min -1 , specifically 2 °C / min -1 ; Heat up to 800 - 1000 °C, specifically 900 °C, and keep the temperature constant for calcination for 1 - 5 h, specifically 2 h; The solvent used for etching is hydrofluoric acid, specifically hydrofluoric acid with a concentration of 5 - 20 wt%, more specifically hydrofluoric acid with a concentration of 10 wt%; The duration of the etching can be 15 - 30 h; In step (3) of the above method, the soluble ruthenium salt is at least one of ruthenium(III) chloride trihydrate, ruthenium(III) acetylacetonate, and dodecacarbonyltrioctylruthenium; The soluble nickel salt is at least one of nickel(II) chloride hexahydrate, nickel(II) nitrate hexahydrate, and nickel(II) acetate; The ratio of the soluble ruthenium salt (calculated as ruthenium), the soluble nickel salt (calculated as nickel), monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material (3DONMC) can be 1 - 1.5 mg: 0.4 - 1 mg: 5 - 9 mg: 30 - 45 mg in sequence; specifically 1.2 mg: 0.5 mg: 7 mg: 35 mg; The soluble ruthenium salt is added in the form of a solution, and the concentration of the soluble ruthenium salt in the soluble ruthenium salt solution (calculated as ruthenium) can be 0.05 g / mL - 0.08 g / mL, specifically 0.066 g / mL; The soluble nickel salt is added in the form of a solution, and the concentration of the soluble nickel salt in the soluble nickel salt solution (calculated as nickel) can be 0.01 g / mL - 0.05 g / mL, specifically 0.02 g / mL; The monocyanamide is added in the form of a solution, and the concentration of the monocyanamide in the monocyanamide solution can be 0.02 g / mL - 0.08 g / mL, specifically 0.04 g / mL.

[0010] In step (3) of the above method, the duration of the impregnation can be 1 - 4 h, specifically 2 h; The temperature of the drying can be 40 - 60 °C, specifically 45 °C; The duration of the drying can be 20 - 28 h, specifically 24 h; In the above preparation method, in step (3), the calcination is carried out under the protection of an inert atmosphere; The heating rate of the calcination can be 5-15 °C / min -1 , specifically it can be 10 °C / min -1 ; Heat up to 300-700 °C, specifically it can be 500 °C, and keep the temperature constant for calcination for 1-5 h, specifically it can be 2 h.

[0011] The Ru / Ni-3DONMC catalyst prepared by the above preparation method also belongs to the protection scope of the present invention.

[0012] The present invention also provides the application of the above Ru / Ni-3DONMC catalyst in the hydrogen electrode reaction.

[0013] In the said application, the Ru / Ni-3DONMC is used as a bifunctional catalyst for electrocatalytic hydrogen evolution reaction and hydrogen oxidation reaction.

[0014] The present invention first uses the self-assembly technology to prepare SiO2 nano-microspheres with regular arrangement and uniform size, and uses them as template agents. Using glucose as the carbon source precursor and monocyanamide as the nitrogen doping agent, a hierarchical porous carbon material with a three-dimensional ordered structure is constructed by the strategy of high-temperature pyrolysis-etching to remove the template agent. Subsequently, a wet chemical process is used to impregnate and adsorb Ru salt and Ni salt on the surface of the carrier, and monocyanamide is added at the same time. Under the protection of an inert atmosphere, it is calcined. The addition of monocyanamide further performs N doping on the one hand, and is used to anchor metals and metal coordination on the other hand. Ni species are uniformly embedded in the carbon carrier in the form of single atoms to form highly dispersed metal sites, while the noble metal Ru that is easy to reduce is loaded on the surface of the carrier in the form of clusters. Thanks to the strong interaction between the metal and the carrier interface and the synergistic effect between the clusters and single atoms, the aggregation of Ru caused by Ostwald ripening is effectively restricted, thereby realizing the high dispersion and stabilization of metal active sites and significantly improving the catalytic performance of the material. Through unique material design and preparation process, the present invention realizes the optimized distribution and synergistic effect of Ru and Ni on the carbon carrier, providing a new idea and method for the development of high-performance hydrogen electrode bifunctional catalysts.

[0015] The rich pore structure on the surface of the carrier of the Ru / Ni-3DONMC catalyst of the present invention can effectively restrict the agglomeration of active component nanoparticles at high temperature. In addition, the synergistic effect of Ni single atoms and Ru nano-clusters precisely regulates the adsorption strength of intermediates, optimizes the catalytic reaction path, significantly improves the catalytic activity of the hydrogen electrode reaction, and provides a strong guarantee for efficient energy conversion.

[0016] Compared with the prior art, the present invention has the following advantages: (1) The three-dimensional ordered N-doped hierarchical porous carbon material constructed in the present invention forms a rich and interconnected pore structure network through precise regulation of the multi-level pore system. This structural feature provides an efficient transmission channel for reactant molecules, significantly accelerating the hydrogen evolution and facilitating the rapid transmission of reactants and the rapid evolution of hydrogen, effectively enhancing its mass transfer efficiency. In addition, its large specific surface area also provides an ideal carrier for the highly dispersed metal active components, effectively increasing the number of active centers and thus enhancing the catalyst activity and conversion efficiency.

[0017] (2) By doping and modifying the carbon material with transition metal Ni single atoms, the present invention realizes the redistribution of surface charges on the carrier and the precise regulation of the coordination environment, forming an interfacial regulation mechanism that enhances the metal-carrier interaction, facilitating the uniform dispersion of active substances, preventing agglomeration, and improving their utilization rate.

[0018] (3) The present invention innovatively designs a synergistic mechanism between Ni single atoms and Ru nanoclusters, activating the strong electron coupling effect at the Ru-carrier interface, not only significantly improving the hydrogen electrocatalytic activity of the material but also enhancing its corrosion resistance in an alkaline environment, endowing the catalyst with a longer service life and higher stability. Description of the Drawings

[0019] Figure 1 In (a) is the scanning electron microscope image of SiO2 microspheres; Figure 1 In (b) is the scanning electron microscope image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention.

[0020] Figure 2 In (a) and (b) are the transmission electron microscope image and high-resolution transmission electron microscope image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention (the inset is the particle size distribution histogram of Ru clusters).

[0021] Figure 3 Is the aberration-corrected electron microscope image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention (the large circle represents Ru clusters and the small circle represents Ni single atoms).

[0022] Figure 4 Is the N2 adsorption-desorption isotherm curve graph of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention.

[0023] Figure 5 Is the hydrogen evolution catalytic performance of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and commercial Pt / C (20 wt%) in 1.0 M KOH electrolyte; (a) is the comparison graph of linear voltammetry scanning polarization curves, and the electrochemical test conditions are: in the potential window of 0~ -0.6 V (vs. RHE) at a scan rate of 5 mV s -1The scanning rate is sampled, and 80% iR compensation is applied to eliminate the influence of solution impedance; (b) is the Tafel curve graph.

[0024] Figure 6 For the hydrogen evolution stability test of Ru / Ni-3DONMC prepared in Example 1 of the present invention at 10 mA cm -2 The electrochemical test conditions are as follows: at a constant current density of 10 mA cm -2 The attenuation amplitude is monitored continuously for 100 h at a constant current density.

[0025] Figure 7 For the catalytic performance of hydrogen oxidation reaction of Ru / Ni-3DONMC prepared in Example 1 of the present invention, Comparative Example 1, Comparative Example 2, Comparative Example 3 and commercial Pt / C (20 wt%) in a H2-saturated 0.1 M KOH electrolyte; (a) is the comparison graph of linear voltammetry scanning polarization curves, and the electrochemical test conditions are as follows: at a potential window of 0 - 0.3 V (vs. RHE), points are taken at a scanning rate of 5 mV s -1 The scanning rate is sampled, and the rotation speed of the rotating disk is 1600 rpm; (b) is the Tafel curve graph.

[0026] Figure 8 For the HOR chronoamperometry test of Ru / Ni-3DONMC prepared in Example 1 of the present invention. Detailed implementation manners

[0027] The present invention will be further described in detail below in conjunction with the detailed implementation manners. The given examples are only for clarifying the present invention, rather than limiting the scope of the present invention. The following examples can be used as a guide for those of ordinary skill in the art to make further improvements, and do not limit the present invention in any way.

[0028] The experimental methods in the following examples are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0029] Example 1. Preparation of a composite catalyst of Ru nanoclusters supported on a Ni single-atom doped hierarchical pore carbon material This example provides a composite catalyst of Ru nanoclusters supported on a Ni single-atom doped hierarchical pore carbon material, and the catalyst is prepared by the following method: (1) Preparation of SiO2 microsphere template agent Ordered SiO2 nanospheres templates were self-assembled and synthesized by an improved Stöber method, which were used as hard template agents for the subsequent preparation of carbon materials. The specific experimental steps were optimized as follows: In a 200 mL beaker, 22.5 mL of tetraethyl orthosilicate (TEOS) and 100 mL of absolute ethanol were successively added, and magnetically stirred for 20 min to form a homogeneous solution. In another 1000 mL beaker, 200 mL of absolute ethanol, 120 mL of deionized water and 50 mL of ammonia water (28 wt%) were successively added to prepare a mixed solvent system. In a 40 °C constant temperature water bath, the TEOS / ethanol solution was slowly added to the reaction system, and the reaction vessel was sealed with plastic wrap throughout the process to maintain the pH value of the system within the range of 9.5 - 10.2, ensuring the kinetic control of the hydrolysis - polycondensation reaction. After reacting for 4 h, a milky white colloidal suspension was obtained. The reaction product was aliquoted into 50 mL centrifuge tubes, centrifuged at 6000 r / min for 10 min to collect the precipitate, washed with deionized water - ethanol respectively, and dried at 45 °C for 48 h under constant temperature to finally obtain SiO2 nanospheres (particle size 200 - 300 nm).

[0030] (2) Construction of three - dimensional ordered N - doped hierarchical porous carbon material (3DONMC) Based on the template - directed strategy, a nitrogen - doped carbon material with a hierarchical pore structure was constructed, and the specific steps are as follows: 14 mL of deionized water was placed in a 50 mL beaker, 6 g of glucose (carbon source) and 3 g of monocyanamide (nitrogen source) were successively added and ultrasonicated to completely dissolve them. Subsequently, 3 g of SiO2 template agent was added and vacuum impregnated at room temperature for 6 h to initially construct a molecular cross - linked structure. The surface residual liquid was removed by siphoning, and the bottom solid was quickly frozen with liquid nitrogen and then vacuum freeze - dried for 36 h. The obtained porous precursor was heated to 900 °C at a rate of 2 °C min -1 under argon protection, held at a constant temperature for 2 h, and naturally cooled to room temperature. Subsequently, it was etched with 10 wt% HF solution for 24 h to remove the hard template agent, washed alternately with deionized water and ethanol until neutral, and dried in vacuo at 45 °C to obtain 3DONMC material.

[0031] (3) Synthesis of Ru / Ni - 3DONMC catalyst In a 10 mL beaker, 37 μL of ruthenium(III) chloride hydrate (RuCl3·H2O, 0.066 g / mL), 105 μL of nickel(II) chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL) and 184 μL of monocyanamide solution (C2H4N2, 0.04 g / mL) were accurately added successively. After adding deionized water to make up the volume, 0.035 g of 3DONMC support was added and ultrasonically dispersed for 30 minutes. The mixed system was impregnated at room temperature in the dark for 2 h and dried in an oven at 45 °C for 24 h to obtain a precursor. The precursor sample was placed in a porcelain boat and heated to 500 °C at a rate of 10 °C min -1 under argon protection, held at a constant temperature for 2 h, and cooled to obtain the Ru / Ni - 3DONMC catalyst.

[0032] Comparative Example 1 Accurately add 105 μL of nickel chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL) and 184 μL of monocyanamide solution (C2H4N2, 0.04 g / mL) into a 10 mL beaker in sequence. After making up with deionized water, add 0.035 g of 3DONMC support (prepared in step (2) of Example 1), and ultrasonically disperse for 30 minutes. The mixed system is impregnated at room temperature in the dark for 2 hours and dried in an oven at 45°C for 24 hours to obtain a precursor. Place the precursor sample in a porcelain boat, and under argon protection, heat it at 10°C min -1 Heat to 500°C and keep it constant for 2 hours, and then cool to prepare Ni-3DONMC.

[0033] Comparative Example 2 Accurately add 37 μL of ruthenium(III) chloride hydrate (RuCl3·H2O, 0.066 g / mL) and 184 μL of monocyanamide solution (C2H4N2, 0.04 g / mL) into a 10 mL beaker in sequence. After making up with deionized water, add 0.035 g of 3DONMC support (prepared in step (2) of Example 1), and ultrasonically disperse for 30 minutes. The mixed system is impregnated at room temperature in the dark for 2 hours and dried in an oven at 45°C for 24 hours to obtain a precursor. Place the precursor sample in a porcelain boat, and under argon protection, heat it at 10°C min -1 Heat to 500°C and keep it constant for 2 hours, and then cool to prepare the Ru / 3DONMC catalyst.

[0034] Comparative Example 3 Accurately add 105 μL of nickel chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL), 37 μL of ruthenium(III) chloride hydrate (RuCl3·H2O, 0.066 g / mL) into a 10 mL beaker in sequence. After making up with deionized water, add 0.035 g of 3DONMC support (prepared in step (2) of Example 1), and ultrasonically disperse for 30 minutes. The mixed system is impregnated at room temperature in the dark for 2 hours and dried in an oven at 45°C for 24 hours to obtain a precursor. Place the precursor sample in a porcelain boat, and under argon protection, heat it at 10°C min -1 Heat to 500°C and keep it constant for 2 hours, and then cool to prepare Comparative Example 3.

[0035] Figure 1 In (a) are the microscopic morphological characteristics of the SiO2 microspheres prepared in step (1) of Example 1 and (b) are the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1.

[0036] As Figure 1As shown in (a), the SiO2 microspheres formed by self-assembly are highly ordered and regularly arranged, with an average particle size of about 250 nm. The surface of the spheres presents a stepped hierarchical structure. This three-dimensional ordered topological feature provides an accurate morphological template for the subsequent construction of hierarchical porous carbon-based materials. It is worth noting that the ordered gaps between the microspheres can effectively adsorb the glucose-mono-cyanamide precursor solution, inducing the formation of a three-dimensional interconnected carbon network framework during the confined carbonization process. After removing the SiO2 template by HF chemical etching, from Figure 1 As can be seen from (b), the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 successfully replicated the three-dimensional interconnected hierarchical pore structure of the template. This unique topological morphology not only creates an ideal microenvironment for liquid water transfer and H2 desorption, significantly improving the mass transfer efficiency, but also its rich hierarchical pores and stable carbon skeleton structure are more conducive to the loading of active sites and the stable progress of the high-temperature reduction roasting process.

[0037] Figure 2 Figure Figure 1 is the transmission electron microscopy analysis result of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1, studying the element distribution of the catalyst and the existence state of the active components. Figure 2 As shown in (a), the catalyst still maintains a complete and ordered hierarchical pore structure and carbon skeleton after undergoing grinding and ultrasonic treatment (ball milling at 50 Hz for 10 min; ultrasonic frequency of 40 kHz, ultrasonic treatment for 30 min), indicating that external factors during the catalyst preparation process do not damage its structure, highlighting its structural stability. In addition, as Figure 2 shown in (b), the (Ru) metal particles are evenly dispersed on the surface of the support without obvious agglomeration. This benefits from the rich anchoring sites provided by the high specific surface area and the effective suppression of the Ostwald ripening effect by the strong metal-support interaction. Such ultra-fine nanoclusters have unique electronic and geometric properties and are the main catalytic sites for HER and HOR, which can expose more active sites and effectively improve the utilization rate of Ru atoms. In addition, no state of Ni-related particles or clusters was observed, and after screening the lattice fringes of the metal nanoparticles, no lattice fringes attributed to Ni were detected. It is speculated that Ni in the Ru / Ni-3DONMC catalyst exists in the form of highly dispersed Ni single atoms.

[0038] Figure 3 Figure is the aberration-corrected transmission electron microscopy of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1. Further analysis found that the size of the Ru nanoclusters is between 1 - 2.5 nm, with a uniform particle size distribution, and a large number of Ni single-atom bright spots (small circles) are distributed around the Ru clusters (large circles). This unique regulation mechanism of the synergistic action between clusters and single atoms optimizes the reaction energy barrier, thus significantly improving the kinetic performance of the hydrogen electrode reaction.

[0039] Figure 4 The N2 adsorption - desorption isotherms of Example 1, Comparative Example 1 and Comparative Example 2 can be clearly observed to all exhibit typical Type - IV isotherms. According to the theoretical calculation results of Brunauer - Emmett - Teller (BET), the specific surface area of Example 1 is 508.05 m 2 g -1 compared with the specific surface area of Comparative Example 1 (522.06 m 2 g -1 ), and the specific surface area of Comparative Example 2 (499.72 m 2 g -1 ), which further indicates that the hierarchical pore carbon microstructure is not damaged after metal loading, showing good structural stability. In addition, there is an obvious hysteresis loop in its adsorption - desorption curve, proving that there are abundant mesoporous and microporous structures on the surface. This hierarchical pore structure with a larger surface area and higher porosity provides rich attachment sites for active components, which is conducive to significantly increasing electron transfer, proton diffusion and bubble release during the reaction process, thereby improving the electrocatalytic performance.

[0040] Figure 5 The hydrogen evolution catalytic performances of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and commercial Pt / C (20 wt%) (purchased from Shanghai Macklin Biochemical Co., Ltd.) were measured. An electrochemical workstation (CHI760e) with a standard three - electrode system was used, including a glassy carbon electrode (diameter 3 mm) coated with a catalyst layer (catalyst loading of 5 μg cm -2 ), as the working electrode, a graphite rod as the counter electrode, and Hg / HgO (1.0 M KOH) as the reference electrode. The HER performances of various catalysts in 1 M KOH were systematically evaluated, and the regulation mechanism of Ni single - atom activation of the metal - support interface interaction and the synergistic effect between single atoms and nanoclusters on the hydrogen evolution performance of the catalyst were explored. As shown in (a) of Figure 5 , the polarization curve shows that Comparative Example 1 (Ni - 3DONMC) hardly has alkaline hydrogen evolution activity. After impregnating and loading Ru nanoclusters, the synthesized Example 1 (Ru / Ni - 3DONMC), Comparative Example 2 (Ru - 3DONMC) and Comparative Example 3 catalysts show significantly improved performances, and their performances are far superior to the commercial Pt / C (20 wt%) sample. This result strongly proves that Ru nanoclusters are the main catalytic active sites. In addition, compared with Comparative Example 2 (Ru - 3DONMC), Example 1 (Ru / Ni - 3DONMC) shows more excellent hydrogen evolution performance, reaching 10 mAcm -2Only a minimum overpotential of 16 mV is required, showing great potential for industrial development. This performance improvement is mainly attributed to the regulation mechanism of enhancing the metal-support interface interaction by introducing Ni single atoms, as well as the synergistic effect between Ni single atoms and Ru nanoclusters, which induces the rearrangement of electrons between the Ru metal and the support interface and optimizes the hydrogen adsorption free energy, improving the hydrogen evolution activity of the Ru-based catalyst. It is worth noting that the Tafel slope Figure 5 in (b) shows that compared with Comparative Example 2 (49.77 mV dec -1 ), Comparative Example 3 (57.02 mV dec -1 ), and commercial Pt / C (59.61 mV dec -1 ), Example 1 exhibits a low Tafel slope of 40.54 mV dec -1 in 1.0 M KOH electrolyte, indicating that the hydrogen evolution process mainly follows the Volmer-Heyrovsky mechanism, showing significant hydrogen evolution kinetic advantages.

[0041] Figure 6 For the evaluation of the chronopotentiometric stability of hydrogen evolution of Ru / Ni-3DONMC prepared in Example 1, after Example 1 (Ru / Ni-3DONMC) continuously operates at a current density of 10 mA cm -2 for 100 h, the overpotential decay amplitude is small, indicating its good long-term stability. This excellent stability stems from the multiple protection mechanisms of the material system. The three-dimensional porous carbon support not only exhibits excellent structural stability and alkali corrosion resistance, but also effectively inhibits the dissolution and agglomeration of active components during the HER process through strong metal-support interaction and the synergistic effect between Ni single atoms and Ru clusters, thus ensuring the long-term stability of catalytic active sites.

[0042] Figure 7 For the hydrogen oxidation catalytic performance of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and commercial Pt / C (20 wt%) in H2-saturated 0.1 M KOH electrolyte, it was tested using an electrochemical workstation (CHI760e) with a standard three-electrode system, including a rotating disk electrode (with an area of 0.19625 cm -2 ) coated with a catalyst layer (catalyst loading of 5 μg cm -2 ) as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl (1.0 M KCl) as the reference electrode. As shown by the polarization curve in (a) of Figure 7 , the HOR anodic current of Example 1 (Ru / Ni-3DONMC) increases sharply with the increase of potential, showing 2.55 mA cm -2The highest limiting current density, which is superior to Comparative Example 2 (Ru-3DONMC), Comparative Example 3, and commercial Pt / C. This performance improvement can be attributed to the unique dual-active-site synergistic mechanism, where Ru nanoclusters serve as the adsorption sites for hydrogen intermediates (H ad ), while the highly oxygenophilic Ni single atoms act as the adsorption centers for hydroxyl intermediates (OH ad ). The interfacial synergistic effect formed by the two effectively reduces the activation energy barrier of the HOR reaction, confirming the important role of the single-atom-cluster multi-active-site system in enhancing catalytic activity. In addition, the kinetic current density (j k ) of the studied samples was calculated based on the Koutecky-Levich equation, and the Tafel slope was determined by analyzing the relationship between the kinetic current density (j k ) and the overpotential. As shown in (b) of Figure 7 , the Tafel slope of Example 1 (Ru / Ni-3DONMC) exhibits typical asymmetric characteristics, indicating that its HOR reaction follows the Heyrovsky-Volmer mechanism, where the Volmer step is the rate-determining step of the reaction.

[0043] Figure 8 To evaluate the stability of the Ru / Ni-3DONMC hydrogen oxidation reaction prepared in Example 1 using a chronoamperometry test system, after continuous operation of Example 1 (Ru / Ni-3DONMC) at 0.1 V potential for 30000 s, the relative current retention rate reached 80%, demonstrating excellent long-term stability. This excellent stability stems from the multiple protection mechanisms of the material system. The three-dimensional porous carbon support not only exhibits excellent structural stability and alkali corrosion resistance characteristics but also effectively inhibits the dissolution and agglomeration of active components during the HOR process through strong metal-support interactions and the synergistic effect between Ni single atoms and Ru clusters, thus ensuring the long-term stability of catalytic active sites.

[0044] Through the above structural analysis and performance tests, it can be seen that the Ru / Ni-3DONMC bifunctional catalyst provided by the present invention has the synergistic effect of "single-atom-nanocluster" multi-active centers and exhibits high activity and excellent stability in electrocatalytic hydrogen evolution and hydrogen oxidation reactions. Its excellent catalytic performance stems from the unique interfacial synergistic mechanism. The Ni single atoms regulate the electronic structure of the carbon matrix through atomic-level uniform dispersion, and the coordination environment formed between the Ru nanoclusters and the single-atom sites synergistically promotes the charge transfer process. This three-dimensional porous confinement structure combined with the interfacial charge redistribution effect effectively stabilizes the chemical state of metal active sites and greatly enhances the intrinsic activity and long-term operation stability of the catalyst for hydrogen electroreactions.

[0045] The present invention has been described in detail above. For those skilled in the art, without departing from the gist and scope of the present invention and without unnecessary experiments, the present invention can be implemented within a relatively wide range under equivalent parameters, concentrations and conditions. Although specific embodiments of the present invention are given, it should be understood that the present invention can be further improved. In general, according to the principle of the present invention, this application intends to cover any modifications, uses or improvements of the present invention, including changes made using conventional techniques known in the art that depart from the scope disclosed in this application.

Claims

1. A ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst, with a hierarchical porous carbon material having a three-dimensional ordered structure as the carrier and ruthenium and nickel as the active components; wherein, Nickel species are uniformly embedded in the interior of the carrier in the form of single atoms to form highly dispersed metal sites, and ruthenium is loaded on the surface of the carrier in the form of clusters.

2. The composite catalyst according to claim 1, characterized in that, The size of the Ru nanoclusters is between 1 - 2.5 nm.

3. A method for preparing the composite catalyst according to claim 1 or 2, comprising the following steps: (1) Mix and react a silicon source, absolute ethanol, ammonia water, and water to obtain a microemulsion solution, centrifuge, wash, and dry to self-assemble to obtain SiO2 nanospheres with uniform particle size and tightly arranged and regular arrangement; (2) Mix the SiO2 nanospheres prepared in step (1), a carbon source precursor, a nitrogen dopant, and water, impregnate under vacuum, remove the residual liquid on the surface, freeze-dry the bottom solid under vacuum, and calcine and etch to obtain a three-dimensional ordered N-doped hierarchical porous carbon material; (3) Mix a soluble ruthenium salt, a soluble nickel salt, monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material obtained in step (2), impregnate, dry, and calcine to obtain the composite catalyst, the Ru / Ni-3DONMC catalyst.

4. The method according to claim 3, wherein In step (1), the silicon source is selected from: tetraethyl orthosilicate, sodium silicate, tetramethyl orthosilicate, methyltrimethoxysilane; The silicon source is tetraethyl orthosilicate; The volume ratio of tetraethyl orthosilicate to absolute ethanol is 1:12 - 14; The volume ratio of ammonia water, absolute ethanol, and water can be 0.5 - 1.5:4 - 8:2 - 3 in sequence, specifically 1:6:2.4; The temperature of the reaction is 35 - 45 °C; the duration of the reaction is 2 - 6 h; The temperature of the drying is 40 - 50 °C; The duration of the drying is 40 - 75 h; The particle size of the obtained SiO2 nanospheres is 200 - 300 nm.

5. The method according to claim 3, wherein In step (2), the carbon source precursor is glucose; The nitrogen dopant is monocyanamide; The mass ratio of SiO2 nanospheres, glucose, and monocyanamide is in sequence: 0.5-1.5：1.5-2.5：0.5-1.5。 6. The method according to claim 3, wherein In step (2), the duration of the vacuum impregnation is 4 - 8 h; The duration of the vacuum freeze-drying is 30 - 40 h; The calcination is carried out under the protection of an inert atmosphere; The heating rate of the roasting is 1-5 °C / min -1 ; Heat up to 800 - 1000 °C and keep the temperature constant for calcination for 1 - 5 h; The solvent used for etching is hydrofluoric acid; The duration of the etching is 15 - 30 h.

7. The method according to claim 3, wherein In step (3), the soluble ruthenium salt is at least one of ruthenium(III) chloride trihydrate, ruthenium(III) acetylacetonate, dodecacarbonyltriruthenium; The soluble nickel salt is at least one of nickel(II) chloride hexahydrate, nickel(II) nitrate hexahydrate, nickel(II) acetate; The ratio of the soluble ruthenium salt calculated by ruthenium, the soluble nickel salt calculated by nickel, monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material is in sequence: 1 - 1.5 mg:0.4 - 1 mg:5 - 9 mg:30 - 45 mg.

8. The method according to claim 3, wherein In step (3), the duration of the impregnation is 1 - 4 h; The temperature of the drying is 40 - 60 °C; The duration of the drying is 20 - 28 h; The calcination is carried out under the protection of an inert atmosphere; The heating rate of the roasting is 5-15 °C / min -1 ; Heat up to 300 - 700 °C and keep the temperature constant for calcination for 1 - 5 h.

9. Use of the ruthenium / nickel-three-dimensionally ordered nitrogen-doped hierarchical porous carbon-based composite catalyst according to claim 1 or 2, or the ruthenium / nickel-three-dimensionally ordered nitrogen-doped hierarchical porous carbon-based composite catalyst prepared by the method according to any one of claims 3-8, in a hydrogen electrode reaction.

10. The application according to claim 9, wherein In the said use, the ruthenium / nickel-three-dimensionally ordered nitrogen-doped hierarchical porous carbon-based composite catalyst is used as a bifunctional catalyst for electrocatalytic hydrogen evolution reaction and hydrogen oxidation reaction.

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