Cox-N-MoO2 catalytic material as well as preparation method and application thereof

Abstract

The invention provides a Cox-N-MoO2 catalytic material as well as a preparation method and application of the Cox-N-MoO2 catalytic material. The method comprises the following steps: (1) putting molybdenum trioxide and cobalt carbonate into an agate mortar, and grinding until the molybdenum trioxide and the cobalt carbonate are uniformly mixed until light pink powder is formed; (2) putting the powder into a quartz tube, and carrying out heat treatment in an NH3 atmosphere; and 3) putting the powder sample into deionized water for repeated cleaning, and then drying to obtain Co-N-MoO2, thereby obtaining the catalytic material. Through a simple hot nitrogen method, the influence of the reaction atmosphere, the reaction temperature and the cobalt doping amount on the activity of the catalytic material is explored by changing the reaction atmosphere and the doping amount of the cobalt source, so that the optimal reaction condition is selected. The doping of cobalt can effectively reduce the reaction energy barrier of water dissociation; meanwhile, the electronic state of Mo in MoO2 is regulated and controlled by combining nitrogen doping and the synergistic coupling effect of N and Co, the hydrogen evolution reaction activity of the catalytic material and the long-acting stability of the catalytic material under the large current density are improved, and the important application prospect is achieved in the alkaline environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolyzing water, and particularly relates to a Co x -N-MoO2 catalytic material prepared by a thermal nitrogen method, and a preparation method and application thereof.

[0002] Background Introduction

[0003] Since the Industrial Revolution, human society has experienced rapid development. However, with the large-scale exploitation and use of fossil fuels, environmental pollution problems have become increasingly serious. Currently, the energy crisis is intensifying day by day, and the trend of global warming has further exacerbated this challenge. To address these issues, renewable energy sources such as solar energy, wind energy, and tidal energy have gradually become the focus of attention and have been widely developed and applied. However, due to the intermittency and unpredictability of most renewable energy sources, their energy output and utilization efficiency are relatively low. Therefore, in recent years, the research on high-efficiency energy storage and energy conversion technologies has received extensive attention. Among many potential energy carriers, hydrogen is considered a promising sustainable clean energy solution due to its high energy density (142 MJ·kg -1 ), and is expected to replace traditional fossil fuels. In hydrogen production technologies, hydrogen production by electrolyzing water has become a favored technology due to its environmental protection, sustainability, etc. However, existing electrocatalytic materials usually exhibit a high overpotential in the hydrogen evolution reaction (HER), resulting in the need to consume more energy. Therefore, developing efficient electrode materials, reducing energy consumption, and improving electrolysis efficiency have become the current research focus.

[0004] Noble metal-based materials such as platinum (Pt) have excellent electrocatalytic activity for the hydrogen evolution reaction (HER), but their scarce terrestrial abundance and high cost limit their wide application in actual industries. To overcome this challenge, researchers have explored non-noble metal catalysts, such as nickel (Ni), molybdenum (Mo), tungsten (W), and their hydroxides, nitrides, oxides, and mixed metal alloys, etc., as alternative noble metal catalysts to promote the large-scale application of hydrogen production by electrolyzing water technology.

[0005] Chinese Patent (CN112563522A) invention discloses a cobalt-doped molybdenum dioxide catalyst, its preparation method and uses. The cobalt-doped molybdenum dioxide nanowire catalyst is prepared by a hydrothermal method and a thermal reduction method. As atomic defects, vacancies can not only promote the exposure of active sites or act as active sites, but also reduce the energy barrier to achieve the purpose of surface modification and improvement of the water decomposition performance of the catalyst. However, this method has the problem of low intrinsic catalytic activity. Although Co doping can improve the HER activity of MoO2, the number of active sites and the optimization of the electronic structure are limited, and the adsorption energy of intermediate products is not optimal, which fails to effectively solve the problem of high energy required for the water dissociation step, resulting in poor long-term stability of the catalyst. This patent does not propose a clear solution for the preparation of a catalyst with both high catalytic activity and high stability. Summary of the Invention

[0006] The main purpose of the present invention is to provide a Co x -N-MoO2 catalytic material prepared by thermal nitridation. By changing the type of molybdenum source, the molar ratio of cobalt source feed, the reaction atmosphere and the heat treatment temperature, a series of Co x -N-MoO2 catalyst materials (X is the molar ratio of cobalt source feed, where X = 0.10 - 0.20) are obtained. This catalytic material is a Co x -N-MoO2 catalytic material of cobalt-loaded powder particles. The loading of cobalt can effectively reduce the reaction energy barrier of the water dissociation step in the electrolytic water hydrogen evolution reaction and improve the reaction activity of the catalyst; the doping of non-metallic nitrogen can regulate the electronic structure of the material, thereby further enhancing the stability of the material and the hydrogen evolution reaction rate of the material at a large current density under alkaline conditions by changing the density of states of the d-band center of the material.

[0007] To solve the above technical problems, the technical solution of the present invention is as follows:

[0008] A preparation method of a Co x -N-MoO2 catalytic material, comprising the following steps:

[0009] 1) Grind molybdenum trioxide and cobalt carbonate until they are evenly mixed until a light pink powder is presented;

[0010] 2) Place the obtained powder in an ammonia atmosphere for heat treatment, then naturally cool it under an inert protective atmosphere, wash it, and dry it to obtain the catalyst material.

[0011] In the above scheme, the molar ratio of the cobalt source to the molybdenum source is 0.1 - 0.2:1.

[0012] In the above scheme, the heat treatment conditions in step 2) are 500°C to 550°C, and the reaction time is 2 to 5 h.

[0013] In the above solution, the heating rate of the heat treatment in step 2) is 5-10 °C / min. -1 .

[0014] In the above solution, the ammonia gas flow rate in step 2) is 100-150 sccm.

[0015] In the above solution, the inert protective atmosphere is argon or nitrogen.

[0016] In the above solution, the drying temperature is 50-80 °C.

[0017] The Co x -N-MoO2 catalytic material obtained by the preparation method, where x is 0.1-0.2. The catalytic material includes a MoO2 substrate, nitrogen incorporated into the MoO2 lattice, and Co clusters formed on the surface of the MoO2 substrate.

[0018] Application of the catalytic material in the hydrogen evolution reaction under high current density in an alkaline environment.

[0019] In the present invention, Co and N significantly improve the hydrogen evolution reaction (HER) performance of the material through synergistic effects in the MoO2 matrix. N doping changes the electronic structure of MoO2, forms Mo-N bonds, causes the migration of Mo 3d orbital electron states, increases the electron cloud density, thereby optimizing the adsorption ability of Mo and contributing to the dissociation of H2O in the HER reaction. At the same time, due to the strong electronegativity of N, its doping can also affect the electronic environment of adjacent Co, making Co have a more suitable d electron arrangement, improving the adsorption ability of Co to intermediates (such as *H), and enhancing the reaction kinetics. On the other hand, the introduction of Co not only provides highly efficient hydrolysis dissociation active sites but also forms a local electron coupling effect with N, further optimizing the electronic structure of MoO2 and reducing the reaction energy barrier. In addition, the synergy of Co and N can effectively regulate the charge distribution on the surface of MoO2, enhance the charge migration ability of the active sites, and promote the kinetic process of the HER reaction. Therefore, compared with the materials loaded with Co or N alone, the Co-N-MoO2 system provided by the present invention shows significant advantages in both HER activity and stability.

[0020] In the present invention, compared with conventional molybdenum sources such as sodium molybdate, molybdenum trioxide (MoO₃) has a layered structure. This layered structure can provide spatial and surface positions to help disperse cobalt metal. Through this structure, molybdenum can limit the aggregation behavior of cobalt during the reaction. Therefore, the layered structure of molybdenum can not only provide a catalytic effect during the reaction but also promote the uniform distribution of cobalt. In addition, molybdenum trioxide has an octahedral coordination structure, where Mo-O is bonded by covalent bonds, and its oxidizing property is stronger than that of sodium molybdate. In the case of ammonia reduction, MoO₂ is formed, and at the same time, cobalt carbonate decomposes into Co, forming an intermediate state of Co-Mo-O, effectively reducing the surface energy of cobalt, so that cobalt atoms or small particles are not easily aggregated into large particles but exist stably with a smaller particle size.

[0021] Meanwhile, the present invention selects cobalt carbonate as the cobalt source. Compared with conventional cobalt nitrate and cobalt chloride, at 500 °C in an ammonia atmosphere, cobalt carbonate undergoes thermal decomposition and ammonia reduction to form metallic Co. These Co atoms spontaneously aggregate to form nanoscale clusters at high temperatures. At the same time, the active nitrogen (such as N⁻) decomposed from NH₃ replaces some oxygen sites in MoO₂ to form N-MoO₂. Finally, Co and N synergistically act at the interface to construct a Co-loaded and N-doped Co-N-MoO₂ composite material.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) Provide a Co-N-MoO₂ catalyst with MoO₂ as the carrier, metal Co clusters loaded, and non-metal N doped, and its preparation method. By changing the type of molybdenum source, the molar feed of the cobalt source, the reaction gas atmosphere, and the temperature of reaction heat treatment, a catalytic material under high current density in alkaline conditions is prepared by the thermal nitrogen method. In terms of hydrogen evolution, the overpotential of the prepared catalyst electrode at a current density of 250 mA cm -2 is only 275 mV.

[0024] (2) By forming a comparison by changing the input amount of Co, on the premise of selecting MoO₃ as the molybdenum source, when the Co content is 3.0 - 3.8 at%, the Co cluster particle size is appropriate and evenly dispersed on the surface of MoO₂. On the one hand, Co acts as an H adsorption modifier for MoO₂, and at the same time, it also serves as a highly active site to facilitate the conversion of adsorbed hydrogen.

[0025] (3) By forming a comparison by changing the reduction atmosphere, using ammonia as the reduction atmosphere, the nitrogen doping amount is 0.5 - 3 at%, and N atoms exist in the MoO₂ lattice in the form of pyridine nitrogen and metal-N bonds. Nitrogen doping causes oxygen vacancies and electron enrichment regions to be generated on the surface of MoO₂, enhancing the electron interaction with Co clusters and inhibiting their migration and aggregation.

[0026] (4) The preparation method has a simple process, and the raw materials are widely sourced and inexpensive, making it an ideal catalytic material for achieving hydrogen evolution reaction under high current density in alkaline conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0028] Figure 1 XRD diagrams of Co x -N-MoO2 electrodes prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

[0029] Figure 2 SEM diagrams of Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

[0030] Figure 3 N1s diagram of XPS for Example 1.

[0031] Figure 4 XPS comparison diagram of Mo 3d between Example 1 and Comparative Example 5.

[0032] Figure 5 EDS element distribution diagram for Example 1.

[0033] Figure 6 Current density-voltage relationship diagram (a) and EIS impedance spectrum diagram (b) of Co x -N-MoO2 doped with different Co contents.

[0034] Figure 7 Current density-voltage relationship diagram (a) and EIS impedance spectrum diagram (b) of hydrogen evolution for cobalt-doped Co 0.2 -N-MoO2-T electrode.

[0035] Figure 8 Current density-voltage relationship diagrams of hydrogen evolution for the electrodes of Example 1, Comparative Example 3, and Comparative Example 5.

[0036] Figure 9 LSV polarization curve comparison diagram of Example 1 after 3000 CV cycles.

[0037] Figure 10 Stability diagram of Example 1 under constant current. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The principles and features of the present invention will be described below in conjunction with examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Additionally, it is worth noting that the raw materials involved in the present invention are all ordinary commercially available products unless otherwise specified.

[0039] Example 1

[0040] As Figure 1 shown, this example provides a method for preparing a Co-N-MoO2 catalytic material, which includes the following steps:

[0041] (1) Place 576 mg (4 mmol) of MoO3 and 95.2 mg (0.8 mmol) of CoCO3 in an agate mortar and grind for 30 min until a uniform light pink powder is obtained.

[0042] (2) Place the dry powder obtained in step (1) in a quartz crucible and put it in the heating area of a vacuum tube furnace. Heat it to 500 °C at a rate of 5 °C / min in an NH3 atmosphere, then hold for 3 h. The NH3 gas flow rate is 150 sccm. After holding, wait until it cools to 150 °C, switch to an Ar atmosphere (to terminate the reaction, inhibit unnecessary side reactions, protect the product, and ensure experimental safety), and until the furnace cools to room temperature. Wash it several times with deionized water, put it in an oven to dry, and finally obtain the Co -1 -N-MoO2 catalyst material. 0.2 -N-MoO2 catalyst material.

[0043] Use the Co 0.2 -N-MoO2 obtained in Example 1 as the catalyst material to prepare a working electrode. Weigh the catalyst material and carbon black powder according to a mass ratio of 0.45:0.05 and mix them evenly. Then, successively add 20 μL of 5% Nafion solution, 1 mL of deionized water, and 1 mL of isopropanol solution, and perform ultrasonic treatment for 30 min. After uniform dispersion, drop the obtained ultrasonic solution onto a copper foam substrate, dry it to obtain the working electrode. Place the prepared working electrode in a 1 M KOH solution to test its electrochemical performance.

[0044] Example 2

[0045] This Example 2 uses basically the same experimental raw materials and conditions as Example 1, specifically:

[0046] (1) Place 576 mg of MoO3 and 142.8 mg of CoCO3 in an agate mortar and grind for 30 min until a uniform light pink powder is obtained.

[0047] (2) The steps are the same as those in Example 1 and will not be repeated here. Finally, obtain the Co 0.1 -N-MoO2 catalyst material.

[0048] Comparative Example 1

[0049] In this Comparative Example 1, the same experimental raw materials and conditions as in Example 1 were used. Specifically:

[0050] (1) 576 mg of MoO3 and 47.6 mg of CoCO3 were placed in an agate mortar and ground for 30 min until a uniform light pink powder was obtained.

[0051] (2) The steps were the same as those in Example 1 and will not be repeated here. Finally, Co 0.3 -N-MoO2 catalyst material was obtained.

[0052] Comparative Example 2

[0053] In this Comparative Example 2, the same experimental raw materials and conditions as in Example 1 were used. Specifically:

[0054] (1) 576 mg of MoO3 and 190.4 mg of CoCO3 were placed in an agate mortar and ground for 30 min until a uniform light pink powder was obtained.

[0055] (2) The steps were the same as those in Example 1 and will not be repeated here. Finally, Co 0.4 -N-MoO2 catalyst material was obtained.

[0056] Comparative Example 3

[0057] In this example, the same experimental raw materials and conditions as in Example 1 were used, and only the cobalt doping process in step (1) was removed. Specifically:

[0058] (1) 576 mg of MoO3 was placed in an agate mortar and ground for 30 min;

[0059] (2) The dried powder obtained in step (1) was placed in a tubular furnace under an ammonia atmosphere and heat-treated at 500 °C for 3 h, with a heating rate of 5 °C / min -1 , and the ammonia flow rate was 100 sccm. Finally, N-MoO2 catalytic material was obtained.

[0060] Example 3

[0061] (1) The steps were the same as those in step (1) of Example 1 and will not be repeated here;

[0062] (2) The dried powder obtained in step (1) was placed in a quartz crucible and put into the heating area of a vacuum tubular furnace. Under an NH3 atmosphere, it was heated to 550 °C at 5 °C / min -1 and then held at this temperature for 3 h. The NH3 gas flow rate was 150 sccm. After the holding ended and it was cooled to 150 °C, the atmosphere was switched to Ar until the furnace cooled to room temperature. Then it was washed several times with deionized water and dried in an oven. Finally, Co0.2 -N-MoO2 -550 catalyst material.

[0063] Comparative Example 4

[0064] (1) The steps are the same as those in step (1) of Example 1 and will not be elaborated here;

[0065] (2) Place the dried powder obtained in step (1) in a quartz crucible, put it in the heating area of a vacuum tube furnace, and heat it to 600 °C at a rate of 5 °C / min in an NH3 atmosphere, then hold for 3 h. The flow rate of NH3 gas is 150 sccm. After the holding is completed and cooled to 150 °C, switch to an Ar atmosphere. After the furnace is cooled to room temperature, wash it several times with deionized water and dry it in an oven to finally obtain Co -1 -N-MoO2 -600 catalyst material. 0.2 -N-MoO2 -600 catalyst material.

[0066] Comparative Example 5

[0067] (1) The steps are the same as those in step (1) of Example 1 and will not be elaborated here;

[0068] (2) Place the dried powder obtained in step (1) in a quartz crucible, put it in the heating area of a vacuum tube furnace, and heat it to 500 °C at a rate of 5 °C / min in an Ar atmosphere, then hold for 3 h. The flow rate of Ar gas is 150 sccm. After the furnace is cooled to room temperature, wash it several times with deionized water and dry it in an oven to finally obtain Co -1 -MoO2 catalyst material. 0.2 -MoO2 catalyst material.

[0069] Figure 1 For the XRD patterns of the Co x -N-MoO2 electrodes obtained in Examples 1 and 2, it can be seen that: the phase composition of this catalyst is MoO2, corresponding to the standard card (MoO2#32-0671). At the same time, no diffraction peaks of cobalt compounds are detected. This is because the Co content is relatively low, so the corresponding peaks are not found in the XRD. At the same time, this result confirms that the introduction of Co does not change the crystal structure of MoO2 and no other crystalline phase substances are formed.

[0070] Figure 2 The SEM images of Examples 1, 2, Comparative Example 1, and Comparative Example 2 are shown. It can be observed from the figure that the powder particle sizes of Examples 1 and 2 are both concentrated in the range of 20 - 50 nm, and excellent hydrogen evolution reaction performance is exhibited within this particle size range; while when the powder particle size increases to 60 - 100 nm (such as Comparative Examples 3 and 4), the hydrogen evolution performance of the material significantly decreases. The above results prove that with the increase of Co doping amount, the particle size of the material increases and agglomeration occurs, resulting in the reduction of hydrogen evolution reaction performance.

[0071] Figure 3 It is the N 1s spectrum of XPS for Example 1. It can be seen that the N 1s spectrum shows pyridine nitrogen (398.5 eV) and metal-N bond (396.8 eV), indicating that N is successfully incorporated into the lattice.

[0072] Figure 4 It is the Mo 3d comparison spectrum of XPS for Example 1 and Comparative Example 5. Since the electronegativity of N (3.04) is lower than that of O (3.44), when N atoms replace O and enter the MoO2 lattice, the electron density of the Mo-N bond is lower than that of the Mo-O bond, which will cause Mo 4+ to shift towards a higher binding energy direction, reduce the hydrolysis dissociation energy barrier through electronic structure regulation, and optimize the adsorption behavior of H*, thereby enhancing the HER activity of the catalyst.

[0073] Figure 5 It is the EDS elemental distribution map of Co-N-MoO2. It can be seen that the content of Co is 3.5 at%, and the content of N is 2.1 at%, indicating the successful preparation of Co-N-MoO2.

[0074] Figure 6 Figures 6a and 6b respectively show the current density-voltage relationship diagram and EIS impedance diagram of Co x -N-MoO2 electrodes doped with different Co contents. It can be seen that the co-doping of Co and N produces a synergistic effect in the material, significantly reducing the reaction energy barrier required for the hydrolysis dissociation step and optimizing the adsorption energy of active hydrogen in the material. At the same time, by adjusting the doping amount of Co, the lattice structure of the material can be effectively regulated, further enhancing its electrochemical performance. Therefore, compared with the singly doped Co-MoO2 or N-MoO2, the Co x -N-MoO2 electrode exhibits higher catalytic activity, accelerating the electron transfer rate of the catalyst during the reaction process.

[0075] Figure 7 Figures 7a and 7b are respectively the current density-voltage relationship diagram and EIS impedance spectrum of hydrogen evolution of Co 0.2 -N-MoO2-T electrodes with different Co contents. It can be seen that: due to the increase in temperature, the overpotential of the catalyst to reach a current density of 200 mA cm -2 gradually increases, and the electron transfer rate during the reaction process gradually decreases.

[0076] Figure 8 It is the current density-voltage relationship diagram of hydrogen evolution of the electrodes for Example 1, Comparative Example 3 and Comparative Example 5. It can be seen that: the synergistic effect of the dual active centers, that is, the co-doping of Co and N forms efficient bifunctional active sites through electron coupling and structure regulation. Promote the improvement of the hydrogen evolution reaction performance of the catalyst. Figure 9LSV polarization curve comparison diagram of Example 1 after 3000 CV cycles. After 3000 cycles, Co 0.2 -N-MoO2-500 catalytic material drives 200 mA cm -2 The overpotential of the current density only increases by 53 mV.

[0077] Figure 10 Stability diagram of Example 1 under constant current. At a voltage of 0.25 V, after 50 h of testing, the change in current compared with the initial value is not significant.

[0078] For the Co prepared in Example 1 of the present invention 0.2 -N-MoO2, Co prepared in Example 2 0.1 -N-MoO2, Co prepared in Comparative Example 1 0.3 -N-MoO2, Co prepared in Comparative Example 2 0.4 -N-MoO2 SEM images were analyzed. As Figure 2 shown, with the increase of cobalt content, the morphology of the catalytic material gradually shows an agglomeration trend, which directly leads to the reduction of the specific surface area of the catalyst. When the molar ratio of cobalt source to molybdenum source is 0.1 - 0.2:1, the catalytic material particles are evenly dispersed and the particle size is appropriate. This morphology improves the specific surface area of the catalytic material and increases the active sites for hydrogen evolution reaction.

[0079] XPS analysis was performed on Example 1 and Comparative Example 5 of the present invention. Figure 3 This is the N1s diagram of Example 1. It can be seen from the figure that pyridine nitrogen at 398.5 eV and Mo-N bond at 396.8 eV indicate that N is successfully incorporated into the lattice. Figure 4 This is the Mo 3d comparison diagram of Example 1 and Comparative Example 5. It can be seen that the doping of N changes the electronic structure of Mo. The introduction of N forms nitrogen-metal bonds (such as Mo-N), enhances the metallicity of the material, and reduces the charge transfer impedance.

[0080] Electrochemical performance analysis was performed on all examples and comparative examples of the present invention. As Figure 6 、 Figure 7 shown, it can be seen that Example 1 has the lowest overpotential for hydrogen evolution reaction and the fastest electron transfer rate when driving a current density of 200 mA cm -2 . And according to Figure 6 it is known that when the thermal reaction temperature is 500 - 550 °C, the electrochemical performance of the catalyst is not very different.

[0081] Electrochemical performance analysis was performed on Example 1, Comparative Example 3 and Comparative Example 5 of the present invention. As Figure 8 shown, it can be seen that the co-doping of N with Co can effectively improve the hydrogen evolution reaction ability of the catalyst through electronic synergistic regulation.

[0082] Stability test of the Co 0.2 -N-MoO2 electrode prepared in Example 1 of the present invention as the cathode for water electrolysis, as Figure 10 shown, it can be seen that: after 50 hours of testing, the change in current is not significant, and this cathodic hydrogen evolution reaction exhibits good stability.

[0083] Thus, through a simple one-step thermal nitrogen method, the Co-N dual-doped Co-N-MoO2 catalyst can achieve the synergistic optimization of dual active centers and defect-conductivity, break through the bottleneck of single metal doping, effectively improve the activity, conductivity and stability, and has strong process compatibility and is suitable for large-scale production, providing an innovative solution for low-cost and high-efficiency hydrogen production by water electrolysis.

[0084] It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A Co x -N-MoO2 catalytic material preparation method, characterized in that It includes the following steps: 1) Grind molybdenum trioxide and cobalt carbonate until they are evenly mixed until a light pink powder is presented; 2) Place the obtained powder in an ammonia atmosphere for heat treatment, and then naturally cool it under an inert protective atmosphere, wash it, and dry it to obtain the catalyst material.

2. The preparation method according to claim 1, wherein The molar ratio of the cobalt source to the molybdenum source is 0.1-0.2:

1.

3. The preparation method according to claim 1, characterized in that, The heat treatment conditions in step 2) are 500°C to 550°C, and the reaction time is 2 to 5 h.

4. The preparation method according to claim 1, characterized in that, The heating rate during the heat treatment in step 2) is 5 to 10 °C / min -1 .

5. The preparation method according to claim 1, characterized in that, The gas flow rate in step 2) is 100-150 sccm.

6. The preparation method according to claim 1, characterized in that, The inert protective atmosphere is argon or nitrogen.

7. The preparation method according to claim 1, characterized in that The drying temperature is 50-80°C.

8. The Co x -N-MoO2 catalytic material obtained by the preparation method according to claim 1, characterized in that Where X is 0.1-0.2, the catalytic material includes a MoO2 substrate, nitrogen incorporated into the MoO2 lattice, and Co clusters formed on the surface of the MoO2 substrate.

9. Use of the catalytic material according to claim 8 in the hydrogen evolution reaction at a large current density in an alkaline environment.

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