Preparation method and application of rod-like Co-Mo2C catalyst
By preparing rod-shaped Co-Mo2C composite material with carbon cladding, the activity and stability problems of β-Mo2C electrolytic catalysts are solved, and efficient electrolytic catalytic performance and safe production process are achieved.
Patent Information
- Application Number
- CN202510541709.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-08-12
AI Technical Summary
The existing β-Mo2C electrolytic catalysts have problems such as poor hydrogen evolution reaction activity, poor oxygen evolution reaction stability, and safety hazards in the synthesis process.
Using a preparation method, a Co-MoO3 substance with one-dimensional nanorod morphology is prepared, and Co-Mo precursor is formed, and calcined at high temperature under an inert atmosphere to form a rod-shaped Co-Mo2C composite material with a carbon cladding layer and a β-Mo2C catalyst modified by cobalt particles.
The catalytic hydrogen evolution activity and oxygen evolution activity are improved, the catalytic stability is enhanced, and high-temperature calcination is carried out under an inert atmosphere to ensure production safety and is suitable for large-scale production.
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Figure CN120465046A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a preparation method and application of a rod-shaped Co-Mo2C catalyst, belonging to the technical field of advanced nonferrous metal materials, in particular to the technical field of precious metal nanocatalytic materials. Background Art
[0002] With the acceleration of global industrialization, the non-renewable nature and shortage of traditional fossil energy sources are becoming increasingly prominent. Overreliance on such energy sources has led to serious environmental problems such as air pollution and the greenhouse effect. Against this backdrop, hydrogen, with its high mass energy density and zero-pollution combustion products, has become the most promising clean energy alternative. Water electrolysis has attracted considerable attention for its clean process and high compatibility with renewable energy sources. The product hydrogen purity can reach over 99.99%, making it a perfect match for high-end applications such as hydrogen fuel cells. However, the large-scale application of this technology is hampered by the high overpotential bottlenecks of the hydrogen and oxygen evolution reactions (HERs). Its energy conversion efficiency is directly related to catalyst performance. Currently, commercial catalysts are still dominated by platinum- and iridium-based precious metal materials. While they possess high intrinsic activity, their scarcity leads to high costs. While recent developments in non-precious metal catalysts have made progress in cost control, they generally suffer from complex preparation processes and poor activity. Therefore, the development of new water electrolysis catalysts that have simple preparation processes, environmentally friendly properties, long-term stable activity and economic feasibility has become a key technical proposition to break through the bottleneck of hydrogen energy industrialization.
[0003] Molybdenum carbide (β-Mo2C) has the potential to replace precious metal catalysts in the hydrogen evolution reaction (HER) due to its unique d-band electronic configuration and platinum (Pt)-like Fermi level characteristics. However, the strong binding energy of the Mo-H bond on its surface leads to an increased hydrogen desorption energy barrier and severely limited reaction kinetics. In addition, the current preparation process generally uses a hydrogen-argon mixture at high temperature to reduce the molybdenum precursor, which has the risk of flammability and explosion and high energy consumption, restricting large-scale production. In the field of oxygen evolution reaction, Mo2C faces the dual challenges of insufficient intrinsic activity and structural instability. Although existing modification strategies (such as constructing composite materials) can improve OER performance, they often sacrifice hydrogen evolution activity or increase preparation complexity. Therefore, constructing a bifunctional β-Mo2C-based catalyst that optimizes hydrogen adsorption free energy, enhances oxygen evolution catalytic activity, and improves structural stability has become a key direction to break through the barriers to the industrialization of water electrolysis technology.
[0004] Therefore, those skilled in the art hope to solve the problems existing in the prior art such as the single function of the β-Mo2C water electrolysis catalyst, poor hydrogen evolution reaction activity, poor oxygen evolution reaction stability, and safety hazards in the synthesis process. Summary of the Invention
[0005] In order to solve the above technical problems, the present invention provides a method for preparing a Co-Mo2C catalyst, wherein the preparation method comprises the following steps:
[0006] S1. Preparation of one-dimensional nanorod α-MoO3 material with a microscopic length parameter of 5 to 8 μm and a diameter parameter of 150 to 200 nm;
[0007] S2. preparing a Co-Mo precursor;
[0008] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept stirred at 300 to 600 r / min, a 2-methylimidazole solution is poured therein, and the stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying;
[0009] S3, high temperature calcination;
[0010] The Co-Mo precursor is placed in an inert gas environment and calcined at a high temperature of 600-1000°C to convert the organic components in the ZIF-67 coating layer in the Co-Mo precursor into a carbon coating layer. The Co element and α-MoO3 substance in the Co-Mo precursor are then carbon thermally reduced to obtain the Co-Mo2C catalyst. The Co-Mo2C catalyst is a composite material of β-Mo2C modified with Co particles and having a carbon coating layer, and has a rod-like morphology.
[0011] In some preferred embodiments of the present invention, the solute of the cobalt salt solution is selected from any one of cobalt nitrate, cobalt acetate, cobalt sulfate or cobalt chloride or any hydrate of any one of them; preferably, the solute of the cobalt salt solution is cobalt nitrate hexahydrate, cobalt acetate tetrahydrate or cobalt sulfate heptahydrate.
[0012] In some preferred embodiments of the present invention, the solvent of the cobalt salt solution or the solvent of the 2-methylimidazole solution is selected from any one of methanol, ethanol or deionized water; preferably, the cobalt salt solution and the 2-methylimidazole solution are the same solvent; more preferably, the solvent of the cobalt salt solution and the solvent of the 2-methylimidazole solution are both methanol.
[0013] In some preferred embodiments of the present invention, in S2, under stirring conditions of 500 to 800 r / min, the α-MoO3 substance is slowly added to the cobalt salt solution, and ultrasonic treatment is performed at a frequency of 30 to 70 kHz to fully disperse the α-MoO3 substance, and then stirred to allow the Co element to be adsorbed on the α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0014] In some preferred embodiments of the present invention, in S3, the inert gas is selected from either argon or nitrogen; preferably, the inert gas is argon; more preferably, the flow rate of the inert gas is 90 to 200 sccm.
[0015] In some preferred embodiments of the present invention, in S3, the Co-Mo precursor is placed in a tube furnace, heated to 600-1000°C at a heating rate of 2-8°C / min, then calcined at high temperature for 2-4 hours, and then cooled to room temperature.
[0016] In some preferred embodiments of the present invention, in S1, α-MoO3 powder with a particle size range of 0.3 to 1.0 μm is uniformly dispersed in hydrogen peroxide, and 0.8 to 1.5 g of the α-MoO3 powder is added to every 10 mL of the hydrogen peroxide; the mixture is fully stirred and mixed under acidic conditions of pH 0.3 to 1.0, and the MoO3 powder and hydrogen peroxide undergo an oxidation-reduction reaction; the obtained reaction product solution is then placed in a reactor, maintained at a temperature of 150 to 280°C for at least 15 hours, cooled to room temperature, and the product is washed and dried to obtain the one-dimensional nanorod morphology of the α-MoO3 material.
[0017] In some preferred embodiments of the present invention, 7% to 14 wt% of nitric acid solution or sulfuric acid solution is added to S1 to achieve acidic conditions of pH 0.3 to 1.0; preferably, the nitric acid solution or sulfuric acid solution is a deionized aqueous solution of nitric acid or sulfuric acid; preferably, the α-MoO3 powder is uniformly dispersed in the hydrogen peroxide by ultrasonic treatment and stirring.
[0018] Another aspect of the present invention provides a Co-Mo2C catalyst, wherein the Co-Mo2C catalyst is prepared using the above-mentioned preparation method.
[0019] In another aspect, the present invention provides the use of the above-mentioned Co-Mo2C catalyst, or the Co-Mo2C catalyst prepared by the above-mentioned preparation method, in the field of water electrolysis; preferably, the application is the use of the catalyst for hydrogen or oxygen evolution in water electrolysis.
[0020] The Co-Mo2C catalyst prepared by the preparation method of the present invention is a rod-shaped, carbon-coated, Co-particle-modified β-Mo2C composite material. In the composite material, the electronic interaction between the cobalt particles and the β-Mo2C particles optimizes the electronic structure of the β-Mo2C, thereby enhancing the catalytic hydrogen evolution activity. Furthermore, the reconstruction of the cobalt particles improves the overall catalytic oxygen evolution activity and stability. The rod-shaped Co-Mo2C catalyst of the present invention is coated with a carbon coating layer, thereby alleviating corrosion of the internal active components by the electrolyte and further enhancing the catalytic stability. In addition, the high-temperature calcination process in the preparation method of the present invention can be carried out under an inert atmosphere without involving a hydrogen / argon mixed gas, resulting in a safer production process and suitability for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 Schematic diagram of the synthesis of rod-shaped Co-Mo2C catalyst;
[0022] Figure 2 This is the SEM image of α-MoO3 material with one-dimensional nanorod morphology;
[0023] Figure 3 This is the XRD pattern of α-MoO3 material with one-dimensional nanorod morphology;
[0024] Figure 4 is the SEM image of Co-Mo precursor;
[0025] Figure 5 is the XRD pattern of Co-Mo precursor;
[0026] Figure 6 This is the XRD pattern of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention;
[0027] Figure 7 TEM image of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention;
[0028] Figure 8 Figure a is a graph showing the hydrogen evolution reaction activity test of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention; Figure 8 Figure b is a test diagram of the hydrogen evolution reaction stability of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention.
[0029] Figure 9 Figure a is a graph showing the oxygen evolution reaction activity test of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention; Figure 9 Figure b is a graph showing the stability of the oxygen evolution reaction of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention;
[0030] Figure 10 This is a comparison chart of Co element XPS of samples of Example 1 and Comparative Example 1;
[0031] Figure 11 This is the quasi-in-situ XPS of Mo and Co in the rod-shaped Co-Mo2C catalyst prepared in Example 1 during the oxygen evolution process. DETAILED DESCRIPTION
[0032] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to the scope of the examples. The process parameters not specified in the examples of this application can be carried out according to conventional methods, and the raw materials used can be obtained through commercial channels.
[0033] Example 1
[0034] The preparation method of the rod-shaped Co-Mo2C catalyst of the present invention includes the following steps S1 to S3.
[0035] S1. Preparation of one-dimensional nanorod α-MoO3 material with a microscopic length parameter of 5 to 8 μm and a diameter parameter of 150 to 200 nm;
[0036] S2. preparing a Co-Mo precursor;
[0037] S3. High temperature calcination.
[0038] Regarding step S1:
[0039] In some embodiments of the present invention, α-MoO3 materials having a one-dimensional nanorod morphology can be prepared by a hydrothermal method, a solvothermal method, a hydrothermal crystallization method or a template method; in a preferred embodiment of the present invention, α-MoO3 powder with a specific particle size is used to generate an α-MoO3 material having a one-dimensional nanorod morphology by a hydrothermal method.
[0040] In a specific embodiment of the present invention, in S1, α-MoO3 powder with a particle size range of 0.3 to 1.0 μm is uniformly dispersed in hydrogen peroxide, and 0.8 to 1.5 g of the α-MoO3 powder is added to every 10 mL of the hydrogen peroxide; the mixture is fully stirred and mixed under acidic conditions of pH 0.3 to 1.0, and the MoO3 powder and the hydrogen peroxide undergo a redox reaction; the obtained reaction product solution is then placed in a reactor, maintained at a temperature of 150 to 280° C. for at least 15 hours, cooled to room temperature, and the product is washed and dried to obtain the α-MoO3 material having the morphology of one-dimensional nanorods;
[0041] In a preferred embodiment of the present invention, 7-14 wt% nitric acid solution or sulfuric acid solution is added to S1 to achieve acidic conditions of pH 0.3-1.0; more preferably, the nitric acid solution or sulfuric acid solution is a deionized aqueous solution of nitric acid or sulfuric acid.
[0042] Specifically in Example 1, 2 g of commercially available α-MoO3 powder (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number: M294927, with a powder particle size range of 0.3 to 1.0 μm) was first uniformly dispersed in 20 mL of hydrogen peroxide. To achieve uniform dispersion of the α-MoO3 powder in the hydrogen peroxide, in this example, ultrasonic treatment combined with stirring (e.g., magnetic stirring) was used.
[0043] Specifically in Example 1, the mixed solution obtained above was added to a mixed solution containing 30 mL of deionized water and 5 mL of concentrated nitric acid, and stirred for another 10 minutes to ensure sufficient mixing, and the α-MoO3 powder and hydrogen peroxide underwent an oxidation-reduction reaction; the obtained reaction product solution was then transferred to a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, maintained at 200°C for 20 hours, and then naturally cooled to room temperature. After multiple washings with ethanol and deionized water, the solution was dried in air to obtain an α-MoO3 material with a one-dimensional nanorod morphology.
[0044] The SEM image of the one-dimensional nanorod morphology of α-MoO3 obtained in S1 of Example 1 is as follows: Figure 2 As shown in Figure 2, its microscopic length parameters are 5 to 8 μm and its diameter parameters are 150 to 200 nm; XRD Figure 3 As shown, it is consistent with the XRD standard card (α-MoO3, PDF#47-1320), indicating that α-MoO3 material was successfully prepared.
[0045] Regarding step S2:
[0046] In some embodiments of the present invention, the method for preparing a Co-Mo precursor is as follows: preparing a cobalt salt solution, and then uniformly dispersing the one-dimensional nanorod morphology of α-MoO3 obtained in S1 into the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; keeping the cobalt salt-MoO3 adsorption dispersion under stirring conditions of 300 to 600 r / min, pouring a 2-methylimidazole solution thereinto, and continuously stirring to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; collecting the precipitate by centrifugation, and obtaining the Co-Mo precursor after washing and drying.
[0047] In some preferred embodiments of the present invention, the solute of the cobalt salt solution is selected from any one of cobalt nitrate, cobalt acetate, cobalt sulfate or cobalt chloride or any hydrate of any one of them; more preferably, the solute of the cobalt salt solution is cobalt nitrate hexahydrate, cobalt acetate tetrahydrate or cobalt sulfate heptahydrate.
[0048] In some preferred embodiments of the present invention, the solvent of the cobalt salt solution or the solvent of the 2-methylimidazole solution is selected from any one of methanol, ethanol, and deionized water; more preferably, the cobalt salt solution and the 2-methylimidazole solution are the same solvent.
[0049] In some preferred embodiments of the present invention, methanol is selected as the solvent for the cobalt salt solution and the solvent for the 2-methylimidazole solution.
[0050] In some preferred embodiments of the present invention, in S2, under stirring conditions of 500 to 800 r / min, the α-MoO3 substance is slowly added to the cobalt salt solution and mixed evenly, and then ultrasonic treatment is performed at a frequency of 30 to 70 kHz to fully disperse the α-MoO3 substance, so that the Co element is adsorbed on the α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0051] Specifically in this embodiment, 0.5 g of cobalt nitrate hexahydrate was dissolved in 15 mL of methanol to form a uniform cobalt salt solution; then 0.1 g of α-MoO3 substance (α-MoO3 substance with one-dimensional nanorod morphology obtained in S1) was weighed and slowly added to the above solution. The solution was kept in a stirring state throughout the whole process (under stirring conditions of 500 to 800 r / min). After stirring evenly, the mixed solution was ultrasonically treated at a frequency of 30 to 70 kHz for 5 minutes to fully disperse the α-MoO3 substance, and then stirred for 2 to 4 hours to allow the Co element to be adsorbed on the α-MoO3 substance with one-dimensional nanorod morphology to form a cobalt salt-MoO3 adsorption dispersion.
[0052] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, and a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of methanol) is poured thereinto, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0053] The SEM image of the Co-Mo precursor obtained from S2 of Example 1 is as follows: Figure 4 The microscopic length parameters of the Co-Mo precursor obtained in this embodiment are about 5.5 to 9 μm, and the diameter parameters are about 0.8 to 1.2 μm; XRD is as follows Figure 5 As shown, it is consistent with the XRD standard card (α-MoO3, PDF#47-1320; ZIF-67 simulated), indicating that the Co-Mo precursor sample was successfully prepared.
[0054] Regarding step S3:
[0055] In some embodiments of the present invention, the Co-Mo precursor is placed in an inert gas environment and calcined at a high temperature of 600-1000°C. The organic components in the ZIF-67 coating layer in the Co-Mo precursor are converted into a carbon coating layer, and then the Co element and α-MoO3 substance in the Co-Mo precursor are carbon thermally reduced to obtain the Co-Mo2C catalyst; the Co-Mo2C catalyst is a composite material of β-Mo2C modified with Co particles and having a carbon coating layer, which has a rod-like morphology.
[0056] In some embodiments of the present invention, the inert gas is selected from argon and nitrogen, and preferably argon.
[0057] In some preferred embodiments of the present invention, the flow rate of the inert gas is 90-200 sccm.
[0058] In some preferred embodiments of the present invention, the Co-Mo precursor is placed in a tube furnace, heated to 600-1000° C. at a heating rate of 2-8° C. / min, then calcined at high temperature for 2-4 hours, and then cooled to room temperature.
[0059] Specifically in this embodiment, the Co-Mo precursor was placed in a tube furnace, heated to 800°C at a rate of 5°C / min under an argon atmosphere, and then heat treated for 2 hours. After cooling to room temperature, a rod-shaped Co-Mo2C catalyst was obtained. The SEM image of the Co-Mo2C catalyst obtained in S3 of Example 1 is shown in FIG. Figure 7 As shown, from Figure 7 It can be seen that the Co-Mo2C particles are evenly distributed and the outermost layer is a carbon layer; the XRD pattern is as follows Figure 6 As shown, the XRD pattern is consistent with the XRD standard card (β-Mo2C, PDF#15-0806; Co, PDF#35-0787), indicating that the rod-shaped Co-Mo2C catalyst was successfully prepared.
[0060] Example 2
[0061] S1: Same as Example 1;
[0062] S2: Dissolve 0.5 g of cobalt nitrate hexahydrate in 15 mL of ethanol to form a uniform cobalt salt solution; then weigh 0.1 g of α-MoO3 substance (obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800 r / min) during the whole process. After stirring evenly, the mixed solution is ultrasonically treated at a frequency of 30-70 kHz for 5 minutes to allow the Co element to be adsorbed on the α-MoO3 substance with a one-dimensional nanorod morphology to form a cobalt salt-MoO3 adsorption dispersion.
[0063] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of ethanol) is poured therein, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0064] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0065] Example 3
[0066] S1: Same as Example 1;
[0067] S2: Dissolve 0.5g of cobalt nitrate hexahydrate in 15mL of deionized water to form a uniform cobalt salt solution; then weigh 0.1g of α-MoO3 substance (one-dimensional nanorod morphology obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800r / min) during the whole process. After stirring evenly, the mixed solution is subjected to ultrasonic treatment at a frequency of 30-70kHz for 5min to allow the Co element to be adsorbed on the one-dimensional nanorod morphology of α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0068] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of deionized water) is poured therein, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0069] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0070] Example 4
[0071] S1: Same as Example 1;
[0072] S2: Dissolve 0.2 g of cobalt nitrate hexahydrate in 15 mL of methanol to form a uniform cobalt salt solution; then weigh 0.1 g of α-MoO3 substance (one-dimensional nanorod morphology obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800 r / min) during the whole process. After stirring evenly, the mixed solution is ultrasonically treated at a frequency of 30-70 kHz for 5 minutes to allow the Co element to be adsorbed on the one-dimensional nanorod morphology of the α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0073] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, and a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of methanol) is poured thereinto, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0074] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0075] Example 5
[0076] S1: Same as Example 1;
[0077] S2: Dissolve 1.0 g of cobalt nitrate hexahydrate in 15 mL of methanol to form a uniform cobalt salt solution; then weigh 0.1 g of α-MoO3 substance (one-dimensional nanorod morphology obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800 r / min) during the whole process. After stirring evenly, the mixed solution is ultrasonically treated at a frequency of 30-70 kHz for 5 minutes to allow the Co element to be adsorbed on the one-dimensional nanorod morphology of the α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0078] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, and a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of methanol) is poured thereinto, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0079] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0080] Example 6
[0081] S1: Same as Example 1;
[0082] S2: Dissolve 0.5g of cobalt acetate tetrahydrate in 15mL of methanol to form a uniform cobalt salt solution; then weigh 0.1g of α-MoO3 substance (one-dimensional nanorod morphology obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800r / min) during the whole process. After stirring evenly, the mixed solution is ultrasonically treated at a frequency of 30-70kHz for 5min to allow the Co element to be adsorbed on the one-dimensional nanorod morphology of α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0083] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, and a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of methanol) is poured thereinto, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0084] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0085] Example 7
[0086] S1: Same as Example 1;
[0087] S2: Dissolve 0.5g of cobalt sulfate heptahydrate in 15mL of methanol to form a uniform cobalt salt solution; then weigh 0.1g of α-MoO3 substance (one-dimensional nanorod morphology obtained in S1) and slowly add it to the above solution. Keep the solution in a stirring state (under stirring conditions of 500-800r / min) during the whole process. After stirring evenly, the mixed solution is ultrasonically treated at a frequency of 30-70kHz for 5min to allow the Co element to be adsorbed on the one-dimensional nanorod morphology of α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
[0088] A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept under stirring conditions of 300 to 600 r / min, and a 2-methylimidazole solution (1 g of 2-methylimidazole is dissolved in 15 mL of methanol) is poured thereinto, and continuous stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying.
[0089] S3: Place the Co-Mo precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours. Cool it to room temperature to obtain a rod-like Co-Mo2C catalyst.
[0090] Application Testing
[0091] The linear sweep voltammetry (LSV) method was used to test the hydrogen evolution and oxygen evolution reaction activities of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention. In the test, the Co-Mo2C catalyst was used as the working electrode, a three-electrode system was used, a voltage was applied in the electrolyte at a certain sweep rate, and the current density versus voltage curve was recorded. The stability test usually uses a long-term constant current or constant potential electrolysis experiment; in this test, the Co-Mo2C catalyst was placed in the electrolytic cell as the working electrode, and the current density was 0.13V at the selected current density (10mA / cm 2 ) Turn on the power, perform long-term electrolysis, and record the curve of current or potential changing with time.
[0092] Figure 8 Figure a is a graph showing the hydrogen evolution reaction activity test of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention; Figure 8 Figure b is a graph showing the stability of the hydrogen evolution reaction of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention. Figure 8 It can be seen from a and 8b that at 10 mA / cm 2 The overpotential is 148mV at a current density of 1.58kV. After 20h of testing, the overpotential does not increase significantly.
[0093] Figure 9 Figure a is a graph showing the oxygen evolution reaction activity test of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention; Figure 9 Figure b is a graph showing the stability of the oxygen evolution reaction of the rod-shaped Co-Mo2C catalyst prepared in Example 1 of the present invention. Figure 9 It can be seen from a and 9b that at 10 mA / cm 2 The overpotential is 340mV at a current density of 1.58kV. After 20h of testing, the overpotential does not increase significantly.
[0094] The preparation process of the Co catalyst of Comparative Example 1 is as follows:
[0095] S1: Dissolve 0.5 g of cobalt nitrate hexahydrate in 15 mL of methanol to form a uniform cobalt salt solution; dissolve 1 g of 2-methylimidazole in 15 mL of methanol to form a uniform 2-methylimidazole solution; pour the 2-methylimidazole solution into the cobalt salt solution and continue stirring for 5 minutes; collect the precipitate by centrifugation, wash, and dry to obtain the ZIF-67.
[0096] S2: Place the ZIF-67 precursor in a tube furnace and heat it to 800°C at a rate of 5°C / min under an argon atmosphere. Then heat it for 2 hours and cool it to room temperature to obtain the Co catalyst.
[0097] The Co-Mo2C catalyst obtained in Example 1 and the Co catalyst obtained in Comparative Example 1 were placed on the sample stage of the XPS instrument, and the X-ray source (Mg Kα) and test parameters were selected. Full spectrum scanning and high-resolution scanning of the Co element were performed to obtain an XPS comparison diagram of the Co element. Figure 10 This is a comparison chart of the Co element XPS of the samples of Example 1 and Comparative Example 1.
[0098] In the above oxygen evolution reaction activity test, the working electrodes under different states were removed from the electrolyte for cleaning and transferred to the XPS system via a vacuum transfer sample stage for XPS testing. Full spectrum scanning and high-resolution scanning of Mo and Co elements were performed to compare the changes in the binding energy of Mo and Co in the Co-Mo2C catalyst under different states, and the changes in the relative content of Mo and Co elements under different states. Figure 11 This is the quasi-in-situ XPS of Mo and Co in the rod-shaped Co-Mo2C catalyst prepared in Example 1 during the oxygen evolution process.
[0099] from Figure 10The results show that the Co 2p XPS peak of the Co-Mo2C obtained in Example 1 shifts to a higher binding energy compared to the Co catalyst obtained in Comparative Example 1, indicating that electrons are transferred from Co to Mo2C. The electronic interaction effectively reduces the hydrogen binding energy of the Mo2C active site, thereby promoting the desorption of adsorbed protons during the HER process.
[0100] like Figure 11 As shown in a, after immersion in 1M KOH solution, no Mo can be detected. 2+ species. As the potential increases, Mo 4 + and Mo 6+ The related characteristic peaks gradually decrease, the Mo signal almost disappears at 1.23 V, and then recovers slightly between 1.57 and 1.67 V. These observations indicate that molybdenum ions undergo dynamic dissolution and re-adsorption during the alkaline OER process. 2- The re-adsorption of OH* is beneficial to the adsorption of OOH* intermediates, thereby improving the OER activity.
[0101] like Figure 11 As shown in b, the increase in potential leads to the 0 and Co 2+ The related characteristic peaks gradually weakened, and Co 0 The peak disappears completely at 1.23 V. At the same time, the Co 3+ The corresponding peak area shows a trend of gradual increase. This phenomenon can be attributed to the interaction between Co and Mo2C, which promotes the electron transfer from Co to Mo2C, thereby promoting the transformation of Co to CoOOH.
[0102] The above analysis shows that in this composite material, the electronic interaction between the cobalt particles and the β-Mo2C particles optimizes the electronic structure of β-Mo2C and enhances the catalytic hydrogen evolution activity. The dynamic dissolution and re-adsorption of molybdenum ions and the reconstruction of the cobalt particles improve the overall catalytic oxygen evolution activity and stability.
[0103] The present invention is not limited to the above-described embodiments. Any changes in shape or structure fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims. Those skilled in the art may make various changes, modifications, substitutions, combinations, and simplifications to these embodiments without departing from the principles and essence of the present invention. All such changes shall be considered equivalent replacements and fall within the scope of protection of the present invention.
Claims
1. A method for preparing a Co-Mo2C catalyst, characterized in that: The preparation method comprises the following steps: S1. Preparation of one-dimensional nanorod α-MoO3 material with a microscopic length parameter of 5 to 8 μm and a diameter parameter of 150 to 200 nm; S2. preparing a Co-Mo precursor; A cobalt salt solution is prepared, and then the α-MoO3 substance is uniformly dispersed in the cobalt salt solution to form a cobalt salt-MoO3 adsorption dispersion; the cobalt salt-MoO3 adsorption dispersion is kept stirred at 300 to 600 r / min, a 2-methylimidazole solution is poured therein, and the stirring is continued to allow a ZIF-67 coating layer to grow in situ on the surface of the α-MoO3 substance; the precipitate is collected by centrifugation, and the Co-Mo precursor is obtained after washing and drying; S3, high temperature calcination; The Co-Mo precursor is placed in an inert gas environment and calcined at a high temperature of 600-1000°C to convert the organic components in the ZIF-67 coating layer in the Co-Mo precursor into a carbon coating layer. The Co element and α-MoO3 substance in the Co-Mo precursor are then carbon thermally reduced to obtain the Co-Mo2C catalyst. The Co-Mo2C catalyst is a composite material of β-Mo2C modified with Co particles and having a carbon coating layer, and has a rod-like morphology.
2. The preparation method according to claim 1, wherein The solute of the cobalt salt solution is selected from any one of cobalt nitrate, cobalt acetate, cobalt sulfate or cobalt chloride or any hydrate of any one of them; preferably, the solute of the cobalt salt solution is cobalt nitrate hexahydrate, cobalt acetate tetrahydrate or cobalt sulfate heptahydrate.
3. The preparation method according to claim 2, wherein The solvent of the cobalt salt solution or the solvent of the 2-methylimidazole solution is selected from any one of methanol, ethanol or deionized water; preferably, the cobalt salt solution and the 2-methylimidazole solution are the same solvent; more preferably, the solvent of the cobalt salt solution and the solvent of the 2-methylimidazole solution are both methanol.
4. The preparation method according to claim 1, wherein In S2, under the stirring condition of 500-800 r / min, the α-MoO3 substance is slowly added to the cobalt salt solution, and ultrasonic treatment is performed at a frequency of 30-70 kHz to fully disperse the α-MoO3 substance, and then stirred to allow the Co element to be adsorbed on the α-MoO3 substance to form a cobalt salt-MoO3 adsorption dispersion.
5. The preparation method according to claim 1, wherein In S3, the inert gas is selected from either argon or nitrogen; preferably, the inert gas is argon; more preferably, the flow rate of the inert gas is 90 to 200 sccm.
6. The preparation method according to claim 5, wherein In S3, the Co-Mo precursor is placed in a tube furnace, heated to 600-1000°C at a heating rate of 2-8°C / min, then calcined at high temperature for 2-4 hours, and then cooled to room temperature.
7. The preparation method according to any one of claims 1 to 5, characterized in that In S1, α-MoO3 powder with a particle size range of 0.3 to 1.0 μm is uniformly dispersed in hydrogen peroxide, and 0.8 to 1.5 g of the α-MoO3 powder is added to every 10 mL of the hydrogen peroxide; the mixture is fully stirred and mixed under acidic conditions of pH 0.3 to 1.0, and the MoO3 powder and hydrogen peroxide undergo an oxidation-reduction reaction; the obtained reaction product solution is then placed in a reactor, maintained at a temperature of 150 to 280° C. for at least 15 hours, cooled to room temperature, and the product is washed and dried to obtain the α-MoO3 material with the one-dimensional nanorod morphology.
8. The preparation method according to claim 7, wherein In the S1, 7% to 14wt% nitric acid solution or sulfuric acid solution is added to achieve acidic conditions of pH 0.3 to 1.0; preferably, the nitric acid solution or sulfuric acid solution is a deionized aqueous solution of nitric acid or sulfuric acid; preferably, the α-MoO3 powder is uniformly dispersed in the hydrogen peroxide by ultrasonic treatment and stirring.
9. A Co-Mo2C catalyst, characterized in that The Co-Mo2C catalyst is prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the Co-Mo2C catalyst according to claim 9, or the Co-Mo2C catalyst prepared by the preparation method according to any one of claims 1 to 8 in the field of water electrolysis; preferably, the application is use as a catalyst for hydrogen or oxygen evolution in water electrolysis.