Preparation and application of metal-carbon-based composite material with multi-layer core-shell structure

Abstract

The invention discloses preparation and application of a metal-carbon-based composite material with a multi-layer core-shell nanostructure. According to the invention, a carbon material with a unique hollow structure is used as a carbon carrier, and the transition metal doped molybdenum sulfide carbon-based catalyst is designed and synthesized by using a multi-stage porous structure and rich reaction sites of the carbon material; a metal-carbon multi-layer core-shell nanotube structure constructed through an adsorption-anchoring strategy can realize uniform loading of the modified ultrathin molybdenum sulfide nanosheet (the thickness is less than 5 nm); meanwhile, due to the rich defect structure, more additional active edge sites can be brought. The obtained composite material combines the synergistic effect of metal and a carbon substrate, optimizes a charge transfer path, is suitable for high-performance electrolytic water hydrogen evolution reaction (HER), can provide a new research thought for developing a novel efficient non-noble metal-carbon-based electrocatalyst, and shows potential application value in energy conversion and related fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and specifically relates to the preparation and application of a multi-layer core-shell structured metal-carbon based composite material. Background Art

[0002] Non-renewable fossil fuels such as coal, oil, and natural gas are currently the main energy sources, and their continued consumption leads to the greenhouse effect and environmental pollution. Hydrogen energy, due to its high energy density, renewability, and zero-carbon emissions, is crucial to meeting global energy needs and environmental challenges. Electrocatalytic water splitting to produce hydrogen is a highly efficient technology for producing hydrogen energy. However, its reliance on scarce, expensive, and unstable platinum group precious metal hydrogen evolution catalysts has severely restricted its development. Therefore, there is an urgent need to develop efficient and stable non-precious metal alternatives based on Earth's abundant elements.

[0003] Among the abundant transition metal compounds, molybdenum sulfide (MoS2) has been widely studied due to its high stability, environmental friendliness, and low cost. Theoretical calculations indicate that the hydrogen adsorption free energy at its edge sites is close to that of platinum (Hinnemann B, Moses PG, Bonde J, et al, J. Am. Chem. Soc., 2005, 127:5308-5309), providing a theoretical basis for MoS2 as an electrocatalyst for the hydrogen evolution reaction (HER). However, MoS2's low intrinsic conductivity and inactive basal plane sites severely limit its HER catalytic performance. Current research focuses on activating the MoS2 basal plane through electronic structure manipulation. Metal doping can effectively induce charge redistribution, modulate the electronic density of states, and optimize the hydrogen adsorption free energy, thereby enhancing HER activity. For example, single-atom nickel doping can activate inactive sites within the MoS2 surface (Q. Wang, ZL Zhao, S. Dong, et al. NanoEnergy 2018, 53, 458-467); zinc doping has also been shown to enhance the HER activity of MoS2 (Y. Shi, Y. Zhou, et al. J. Am. Chem. Soc., 2017, 139: 15479-15485).

[0004] In recent years, carbon materials have become a novel catalyst support due to their high specific surface area, excellent thermal stability, chemical inertness, and surface modifiability. This paper provides a method for preparing a novel multilayer core-shell metal-carbon composite material. This method achieves a synergistic improvement in active site density and electron conductivity through the interaction of active metal-carbon multilayer interfaces, providing a technical path for the development of highly active composite catalyst systems that can be prepared on a large scale. Summary of the Invention

[0005] In order to obtain a metal-carbon-based catalyst with a unique structure that is both efficient and stable, the present invention provides a preparation and application of a new type of multi-layer core-shell structured metal-carbon-based composite material. It uses a carbon material with a unique hollow structure as a carbon carrier, adopts an "adsorption-anchoring" strategy to inhibit metal agglomeration, uses a sulfur vapor atmosphere to induce MoS2 phase transition, and regulates the MoS2 electronic state distribution through transition metal atoms to enhance the hydrogen evolution reaction (HER) activity and stability. Not only is the synthesis process simple and the cost low, but the synthesized catalyst also exhibits excellent catalytic activity.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A multilayer core-shell structure metal-carbon based composite material, the preparation method of which comprises the following steps: 1) Dispersing the biomolecules, phenolic source, and aldehyde source in water, thoroughly mixing and ultrasonically treating the mixture, and then transferring the mixture to a reactor for reaction. After the reaction is completed, the mixture is allowed to cool, and the lower layer product is collected and dispersed in methanol. After centrifugation and drying, the mixture is carbonized under an inert atmosphere and cooled naturally to room temperature to obtain a carbon precursor. 2) The carbon precursor prepared in step 1) is uniformly dispersed with a molybdenum source and a transition metal source in a solvent, and after thorough mixing and ultrasonic treatment, a sulfur source is added and mixed. The resulting mixture is transferred to a reactor for a hydrothermal reaction. After the reaction is completed, the mixture is allowed to stand and cool naturally, and then centrifuged, filtered, and dried to obtain a molybdenum-based metal-carbon precursor; 3) The molybdenum-based metal-carbon precursor obtained in step 2) is subjected to a sulfurization treatment in an inert gas atmosphere and naturally cooled to room temperature to obtain a multi-layer core-shell structured metal-carbon-based composite material.

[0007] Furthermore, the bio-small molecule in step 1) includes at least one of guanine, adenine, xanthine, hypoxanthine, and cytosine.

[0008] Furthermore, the phenol source in step 1) includes at least one of resorcinol, phloroglucinol, o-aminophenol, m-aminophenol, and p-aminophenol.

[0009] Furthermore, the aldehyde source in step 1) includes at least one of formaldehyde, hexamethylenetetramine, and glyoxylic acid.

[0010] Furthermore, the molar ratio of the bio-small molecule, the phenol source and the aldehyde source used in step 1) is 1:0.88:3.

[0011] Furthermore, the reaction temperature in step 1) is 50-100°C and the reaction time is 12-72 h.

[0012] Furthermore, the temperature of the carbonization treatment in step 1) is 700-1200°C, and the time is 1-4 hours.

[0013] Furthermore, in step 2), the molybdenum source includes at least one of ammonium molybdate, sodium molybdate, potassium molybdate, and molybdenum chloride.

[0014] Furthermore, in step 2), 50-150 mg of carbon precursor is used per mole of molybdenum source.

[0015] Furthermore, the transition metal source in step 2) includes at least one of iron nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, copper nitrate, zinc nitrate, vanadium nitrate, and cerium nitrate.

[0016] Furthermore, the molar ratio of the molybdenum source to the transition metal source used in step 2) is 1:1 to 20:1.

[0017] Furthermore, the sulfur source in step 2) includes at least one of sulfur powder, sodium sulfide, ammonium sulfide, thiourea, thioacetamide, and sodium thiosulfate.

[0018] Furthermore, the molar ratio of the molybdenum source to the sulfur source used in step 2) is 1:10 to 1:30.

[0019] Furthermore, the solvent in step 2) includes at least one of N,N-dimethylformamide, water, ethanol, and ethylene glycol.

[0020] Furthermore, the temperature of the hydrothermal reaction in step 2) is 120-200°C, and the time is 6-48 h.

[0021] Furthermore, the sulfurization treatment in step 3) is a heating treatment in the presence of reducing sulfur.

[0022] Furthermore, the reducing sulfur is at least one of sublimed sulfur, thiourea, thioacetamide, hydrogen sulfide, and carbon disulfide.

[0023] Furthermore, the temperature of the heat treatment is 300-600°C, the heating rate is 2-10°C / min, and the heating time is 1-4 h.

[0024] The obtained multilayer core-shell structured metal-carbon based composite material can be used for hydrogen evolution reaction in water electrolysis.

[0025] The carbon material used in the composite material of this invention features a structure characterized by two-dimensional graphene-like sheets encapsulated by a one-dimensional phenolic resin shell. High-temperature carbonization forms a three-dimensional porous network of interconnected carbon tubes. This carbon material then serves as a carrier, utilizing the enriched hydroxyl (-OH) and amino (-NH2) functional groups in the phenolic resin-derived carbon shell to achieve high-density loading of cobalt and transition metal ions via electrostatic adsorption. Simultaneously, a sulfur source is introduced for in-situ sulfurization, resulting in a uniformly distributed composite material of transition-metal-doped molybdenum sulfide. The transition metal atoms provide electron injection into the MoS2 and increase the concentration of sulfur vacancies. Sublimated sulfur treatment then induces the transition of the molybdenum sulfide from a semiconducting 2H phase to a metallic 1T phase, effectively improving the material's charge transfer capability and electronic conductivity. Due to the material's unique three-layer core-shell nanotube structure and in-situ co-doping with N, O, and S, the resulting composite exhibits high electrochemical activity in the hydrogen evolution reaction (HER).

[0026] Compared with the prior art, the present invention has the following advantages: 1) This invention utilizes the enriched functional groups of phenolic resin-derived carbon materials to provide high-density reaction sites, adopts an "adsorption-anchoring" strategy to achieve effective loading of active metals, and constructs a three-layer core-shell nanotube structure that is conducive to charge transfer pathways; 2) The interfacial synergistic effect between the carbon material and the metal component of the present invention significantly enhances the overall activity of the catalytic system, optimizes the electronic structure of the catalytic center, and effectively solves the problems of easy agglomeration and poor conductivity of traditional molybdenum sulfide; 3) The synthesis process of the present invention is simple, the raw materials are easily available, and the cost is low; the prepared material has high conductivity and excellent catalytic performance. When applied to HER catalysis, it exhibits excellent catalytic performance close to that of commercial 20 wt% Pt / C catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FESEM images of Co-MoS2 / GC (a) prepared in comparative example 1, MoS2 / GRFC (b) prepared in comparative example 2, and Co-MoS2 / GRFC (c) prepared in example.

[0028] Figure 2 HAADF-STEM image (a) and EDX element surface scanning distribution map (b) of Co-MoS2 / GRFC prepared in Example.

[0029] Figure 3 Mo 3d fine spectra of Co-MoS2 / GRFC As-prepared (a) and Co-MoS2 / GRFC (b) prepared in the example.

[0030] Figure 4LSV performance diagrams of Co-MoS2 / GRFC As-prepared, Co-MoS2 / GRFC, Co-MoS2 / GC, MoS2 / GRFC and Co0.10-MoS2 / GRFC, Co0.15-MoS2 / GRFC, and Co0.25-MoS2 / GRFC prepared in the examples and comparative examples and applied to HER tests. DETAILED DESCRIPTION

[0031] A multilayer core-shell structure metal-carbon based composite material, the preparation method of which comprises the following steps: 1) The biomolecule, phenol source, and aldehyde source were dispersed in water at a molar ratio of 1:0.88:3. After thorough mixing and ultrasonic treatment, the mixture was transferred to a reactor and reacted at 50-100°C for 12-72 hours. After the reaction was completed, the mixture was allowed to cool. The lower layer of product was collected and dispersed in methanol. After centrifugation and drying, the mixture was carbonized at 700-1200°C under an inert atmosphere for 1-4 hours and then naturally cooled to room temperature to obtain a carbon precursor. 2) adding the carbon precursor prepared in step 1) to a molybdenum source at a molar ratio of 50-150 mg / mol of molybdenum source, and adding a transition metal source at a molar ratio of 1:1 to 1:20 to the molybdenum source, uniformly dispersing the carbon precursor in a solvent, thoroughly mixing the precursor, and ultrasonically treating the precursor. Then, adding a sulfur source at a molar ratio of 10:1 to 30:1 to the molybdenum source, and mixing the mixture. The resulting mixture is transferred to a reactor, subjected to a hydrothermal reaction at 120-200° C. for 6-48 h, and after the reaction is completed, allowed to stand and cool naturally, followed by centrifugation, filtration, and drying to obtain a molybdenum-based metal-carbon precursor. 3) The molybdenum-based metal-carbon precursor obtained in step 2) is sulfurized at 300-600 ° C for 1-4 h in an inert gas atmosphere in the presence of reducing sulfur, and then naturally cooled to room temperature to obtain a multi-layer core-shell structured metal-carbon-based composite material.

[0032] The biosmall molecule in step 1) includes at least one of guanine, adenine, xanthine, hypoxanthine, and cytosine. The phenol source includes at least one of resorcinol, phloroglucinol, o-aminophenol, m-aminophenol, and p-aminophenol. The aldehyde source includes at least one of formaldehyde, hexamethylenetetramine, and glyoxylic acid.

[0033] In step 2), the molybdenum source includes at least one of ammonium molybdate, sodium molybdate, potassium molybdate, and molybdenum chloride. The transition metal source includes at least one of ferric nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, copper nitrate, zinc nitrate, vanadium nitrate, and cerium nitrate. The solvent includes at least one of N,N-dimethylformamide, water, ethanol, and ethylene glycol. The sulfur source includes at least one of sulfur powder, sodium sulfide, ammonium sulfide, thiourea, thioacetamide, and sodium thiosulfate.

[0034] The reducing sulfur in step 3) is at least one of sublimed sulfur, thiourea, thioacetamide, hydrogen sulfide, and carbon disulfide.

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] The test conditions in the embodiment are as follows: the transmission electron microscope (TEM) test instrument model is Talo F200S; the scanning electron microscope (SEM) test instrument model is Regulus8100; the HER performance test is carried out using a Shanghai Chenhua CHI660e electrochemical workstation, and the HER electrocatalytic performance of the sample is tested in 1 M KOH. Before the test, the electrolyte is purged with nitrogen for 30 minutes. The test is carried out in a three-electrode electrolytic cell, in which the counter electrode is a carbon rod electrode, the reference electrode is an Ag / AgCl electrode, and the catalyst is loaded on carbon paper with a loading of 1 mg / cm 2 .

[0037] Example: (1) 2.3 g of guanine, 1.92 g of resorcinol, and 3.7 ml of formaldehyde were dispersed in 70 ml of deionized water and ultrasonically treated at room temperature for 30 min to obtain a mixed solution. The mixed solution was then transferred to a reactor and allowed to react at 85 °C for 72 h. After the reaction was completed, it was naturally cooled to room temperature. The lower layer of light yellow gel precipitate was collected and dispersed in methanol. After stirring at room temperature overnight, it was centrifuged and separated. The obtained precipitate was vacuum dried and ground. It was then placed in a tube furnace and heated to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere. The temperature was maintained at this temperature for 2 h. After it was naturally cooled to room temperature, it was ground to obtain a black powdered carbon precursor, which was recorded as GRFC.

[0038] (2) Weigh 58 mg of cobalt nitrate hexahydrate and 123.6 mg of ammonium molybdate tetrahydrate respectively and dissolve them in an appropriate amount of deionized water to prepare solution A. Weigh 100 mg of the carbon precursor obtained in step (1) and disperse it in 30 ml of N,N-dimethylformamide. Ultrasonicate it at room temperature for 30 min to obtain a suspension. Pour solution A into the suspension and stir it at room temperature for 12 h. Then add 228.4 mg of thiourea and ultrasonicate it at room temperature for 30 min. Then transfer the resulting mixture to a reactor and react it at 180 °C for 24 h. After the reaction is completed, let it stand and cool to room temperature. After the product is washed with deionized water and ethanol several times, the resulting precipitate is vacuum dried at 60 °C for 12 h and fully ground to obtain a metal-carbon precursor, which is recorded as Co-MoS2 / GRFC As-prepared.

[0039] (3) 500 mg of sublimed sulfur and 50 mg of the metal-carbon precursor prepared in step (2) were placed in the upstream and downstream areas of the tube furnace, respectively. Under a nitrogen atmosphere, the temperature was raised to 500 °C at a rate of 5 °C / min and sulfurized for 1 h. After naturally cooling to room temperature, the product was fully ground to obtain a modified molybdenum-based metal-carbon-based composite material, which was recorded as Co-MoS2 / GRFC.

[0040] Comparative Example 1: (1) Weigh 2 g of guanine and place it in a tube furnace. Heat it to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere and keep it at this temperature for 2 h. Allow it to cool naturally to room temperature and grind it to obtain a black powdered carbon precursor (denoted as GC).

[0041] (2) Weigh 58 mg of cobalt nitrate hexahydrate and 123.6 mg of ammonium molybdate tetrahydrate and dissolve them in an appropriate amount of deionized water to prepare solution A. Weigh another 100 mg of the carbon precursor obtained in step (1) and disperse it in 30 ml of N,N-dimethylformamide. Ultrasonicate it at room temperature for 30 min to obtain a suspension. Pour solution A into the suspension and stir it at room temperature for 12 h. Then add 228.4 mg of thiourea and ultrasonicate it at room temperature for 30 min. The resulting mixture is transferred to a reactor and reacted at 180 °C for 24 h. After the reaction is completed, let it stand and cool to room temperature. After the product is washed with deionized water and ethanol several times, the resulting precipitate is vacuum dried at 60 °C for 12 h and fully ground to obtain a metal-carbon precursor.

[0042] (3) 500 mg of sublimed sulfur and 50 mg of the metal-carbon precursor prepared in step (2) were placed in the upstream and downstream areas of the tube furnace, respectively. Under a nitrogen atmosphere, the temperature was raised to 500 °C at a rate of 5 °C / min and sulfurized for 1 h. After cooling naturally to room temperature, the product was fully ground to obtain a modified molybdenum-based metal-carbon-based composite material, which was recorded as Co-MoS2 / GC.

[0043] Comparative Example 2: (1) 2.3 g of guanine, 1.92 g of resorcinol, and 3.7 ml of formaldehyde were dispersed in 70 ml of deionized water and ultrasonically treated at room temperature for 30 min to obtain a mixed solution. The mixed solution was then transferred to a reactor and allowed to react at 85 °C for 72 h. After the reaction was completed, it was naturally cooled to room temperature. The lower layer of light yellow gel precipitate was collected and dispersed in methanol. After stirring at room temperature overnight, it was centrifuged and separated. The obtained precipitate was vacuum dried and ground. It was then placed in a tube furnace and heated to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere. The temperature was maintained at this temperature for 2 h. After it was naturally cooled to room temperature, it was ground to obtain a black powdered carbon precursor, which was recorded as GRFC.

[0044] (2) Weigh 123.6 mg of ammonium molybdate tetrahydrate and dissolve it in an appropriate amount of deionized water to prepare solution A. Weigh another 100 mg of the carbon precursor obtained in step (1) and disperse it in 30 ml of N,N-dimethylformamide. Ultrasonicate it at room temperature for 30 min to obtain a suspension. Pour solution A into the suspension and stir it at room temperature for 12 h. Then add 228.4 mg of thiourea and ultrasonicate it at room temperature for 30 min. The resulting mixture is transferred to a reactor and reacted at 180 °C for 24 h. After the reaction is completed, let it stand and cool to room temperature. After the product is washed with deionized water and ethanol several times, the resulting precipitate is vacuum dried at 60 °C for 12 h and fully ground to obtain a metal-carbon precursor.

[0045] (3) 500 mg of sublimed sulfur and 50 mg of the metal-carbon precursor prepared in step (2) were placed in the upstream and downstream areas of the tube furnace, respectively. Under a nitrogen atmosphere, the temperature was raised to 500 °C at a rate of 5 °C / min and sulfurized for 1 h. After cooling naturally to room temperature, the product was fully ground to obtain a molybdenum-based metal-carbon-based composite material, which was recorded as MoS2 / GRFC.

[0046] Comparative Example 3: (1) 2.3 g of guanine, 1.92 g of resorcinol, and 3.7 ml of formaldehyde were dispersed in 70 ml of deionized water and ultrasonically treated at room temperature for 30 min to obtain a mixed solution. The mixed solution was then transferred to a reactor and allowed to react at 85 °C for 72 h. After the reaction was completed, it was naturally cooled to room temperature. The lower layer of light yellow gel precipitate was collected and dispersed in methanol. After stirring at room temperature overnight, it was centrifuged and separated. The obtained precipitate was vacuum dried and ground. It was then placed in a tube furnace and heated to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere. The temperature was maintained at this temperature for 2 h. After it was naturally cooled to room temperature, it was ground to obtain a black powdered carbon precursor, which was recorded as GRFC.

[0047] (2) Weigh 29 mg, 44 mg, and 73 mg of cobalt nitrate hexahydrate, respectively, and dissolve them together with 123.6 mg of ammonium molybdate tetrahydrate in an appropriate amount of deionized water to prepare solution A. Weigh another 100 mg of the carbon precursor obtained in step (1) and disperse it in 30 ml of N,N-dimethylformamide. Ultrasonicate it at room temperature for 30 min to obtain a suspension. Pour solution A into the suspension and stir it at room temperature for 12 h. Then add 228.4 mg of thiourea and ultrasonicate it at room temperature for 30 min. The resulting mixture is transferred to a reactor and reacted at 180 °C for 24 h. After the reaction is completed, let it stand and cool to room temperature. After the product is washed with deionized water and ethanol several times, the resulting precipitate is vacuum-dried at 60 °C for 12 h and fully ground to obtain a metal-carbon precursor.

[0048] (3) 500 mg of sublimed sulfur and 50 mg of the metal-carbon precursor prepared in step (2) were placed in the upstream and downstream areas of the tube furnace, respectively. Under a nitrogen atmosphere, the temperature was raised to 500 °C at a rate of 5 °C / min and sulfurized for 1 h. After naturally cooling to room temperature, the product was fully ground to obtain modified molybdenum-based metal-carbon-based composite materials, which were recorded as Co0.10-MoS2 / GRFC, Co0.15-MoS2 / GRFC, and Co0.25-MoS2 / GRFC, respectively.

[0049] Figure 1 Field emission scanning electron microscopy (FESEM) images of Co-MoS2 / GC and MoS2 / GRFC prepared in Comparative Examples 1 and 2 and Co-MoS2 / GRFC prepared in Example 1 are shown. Figure 2High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and EDX elemental mapping of the Co-MoS2 / GRFC composite prepared in Example 1. FESEM analysis combined with HAADF-STEM images show that the Co-MoS2 / GRFC composite fully retains the three-dimensional network structure of the original carbon skeleton. Meanwhile, the surface morphology of the hollow carbon tubes undergoes significant changes, exhibiting a distinct roughening characteristic. High-magnification observation reveals that this surface roughening originates from the directional growth of ultrathin molybdenum sulfide nanosheets on the outer surface of the carbon tubes, forming a typical nanoflower-like structure. The Co-MoS2 / GC composite, on the other hand, exhibits a tendency to aggregate within the field of view, similar to conventional MoS2, forming nanoflower-like balls. It does not closely bind to guanine after high-temperature carbonization to form a graphene-like layered structure, and its distribution is uneven, indicating that the metal and carbon materials are simply physically mixed. This indicates that the GRFC carbon material formed after carbonization can effectively adsorb metals, achieving in-situ growth of ultrathin molybdenum sulfide nanosheets. This unique "adsorption-anchoring" strategy of the GRFC carbon material can stabilize the ultrathin molybdenum sulfide nanosheet structure, thereby constructing a unique three-layer core-shell nanotube structure: ultrathin molybdenum sulfide nanosheets, phenolic resin-derived carbon shells, and two-dimensional graphene-like carbon nanosheets are evenly distributed from the outside to the inside. At the same time, through comparison with MoS2 / GRFC composite materials, it can be found that cobalt doping can reduce the size of molybdenum sulfide nanosheets. This effect allows the carbon tubes to load more active nanosheets per unit area, thereby effectively increasing the density of catalytic active sites.

[0050] To further elucidate the chemical composition and elemental distribution of Co-MoS2 / GRFC, energy dispersive spectroscopy (EDX) was used for characterization. EDX elemental surface distribution analysis revealed that C, N, and O are uniformly distributed within the carbon skeleton. Furthermore, S, Co, and Mo are evenly dispersed on the carbon nanotube surface, confirming the incorporation of cobalt into the molybdenum sulfide lattice structure. Furthermore, the elemental distribution map revealed consistent spatial distribution of the various components, demonstrating the effectiveness of the "adsorption-anchoring" strategy.

[0051] Figure 3 Mo 3d fine spectra of Co-MoS2 / GRFC As-prepared and Co-MoS2 / GRFC prepared in Example. 4+The 3d orbitals can be deconvoluted into two pairs of characteristic peaks: at 229.22 eV and 232.35 eV, attributed to the 1T-MoS2 phase, and at 230.14 eV and 233.45 eV, attributed to the 2H-MoS2 phase. Based on peak area calculations, the 1T to 2H phase ratio in the As-prepared Co-MoS2 / GRFC is approximately 44:56, while the 1T to 2H phase ratio in the Co-MoS2 / GRFC is approximately 88:12. This demonstrates that sulfur vapor annealing effectively increases the 1T phase content in the composite.

[0052] The standard three-electrode system was used to test the hydrogen evolution reaction (HER) performance of the prepared Co-MoS2 / GRFC As-prepared, Co-MoS2 / GRFC, Co-MoS2 / GC, MoS2 / GRFC and Co0.10-MoS2 / GRFC, Co0.15-MoS2 / GRFC, and Co0.25-MoS2 / GRFC. The results are shown in Figure 4 . Figure 4 The results showed that at a current density of 10 mA / cm 2 The overpotentials for Co-MoS2 / GRFC, Co-MoS2 / GC, MoS2 / GRFC, and Co-MoS2 / GRFC (As-prepared) were 43 mV, 92 mV, 161 mV, and 185 mV, respectively. This indicates that Co-MoS2 / GRFC exhibits the best catalytic performance, while Co-MoS2 / GC exhibits the second-best performance, indicating that simple physical mixing of the metal and carbon substrate fails to form an effective interfacial synergistic effect. Furthermore, the overpotential for Co-MoS2 / GRFC (As-prepared) is significantly higher than that for sulfurized Co-MoS2 / GRFC, confirming that sulfur vapor-induced phase transformation is an effective strategy for enhancing catalytic activity. Furthermore, a comparison reveals that Co-MoS2 / GRFC prepared with a Co content of 58 mg (Example) also significantly outperforms MoS2 / GRFC and other Co-MoS2 / GRFCs with varying Co contents, demonstrating that an appropriate Co content optimizes the electron distribution of the molybdenum-sulfur system and induces valence electron excitation, resulting in an increase in the electron density of the MoS2 domain.

[0053] Based on the above analysis, GRFC carbon supports exhibit advantages that GC does not have. At the same time, the interfacial synergistic mechanism between carbon materials and active components effectively optimizes the charge transfer path, which can further significantly enhance the catalytic activity of the hydrogen evolution reaction.

[0054] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a multilayer core-shell structured metal-carbon based composite material, characterized by: The following steps are involved: 1) Dispersing the biomolecules, phenolic source, and aldehyde source in water, thoroughly mixing and ultrasonically treating the mixture, and then transferring the mixture to a reactor for reaction. After the reaction is completed, the mixture is allowed to cool, and the lower layer product is collected and dispersed in methanol. After centrifugation and drying, the mixture is carbonized under an inert atmosphere to obtain a carbon precursor. 2) The carbon precursor prepared in step 1) is uniformly dispersed with a molybdenum source and a transition metal source in a solvent, and after thorough mixing and ultrasonic treatment, a sulfur source is added and mixed. The resulting mixture is transferred to a reactor for a hydrothermal reaction. After the reaction is completed, the mixture is allowed to stand and cool naturally, and then centrifuged, filtered, and dried to obtain a molybdenum-based metal-carbon precursor; 3) The molybdenum-based metal-carbon precursor obtained in step 2) is subjected to a sulfurization treatment in an inert gas atmosphere to obtain a multi-layer core-shell nanotube structured metal-carbon-based composite material.

2. The method for preparing the metal-carbon based composite material according to claim 1, wherein: The molar ratio of the bio-small molecule, phenol source and aldehyde source used in step 1) is 1:0.88:

3.

3. The method for preparing the metal-carbon based composite material according to claim 1 or 2, characterized in that: The biological small molecules include at least one of guanine, adenine, xanthine, hypoxanthine, and cytosine; the phenol source includes at least one of resorcinol, phloroglucinol, o-aminophenol, m-aminophenol, and p-aminophenol; and the aldehyde source includes at least one of formaldehyde, hexamethylenetetramine, and glyoxylic acid.

4. The method for preparing the metal-carbon based composite material according to claim 1, wherein: The reaction temperature in step 1) is 50-100°C and the reaction time is 12-72 hours; the carbonization temperature is 700-1200°C and the reaction time is 1-4 hours.

5. The method for preparing the metal-carbon based composite material according to claim 1, characterized in that: In step 2), 50-150 mg of carbon precursor is used per mole of molybdenum source; the molar ratio of the molybdenum source to the transition metal source is 1:1-20:1; and the molar ratio of the molybdenum source to the sulfur source is 1:10-1:

30.

6. The method for preparing the metal-carbon based composite material according to claim 1 or 5, characterized in that: The molybdenum source includes at least one of ammonium molybdate, sodium molybdate, potassium molybdate, and molybdenum chloride; the transition metal source includes at least one of iron nitrate, cobalt nitrate, nickel nitrate, manganese nitrate, copper nitrate, zinc nitrate, vanadium nitrate, and cerium nitrate; and the sulfur source includes at least one of sulfur powder, sodium sulfide, ammonium sulfide, thiourea, thioacetamide, and sodium thiosulfate.

7. The method for preparing the metal-carbon based composite material according to claim 1, wherein: In step 2), the solvent comprises at least one of N,N-dimethylformamide, water, ethanol, and ethylene glycol; the temperature of the hydrothermal reaction is 120-200° C., and the time is 6-48 h.

8. The method for preparing the metal-carbon based composite material according to claim 1, wherein: The sulfurization treatment in step 3) is a heat treatment in the presence of reducing sulfur; the reducing sulfur is at least one of sublimed sulfur, thiourea, thioacetamide, hydrogen sulfide, and carbon disulfide. The heating temperature is 300-600°C and the time is 1-4 hours.

9. A multi-layer core-shell nanotube structured metal-carbon based composite material prepared by the method of claim 1.

10. Use of the multi-layer core-shell nanotube structured metal-carbon based composite material according to claim 9 in hydrogen evolution reaction by water electrolysis.

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