Composite catalytic material, preparation method and application thereof

Abstract

The application discloses a composite catalytic material and a preparation method and application thereof, and belongs to the technical field of electrocatalytic materials.The preparation method comprises the following steps: performing mixed acid oxidation pretreatment on carbon cloth; placing the pretreated carbon cloth in a precursor solution containing a molybdenum source, a sulfur source and a cobalt source to perform a first hydrothermal reaction, and then placing the carbon cloth in a solution containing a ruthenium source to perform a second hydrothermal reaction, and thus the composite catalytic material is obtained.The cobalt-doped molybdenum disulfide layer is in-situ grown on the surface of the carbon cloth, and the ruthenium-molybdenum composite oxide layer is further formed on the surface of the carbon cloth through a low-temperature hydrothermal reaction, so that the hydrogen evolution catalytic activity and the cycle stability of the material in a wide pH range are improved while the amount of noble metal is reduced.In addition, the preparation of the composite catalytic material is completed by adopting a two-step liquid phase method, without the need of complex equipment such as high-temperature calcination and vacuum deposition, and the process condition is mild, the process is simple, and the repeatability is good.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and in particular to a composite catalytic material, its preparation method, and its application. Background Technology

[0002] Two-dimensional layered molybdenum disulfide (MoS2) is considered a potential alternative to platinum-based catalysts due to its unique electronic structure and relatively moderate hydrogen adsorption free energy. However, the catalytically active sites of the thermodynamically stable semiconductor 2H phase MoS2 are mainly confined to the material edges, its large-area basal planes are chemically inert, and its intrinsic conductivity is poor, limiting further improvement in the hydrogen evolution reaction kinetics. Although phase engineering strategies to transform the 2H phase into the metallic 1T phase can effectively activate the basal planes and improve conductivity, the metastable 1T phase is prone to structural relaxation under electrochemical conditions, gradually transforming into the 2H phase, leading to a decline in catalytic activity over time.

[0003] To suppress relaxation in the 1T phase and improve catalytic performance, researchers have attempted to introduce transition metal doping to enhance the structural stability of MoS2. Simultaneously, they have utilized noble metal modification or the construction of oxide / sulfide heterostructures to modulate the interfacial electronic structure and optimize the adsorption-desorption behavior of reaction intermediates. However, the design of existing catalytic materials often focuses on single modification methods, and the interfacial bonding mechanisms and synergistic mechanisms between functional components remain to be explored. Due to the differences in hydrogen evolution reaction pathways in acidic and alkaline electrolytes, most catalytic materials can only maintain good catalytic activity and stability in a single pH system, making it difficult to achieve comprehensive performance under a wide pH range. Furthermore, how to achieve effective coupling of functional components under mild preparation conditions while reducing the amount of noble metals used and maintaining long-term service stability remains a technical challenge in this field. Summary of the Invention

[0004] In view of this, the present invention provides a composite catalytic material, its preparation method and application, by growing a cobalt-doped molybdenum disulfide layer in situ on the surface of carbon cloth and further forming a ruthenium-molybdenum composite oxide layer on its surface through a low-temperature hydrothermal reaction, so as to improve the hydrogen evolution catalytic activity and cycle stability of the material over a wide pH range while reducing the amount of precious metals used.

[0005] In a first aspect, the present invention provides a method for preparing a composite catalytic material, comprising the following steps: The carbon cloth was subjected to mixed acid oxidation pretreatment to obtain pretreated carbon cloth; The pretreated carbon is placed in a precursor solution containing a molybdenum source, a sulfur source and a cobalt source for a first hydrothermal reaction to obtain a carbon cloth with a cobalt-doped molybdenum disulfide layer grown in situ on the surface. The carbon of the in-situ grown cobalt-doped molybdenum disulfide layer is arranged in a solution containing a ruthenium source to carry out a second hydrothermal reaction, thereby obtaining the composite catalytic material; The molar ratio of ruthenium atoms in the ruthenium source to molybdenum atoms in the molybdenum source is 1: (8~45); the reaction temperature of the second hydrothermal reaction is 60~100℃.

[0006] Preferably, in the precursor solution containing molybdenum source, sulfur source and cobalt source, the molar ratio of molybdenum to sulfur is 1:(4~10).

[0007] Preferably, in the precursor solution containing molybdenum source, sulfur source and cobalt source, the molar ratio of molybdenum to cobalt is (2~8):1.

[0008] Preferably, the reaction temperature of the first hydrothermal reaction is 160~220℃, and the reaction time of the first hydrothermal reaction is 12~36 h.

[0009] Preferably, the reaction time of the second hydrothermal reaction is 1 to 5 hours.

[0010] Preferably, the molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, or molybdenum trioxide; the sulfur source is selected from at least one of thiourea, thioacetamide, or L-cysteine; the cobalt source is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride; and the ruthenium source is selected from at least one of ruthenium trichloride, ruthenium nitrate, or ruthenium dioxide.

[0011] Preferably, the mixed acid oxidation pretreatment specifically involves immersing the carbon cloth in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid for 12-36 hours, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is (1-3):1.

[0012] Preferably, the area of ​​the carbon cloth to the mass ratio of the molybdenum source is 1 cm². 2 : (50~150) mg.

[0013] Secondly, the present invention provides a composite catalytic material prepared by the above-described preparation method.

[0014] Thirdly, the present invention provides the application of the above-mentioned composite catalytic material in the electrocatalytic hydrogen evolution reaction.

[0015] Compared with the prior art, the present invention has achieved the following beneficial effects: This invention introduces oxygen-containing functional groups into the surface of carbon cloth through mixed acid oxidation pretreatment, enhancing the bonding force between the carbon cloth and the subsequent loading layer. A cobalt-doped molybdenum disulfide layer is grown in situ on the carbon cloth surface via a first hydrothermal reaction. The introduction of cobalt suppresses the structural relaxation of the 1T phase of molybdenum disulfide under electrochemical conditions, improving the conductivity and structural stability of the material. A ruthenium-molybdenum composite oxide layer is formed in situ on the surface of the cobalt-doped molybdenum disulfide layer via a second hydrothermal reaction, constructing an oxide / sulfide heterogeneous interface, which is beneficial for improving interfacial electron transport and structural stability. The low-temperature hydrothermal reaction with a relatively low ruthenium content reduces the amount of precious metal used while achieving a uniform coating layer, avoiding phase transitions and active component agglomeration caused by high-temperature treatment. This results in a composite catalytic material exhibiting good hydrogen evolution catalytic performance and cycle stability in both acidic and alkaline electrolytes. Furthermore, this invention employs a two-step liquid-phase method to prepare the composite catalytic material, eliminating the need for complex equipment such as high-temperature calcination and vacuum deposition. The process conditions are mild, the procedure is simple, and the reproducibility is good. Attached Figure Description

[0016] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] Figure 1 This invention comprises Co-MoS2 / CC in Comparative Example 2 and RuO2-MoO in Example 1. x Scanning electron microscope (SEM) images of Co-MoS2 / CC; where (a) is the SEM image of Co-MoS2 / CC in Comparative Example 2, and (b) is the SEM image of RuO2-MoO2 in Example 1. x SEM image of @Co-MoS2 / CC.

[0018] Figure 2 It is RuO2-MoO in Embodiment 1 of the present invention. x Microscopic morphology images of @Co-MoS2 / CC; where (a) is a transmission electron microscope (TEM) image, (b) is a high-resolution transmission electron microscope (HRTEM) image, and (c) is a selected area electron diffraction (SAED) image.

[0019] Figure 3 It is RuO2-MoO in Embodiment 1 of the present invention. xElemental distribution (Mapping) of @Co-MoS2 / CC; where (a) is the original image from transmission electron microscopy (TEM), and (b)~(f) are the distribution maps of Mo, S, Co, Ru and O, respectively.

[0020] Figure 4 It is RuO2-MoO in Embodiment 1 of the present invention. x Raman spectrum of @Co-MoS2 / CC.

[0021] Figure 5 It is RuO2-MoO in Embodiment 1 of the present invention. x X-ray photoelectron spectroscopy (XPS) comparison of Mo 3d between Co-MoS2 / CC and Comparative Example 2 Co-MoS2 / CC.

[0022] Figure 6 It is RuO2-MoO in Embodiment 1 of the present invention. x XPS Ru 3p spectrum of @Co-MoS2 / CC.

[0023] Figure 7 It is RuO2-MoO in Embodiment 1 of the present invention. x XPS O 1s spectrum of @Co-MoS2 / CC.

[0024] Figure 8 It is RuO2-MoO in Embodiment 1 of the present invention. x X-ray diffraction (XRD) pattern of @Co-MoS2 / CC; CC in the figure represents carbon cloth.

[0025] Figure 9 These are comparative graphs of the electrocatalytic hydrogen evolution performance of Examples 1, 2, and 3 of the present invention; where (a) is the hydrogen evolution reaction (HER) polarization curve in 0.5 mol / L H2SO4 acidic electrolyte, and (b) is the HER polarization curve in 1 mol / L KOH alkaline electrolyte. In the graphs, RHE represents the reversible hydrogen electrode.

[0026] Figure 10 This is a comparison chart of the electrocatalytic hydrogen evolution performance of Example 1 and Comparative Examples 1-3 of the present invention; wherein, (a) is the hydrogen evolution reaction (HER) polarization curve in 0.5 mol / L H2SO4 acidic electrolyte, and (b) is the HER polarization curve in 1 mol / L KOH alkaline electrolyte. In the figure, RHE represents the reversible hydrogen electrode.

[0027] Figure 11This is a comparison chart of the electrocatalytic hydrogen evolution performance of Example 1 of the present invention with Comparative Examples 2, 4, and 5; wherein, (a) is the HER polarization curve in 0.5 mol / L H2SO4 acidic electrolyte, and (b) is the HER polarization curve in 1 mol / L KOH alkaline electrolyte. In the figure, RHE represents the reversible hydrogen electrode.

[0028] Figure 12 This is a comparison chart of the electrocatalytic hydrogen evolution performance of Example 1 and Comparative Examples 6-7 of the present invention; wherein, (a) is the HER polarization curve in 0.5 mol / L H2SO4 acidic electrolyte, and (b) is the HER polarization curve in 1 mol / L KOH alkaline electrolyte. In the figure, RHE represents the reversible hydrogen electrode.

[0029] Figure 13 The figures show the initial HER polarization curves and the HER polarization curves after 5000 cyclic voltammetry (CV) cycles of the composite catalytic material prepared in Example 1 of this invention; where (a) is the test result in 0.5 mol / L H2SO4 acidic electrolyte and (b) is the test result in 1 mol / L KOH alkaline electrolyte. In the figures, RHE represents the reversible hydrogen electrode.

[0030] Figure 14 The figures show the current density-time curves of the composite catalytic material prepared in Example 1 of this invention during a 12-h chronoamperometry test; where (a) is the test result in 0.5 mol / L H2SO4 acidic electrolyte and (b) is the test result in 1 mol / L KOH alkaline electrolyte. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," and "third aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," and "third" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0033] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean including or including other components not listed, or only including or including the listed components.

[0034] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0035] Unless otherwise specified, in this invention, "source" refers to a substance capable of providing the corresponding element. For example, "molybdenum source" refers to a substance capable of providing molybdenum, including but not limited to elemental molybdenum, oxides, salts, acids, complexes, or organic compounds; "sulfur source" refers to a substance capable of providing sulfur, including but not limited to elemental sulfur, inorganic sulfides, and organic sulfides; "cobalt source" refers to a substance capable of providing cobalt, including but not limited to elemental cobalt, oxides, salts, and complexes; and "ruthenium source" refers to a substance capable of providing ruthenium, including but not limited to elemental ruthenium, oxides, salts, and complexes.

[0036] Unless otherwise specified, in this invention, "hydrothermal reaction" refers to a process in which water or an aqueous solution containing solute is used as the reaction medium in a closed reaction vessel, and the reaction system is heated to generate a high temperature and autogenous pressure, thereby accelerating the dissolution, diffusion, and chemical reaction between reactants. Hydrothermal reactions are typically carried out in a reaction vessel (e.g., a stainless steel hydrothermal reaction vessel lined with polytetrafluoroethylene).

[0037] The hydrogen evolution reaction (HER) is a crucial cathode reaction in the water electrolysis process for hydrogen production, and its efficiency directly affects the conversion efficiency of electrical energy to hydrogen energy. Molybdenum disulfide, a two-dimensional layered material, is considered a potential alternative to platinum-based catalysts due to its unique electronic structure and relatively moderate hydrogen adsorption free energy. However, molybdenum disulfide still suffers from several shortcomings in catalytic activity and long-term stability. Therefore, this invention provides a composite catalytic material, its preparation method, and its applications.

[0038] In a first aspect, the present invention provides a method for preparing a composite catalytic material, comprising the following steps: The carbon cloth was subjected to mixed acid oxidation pretreatment to obtain pretreated carbon cloth; The pretreated carbon is placed in a precursor solution containing a molybdenum source, a sulfur source and a cobalt source for a first hydrothermal reaction to obtain a carbon cloth with a cobalt-doped molybdenum disulfide layer grown in situ on the surface. The carbon of the in-situ grown cobalt-doped molybdenum disulfide layer is arranged in a solution containing a ruthenium source to carry out a second hydrothermal reaction, thereby obtaining the composite catalytic material; The molar ratio of ruthenium atoms in the ruthenium source to molybdenum atoms in the molybdenum source is 1: (8~45); the reaction temperature of the second hydrothermal reaction is 60~100℃.

[0039] This invention introduces oxygen-containing functional groups into the surface of carbon cloth through mixed acid oxidation pretreatment, thereby improving the hydrophilicity and chemical activity of the carbon cloth surface. The oxygen-containing functional groups (e.g., hydroxyl, carboxyl, epoxy groups, etc.) on the carbon cloth surface can serve as nucleation sites for in-situ catalyst growth in subsequent hydrothermal reactions, enhancing the bonding force between the carbon cloth and the supported layer. This facilitates the uniform and robust growth of the cobalt-doped molybdenum disulfide layer on the carbon cloth surface and helps reduce the risk of interfacial contact resistance and active material shedding during electrode use.

[0040] This invention utilizes a first hydrothermal reaction to grow a cobalt-doped molybdenum disulfide (Co-MoS2) layer in situ on the surface of carbon cloth (CC), achieving direct chemical bonding between the molybdenum disulfide and the carbon cloth substrate. This avoids the use of binders and the increase in interfacial resistance associated with traditional coating processes. The introduction of cobalt allows it to enter the molybdenum disulfide lattice as lattice doping, suppressing the relaxation from the metastable 1T phase to the 2H phase through lattice pinning, thereby improving the material's conductivity and structural stability. Simultaneously, the in-situ growth method maintains the integrity of the three-dimensional network structure of the carbon cloth, facilitating electrolyte penetration and gas escape.

[0041] This invention forms a ruthenium-molybdenum composite oxide layer (RuO2-MoO2) in situ on the surface of a cobalt-doped molybdenum disulfide layer via a second hydrothermal reaction. x This process enables the construction of oxide / sulfide heterojunction interfaces at relatively low temperatures. These heterojunctions facilitate interfacial charge transfer and regulate the electronic structure of surface active sites, thereby improving the adsorption-desorption behavior of hydrogen evolution reaction intermediates. The second hydrothermal reaction directly utilizes the interaction between molybdenum on the surface of the cobalt-doped molybdenum disulfide layer and ruthenium from the ruthenium source to form a ruthenium-molybdenum composite oxide layer in situ. This eliminates the need for an external molybdenum source, ensuring chemical compatibility and interfacial bonding strength between the coating layer and the substrate. By conducting the low-temperature hydrothermal reaction with a relatively low ruthenium content, a uniform coating layer can be formed while reducing the amount of precious metals used. This avoids phase transitions and agglomeration of active components caused by high-temperature treatment, resulting in a composite catalytic material that exhibits excellent hydrogen evolution catalytic performance and cycle stability in both acidic and alkaline electrolytes.

[0042] In some embodiments of the present invention, in the precursor solution containing molybdenum source, sulfur source, and cobalt source, the molar ratio of molybdenum to sulfur is 1:(4~10), including but not limited to any point value or range between any two of 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, and 1:10, for example, more preferably 1:(5~8). The present invention can regulate the crystallinity and morphology of molybdenum disulfide by controlling the molar ratio of molybdenum source to sulfur source. When the amount of sulfur source is too low, molybdenum cannot be fully sulfidated, resulting in a decrease in the crystallinity and yield of molybdenum disulfide; when the amount of sulfur source is too high, excess sulfur source may act as a capping agent adsorbed on the surface of molybdenum disulfide, covering active sites and inhibiting catalytic activity. Controlling the molar ratio of molybdenum to sulfur within the above range is beneficial for obtaining a molybdenum disulfide layer with good crystallinity and suitable nanosphere size.

[0043] In some embodiments of the present invention, the molar ratio of molybdenum to cobalt in the precursor solution containing molybdenum, sulfur, and cobalt sources is (2-8):1, including but not limited to any one of 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, and 8:1, or any range between two, and preferably (3-6):1. The present invention can adjust the amount of cobalt doping in the molybdenum disulfide lattice by controlling the molybdenum to cobalt source molybdenum source molybdenum disulfide. When the cobalt doping amount is too low, the stabilizing effect on the 1T phase is insufficient, and the improvement in the conductivity and structural stability of the material is limited; when the cobalt doping amount is too high, the excess cobalt may exist in an amorphous or second-phase form, destroying the lattice order of molybdenum disulfide and reducing the density of active sites. Controlling the molar ratio of molybdenum to cobalt within the above range is beneficial for obtaining a molybdenum disulfide layer uniformly doped with cobalt.

[0044] In some embodiments of the present invention, the reaction temperature of the first hydrothermal reaction is 160~220℃, including but not limited to any one of 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, and 220℃, or a range between any two, preferably 180~200℃. In some embodiments of the present invention, the reaction time of the first hydrothermal reaction is 12~36 h, including but not limited to any one of 12 h, 15 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h, 30 h, 32 h, 34 h, and 36 h, or a range between any two, preferably 20~28 h. The present invention, by controlling the reaction temperature and reaction time of the first hydrothermal reaction, can regulate the crystal phase composition and morphological characteristics of molybdenum disulfide. When the reaction temperature is too low or the reaction time is too short, the precursor decomposes incompletely, the crystallinity of molybdenum disulfide is insufficient, the nano-flower structure is difficult to fully form, and the density of active sites and specific surface area are limited. When the reaction temperature is too high or the reaction time is too long, molybdenum disulfide grains grow excessively, the 1T phase may undergo an irreversible transformation to the 2H phase, and the nanofloral structure may agglomerate or collapse. Controlling the reaction temperature and reaction time of the first hydrothermal reaction within the above-mentioned range is beneficial for obtaining a cobalt-doped molybdenum disulfide layer with good crystallinity and an open nanofloral structure.

[0045] In some embodiments of the present invention, the molar ratio of ruthenium to molybdenum in the solution containing the ruthenium source is 1:(8~45), for example, it can be any point value or a range between any two of 1:8, 1:10, 1:16, 1:21, 1:28, 1:35, 1:42 or 1:45, and more preferably 1:(15~30), and even more preferably 1:(18~25). When the relative amount of ruthenium is too low, the interface modification effect of the coating layer is limited; when the relative amount of ruthenium is too high, the coating layer may be too thick or agglomerate, obscuring the active sites and increasing costs. Controlling the molar ratio of ruthenium to molybdenum within the above range is beneficial to obtain a good interface modification effect while maintaining a low amount of precious metal.

[0046] In some embodiments of the present invention, the temperature of the second hydrothermal reaction is 60-100°C, for example, it can be any value or a range between any two of 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, and 100°C, more preferably 70-90°C, and even more preferably 75-85°C. When the reaction temperature is too low, the ruthenium source hydrolysis reaction rate is insufficient, making it difficult to form a complete coating layer; when the reaction temperature is too high, the coating layer grows too quickly and may crystallize, forming crystalline particles rather than a continuous thin layer with low crystallinity, which is not conducive to the performance of the interface electronic regulation effect, and may also induce relaxation of the core 1T phase. The time of the second hydrothermal reaction is 1-5 h, for example, it can be any value or a range between any two of 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, and 5 h, more preferably 1.5-3.5 h. If the reaction time is too short, the coating layer will not form completely or will cover unevenly; if the reaction time is too long, the coating layer thickness will increase excessively, which may cover the active sites. Controlling the temperature and time of the second hydrothermal reaction within the above range is beneficial to forming a uniform and continuous low-crystallinity molybdenum composite oxide coating layer, and forming a tight oxide / sulfide heterostructure interface with the cobalt-doped molybdenum disulfide layer.

[0047] In some embodiments of the present invention, the molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, and molybdenum trioxide, or may be a hydrate of the above compounds; the sulfur source is selected from at least one of thiourea, thioacetamide, and L-cysteine; the cobalt source is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride, or may be a hydrate of the above compounds; the ruthenium source is selected from at least one of ruthenium trichloride, ruthenium nitrate, and ruthenium dioxide, or may be a hydrate of the above compounds.

[0048] In some embodiments of the present invention, the molybdenum source is ammonium molybdate tetrahydrate; the sulfur source is thiourea; the cobalt source is cobalt sulfate, cobalt nitrate, or cobalt chloride; and the ruthenium source is ruthenium trichloride. Ammonium molybdate tetrahydrate, as a molybdenum source, exhibits good water solubility and thermal stability, and can slowly release molybdate ions under hydrothermal conditions, which is beneficial for the controllable nucleation and growth of molybdenum disulfide. Thiourea can slowly decompose under high-temperature hydrothermal conditions to produce hydrogen sulfide or sulfide ions, which react with the molybdenum source to generate molybdenum disulfide. Simultaneously, the gas generated by its decomposition helps to suppress interlayer stacking of nanosheets. Cobalt sulfate, cobalt nitrate, or cobalt chloride have good water solubility and can be uniformly dispersed in the precursor solution, thereby achieving uniform doping of cobalt in the molybdenum disulfide lattice. Ruthenium trichloride, as a ruthenium source, has good water solubility and can hydrolyze under low-temperature hydrothermal conditions to form ruthenium oxide, which then reacts with molybdenum on the surface of the cobalt-doped molybdenum disulfide layer to form a ruthenium-molybdenum composite oxide.

[0049] In some embodiments of the present invention, the carbon cloth is ultrasonically cleaned before use to remove dust, organic matter, and other impurities adhering to its surface. Ultrasonic cleaning may be performed sequentially in acetone, ethanol, and deionized water for 10-30 minutes each.

[0050] In some embodiments of the present invention, the mixed acid oxidation pretreatment specifically involves immersing the carbon cloth in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid for 12-36 hours, including but not limited to any one of 12 hours, 15 hours, 18 hours, 24 hours, 28 hours, 32 hours, and 36 hours, or any range between two, preferably 20-28 hours; the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is (1-3):1, including but not limited to any one of 1:1, 1.5:1, 2:1, 2.5:1, and 3:1, or any range between two, preferably (2-3):1. The concentrated sulfuric acid is a concentrated sulfuric acid with a mass concentration of not less than 95%, preferably 98%; the concentrated nitric acid is a concentrated nitric acid with a mass concentration of not less than 65%, preferably 68%; the concentrated sulfuric acid and concentrated nitric acid are commonly used strong oxidizing concentrated inorganic acids in the art.

[0051] The mixed acid system of concentrated sulfuric acid and concentrated nitric acid possesses strong oxidizing properties. Concentrated sulfuric acid acts as a dehydrating and oxidizing agent, while concentrated nitric acid provides highly oxidizing nitrate ions and nitrogen oxides. Mixed acid treatment can introduce a large number of oxygen-containing functional groups (such as carboxyl, hydroxyl, and epoxy groups) onto the carbon fiber surface, effectively improving the hydrophilicity and chemical activity of the carbon cloth surface. Simultaneously, the strong oxidative etching effect of the mixed acid can form nanoscale rough structures and defects on the carbon fiber surface, increasing the specific surface area of ​​the carbon cloth and providing more nucleation sites for the subsequent in-situ growth of the catalyst layer. This is beneficial for enhancing the bonding strength and electron transport efficiency between the catalyst layer and the carbon cloth substrate. Immersion time within the aforementioned range ensures sufficient oxidation and functionalization of the carbon cloth surface while avoiding excessive oxidation that could significantly damage the carbon fiber structure.

[0052] In some embodiments of the present invention, the area of ​​the carbon cloth to the mass ratio of the molybdenum source is 1 cm². 2 (50~150) mg, including but not limited to 1 cm 2 50 mg, 1 cm 2 60 mg, 1 cm 2 70 mg, 1 cm 2 80 mg, 1 cm 2 90 mg, 1 cm 2 100 mg, 1 cm 2 110 mg, 1 cm 2 120 mg, 1 cm2 130 mg, 1 cm 2 140 mg, 1 cm 2 The point value of any one of 150 mg or the range between any two, for example, more preferably 1 cm. 2 (70~120) mg. Carbon cloth serves as the substrate for the composite catalytic material, supporting a cobalt-doped molybdenum disulfide layer and a ruthenium-molybdenum composite oxide layer. The area of ​​the carbon cloth determines the size of the composite catalytic material and the catalyst loading. By controlling the mass ratio of the carbon cloth area to the molybdenum source, the molybdenum disulfide loading per unit area of ​​carbon cloth can be controlled. Maintaining the carbon cloth area to molybdenum source mass ratio within the aforementioned range is beneficial for obtaining a suitable catalyst layer loading on the carbon cloth surface.

[0053] In some embodiments of the present invention, the mixed acid oxidation pretreatment is followed by washing and drying steps to remove residual mixed acid and reaction products from the carbon cloth surface. Washing can be performed using deionized water and anhydrous ethanol until neutral, and drying can be performed under vacuum at 40-80°C for 4-12 hours.

[0054] In some embodiments of the present invention, the first hydrothermal reaction is carried out in a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. After the reaction is completed, the product is repeatedly washed with deionized water and ethanol to remove unreacted ions and impurities, and then vacuum dried. The washing can be performed by alternating between deionized water and anhydrous ethanol 2 to 5 times, and the drying can be performed by vacuum drying at 40 to 80°C for 4 to 12 hours.

[0055] In some embodiments of the present invention, the second hydrothermal reaction is carried out in a stainless steel hydrothermal reactor lined with polytetrafluoroethylene. After the reaction is completed, the product is repeatedly washed with deionized water and ethanol to remove unreacted ions and impurities, and then vacuum dried. The washing can be performed by alternating between deionized water and anhydrous ethanol 2 to 5 times, and the drying can be performed by vacuum drying at 50 to 80°C for 4 to 12 hours.

[0056] Secondly, the present invention provides a composite catalytic material prepared by the above-described preparation method.

[0057] In some embodiments of the present invention, the composite catalytic material comprises a carbon cloth substrate (CC), a cobalt-doped molybdenum disulfide layer (Co-MoS2) composited on the surface of the carbon cloth, and a ruthenium-molybdenum composite oxide layer (RuO2-MoO2) coating the surface of the cobalt-doped molybdenum disulfide layer. xThe cobalt-doped molybdenum disulfide layer is formed by densely packed cobalt-doped molybdenum disulfide nanosheets, with cobalt existing in the molybdenum disulfide lattice as a lattice dopant. The ruthenium-molybdenum composite oxide layer contains ruthenium oxide and molybdenum oxide, and an oxide / sulfide heterostructure is formed between the ruthenium-molybdenum composite oxide layer and the cobalt-doped molybdenum disulfide layer. This heterostructure facilitates interfacial charge transfer, modulates the electronic structure of active sites, and thus improves the adsorption-desorption behavior of hydrogen evolution reaction intermediates.

[0058] In some embodiments of the present invention, the cobalt-doped molybdenum disulfide layer has a nanoflower structure, the size of which is 200-500 nm, including but not limited to point values ​​of any one of 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, and 500 nm, or a range between any two.

[0059] In some embodiments of the present invention, the ruthenium-molybdenum composite oxide layer is a continuous amorphous or low-crystallinity thin layer with a thickness of 2 to 10 nm, including but not limited to point values ​​of any one of 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm, or a range of values ​​between any two.

[0060] The ruthenium-molybdenum composite oxide layer formed by the low-temperature hydrothermal reaction of this invention exhibits amorphous or low-crystallinity characteristics. The amorphous or low-crystallinity oxide layer has more defect sites and unsaturated coordination atoms, which is beneficial for providing more catalytic active centers. At the same time, its isotropic structural characteristics contribute to the uniformity and density of the coating layer, providing effective physical protection for the metastable 1T phase core and suppressing structural relaxation and corrosion under electrochemical conditions.

[0061] Thirdly, the present invention provides the application of the above-mentioned composite catalytic material in the electrocatalytic hydrogen evolution reaction.

[0062] In some embodiments of the present invention, the application includes using the composite catalytic material directly as a self-supporting electrode without the need for binders or additional current collectors. Compared to traditional powder catalysts that require binders to be coated onto supports such as glassy carbon electrodes, the composite catalytic material provided by the present invention uses carbon cloth as a substrate, and the catalytic layer and the substrate achieve chemical bonding through in-situ growth. This allows it to be used directly as a working electrode, avoiding the use of binders and coating processes. This helps reduce electrode fabrication costs and interfacial contact resistance, and improves the structural stability and electron transport efficiency of the catalytic layer.

[0063] The electrocatalytic hydrogen evolution reaction can be carried out in an acidic electrolyte, such as a 0.5 mol / L aqueous sulfuric acid solution, or in an alkaline electrolyte, such as a 1 mol / L aqueous potassium hydroxide solution. By constructing an oxide / sulfide heterostructure on the carbon cloth surface and achieving lattice doping of cobalt, the composite catalytic material of the present invention exhibits good hydrogen evolution catalytic activity and cycle stability in both acidic and alkaline electrolytes.

[0064] The technical solution of the present invention will be further described below with reference to specific embodiments. The present invention does not impose any special restrictions on the source of reagents used in the following embodiments; commercially available products well known to those skilled in the art can be used.

[0065] Example 1 This embodiment provides a method for preparing a composite catalytic material, including the following steps: (1) Acid treatment of carbon cloth: The carbon cloth was ultrasonically cleaned in acetone, ethanol and deionized water for 15 min in turn to remove surface impurities; the ultrasonically cleaned carbon cloth was immersed in a mixed acid solution composed of concentrated sulfuric acid and concentrated nitric acid, with the mass concentrations of the two acids being 98% and 68% respectively, and the volume ratio being 3:1, for a soaking time of 24 h; after soaking, it was repeatedly washed with deionized water and ethanol until neutral, and then vacuum dried for later use.

[0066] (2) In-situ growth of cobalt-doped molybdenum disulfide layer: 0.088 g ammonium molybdate tetrahydrate (0.071 mmol, calculated as 0.498 mmol as Mo), 0.190 g thiourea (2.500 mmol) and 0.035 g cobalt sulfate (0.125 mmol) were dissolved in 15 mL of deionized water and magnetically stirred until completely dissolved to obtain a homogeneous precursor solution; in this precursor solution, the molar ratio of molybdenum to sulfur was approximately 1:5, and the molar ratio of molybdenum to cobalt was approximately 4:1; the carbon cloth (1 cm × 1 cm) treated in step (1) was placed in the above precursor solution and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, and the first hydrothermal reaction was carried out at 200 °C for 24 h; after the reaction was completed, it was naturally cooled to room temperature, the product was taken out, washed several times alternately with deionized water and anhydrous ethanol, and then vacuum dried at 60 °C for 12 h. h, a carbon cloth with a cobalt-doped molybdenum disulfide layer grown in situ on the surface is obtained, denoted as Co-MoS2 / CC.

[0067] (3) In-situ coating of ruthenium-molybdenum composite oxide layer: 0.006 g of ruthenium trichloride hydrate (0.024 mmol) was dissolved in 15 mL of deionized water and magnetically stirred until completely dissolved to obtain a solution containing ruthenium source, so that the molar ratio of ruthenium to molybdenum in step (2) was controlled to be about 1:21; the carbon of the cobalt-doped molybdenum disulfide layer obtained in step (2) was arranged in the above solution containing ruthenium source, transferred to a stainless steel hydrothermal reactor with polytetrafluoroethylene lining, and carried out a second hydrothermal reaction at 80°C for 2 h; after the reaction was completed, it was naturally cooled to room temperature, the product was taken out, washed several times with deionized water and anhydrous ethanol alternately, and then vacuum dried at 60°C for 12 h to obtain the composite catalyst material, denoted as RuO2-MoO x @Co-MoS2 / CC.

[0068] Example 2 The only differences between this embodiment and Example 1 are: in step (1), the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 2:1, and the soaking time is 18 h; in step (2), the amount of cobalt sulfate used is 0.070 g (0.249 mmol), so that the molar ratio of molybdenum to cobalt is approximately 2:1, and the first hydrothermal reaction temperature is 180℃; in step (3), the amount of ruthenium trichloride hydrate used is 0.012 g (0.048 mmol), so that the molar ratio of ruthenium to molybdenum is approximately 1:10, the second hydrothermal reaction temperature is 60℃, and the time is 1 h. The remaining steps and conditions are the same as in Example 1.

[0069] Example 3 The only differences between this embodiment and Example 1 are: in step (1), the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 1:1, and the soaking time is 12 h; in step (2), the amount of cobalt sulfate used is 0.018 g (0.064 mmol), so that the molar ratio of molybdenum to cobalt is approximately 7.8:1, and the first hydrothermal reaction temperature is 160℃; in step (3), the amount of ruthenium trichloride hydrate used is 0.003 g (0.012 mmol), so that the molar ratio of ruthenium to molybdenum is 1:42, the second hydrothermal reaction temperature is 100℃, and the time is 3 h. The remaining steps and conditions are the same as in Example 1.

[0070] Comparative Example 1 The difference between this comparative example and Example 1 is that no cobalt source or ruthenium source is added. The preparation method includes the following steps: (1) Acid treatment of carbon cloth: Same as step (1) in Example 1.

[0071] (2) In-situ growth of molybdenum disulfide layer: 0.088 g ammonium molybdate tetrahydrate (0.071 mmol, calculated as 0.498 mmol as Mo) and 0.190 g thiourea (2.500 mmol) were dissolved in 15 mL of deionized water and magnetically stirred until completely dissolved to obtain a homogeneous precursor solution; in the precursor solution, the molar ratio of molybdenum to sulfur was approximately 1:5; the carbon cloth (1 cm × 1 cm) treated in step (1) was placed in the above precursor solution and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, and the first hydrothermal reaction was carried out at 200 °C for 24 h; after the reaction was completed, it was naturally cooled to room temperature, the product was taken out, and washed several times alternately with deionized water and anhydrous ethanol, and then vacuum dried at 60 °C for 12 h to obtain carbon cloth with molybdenum disulfide layer grown on the surface, denoted as MoS2 / CC.

[0072] Comparative Example 2 The difference between this comparative example and Example 1 is that no ruthenium source is added, that is, step (3) is not performed, and finally a carbon cloth with a cobalt-doped molybdenum disulfide layer grown in situ on the surface is obtained, which is denoted as Co-MoS2 / CC.

[0073] Comparative Example 3 The difference between this comparative example and Example 1 is that no cobalt source is added. The preparation method includes the following steps: (1) Acid treatment of carbon cloth: Same as step (1) of Comparative Example 1.

[0074] (2) In-situ growth of molybdenum disulfide layer: Same as step (2) of Comparative Example 1, to obtain MoS2 / CC.

[0075] (3) In-situ coating of ruthenium-molybdenum composite oxide layer: 0.006 g of ruthenium trichloride hydrate (0.024 mmol) was dissolved in 15 mL of deionized water and magnetically stirred until completely dissolved to obtain a solution containing ruthenium source, so as to control the molar ratio of ruthenium to molybdenum in step (2) to be about 1:21; the MoS2 / CC obtained in step (2) was placed in the above solution containing ruthenium source and transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, and a second hydrothermal reaction was carried out at 80°C for 2 h; after the reaction was completed, it was naturally cooled to room temperature, the product was taken out, washed several times with deionized water and anhydrous ethanol alternately, and vacuum dried at 60°C for 12 h to obtain the composite catalyst material, denoted as RuO2-MoO x @MoS2 / CC.

[0076] Comparative Example 4 The difference between this comparative example and Example 1 is that the amount of ruthenium trichloride hydrate used in step (3) is 0.030 g (0.119 mmol) to control the molar ratio of ruthenium to molybdenum in step (2) to be 1:4.2.

[0077] Comparative Example 5 The difference between this comparative example and Example 1 is that the amount of ruthenium trichloride hydrate used in step (3) is 0.075 g (0.297 mmol) to control the molar ratio of ruthenium to molybdenum in step (2) to be 1:1.7.

[0078] Comparative Example 6 The difference between this comparative example and Example 1 is that step (3) is performed in liquid phase at room temperature for 2 h.

[0079] Comparative Example 7 The difference between this comparative example and Example 1 is that step (3) involves a second hydrothermal reaction at 120°C for 2 hours.

[0080] Test case 1. Microscopic morphology testing The microstructure of the samples was observed using field emission scanning electron microscopy (SEM); the microstructure and coating morphology of the samples were observed using transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM).

[0081] Figure 1 In the figures (a) and (b), Co-MoS2 / CC from Comparative Example 2 and RuO2-MoO from Example 1 of the present invention are respectively. x SEM images of @Co-MoS2 / CC. The images show that Co-MoS2 grows on the carbon cloth surface in the form of nanoflora-like structures, with nanoflora sizes ranging from 200 to 300 nm, exhibiting an open three-dimensional structure. After ruthenium modification, the overall nanoflora structure of the sample is well preserved, and the surface of the nanoflora becomes slightly rougher with rounded edges, indicating that RuO2-MoO2 formed on the material surface after low-temperature hydrothermal treatment. x The coating layer did not significantly affect the overall morphology of the Co-MoS2 nanoflora.

[0082] Figure 2 (a), (b), and (c) in the figure represent RuO2-MoO2 in Embodiment 1 of the present invention, respectively. x Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) patterns of @Co-MoS2 / CC. From Figure 2 As can be seen from (a) in the figure, RuO2-MoO x @Co-MoS2 / CC still maintains a flower-like hierarchical structure composed of a large number of ultrathin nanosheets stacked in an interlaced manner, with an intact overall morphology and no obvious aggregation phenomenon; Figure 2In (b), regular lattice fringes can be clearly observed, and the interplanar spacings of 0.62 nm, 0.24 nm and 0.15 nm can be distinguished, which correspond to the (002), (103) and (110) crystal planes of Co-MoS2, respectively, indicating that the crystalline structure of the main body of the material has been well preserved. Figure 2 (c) shows characteristic diffraction spots matching the crystal plane of Co-MoS2, while the diffraction background exhibits certain dispersion characteristics, confirming the presence of low-crystallinity molybdenum oxide components on the material surface. Thanks to the low-temperature hydrothermal post-modification strategy employed in this invention, the intrinsic crystal phase and hierarchical structure of Co-MoS2 remain intact, and the oxide components can be uniformly loaded under mild conditions. The constructed oxide / sulfide heterostructure can effectively regulate the electronic structure of the material surface, providing structural support for the material's hydrogen evolution catalytic performance and cycle stability.

[0083] Figure 3 The RuO2-MoO in Embodiment 1 of the present invention x The elemental distribution (mapping) of @Co-MoS2 / CC is shown in the figure. The uniform distribution of Mo, S, Co, Ru, and O in the composite material is clearly visible. The signals of Mo and S closely match the contours of the nanospheres. Co is uniformly doped throughout the MoS2 framework, while the distribution areas of Ru and O completely overlap with those of Mo and S, indicating a good spatial correspondence between Ru, O, Mo, and S elements, suggesting that RuO2-MoO x The coating layer is relatively evenly distributed.

[0084] 2. Raman spectroscopy test The molecular vibrational information of the sample was analyzed using Raman spectroscopy. Figure 4 The RuO2-MoO in Embodiment 1 of the present invention x Raman spectrum of @Co-MoS2 / CC. Besides the D and G bands of the carbon cloth, the spectrum is visible in the 800–1000 cm⁻¹ range. -1 Vibrational peaks related to Mo-O were also observed at the sample surface, indicating that molybdenum oxide components were formed on the sample surface.

[0085] 3. X-ray photoelectron spectroscopy (XPS) testing Figure 5 The RuO2-MoO in Embodiment 1 of the present invention x XPS Mo3d comparison images of @Co-MoS2 / CC and Comparative Example 2 Co-MoS2 / CC. The Mo 3d spectrum of Co-MoS2 / CC can be fitted to multiple components, each corresponding to Mo. 4+ 3D 5 / 2 and 3D 3 / 2 Characteristic peaks and a small amount of Mo 6+The oxidation state peaks. After ruthenium modification, the 3d peak position of Mo showed a significant shift, and Mo... 6+ The significant increase in the relative content of the components indicates that localized oxidation occurred on the Co-MoS2 surface during the low-temperature hydrothermal treatment, forming MoO. x The composition is RuO2-MoO x The formation of the coating layer provides the interface basis.

[0086] Figure 6 The RuO2-MoO in Embodiment 1 of the present invention x XPS Ru 3p spectrum of @Co-MoS2 / CC. Ru 3p in the spectrum. 3 / 2 and Ru 3p 1 / 2 Both main peaks can be identified, and their binding energy positions are related to Ru in RuO2. 4+ The chemical state was consistent, confirming that ruthenium mainly exists as Ru in the composite material. 4+ It exists in form, consistent with RuO2.

[0087] Figure 7 The RuO2-MoO in Embodiment 1 of the present invention x XPS O 1s spectrum of @Co-MoS2 / CC. The O 1s spectrum can be fitted to multiple components, belonging to metal-oxygen bonds, surface-adsorbed hydroxyl oxygen (-OH), and oxygen adsorbed from water. Among them, the metal-oxygen peak is dominant, indicating that a large number of metal-oxygen bonds have formed on the sample surface, with RuO2-MoO x The formation of the coating layer is consistent.

[0088] 4. X-ray diffraction (XRD) test Figure 8 The RuO2-MoO in Embodiment 1 of the present invention x XRD pattern of @Co-MoS2 / CC. In addition to the broad diffraction peaks attributed to the carbon cloth substrate, the XRD pattern also shows diffraction peaks belonging to MoS2, but not the characteristic peaks of RuO2. Combined with TEM and XPS analysis results, this indicates that the prepared RuO2-MoO2... x The coating layer has low crystallinity.

[0089] 5. Electrocatalytic hydrogen evolution performance test Electrochemical performance was tested using a three-electrode system on an electrochemical workstation. The prepared composite catalyst was used directly as the working electrode, a graphite rod as the counter electrode, and an Ag / AgCl (saturated KCl) electrode as the reference electrode. The electrolytes were 0.5 mol / L H₂SO₄ aqueous solution (acidic) and 1 mol / L KOH aqueous solution (alkaline). High-purity nitrogen gas was bubbled into the electrolyte for 30 min before testing to remove dissolved oxygen. Linear sweep voltammetry (LSV) was performed at a scan rate of 5 mV / s, and the scan potential range was set according to the electrolyte system. All potentials were converted to potentials relative to the reversible hydrogen electrode (RHE).

[0090] Figure 9 The figures show a comparison of the electrocatalytic hydrogen evolution reaction (HER) performance of Examples 1-3 of this invention. (a) is the HER polarization curve in an acidic electrolyte of 0.5 mol / L H₂SO₄, and (b) is the HER polarization curve in an alkaline electrolyte of 1 mol / L KOH. The results show that the composite catalytic materials prepared in all three examples exhibit good HER catalytic activity in both acidic and alkaline environments, indicating that the preferred preparation parameters of this invention enable the composite catalytic materials to achieve good catalytic effects over a wide pH range.

[0091] Figure 10 The figures show a comparison of the electrocatalytic hydrogen evolution performance of Example 1 and Comparative Examples 1-3 of this invention; where (a) is the HER polarization curve in an acidic electrolyte of 0.5 mol / L H2SO4, and (b) is the HER polarization curve in an alkaline electrolyte of 1 mol / L KOH. The results show that Example 1 achieves 10 mA / cm² in both acidic and alkaline media. 2 The required overpotentials were all lower than those of the comparative samples, indicating that the composite catalytic material prepared by this invention has both good hydrogen evolution catalytic performance and a wide pH range.

[0092] Figure 11 The figures show a comparison of the electrocatalytic hydrogen evolution performance of Example 1 and Comparative Examples 2, 4, and 5 of this invention. (a) shows the HER polarization curve in a 0.5 mol / L H₂SO₄ acidic electrolyte, and (b) shows the HER polarization curve in a 1 mol / L KOH alkaline electrolyte. The results indicate that under lower Ru addition conditions (Example 1), the hydrogen evolution overpotential of the composite electrode after low-temperature hydrothermal modification is significantly lower than that of the sample without Ru. When the Ru addition is further increased (Comparative Examples 4 and 5), the hydrogen evolution overpotential of the composite electrode increases, indicating that the Ru addition amount has a significant impact on the hydrogen evolution performance of the composite electrode.

[0093] Figure 12The figures show a comparison of the electrocatalytic hydrogen evolution performance of Example 1 and Comparative Examples 6-7 of this invention; where (a) is the HER polarization curve in an acidic electrolyte of 0.5 mol / L H2SO4, and (b) is the HER polarization curve in an alkaline electrolyte of 1 mol / L KOH. The results show that when the modification temperature of the second hydrothermal reaction is lowered to room temperature or raised to 120°C, the hydrogen evolution overpotential of the resulting composite electrode increases compared to Example 1, and the catalytic performance decreases to varying degrees, indicating that the modification temperature significantly affects the hydrogen evolution performance of RuO2-MoO2. x The formation of the coating layer and the performance of the composite electrode have a significant impact.

[0094] 6. Cyclic stability test Cyclic voltammetry (CV) was performed at a scan rate of 100 mV / s and 5000 scan cycles to evaluate the long-term electrochemical stability of the catalyst. Chorometric voltammetry was performed continuously at a constant potential for 12 h, and the current density was recorded as a function of time.

[0095] Figure 13 The figures show the initial HER polarization curves and the HER polarization curves after 5000 CV cycles of the composite catalytic material prepared in Example 1 of this invention; where (a) is the test result in 0.5 mol / L H2SO4 acidic electrolyte, and (b) is the test result in 1 mol / L KOH alkaline electrolyte. As can be seen from the figures, after 5000 CV cycles in both acidic and alkaline electrolytes, the LSV curves of the composite electrode are basically the same as before the cycles, and the overpotential required to reach the same current density changes only slightly. This indicates that the composite electrode exhibits minimal catalytic activity decay during long-term electrochemical cycling and possesses good electrochemical stability and cycle durability.

[0096] Figure 14 The figure shows the current density-time curve of the composite catalytic material prepared in Example 1 of this invention during a 12-hour chronoamperometry test; (a) shows the test results in a 0.5 mol / L H₂SO₄ acidic electrolyte, and (b) shows the test results in a 1 mol / L KOH alkaline electrolyte. As can be seen from the figure, after 12 hours of continuous potentiostatic hydrogen evolution testing, the current density of the composite electrode did not decrease significantly, indicating that the material has good long-term operational stability in both acidic and alkaline environments.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite catalytic material, characterized in that, Includes the following steps: The carbon cloth was subjected to mixed acid oxidation pretreatment to obtain pretreated carbon cloth; The pretreated carbon is placed in a precursor solution containing a molybdenum source, a sulfur source and a cobalt source for a first hydrothermal reaction to obtain a carbon cloth with a cobalt-doped molybdenum disulfide layer grown in situ on the surface. The carbon of the in-situ grown cobalt-doped molybdenum disulfide layer is arranged in a solution containing a ruthenium source to carry out a second hydrothermal reaction, thereby obtaining the composite catalytic material; The molar ratio of ruthenium atoms in the ruthenium source to molybdenum atoms in the molybdenum source is 1: (8~45); the reaction temperature of the second hydrothermal reaction is 60~100℃.

2. The preparation method according to claim 1, characterized in that, In the precursor solution containing molybdenum source, sulfur source and cobalt source, the molar ratio of molybdenum to sulfur is 1:(4~10).

3. The preparation method according to claim 1, characterized in that, In the precursor solution containing molybdenum source, sulfur source and cobalt source, the molar ratio of molybdenum to cobalt is (2~8):

1.

4. The preparation method according to claim 1, characterized in that, The reaction temperature of the first hydrothermal reaction is 160~220℃, and the reaction time of the first hydrothermal reaction is 12~36 h.

5. The preparation method according to claim 1, characterized in that, The reaction time for the second hydrothermal reaction is 1 to 5 hours.

6. The preparation method according to claim 1, characterized in that, The molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, or molybdenum trioxide; the sulfur source is selected from at least one of thiourea, thioacetamide, or L-cysteine; the cobalt source is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride; and the ruthenium source is selected from at least one of ruthenium trichloride, ruthenium nitrate, or ruthenium dioxide.

7. The preparation method according to claim 1, characterized in that, The mixed acid oxidation pretreatment specifically involves immersing the carbon cloth in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid for 12-36 hours, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is (1-3):

1.

8. The preparation method according to claim 1, characterized in that, The area of ​​the carbon cloth to the mass ratio of the molybdenum source is 1 cm². 2 : (50~150) mg.

9. A composite catalytic material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the composite catalytic material as described in claim 9 in the electrocatalytic hydrogen evolution reaction.

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