A Ru / Ni-3DONMC catalyst and its preparation method and application

Abstract

The present invention discloses a Ru / Ni-3DONMC catalyst, a preparation method, and an application thereof, and relates to the field of new energy materials and electrochemical catalysis technology. The present invention uses independently designed ordered SiO2 microspheres self-assembled as a template to construct a nitrogen-doped carbon carrier with a three-dimensional ordered hierarchical pore structure, and combines a bimetallic precursor adsorption impregnation and thermal reduction process to successfully prepare a composite catalytic system with multi-level active centers. The catalyst of the present invention exhibits excellent bifunctional catalytic performance in alkaline media: the hydrogen evolution reaction is at 10 mA cm ‑2 Only 16 mV overpotential is required at this current density, and the Tafel slope is as low as 40.54 mV / dec; it has a high conductivity of 2.55 mA cm in the hydrogen oxidation reaction. ‑2 High limiting current density and excellent mass activity strongly demonstrate that the single-atom-nanocluster synergistic regulation strategy can effectively enhance the intrinsic catalytic activity and long-term operational stability of hydrogen electrochemical reactions.

Description

Technical Field

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

[0002] The electrochemical generation and conversion of hydrogen, and its role as an energy carrier, are key elements of nearly all future decarbonized energy systems. In this context, the economics and feasibility of hydrogen depend on the efficiency of two technologies: renewable energy-powered electrolysis of water to produce hydrogen, enabling the efficient conversion of "green electricity" into "green hydrogen"; and fuel cell technology, enabling the reversible conversion of hydrogen into electricity. Together, these two technologies form the core technological framework for the future green hydrogen cycle. The hydrogen evolution reaction (HER) in water electrolysis and the hydrogen oxidation reaction (HOR) in hydrogen fuel cells are key steps in determining the efficiency of hydrogen-to-electricity conversion. However, the hydrogen-to-electricity conversion process faces the dual constraints of high overpotential and poor reaction kinetics, which severely hinder its industrialization. Therefore, developing new catalysts that combine high catalytic performance, long-term stability, and economic feasibility is a key breakthrough to overcome existing technological bottlenecks and promote the large-scale development of the hydrogen energy industry.

[0003] Currently, Ru-based materials are among the most promising candidates to replace Pt-based catalysts due to their unique electronic structure, moderate hydrogen adsorption capacity, and significant cost advantage (approximately one-fifth the price of Pt). However, how to precisely manipulate the electronic structure of active sites at the atomic scale to overcome the intrinsic activity bottleneck remains a key scientific challenge restricting their development. Research has shown that strategies such as interface coupling, alloying, strain engineering, defect creation, and heterostructure design can significantly enhance catalytic performance while reducing the noble metal loading.

[0004] In supported catalysts, optimizing the interaction between metal and support interfaces is a feasible control strategy, which can significantly enhance the intrinsic activity of metal active sites through electronic structure control. The weak interaction between traditional carbon-based supports (activated carbon, graphene, etc.) and metal particles can easily cause the migration of Ru, 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-component co-doping control, 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 MNs in the carbon skeleton. x -C active sites can produce more significant synergistic effects with the main active components, providing new ideas for regulating the electronic metal-support interaction and electrocatalytic performance of ruthenium-based nanoparticles. However, the precise synthesis of synergistic hydrogen-electrochemical bifunctional catalysts of single atoms and clusters currently requires precise control of synthesis conditions. In addition, the mechanism of the hydrogen evolution reaction of the synergistic action of single atoms and clusters is relatively complex, involving multi-step electron transfer and intermediate adsorption and desorption processes. This 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 purpose of the present invention is to provide a ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst (Ru / Ni-3DONMC) and a preparation method thereof.

[0006] The Ru / Ni-3DONMC catalyst provided by the present invention uses a three-dimensional ordered nitrogen-doped hierarchical porous carbon material as a carrier, and ruthenium and nickel as active components. 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 the ruthenium is loaded on the surface of the carrier in a cluster state.

[0007] The size of Ru nanoclusters is between 1 and 2.5 nm.

[0008] 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:

[0009] (1) A silicon source, anhydrous ethanol, ammonia water and water are mixed to obtain a microemulsion solution, which is then centrifuged, washed and dried to obtain SiO2 nanospheres with uniform particle size and compact arrangement;

[0010] (2) mixing the SiO2 nanospheres, carbon source precursor, nitrogen dopant and water prepared in step (1), vacuum impregnating, removing the residual liquid on the surface, vacuum freeze-drying the solid at the bottom, calcining, and etching to obtain a three-dimensional ordered N-doped hierarchical porous carbon material (3DONMC);

[0011] (3) Mixing a soluble ruthenium salt, a soluble nickel salt, monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material obtained in step (2), impregnating, drying, and calcining to obtain the Ru / Ni-3DONMC catalyst.

[0012] In step (1) of the above method, the silicon source may be selected from: tetraethyl silicate, sodium silicate, tetramethyl silicate, methyltrimethoxysilane, and may be specifically tetraethyl silicate;

[0013] The volume ratio of tetraethyl silicate to anhydrous ethanol is 1:12-14, specifically 1:13.3;

[0014] The volume of tetraethyl silicate is 20-25 mL, specifically 22.5 mL;

[0015] The volume of ammonia water used is 45-55 mL, specifically 50 mL.

[0016] The volume ratio of ammonia water, anhydrous ethanol and water can be 0.5-1.5:4-8:2-3, specifically 1:6:2.4;

[0017] The reaction temperature may be 35-45°C, specifically 40°C;

[0018] The reaction time is 2-6 h, specifically 4 h;

[0019] The centrifugal speed can be 4000-8000 r min -1 , specifically 6000 r min -1 The centrifugation time may be 5-15 min, specifically 10 min;

[0020] In step (1) of the above method, the drying temperature may be 40-50°C, specifically 45°C;

[0021] The drying time may be 40-75 h, specifically 48 h;

[0022] The particle size of the obtained SiO2 nanospheres is 200-300 nm.

[0023] In step (2) of the above method, the carbon source precursor may be glucose;

[0024] The nitrogen dopant may be cyanamide;

[0025] The mass ratio of SiO2 nanospheres, glucose and cyanamide can be: 0.5-1.5:1.5-2.5:0.5-1.5, specifically 1:2:1;

[0026] The amount of SiO2 nanospheres used is 2.5-3.5 g, specifically 3 g;

[0027] In step (2) of the above method, the duration of the vacuum impregnation may be 4-8 hours, specifically 6 hours;

[0028] The vacuum freeze drying time may be 30-40 h, specifically 36 h;

[0029] In step (2) of the above method, the calcination is carried out under the protection of an inert atmosphere;

[0030] The heating rate of the calcination can be 1-5 ° C min -1 , specifically 2 ℃ min -1 ;

[0031] Raise the temperature to 800-1000°C, specifically 900°C, and calcine at a constant temperature for 1-5 hours, specifically 2 hours;

[0032] The solvent used for the etching is hydrofluoric acid, specifically 5-20 wt % hydrofluoric acid, more specifically 10 wt % hydrofluoric acid;

[0033] The etching time may be 15-30 h;

[0034] In step (3) of the above method, the soluble ruthenium salt is at least one of ruthenium chloride trihydrate, ruthenium acetylacetonate, and triruthenium dodecacarbonyl;

[0035] The soluble nickel salt is at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel acetate;

[0036] The ratio of the soluble ruthenium salt (calculated as ruthenium), the soluble nickel salt (calculated as nickel), monocyanamide, and 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; specifically, 1.2 mg: 0.5 mg: 7 mg: 35 mg;

[0037] 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;

[0038] 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;

[0039] The cyanamide is added in the form of a solution, and the concentration of cyanamide in the cyanamide solution can be 0.02 g / mL-0.08 g / mL, specifically 0.04 g / mL.

[0040] In step (3) of the above method, the immersion time may be 1-4 h, specifically 2 h;

[0041] The drying temperature may be 40-60°C, specifically 45°C;

[0042] The drying time may be 20-28 h, specifically 24 h;

[0043] In the above preparation method, in step (3), the calcination is carried out under the protection of an inert atmosphere;

[0044] The heating rate of the calcination can be 5-15 ° C min -1 , specifically 10 ℃ min -1 ;

[0045] The temperature is raised to 300-700°C, specifically 500°C, and calcined at a constant temperature for 1-5 hours, specifically 2 hours.

[0046] The Ru / Ni-3DONMC catalyst prepared by the above preparation method also falls within the protection scope of the present invention.

[0047] The present invention also provides application of the Ru / Ni-3DONMC catalyst in hydrogen electrolysis.

[0048] In the application, the Ru / Ni-3DONMC is used as a bifunctional catalyst for electrocatalytic hydrogen evolution reaction and hydrogen oxidation reaction.

[0049] The present invention first utilizes self-assembly technology to prepare SiO2 nano-microspheres with regular arrangement and uniform size, and uses them as templates. Glucose is used as a carbon source precursor and cyanamide is used as a nitrogen dopant. A hierarchical porous carbon material with a three-dimensional ordered structure is constructed by a high-temperature pyrolysis-etching strategy to remove the template. Subsequently, Ru salts and Ni salts are impregnated and adsorbed on the surface of the carrier using a wet chemical process, and cyanamide is added at the same time. The materials are calcined under the protection of an inert atmosphere. The addition of cyanamide further performs N doping on the one hand, and is used to anchor the metal and coordinate the metal on the other hand. Ni species are uniformly embedded in the interior of the carbon carrier in the form of single atoms to form highly dispersed metal sites, while the easily reduced precious metal Ru is loaded on the surface of the carrier in a cluster state. Thanks to the strong interaction between the metal and the carrier interface and the synergistic effect between the cluster and the single atom, the Ru agglomeration caused by Ostwald ripening is effectively limited, thereby achieving a high dispersion and stabilization of the metal active sites, and significantly improving the catalytic performance of the material. The present invention realizes the optimized distribution and synergistic effect of Ru and Ni on the carbon support through unique material design and preparation process, providing a new idea and method for the development of high-performance hydrogen-electric bifunctional catalysts.

[0050] The rich pore structure on the surface of the Ru / Ni-3DONMC catalyst carrier of the present invention can effectively limit the agglomeration of active component nanoparticles at high temperatures. In addition, the synergistic effect of Ni single atoms and Ru nanoclusters precisely controls the adsorption strength of intermediates, optimizes the catalytic reaction path, and significantly improves the catalytic activity of hydrogen-electric reactions, providing a strong guarantee for efficient energy conversion.

[0051] Compared with the prior art, the present invention has the following advantages:

[0052] (1) The three-dimensional ordered N-doped hierarchical porous carbon material constructed by the present invention forms a rich and interconnected pore structure network through the precise regulation of the multi-level pore system. This structural feature provides an efficient transmission channel for reactant molecules, significantly accelerates the escape of hydrogen, is conducive to accelerating the rapid transmission of reactants and the rapid escape of hydrogen, and effectively improves its mass transfer efficiency. In addition, its rich specific surface area also provides an ideal carrier for the high dispersion of metal active components, effectively increasing the number of active centers, thereby enhancing the catalyst activity and conversion efficiency.

[0053] (2) The present invention achieves the redistribution of surface charge on the carrier and the precise regulation of the coordination environment by doping the carbon material with a single transition metal Ni atom, forming an interface regulation mechanism that enhances the metal-carrier interaction, helps the active material to be evenly dispersed, prevents agglomeration, and improves its utilization rate.

[0054] (3) The present invention innovatively designs the synergistic mechanism of Ni single atoms and Ru nanoclusters, activating the strong electronic coupling effect at the interface between Ru and the carrier, which not only significantly improves the hydrogen electrocatalytic activity of the material, but also enhances its corrosion resistance in alkaline environments, giving the catalyst a longer service life and higher stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 (a) is a scanning electron microscope image of SiO2 microspheres; Figure 1 (b) is a scanning electron microscope image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention.

[0056] Figure 2 (a) and (b) are transmission electron microscopy images and high-resolution transmission electron microscopy images of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention (the inset is a histogram of the Ru cluster size distribution).

[0057] Figure 3 This is a spherical aberration electron microscopy image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 of the present invention (large circles represent Ru clusters, and small circles represent Ni single atoms).

[0058] Figure 4 The N2 adsorption-desorption isotherm curves of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are shown.

[0059] Figure 5 The catalytic performance of hydrogen evolution in 1.0 MKOH electrolyte for Example 1, Comparative Examples 1, 2, and 3 of the present invention and commercial Pt / C (20 wt%) is shown; (a) is a comparison of linear voltammetric polarization curves. The electrochemical test conditions were: a potential window of 0 to -0.6 V (vs. RHE) with a 5 mV s -1 The scanning rate points were taken and 80% iR compensation was applied to eliminate the influence of solution impedance; (b) is the Tafel curve.

[0060] Figure 6 The Ru / Ni-3DONMC prepared in Example 1 of the present invention is -2 The hydrogen evolution stability test under electrochemical test conditions is: at 10 mA cm -2 The decay amplitude was monitored at a constant current density for 100 h.

[0061] Figure 7The catalytic performance of hydrogen oxidation reaction of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 and commercial Pt / C (20 wt%) in H2-saturated 0.1 M KOH electrolyte is shown in Figure 2. (a) is a comparison of linear voltammetric polarization curves. The electrochemical test conditions are: 0 ~ 0.3 V (vs. RHE) potential window at 5 mV s -1 The scanning rate is set at a point with a rotating disk speed of 1600 rpm; (b) is the Tafel curve.

[0062] Figure 8 This is the HOR chronoamperometric test of the Ru / Ni-3DONMC prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0063] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0064] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0065] Example 1. Preparation of Ni single atom-doped hierarchical porous carbon material-supported Ru nanocluster composite catalyst

[0066] This embodiment provides a Ni single atom-doped hierarchical porous carbon material-supported Ru nanocluster composite catalyst, which is prepared by the following method:

[0067] (1) Preparation of SiO2 microsphere template

[0068] The modified Stöber method was used to self-assemble and synthesize regularly arranged SiO2 nanosphere templates, which served as hard templates for the subsequent preparation of carbon materials. The specific experimental steps were optimized as follows:

[0069] To a 200 mL beaker, 22.5 mL of tetraethyl silicate (TEOS) and 100 mL of anhydrous ethanol were added sequentially and magnetically stirred for 20 minutes to form a homogeneous solution. A separate 1000 mL beaker was then added with 200 mL of anhydrous ethanol, 120 mL of deionized water, and 50 mL of 28 wt% ammonia to prepare a mixed solvent system. The TEOS / ethanol solution was slowly added to the reaction system in a 40°C water bath. The reaction vessel was sealed with plastic wrap throughout the reaction to maintain the pH within the range of 9.5-10.2 and ensure kinetic control of the hydrolysis-polycondensation reaction. After 4 hours of reaction, a milky white colloidal suspension was obtained. The reaction product was aliquoted into 50 mL centrifuge tubes and centrifuged at 6000 rpm for 10 minutes to collect the precipitate. The precipitate was washed with deionized water and ethanol, then dried at 45°C for 48 hours to obtain SiO2 nanospheres (particle size 200-300 nm).

[0070] (2) Construction of three-dimensional ordered N-doped hierarchical porous carbon materials (3DONMC)

[0071] Based on the template-guided strategy, nitrogen-doped carbon materials with hierarchical pore structures were constructed. The specific steps are as follows:

[0072] 14 mL of deionized water was placed in a 50 mL beaker, and 6 g of glucose (carbon source) and 3 g of monocyanamide (nitrogen source) were added in sequence and ultrasonically dissolved. Subsequently, 3 g of SiO2 template was added and vacuum impregnated at room temperature for 6 h to achieve the initial construction of the molecular cross-linked structure. The residual liquid on the surface was removed by siphoning, and the solid at the bottom was quickly frozen with liquid nitrogen and vacuum freeze-dried for 36 h. The resulting porous precursor was then heated at 2 °C min under argon protection. -1 The temperature was raised to 900°C, maintained at this temperature for 2 h, and then naturally cooled to room temperature. The hard template was then removed by etching with a 10 wt% HF solution for 24 h. The 3DONMC material was then obtained by alternately washing with deionized water and ethanol until neutral. The 3DONMC material was then dried in a vacuum at 45°C.

[0073] (3) Synthesis of Ru / Ni-3DONMC catalyst

[0074] In a 10 mL beaker, 37 μL of ruthenium trichloride hydrate (RuCl3·H2O, 0.066 g / mL), 105 μL of nickel chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL) and 184 μL of cyanamide solution (C2H4N2, 0.04 g / mL) were accurately added in sequence. After adding deionized water, 0.035 g of 3DONMC carrier was added and ultrasonically dispersed for 30 minutes. The mixed system was immersed in the dark at room temperature for 2 hours and dried in an oven at 45°C for 24 hours to obtain the precursor. The precursor sample was placed in a porcelain boat and heated at 10°C min under argon protection. -1The temperature was raised to 500° C. and kept constant for 2 hours, and then cooled to obtain a Ru / Ni-3DONMC catalyst.

[0075] Comparative Example 1

[0076] In a 10 mL beaker, 105 μL of nickel chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL) and 184 μL of cyanamide solution (C2H4N2, 0.04 g / mL) were accurately added in sequence. After adding deionized water, 0.035 g of 3DONMC carrier (prepared in step (2) of Example 1) was added and ultrasonically dispersed for 30 minutes. The mixed system was immersed in the dark at room temperature for 2 hours and dried in an oven at 45°C for 24 hours to obtain a precursor. The precursor sample was placed in a porcelain boat and heated at 10°C min under argon protection. -1 The temperature was raised to 500°C and kept constant for 2 hours, and then cooled to obtain Ni-3DONMC.

[0077] Comparative Example 2

[0078] In a 10 mL beaker, 37 μL of ruthenium trichloride hydrate (RuCl3·H2O, 0.066 g / mL) and 184 μL of cyanamide solution (C2H4N2, 0.04 g / mL) were accurately added in sequence. After adding deionized water, 0.035 g of 3DONMC carrier (prepared in step (2) of Example 1) was added and ultrasonically dispersed for 30 minutes. The mixed system was immersed in the dark at room temperature for 2 hours and dried in an oven at 45°C for 24 hours to obtain the precursor. The precursor sample was placed in a porcelain boat and heated at 10°C min under argon protection. -1 The temperature was raised to 500° C. and kept constant for 2 hours, and then cooled to obtain a Ru / 3DONMC catalyst.

[0079] Comparative Example 3

[0080] In a 10 mL beaker, 105 μL of nickel chloride hexahydrate solution (NiCl2·6H2O, 0.02 g / mL), 37 μL of ruthenium trichloride hydrate (RuCl3·H2O, 0.066 g / mL) and deionized water were added in sequence, and 0.035 g of 3DONMC carrier (prepared in step (2) of Example 1) was added and ultrasonically dispersed for 30 minutes. The mixed system was immersed in the dark at room temperature for 2 hours and dried in an oven at 45°C for 24 hours to obtain a precursor. The precursor sample was placed in a porcelain boat and heated at 10°C min under argon protection. -1 The temperature was raised to 500° C. and kept constant for 2 hours, and then cooled to obtain Comparative Example 3.

[0081] Figure 1(a) shows the SiO2 microspheres prepared in step (1) of Example 1 and (b) shows the microscopic morphology of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1.

[0082] like Figure 1 As 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-cyanamide precursor solution, inducing the formation of a three-dimensional interconnected carbon network framework during the confined carbonization process. After the SiO2 template is removed by HF chemical etching, Figure 1 As shown in Figure (b), the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1 successfully replicates the template's three-dimensional, interconnected, hierarchical pore structure. This unique topology not only creates an ideal microenvironment for liquid water transport and H2 desorption, significantly improving mass transfer efficiency, but its abundant multi-level pores and stable carbon framework also facilitate the loading of active sites and the stable high-temperature reduction calcination process.

[0083] Figure 2 This is the transmission electron microscopy analysis result of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1. The element distribution of the catalyst and the existence state of the active components were studied. Figure 2 (a) shows that the catalyst still maintains a complete and ordered hierarchical pore structure and carbon skeleton after undergoing grinding and ultrasonic treatment (ball milling 50 Hz, 10 min; ultrasonic frequency 40 kHz, ultrasonication 30 min), indicating that external factors during the catalyst preparation process do not destroy its structure, highlighting its structural stability. In addition, Figure 2 As shown in (b), the (Ru) metal particles are uniformly dispersed on the support surface without obvious agglomeration, which is due to the abundant anchoring sites provided by the high specific surface area and the effective suppression of the Ostwald ripening effect by the strong metal-support interaction. This ultrafine nanocluster has unique electronic and geometric properties and is the main catalytic site for HER and HOR, which can expose more active sites and effectively improve the utilization of Ru atoms. In addition, no state related to Ni particles or clusters was observed, and after screening the lattice fringes of the metal nanoparticles, no lattice fringes attributable to Ni were detected. It is speculated that Ni in the Ru / Ni-3DONMC catalyst exists as a highly dispersed Ni single atom.

[0084] Figure 3This is a spherical aberration transmission electron microscopy image of the Ru / Ni-3DONMC bifunctional catalyst prepared in Example 1. Further analysis reveals that the Ru nanoclusters range in size from 1 to 2.5 nm, with a uniform size distribution. Numerous Ni single-atom bright spots (small circles) surround the Ru clusters (large circles). This unique regulatory mechanism, where clusters and single atoms work together synergistically, optimizes the reaction energy barrier, significantly improving the kinetics of the hydrogen electrochemical reaction.

[0085] Figure 4 The N2 adsorption-desorption isotherms of Example 1, Comparative Example 1, and Comparative Example 2 show 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 (499.72m 2 g -1 ), further demonstrating that the hierarchical porous carbon microstructure remains intact after metal loading, exhibiting excellent structural stability. Furthermore, the adsorption / desorption curves exhibit distinct hysteresis loops, demonstrating the presence of a rich mesoporous and microporous structure on the surface. This hierarchical porous structure, with its larger surface area and higher porosity, provides abundant attachment sites for active components, significantly increasing electron transfer, proton diffusion, and bubble release during the reaction, thereby enhancing electrocatalytic performance.

[0086] Figure 5 The hydrogen evolution catalytic performance of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and commercial Pt / C (20 wt%) (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.) was measured using an electrochemical workstation (CHI760e) with a standard three-electrode system, including a drop-coated catalyst layer (catalyst loading of 5 μg cm -2 ) glassy carbon electrode (3 mm in diameter) as the working electrode, graphite rod as the counter electrode, and Hg / HgO (1.0 M KOH) as the reference electrode. The HER performance of various catalysts in 1 M KOH was systematically evaluated, and the regulatory mechanism of the interaction between Ni single atoms activated metal and the support interface and the influence of the synergistic effect of single atoms and nanoclusters on the hydrogen evolution performance of the catalyst were explored. Figure 5As shown in (a), the polarization curve shows that Comparative Example 1 (Ni-3DONMC) has almost no alkaline hydrogen evolution activity. After impregnation with Ru nanoclusters, the synthesized Example 1 (Ru / Ni-3DONMC), Comparative Example 2 (Ru-3DONMC) and Comparative Example 3 catalysts showed significantly improved performance, and their performance was far better than that of commercial Pt / C (20 wt%) samples. 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) showed even better hydrogen evolution performance, reaching 10 mAcm -2 It only requires a very small overpotential of 16mV and has great potential for industrial development. This performance improvement is mainly attributed to the regulatory mechanism of the metal-support interface interaction enhanced by the introduction of Ni single atoms, as well as the synergistic effect of 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, thereby improving the hydrogen evolution activity of Ru-based catalysts. It is worth noting that the Tafel slope obtained from the polarization curve is Figure 5 (b) shows that compared with the comparative example 2 (49.77 mV dec -1 )、Comparative Example 3(57.02 mV dec -1 ) and commercial Pt / C (59.61 mVdec -1 ), Example 1 exhibited 40.54 mV dec in 1.0 M KOH electrolyte. -1 The low Tafel slope indicates that the hydrogen evolution process mainly follows the Volmer-Heyrovsky mechanism, showing significant hydrogen evolution kinetic advantages.

[0087] Figure 6 The stability of hydrogen evolution chronopotentiometry of Ru / Ni-3DONMC prepared in Example 1 was evaluated. -2 After 100 hours of continuous operation at the same current density, the overpotential decay was minimal, 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, but also effectively inhibits the dissolution and agglomeration of active components during the HER process through strong metal-support interactions and the synergistic effect of Ni single atoms and Ru clusters, thereby ensuring the long-term stability of the catalytic active sites.

[0088] Figure 7The 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 MKOH electrolyte was tested using a standard three-electrode electrochemical workstation (CHI760e), including a drop-coated catalyst layer (catalyst loading of 5 μg cm -2 ) of a rotating disk electrode (with an area of ​​0.19625 cm -2 ) as the working electrode, graphite rod as the counter electrode, and Ag / AgCl (1.0 M KCl) as the reference electrode. Figure 7 As shown in the polarization curve (a), the HOR anode current of Example 1 (Ru / Ni-3DONMC) increases sharply with the increase of potential, and shows a current of 2.55 mA cm in the full potential range. -2 The highest limiting current density is better than that of 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 act as hydrogen intermediates (H ad ) adsorption sites, while the highly oxygen-affinity Ni single atom serves as a hydroxyl intermediate (OH ad ) adsorption center. 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 improving catalytic activity. In addition, the kinetic current density (j) of the studied samples was calculated based on the Koutecky-Levich equation. k ), by analyzing the kinetic current density (j k ) and the overpotential to determine the Tafel slope. Figure 7 As shown in (b), the Tafel slope of Example 1 (Ru / Ni-3DONMC) shows a typical asymmetric feature, indicating that its HOR reaction follows the Heyrovsky-Volmer mechanism, in which the Volmer step is the rate-determining step of the reaction.

[0089] Figure 8 The stability of the Ru / Ni-3DONMC prepared in Example 1 during the hydrogen oxidation reaction was evaluated using a chronoamperometry test system. After 30,000 s of continuous operation at a potential of 0.1 V, Example 1 (Ru / Ni-3DONMC) maintained a relative current retention of 80%, demonstrating excellent long-term stability. This exceptional stability stems from the material system's multiple protective mechanisms. The three-dimensional porous carbon support not only exhibits excellent structural stability and alkali corrosion resistance, but also effectively inhibits the dissolution and aggregation of active components during the HOR process through strong metal-support interactions and the synergistic effect of Ni single atoms and Ru clusters, thereby ensuring the long-term stability of the catalytic active sites.

[0090] Through the above structural analysis and performance tests, it can be known that the Ru / Ni-3DONMC bifunctional catalyst provided by the present invention has the synergistic effect of multiple active centers of "single atom-nanocluster", and exhibits high activity and excellent stability in electrocatalytic hydrogen evolution and hydrogen oxidation reactions. Its excellent catalytic performance is derived from the unique interface synergistic mechanism. The Ni single atom realizes the electronic structure regulation of the carbon matrix through uniform dispersion at the atomic level, and the coordination environment formed between the Ru nanoclusters and the single atom sites synergistically promotes the charge transfer process. This three-dimensional porous confined structure, combined with the interfacial charge redistribution effect, effectively stabilizes the chemical state of the metal active sites, greatly improving the intrinsic activity and long-term operation stability of the hydrogen electrochemical reaction of the catalyst.

[0091] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that further improvements can be made to the present invention. In short, according to the principles of the present invention, this application is intended to include any changes, uses or improvements to the present invention, including changes that depart from the disclosed scope in this application and are made using conventional techniques known in the art.

Claims

1. Application of Ru / Ni-3D ordered nitrogen-doped hierarchical porous carbon-based composite catalysts in hydrogen electrolysis; In the application, the ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst is used as a bifunctional catalyst for electrocatalytic hydrogen evolution reaction and hydrogen oxidation reaction; The ruthenium / nickel-three-dimensional ordered nitrogen-doped hierarchical porous carbon-based composite catalyst uses a hierarchical porous carbon material with a three-dimensional ordered structure as a carrier and ruthenium and nickel as 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 a cluster state; The method for preparing the composite catalyst comprises the following steps: (1) A silicon source, anhydrous ethanol, ammonia water and water are mixed to obtain a microemulsion solution, which is then centrifuged, washed and dried to obtain SiO2 nanoparticles with uniform particle size and tightly arranged. The average particle size of the obtained SiO2 nanospheres was 250 nm; (2) mixing the SiO2 nanospheres, carbon source precursor, nitrogen dopant and water prepared in step (1), vacuum impregnating, removing the residual liquid on the surface, vacuum freeze-drying the solid at the bottom, calcining, and etching to obtain a three-dimensional ordered N-doped hierarchical porous carbon material; (3) mixing a soluble ruthenium salt, a soluble nickel salt, monocyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material obtained in step (2), impregnating, drying, and calcining to obtain the composite catalyst, Ru / Ni-3DONMC catalyst; In step (2), the carbon source precursor is glucose; The nitrogen dopant is cyanamide; The mass ratios of SiO2 nanospheres, glucose and cyanamide are as follows: 0.5-1.5：1.5-2.5：0.5-1.5； In step (3), the heating rate of the calcination is 5-15 ° C min -1 ; Raise the temperature to 300-700℃ and calcine at constant temperature for 1-5 hours; The average size of the Ru nanoclusters is 1.37 nm.

2. The use according to claim 1, characterized in that In step (1), the silicon source is selected from the group consisting of tetraethyl silicate, sodium silicate, tetramethyl silicate, and methyltrimethoxysilane; The silicon source is tetraethyl silicate; The volume ratio of tetraethyl silicate to anhydrous ethanol is 1:12-14; The specific volume ratio of ammonia water, anhydrous ethanol and water is 1:6:2.4; The reaction temperature is 35-45°C; the reaction time is 2-6 hours; The drying temperature is 40-50°C; The drying time is 40-75 h.

3. The use according to claim 1, characterized in that In step (2), the vacuum impregnation is performed for 4-8 hours; The vacuum freeze drying time is 30-40 h; The calcination is carried out under the protection of an inert atmosphere; The heating rate of the calcination is 1-5 ℃ min -1 ; Raise the temperature to 800-1000℃ and calcine at constant temperature for 1-5 hours; The solvent used for the etching is hydrofluoric acid; The etching time is 15-30 h.

4. The use according to claim 1, characterized in that In step (3), the soluble ruthenium salt is at least one of ruthenium chloride trihydrate, ruthenium acetylacetonate, and triruthenium dodecacarbonyl; The soluble nickel salt is at least one of nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel acetate; The ratios of the soluble ruthenium salt calculated as ruthenium, the soluble nickel salt calculated as nickel, cyanamide, and the three-dimensional ordered N-doped hierarchical porous carbon material are: 1-1.5 mg: 0.4-1 mg: 5-9 mg: 30-45 mg, respectively.

5. The use according to claim 1, characterized in that In step (3), the soaking time is 1-4 hours; The drying temperature is 40-60°C; The drying time is 20-28 h; The calcination is carried out under the protection of an inert atmosphere.

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