Preparation method of high-current-density water electrolysis hydrogen production catalyst

Abstract

The invention discloses a preparation method of a high-current-density water electrolysis hydrogen production catalyst. The preparation method comprises the following steps: weighing raw materials in proportion; after mixing, adding a first solvent, and stirring to fully dissolve to obtain a precursor solution; immersing a foam substrate into the precursor solution for hydrothermal reaction to obtain a foam substrate loaded with a precursor nano array; after the reaction is completed, naturally cooling to room temperature, taking out the foam substrate loaded with the precursor nano array, cleaning and drying; and putting the foam substrate loaded with the precursor nano array into second solvent steam, and reacting to obtain the catalyst. The catalyst has the remarkable effects that the electronic structure can be effectively adjusted, the catalytic activity area is increased to improve the catalytic performance, and the finally obtained catalyst for hydrogen production by electrolysis of water can realize large current density and high stability by combining the self-supporting effect of the foam substrate, and is easy to produce on a large scale.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of catalysts for producing hydrogen by hydrolysis, and in particular to a method for preparing a catalyst for producing hydrogen by electrolyzing water with a high current density. Background Art

[0002] At present, the technology of hydrogen production from fossil fuels is relatively mature. However, the biggest problem with hydrogen production from fossil fuels is that it also emits a large amount of carbon dioxide, that is, the carbon emissions are relatively high. In addition, hydrogen production from fossil fuels is bound to compete with other applications of fossil fuels. Under the premise of the decreasing fossil fuels, hydrogen production from fossil fuels is not sustainable. Compared with hydrogen production from fossil fuels, hydrogen production from water electrolysis has almost no carbon emissions and can use electricity generated by other clean energy sources. It is a clean and sustainable hydrogen production technology.

[0003] In recent years, transition metal catalytic materials have made a lot of progress and are expected to replace traditional precious metal catalysts, but there are still many shortcomings and challenges: first, the electrolysis efficiency of traditional transition metal catalysts is low (current density is less than 1000mA / cm2), the energy consumption is high (overvoltage is greater than 0.5V), and large-scale industrial application is difficult; second, the catalytic active area of ​​traditional transition metal catalysts is limited, resulting in low catalytic efficiency and poor market application prospects. Therefore, it is a very important challenge to explore low-cost and mature process conditions to obtain transition metal catalysts with large active areas and continuous high efficiency. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a catalyst for producing hydrogen by electrolysis of water at a high current density, so as to solve the technical problems existing in the current high current density hydrogen production transition metal catalysts by electrolysis of water.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a catalyst for producing hydrogen by electrolyzing water at a high current density comprises the following steps:

[0007] Step 1, respectively weighing a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, wherein the molar ratio of the nickel source to the molybdenum source is 1:1 to 1:1.5, the molar ratio of the nickel source to the carbon source is 1:3-1:10; the molar ratio of the nickel source to the surfactant is 1:2 to 1:5, and the molar ratio of the reducing agent to the nickel source is not less than 5:1;

[0008] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0009] Step 3, immersing the foam substrate in a precursor solution for hydrothermal reaction to obtain a foam substrate loaded with the precursor nanoarray;

[0010] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and then the foam substrate is taken out for cleaning and drying;

[0011] Step 5: placing the foam substrate loaded with the precursor nanoarray in the second solvent vapor to react and obtain the catalyst.

[0012] Furthermore, in step 1, the nickel source is nickel chloride hexahydrate and / or nickel sulfate hexahydrate; the molybdenum source is at least one of sodium molybdate, potassium molybdate or ammonium molybdate; the carbon source is glucose; the surfactant is one or more of polyvinyl pyrrolidone, arginine and sodium dodecylbenzene sulfonate; and the reducing agent is one of sodium hypophosphite, potassium hypophosphite, formaldehyde, sodium formaldehyde bisulfite, sodium borohydride, thiourea, hydroquinone, ascorbic acid and dimethylamine borane.

[0013] Furthermore, the first solvent is an alkaline solution.

[0014] Furthermore, the pH value of the first solvent is 9-11.

[0015] Furthermore, the foam substrate is any one of foam nickel, foam iron, foam nickel iron, and foam copper.

[0016] Furthermore, the reaction temperature of the hydrothermal reaction in step 3 is 120-160° C., and the reaction time is 12-24 h.

[0017] Furthermore, the cleaning in step 4 includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process and an ethanol ultrasonic cleaning process.

[0018] Furthermore, during the drying in step 4, the product is placed in a vacuum box at a temperature of 50-90°C.

[0019] Furthermore, in step 5, the second solvent includes at least one of methanol, ethanol, ethylene glycol, propylene glycol, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0020] Furthermore, the temperature of the second solvent vapor is 100-250°C.

[0021] The remarkable effects of the present invention are:

[0022] 1. The present invention forms a porous carbon-coated nickel-molybdenum nanocatalyst on a foam substrate through a hydration method and a second solvent vapor-assisted method. The size of the metal active component nanoparticles and the dispersion on the surface of the carbon nanofibers are easy to control. At the same time, since the prepared catalyst has a large number of exposed active sites and rich heterogeneous interfaces, the electronic structure can be effectively adjusted and the catalytic active area can be increased to improve the catalytic performance. Combined with the self-supporting effect of the foam substrate, the finally obtained water electrolysis hydrogen production catalyst can achieve a large current density and high stability.

[0023] 2. In the precursor solution system, due to the high activation energy of the surface of the foam substrate, the nano nickel-molybdenum compound particles generated by the reaction are quickly and evenly attached to the surface of the foam substrate, and the porous carbon-coated nickel-molybdenum compound nanoparticles can be rapidly grown in an all-round and three-dimensional manner on the surface of the foam substrate to form an interlaced or interwoven structure. Then, a steam-driven auxiliary reaction is carried out in a second solvent vapor environment to make the interlaced or interwoven structure of nickel and molybdenum oxides more stable, thereby improving the stability and impact resistance of the catalyst particles and avoiding the shedding of active components.

[0024] 3. The catalyst prepared by the present invention does not contain precious metals, and the raw material cost is low; the preparation process is simple, the operating conditions are mild, the catalyst is evenly distributed, the catalytic activity is high and the stability is high, it is basically not limited by the location or reactor, and is easy to mass-produce.

[0025] 4. The catalyst prepared by the present invention has a compact structure, high activity and stability in the OER reaction under industrial-grade water current density, can operate stably for more than 200 hours, and the foamed nickel substrate does not undergo obvious corrosion, which is of great significance in the industrialization of hydrogen production by water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0027] The specific implementation manner and working principle of the present invention are further described in detail below with reference to the accompanying drawings.

[0028] Embodiment 1:

[0029] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0030] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.48g of sodium molybdate, the carbon source is 0.36g of glucose, the surfactant is 1.2g of polyvinyl pyrrolidone (PVP, average molecular weight 8000-700000); the reducing agent is 0.38g of sodium borohydride;

[0031] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0032] In this example, the first solvent is an ammonia solution with a pH value of 10, and the addition amount is 50 ml;

[0033] Step 3: Using nickel foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 120° C. for a reaction time of 12 h, thereby obtaining a foam substrate loaded with a precursor nanoarray;

[0034] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 50° C. and a drying time of 15 minutes;

[0035] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is methanol at a temperature of 100°C.

[0036] Embodiment 2:

[0037] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0038] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.714g of potassium molybdate, the carbon source is 0.108g of glucose, the surfactant is 0.5226g of arginine; the reducing agent is 0.104g of potassium hypophosphite;

[0039] Step 2: Mix the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, add the first solvent, and stir to fully dissolve them to obtain 50 ml of precursor solution;

[0040] In this example, the first solvent is a sodium hydroxide solution with a pH value of 9;

[0041] Step 3: Using foamed iron as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 160° C. for 24 h to obtain a foam substrate loaded with a precursor nanoarray;

[0042] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 90° C. and a drying time of 60 min;

[0043] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is methanol at a temperature of 250°C.

[0044] Embodiment 3:

[0045] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0046] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.392g of ammonium molybdate, the carbon source is 0.18g of glucose, the surfactant is 0.69696g of sodium dodecylbenzene sulfonate; the reducing agent is 0.54g of sodium hypophosphite;

[0047] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0048] In this example, the first solvent is an ammonia solution with a pH value of 11, and the addition amount is 50 ml;

[0049] Step 3, using nickel iron foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 130° C., the reaction time is 15 h, and a foam substrate loaded with a precursor nanoarray is obtained;

[0050] Step 4: After the reaction is completed, the foam substrate is naturally cooled to room temperature, and the foam substrate loaded with the precursor nanoarray is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 60° C. and a drying time of 25 min;

[0051] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is ethanol at a temperature of 120°C.

[0052] Embodiment 4:

[0053] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0054] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.588g of ammonium molybdate, the carbon source is 0.24g of glucose, the surfactant is 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 0.33g of formaldehyde;

[0055] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0056] In this example, the first solvent is an ammonia solution with a pH value of 9.5, and the addition amount is 50 ml;

[0057] Step 3: Using copper foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 140° C. for 16 h to obtain a foam substrate loaded with a precursor nanoarray;

[0058] Step 4: After the reaction is completed, the foam substrate is naturally cooled to room temperature, and the foam substrate loaded with the precursor nanoarray is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 70° C. and a drying time of 45 minutes;

[0059] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is ethylene glycol and propylene glycol, and the temperature is 160°C.

[0060] Embodiment 5:

[0061] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0062] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.418g of sodium molybdate, the carbon source is 0.36g of glucose, the surfactant is 0.69696g of sodium dodecylbenzene sulfonate; the reducing agent is 0.38g of sodium borohydride;

[0063] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0064] In this example, the first solvent is an ammonia solution with a pH value of 9, and the addition amount is 50 ml;

[0065] Step 3: Using nickel foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 120° C. for a reaction time of 23 h, to obtain a foam substrate loaded with a precursor nanoarray;

[0066] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 90° C. for 15 minutes;

[0067] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is ethylene glycol, propylene glycol, or N,N-dimethylacetamide, and the temperature is 100°C.

[0068] Embodiment 6:

[0069] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0070] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.48g of sodium molybdate, the carbon source is 0.18g of glucose, the surfactant is 0.6g of polyvinyl pyrrolidone, 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 1.36g of sodium formaldehyde bisulfite;

[0071] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0072] In this example, the first solvent is an ammonia solution with a pH value of 11, and the addition amount is 50 ml;

[0073] Step 3: Using copper foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction, wherein the reaction temperature of the hydrothermal reaction is 160° C. and the reaction time is 15 h, to obtain a foam substrate loaded with a precursor nanoarray;

[0074] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 70° C. for 30 minutes;

[0075] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is methanol, ethanol, ethylene glycol, propylene glycol, N,N-dimethylformamide, or N,N-dimethylacetamide, and the temperature is 140°C.

[0076] Embodiment 7:

[0077] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0078] Step 1, respectively weighing a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.424g of ammonium molybdate, the carbon source is 0.27g of glucose, the surfactant is 0.5226g of arginine; the reducing agent is 0.48g of sodium borohydride;

[0079] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0080] In this example, the first solvent is an ammonia solution with a pH value of 9-11, and the addition amount is 50 ml;

[0081] Step 3, using nickel iron foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 150° C., the reaction time is 12 h, and a foam substrate loaded with a precursor nanoarray is obtained;

[0082] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 60° C. and a drying time of 45 minutes;

[0083] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is methanol, ethanol or ethylene glycol, and the temperature is 200°C.

[0084] Embodiment 8:

[0085] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0086] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.618g of sodium molybdate, the carbon source is 0.27g of glucose, the surfactant is 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 0.78g of thiourea;

[0087] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0088] In this example, the first solvent is an ammonia solution with a pH value of 9, and the addition amount is 50 ml;

[0089] Step 3: Using foamed iron as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 130° C. for 14 h to obtain a foam substrate loaded with a precursor nanoarray;

[0090] Step 4: After the reaction is completed, the foam substrate is naturally cooled to room temperature, and the foam substrate loaded with the precursor nanoarray is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and when drying, the foam substrate is placed in a vacuum box at a temperature of 85° C. and a drying time of 55 min;

[0091] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is propylene glycol at a temperature of 220°C.

[0092] Embodiment 9:

[0093] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0094] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.525g of ammonium molybdate, the carbon source is 0.108g of glucose, the surfactant is 0.6g of polyvinyl pyrrolidone, 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 1.12g of hydroquinone;

[0095] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0096] In this example, the first solvent is an ammonia solution with a pH value of 9, and the addition amount is 50 ml;

[0097] Step 3: Using foamed iron as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 140° C. for 19 h, thereby obtaining a foam substrate loaded with a precursor nanoarray;

[0098] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 70° C. for 35 minutes;

[0099] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is ethylene glycol and N,N-dimethylacetamide, and the temperature is 180°C.

[0100] Embodiment 10:

[0101] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0102] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.496g of potassium molybdate, the carbon source is 0.18g of glucose, the surfactant is 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 1.78g of ascorbic acid;

[0103] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0104] In this example, the first solvent is an ammonia solution with a pH value of 11, and the addition amount is 50 ml;

[0105] Step 3, using nickel iron foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 145° C., the reaction time is 21 h, and a foam substrate loaded with a precursor nanoarray is obtained;

[0106] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 70° C. for 35 minutes;

[0107] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is methanol or N,N-dimethylformamide at a temperature of 130°C.

[0108] Embodiment 11:

[0109] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0110] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.475g of nickel chloride hexahydrate; the molybdenum source is 0.684g of potassium molybdate, the carbon source is 0.36g of glucose, the surfactant is 1.2g of polyvinyl pyrrolidone (PVP, average molecular weight 8000-700000); the reducing agent is 2.281g of dimethylamine borane;

[0111] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0112] In this example, the first solvent is an ammonia solution with a pH value of 11, and the addition amount is 50 ml;

[0113] Step 3: Using nickel foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 135° C. for 17 h, to obtain a foam substrate loaded with a precursor nanoarray;

[0114] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 75° C. and a drying time of 45 minutes;

[0115] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is N,N-dimethylformamide or N,N-dimethylacetamide, and the temperature is 230°C.

[0116] Embodiment 12:

[0117] like Figure 1 As shown, this embodiment proposes a method for preparing a catalyst for hydrogen production by electrolysis of water at a high current density, comprising the following steps:

[0118] Step 1, respectively weigh a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, specifically: wherein the nickel source is 0.526g of nickel sulfate hexahydrate; the molybdenum source is 0.595g of potassium molybdate, the carbon source is 0.27g of glucose, the surfactant is 0.34848g of sodium dodecylbenzene sulfonate and 0.15g of arginine; the reducing agent is 0.38g of sodium borohydride;

[0119] Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution;

[0120] In this example, the first solvent is an ammonia solution with a pH value of 10.5, and the addition amount is 50 ml;

[0121] Step 3: Using copper foam as a foam substrate, immersing the foam substrate in a precursor solution for a hydrothermal reaction at a reaction temperature of 155° C. for a reaction time of 22 h, to obtain a foam substrate loaded with a precursor nanoarray;

[0122] Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and the foam substrate is taken out for cleaning and drying; wherein the cleaning process includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process, and an ethanol ultrasonic cleaning process; and the drying process is placed in a vacuum box at a temperature of 80° C. and a drying time of 55 min;

[0123] Step 5: placing the foam substrate loaded with the precursor nanoarray in the vapor of a second solvent to react and obtain the catalyst. In this example, the second solvent is N,N-dimethylacetamide at a temperature of 240°C.

[0124] In the process of attaching porous carbon-coated nickel-molybdenum compound nanosheets on a foam substrate by a hydration method, the embodiment of the present invention adopts a first solvent to provide an alkaline environment. In the alkaline environment, the formation process of nickel-molybdenum compound is slowed down. After glucose is converted into hydrothermal carbon, nickel-molybdenum compound can be uniformly nucleated and grown in the hydrothermal carbon. At the same time, in order to reduce the surface energy, the particles inside the particles will gradually dissolve, while the outer layer will continue to grow. In this process, due to the confinement effect of the hydrothermal carbon, the nickel-molybdenum compound nanoparticles are converted into layered nanosheets. Finally, under the action of the Oswald ripening mechanism, hollow carbon spheres coated with nickel-molybdenum compound nanosheets are formed. Since the nickel-molybdenum compound nanosheets are uniformly coated in the porous carbon sphere matrix and form a hollow structure, the prepared catalyst has a special hollow spherical structure, a large specific surface area and abundant pores, which can promote the transmission and diffusion of metal ions and charges, so that the catalyst has good conductivity and a large energy density.

[0125] Afterwards, a steam-driven auxiliary reaction is carried out in a second solvent vapor environment to make the nickel and molybdenum oxides form an interlaced or interwoven structure more stable, thereby improving the stability and impact resistance of the catalyst particles. In addition, the nickel-molybdenum compound nanosheets are evenly coated with porous carbon spheres, which effectively solves the problem of structural collapse of the nickel-molybdenum compound due to volume expansion during the charge and discharge process. The prepared catalyst has a large number of exposed active sites and rich heterogeneous interfaces, which can effectively adjust the electronic structure to improve the catalytic performance. Combined with the self-supporting effect of the foam substrate, the final water electrolysis hydrogen production catalyst can achieve a large current density and high stability, and is easy to mass-produce.

[0126] The technical solution provided by the present invention is described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a catalyst for producing hydrogen by electrolysis of water at a high current density, characterized in that: The steps include: Step 1, respectively weighing a nickel source, a molybdenum source, a carbon source, a surfactant and a reducing agent, wherein the molar ratio of the nickel source to the molybdenum source is 1:1 to 1:1.5, the molar ratio of the nickel source to the carbon source is 1:3-1:10; the molar ratio of the nickel source to the surfactant is 1:2 to 1:5, and the molar ratio of the reducing agent to the nickel source is not less than 5:1; Step 2, mixing the weighed nickel source, molybdenum source, carbon source, surfactant, and reducing agent, adding the mixture to the first solvent, and stirring the mixture to fully dissolve the mixture to obtain a precursor solution; Step 3, immersing the foam substrate in a precursor solution for hydrothermal reaction to obtain a foam substrate loaded with the precursor nanoarray; Step 4: After the reaction is completed, the foam substrate loaded with the precursor nanoarray is naturally cooled to room temperature, and then the foam substrate is taken out for cleaning and drying; Step 5: placing the foam substrate loaded with the precursor nanoarray in the second solvent vapor to react and obtain the catalyst.

2. The method for preparing a catalyst for producing hydrogen by electrolysis of water at a high current density according to claim 1, wherein: In step 1, the nickel source is nickel chloride hexahydrate and / or nickel sulfate hexahydrate; the molybdenum source is at least one of sodium molybdate, potassium molybdate or ammonium molybdate; the carbon source is glucose; the surfactant is one or more of polyvinyl pyrrolidone, arginine and sodium dodecylbenzene sulfonate; and the reducing agent is one of sodium hypophosphite, potassium hypophosphite, formaldehyde, sodium formaldehyde bisulfite, sodium borohydride, thiourea, hydroquinone, ascorbic acid and dimethylamine borane.

3. The method for preparing a catalyst for producing hydrogen by electrolysis of water at a high current density according to claim 1, wherein: The first solvent is an alkaline solution.

4. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, wherein: The pH value of the first solvent is 9-11.

5. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, wherein: The foam substrate is any one of foam nickel, foam iron, foam nickel iron and foam copper.

6. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, wherein: The reaction temperature of the hydrothermal reaction in step 3 is 120-160° C., and the reaction time is 12-24 hours.

7. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, characterized in that: The cleaning in step 4 includes an N-methylpyrrolidone cleaning process, a deionized water cleaning process and an ethanol ultrasonic cleaning process.

8. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, wherein: During the drying in step 4, the mixture is placed in a vacuum oven at a temperature of 50-90°C.

9. The method for preparing a catalyst for producing hydrogen from water by electrolysis at a high current density according to claim 1, characterized in that: In step 5, the second solvent includes at least one of methanol, ethanol, ethylene glycol, propylene glycol, N,N-dimethylformamide, and N,N-dimethylacetamide.

10. The method for preparing a catalyst for producing hydrogen by electrolysis of water at a high current density according to claim 1 or 9, characterized in that: The temperature of the second solvent vapor is 100-250°C.

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