A molybdenum-doped nickel-cobalt-copper lattice-stretching alloy catalyst and a preparation method thereof

Abstract

The present application relates to a kind of preparation methods of molybdenum-doped nickel-cobalt-copper lattice stretch alloy catalyst, comprising the following steps: 1) over-sulfate and inorganic alkali are dissolved in deionized water to prepare solution, copper substrate material is added in solution, and intermediate sample is obtained by standing;2) metal precursor molybdenum salt, metal precursor nickel salt, metal precursor cobalt salt are dissolved in organic solvent respectively to obtain mixed solution, the mixed solution and intermediate sample are added into reaction kettle to carry out solvothermal reaction, and the reaction liquid in the reaction kettle is taken out to carry out filtration, cleaning, drying after reaction ends, and preliminary sample is obtained;3) preliminary sample is placed in calcining furnace, and mixed gas of hydrogen and argon is introduced, and high-temperature calcination is carried out for 1-5 hours, and the catalyst is obtained.The preparation process of the present application is simple, low in cost, and the product prepared has good HER catalytic performance in alkaline and neutral electrolyte, which lays a technical foundation for preparing high-activity alloy catalyst and reducing hydrogen production cost.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst and its preparation method. Background Technology

[0002] The energy crisis caused by fossil fuels and global warming have led to an increasing demand for clean energy. Among them, hydrogen energy has attracted widespread attention due to its high energy density, renewability, and environmental friendliness.

[0003] Water electrolysis, as a relatively economical, high-purity, and pollution-free method for hydrogen production, is considered one of the most promising approaches. One of the key challenges in developing this technology lies in developing efficient, economical, and environmentally friendly catalysts. Currently, noble metal-based catalysts such as platinum / rhodium / iridium / ruthenium have proven to be highly effective HER catalysts, but their scarcity and high cost limit the large-scale application of water electrolysis for hydrogen production. Therefore, researchers have turned their attention to non-noble metal-based catalysts, which are abundant and relatively inexpensive. However, most non-noble metal-based catalysts corrode in acidic electrolytes, affecting their HER activity; therefore, industrial water electrolysis is primarily carried out in alkaline electrolytes. Furthermore, natural water and commonly used domestic water are generally neutral or weakly alkaline.

[0004] Therefore, it is very important to develop non-precious metal-based catalysts that are highly active and low-cost in alkaline and neutral media. Summary of the Invention

[0005] Therefore, there is a need for a non-precious metal-based catalyst, a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst, and its preparation method, which can maintain high activity and high stability in alkaline and neutral media and has low preparation cost.

[0006] To achieve the above objectives, the inventors provide a method for preparing a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst, which includes the following steps:

[0007] 1) Dissolve persulfate and inorganic base in deionized water to prepare a solution. Add copper substrate material to the solution and let it stand for 10-30 minutes. Take out the copper substrate material, clean it and dry it to obtain an intermediate sample.

[0008] The mass ratio of persulfate to inorganic alkali is 1:2-3;

[0009] 2) Dissolve the metal precursors molybdenum salt, nickel salt, and cobalt salt in an organic solvent to obtain a mixed solution. Add the mixed solution and the intermediate sample obtained in step 1) to a reaction vessel for a solvothermal reaction at a temperature of 100-180 °C for 6-24 hours. After the reaction is completed, cool to room temperature, remove the reaction solution from the reaction vessel, filter it, and wash and dry the filter cake to obtain a preliminary sample.

[0010] In step 2) above, the metal precursors molybdenum salt, nickel salt, and cobalt salt can be dissolved in a solvent separately and then mixed, or they can be dissolved in a portion of organic solvent in sequence, or they can be added to a portion of organic solvent at the same time for dissolution.

[0011] The mass ratio of the metal precursor molybdenum salt, metal precursor nickel salt, and metal precursor cobalt salt is 0-2:10-30:5-30.

[0012] The ratio of the input mass of the cobalt salt precursor to the surface area of ​​the intermediate sample is 5-30:0.9 mg / cm². 2 ;

[0013] 3) Place the preliminary sample prepared in step 2) in a calcination furnace, introduce a mixed gas of hydrogen and argon, wherein the volume fraction of hydrogen in the mixed gas is 10-50%, and heat it to 400-1000 ℃ at a heating rate of 2-10 ℃ / min for high-temperature calcination for 1-5 hours to obtain the molybdenum-doped nickel-cobalt-copper lattice stretched alloy catalyst.

[0014] The present invention uses the above-mentioned preparation method. In step 1), copper substrate materials such as copper wire, copper mesh, copper foil, and copper sheet are used as carriers to prepare a copper substrate with copper hydroxide.

[0015] Following step 2), after drying the copper substrate containing copper hydroxide, a solvothermal synthesis is performed using molybdenum, cobalt, and nickel salts as metal sources. Ni, Co, and Cu are 3D transition metals, essentially ionic solids with high electronic conductivity. The transition metal alloy catalysts composed of these metals, due to their low intrinsic resistivity and high conductivity, can promote charge transfer in electrocatalytic reactions, effectively enhancing the HER performance of the catalyst. Simultaneously, because the d-band electronic structure of Mo is similar to that of Pt, molybdenum-based catalysts exhibit excellent HER activity. When Mo is incorporated as a guest into other compounds, it can effectively adjust the electronic structure of the initial compound, thereby promoting electron redistribution within the compound and enabling the catalyst to obtain better electron transfer capabilities and adsorption / desorption energies for hydrogen reaction intermediates.

[0016] Finally, after high-temperature calcination in step 3), a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst is obtained; the mixed gas added in step 3) acts as a reducing agent to reduce the precursor to generate a nickel-cobalt-copper alloy.

[0017] Furthermore, the inorganic base in step 1) is potassium hydroxide or sodium hydroxide. The inorganic base reacts with persulfate to create conditions suitable for the stable existence of copper hydroxide.

[0018] Further, the organic solvent added in step 2) is one or a mixture of two or more of the following: ethanol, ethylene glycol, methanol, isopropanol, glycerol, n-butanol, N,N-dimethylformamide, oleylamine, oleic acid, polyethylene glycol, toluene, acetonitrile, N,N-dimethylacetamide, dimethyl sulfoxide, pyridine, pyrrole, urea, aniline, N-methylaniline, N,N-dimethylaniline, N-ethylaniline, N,N-diethylaniline, diphenylamine, aniline hydrochloride, dioxane, phenylalanine, 2-hydroxypyridine, 2-amino The organic solvent added in step 2) can be pyridine, 2,6-diaminopyridine, 2-methylpyridine, 3-aminopyridine, 4-methylpyridine, pentachloropyridine, 3-chloropyridine, 3-fluoropyridine, 3-bromopyridine, 2,3-diaminopyridine, 2-amino-3-chloropyridine, 2-pyrrolidone, 2-pyrrolic acid, 3-acetyl-2,4-dimethylpyrrole, hydroxyethylpyrrolidone, 2-acetylpyrrole, 1-methylpyrrole, tetrahydropyrrole, ethyl pyrrole-2-carboxylate, 2,4-dimethylpyrrole, 4-acetylpyridine, 2-acetylpyrrole, N-methylpyrrole, or deionized water. In this invention, the organic solvent added in step 2) can act not only as a solvent but also as a reducing agent.

[0019] Furthermore, the persulfate mentioned in step 1) is one of the following: ammonium persulfate, sodium persulfate, or potassium persulfate.

[0020] Furthermore, the copper substrate material mentioned in step 1) is one of the following: copper wire, copper mesh, copper foil, or copper sheet. The addition of a copper substrate in this invention serves two purposes: firstly, it provides copper metal raw materials; secondly, it facilitates the formation of copper hydroxide as a substrate.

[0021] Furthermore, the molybdenum salt precursor in step 2) is one of the following: molybdic acid, ammonium molybdate tetrahydrate, ammonium heptamolybdate, ammonium dimolybdate, sodium molybdate, phosphomolybdic acid, ammonium phosphomolybdate, sodium phosphomolybdate, molybdenum chloride, lithium molybdate, potassium molybdate, molybdenum hexacarbonyl, molybdenum acetylacetonate, and molybdenum isopropoxide. Because the d-band electronic structure of Mo is similar to that of Pt, molybdenum-based catalysts exhibit excellent HER activity. When Mo is incorporated as a guest into other compounds, it can effectively adjust the electronic structure of the initial compound, thereby promoting the redistribution of electrons in the compound and enabling the catalyst to obtain better electron transfer capabilities and adsorption / desorption energies for hydrogen reaction intermediates.

[0022] Furthermore, the nickel salt precursor in step 2) is one of the following: nickel chloride, nickel acetylacetonate, nickel acetylacetonate, nickel acetate, nickel bromide, nickel iodide, nickel sulfate, nickel nitrate, nickel ammonium sulfate, nickel hypophosphite, nickel ammonium nitrate, nickel aminosulfonate, basic nickel carbonate, nickel formate, nickel dicene, nickel bis(triphenylphosphine)bromide, and nickel bis(triphenylphosphine)chloride.

[0023] Further, the cobalt salt precursor in step 2) is one of the following: cobalt chloride, cobalt acetate, cobalt phosphate, cobalt phthalocyanine, potassium cobalt cyanocyanate, potassium hexacyanocobalaminate, cobalt hexaaminochloride, cobalt perchlorate, cobalt nitrate, cobalt fluoride, cobalt iodide, cobalt bromide, sodium cobalt nitrite, cobalt oxalate, cobalt sulfate, cobalt sulfite, ammonium cobalt sulfate, cobalt naphthenate, and cobalt acetylacetonate. Ni, Co, and Cu are 3D transition metals, which are essentially ionic solids with high electronic conductivity. Transition metal alloy catalysts composed of these metals, due to their low intrinsic resistivity and high electrical conductivity, can promote charge transfer in electrocatalytic reactions, effectively enhancing the HER performance of the catalyst.

[0024] Furthermore, in step 2), after mixing the three solutions to obtain a mixed solution, deionized water is added, and the mixture is ultrasonically stirred and dispersed to obtain a mixed suspension. The mixed suspension and the intermediate sample obtained in step 1) are then added to a reaction vessel for a solvothermal reaction.

[0025] The present invention also discloses a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst, which is prepared by the above-described preparation method.

[0026] Unlike existing technologies, the above technical solution has the following advantages: This invention uses copper substrate materials such as copper wire, copper mesh, copper foil, and copper sheets as a carrier. First, a copper substrate containing copper hydroxide is prepared. After drying, a molybdenum salt, cobalt salt, and nickel salt are used as metal sources. The catalyst is first solvothermally synthesized and then calcined at high temperature to obtain a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst. The preparation process of this invention is simple and low-cost. The product prepared by this invention exhibits good HER catalytic performance in both alkaline and neutral electrolytes, at -10 / -100 / -500 mA cm⁻¹. -2 It exhibits potentials of -35 / -90 / -166 mV in alkaline media and -26 / -123 / -255 mV in neutral media, laying a technical foundation for preparing highly active alloy catalysts to reduce hydrogen production costs. Attached Figure Description

[0027] Figure 1 The XRD patterns are of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalysts prepared in Examples 1-3 of this invention.

[0028] Figure 2In the image, a is a TEM image of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in Example 1 of this invention;

[0029] Figure 2 In the image, b is a TEM image of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in Example 2 of this invention;

[0030] Figure 2 In the image, c is a TEM image of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in Example 3 of this invention;

[0031] Figure 3 Linear sweep voltammetry (LSV) curves of hydrogen evolution in 1.0 mol / L potassium hydroxide solution for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of commercial Pt / C catalyst;

[0032] Figure 4 The Tafel slope data are for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of commercial Pt / C catalyst in 1.0 mol / L potassium hydroxide solution.

[0033] Figure 5 LSV curve data of the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of commercial Pt / C catalyst in 1.0 mol / L PBS solution;

[0034] Figure 6 Tafel slope data of the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of commercial Pt / C catalyst in 1.0 mol / L PBS solution. Detailed Implementation

[0035] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0036] Example 1

[0037] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0038] (1) Dissolve 3 g of ammonium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 20 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0039] (2) Dissolve 200 mg of nickel nitrate in 15 mL of ethanol to prepare a nickel nitrate ethanol solution, and dissolve 100 mg of cobalt nitrate in 15 mL of ethanol to prepare a cobalt nitrate ethanol solution. Then mix the nickel nitrate ethanol solution and the cobalt nitrate ethanol solution, add 15 mL of deionized water and 15 mL of ethanol, and sonicate to disperse. First sonicate for 10 min, then stir for 10 min to obtain a mixed suspension. Put the mixed suspension into a 100 mL reaction vessel, and add the copper mesh with copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1). 2 A solvothermal reaction was carried out at a temperature of 120 °C for 24 hours. After natural cooling, the product obtained from the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0040] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 10% of the volume fraction of the mixed gas), heat it to 400 ℃ at a rate of 2 ℃ / min, and continue to hold it at the temperature for 3 hours for high-temperature calcination to obtain the molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0041] Example 2

[0042] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0043] (1) Dissolve 3 g of ammonium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 20 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0044] (2) Then, 20 mg of ammonium molybdate tetrahydrate was dissolved in 15 mL of ethanol to prepare an ammonium molybdate tetrahydrate ethanol solution, 200 mg of nickel nitrate was dissolved in 15 mL of ethanol to prepare a nickel nitrate ethanol solution, and 100 mg of cobalt nitrate was dissolved in 15 mL of ethanol to prepare a cobalt nitrate ethanol solution. Then, the ammonium molybdate tetrahydrate ethanol solution, the nickel nitrate ethanol solution, and the cobalt nitrate ethanol solution were mixed, 15 mL of deionized water was added, and the mixture was ultrasonically stirred and dispersed. The mixture was ultrasonically stirred for 10 min, and then stirred for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and the copper mesh with copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 120 °C for 24 hours. After natural cooling, the product obtained from the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0045] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 10% of the volume fraction of the mixed gas), heat it to 400 ℃ at a rate of 2 ℃ / min, and continue to hold it at the temperature for 3 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0046] Example 3

[0047] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0048] (1) Dissolve 3 g of ammonium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 20 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0049] (2) Then, 40 mg of ammonium molybdate tetrahydrate was dissolved in 15 mL of ethanol to prepare an ammonium molybdate tetrahydrate ethanol solution, 200 mg of nickel nitrate was dissolved in 15 mL of ethanol to prepare a nickel nitrate ethanol solution, and 100 mg of cobalt nitrate was dissolved in 15 mL of ethanol to prepare a cobalt nitrate ethanol solution. Then, the ammonium molybdate tetrahydrate ethanol solution, the nickel nitrate ethanol solution, and the cobalt nitrate ethanol solution were mixed, and 15 mL of deionized water was added. The mixture was ultrasonically stirred and dispersed for 10 min, followed by stirring for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and the copper mesh with copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 120 °C for 24 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0050] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 10% of the volume fraction of the mixed gas), heat it to 400°C at a rate of 2°C / min, and continue to hold it at the temperature for 3 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0051] Example 4

[0052] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0053] (1) Dissolve 3 g of ammonium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 30 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0054] (2) Then, 20 mg of ammonium molybdate tetrahydrate was dissolved in 45 mL of ethylene glycol to prepare an ammonium molybdate tetrahydrate ethylene glycol solution. 200 mg of nickel chloride was added to the ammonium molybdate tetrahydrate ethylene glycol solution and completely dissolved. Then, 100 mg of cobalt chloride was added to the ammonium molybdate tetrahydrate ethylene glycol solution to dissolve it, resulting in a mixed solution. 15 mL of deionized water was added, and the mixture was ultrasonically stirred and dispersed. The mixture was first ultrasonicated for 10 min, and then stirred for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 120 °C for 24 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0055] (3) The primary sample obtained in step (2) is placed in a tube furnace and a mixture of hydrogen and argon (hydrogen accounts for 20% of the volume fraction of the mixture) is introduced. The temperature is raised to 450 °C at a rate of 3 °C / min and held for 3 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0056] Example 5

[0057] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0058] (1) Dissolve 6 g of ammonium persulfate and 12 g of potassium hydroxide in 150 mL of deionized water to prepare a solution. Add copper sheet to the solution and let it stand for 10 min. Then take out the copper sheet, wash it, and vacuum dry it to obtain a copper sheet with copper hydroxide nanoarray (surface area of ​​18 cm²). 2 ).

[0059] (2) Then, 20 mg of ammonium heptamolybdate was dissolved in 15 mL of methanol to prepare an ammonium heptamolybdate methanol solution, 200 mg of nickel acetylacetonate was dissolved in 15 mL of methanol to prepare a nickel acetylacetonate methanol solution, and 100 mg of cobalt acetate was dissolved in 15 mL of ethanol to prepare a cobalt acetate methanol solution. Then, the ammonium heptamolybdate methanol solution, the nickel acetylacetonate methanol solution, and the cobalt acetate methanol solution were mixed, 15 mL of deionized water was added, and the mixture was ultrasonically stirred and dispersed. The mixture was ultrasonically stirred for 10 min, and then stirred for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and the copper sheet with copper hydroxide nanoarray (surface area of ​​18 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 120 °C for 18 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0060] (3) The primary sample prepared in step (2) is placed in a tube furnace and a mixture of hydrogen and argon (hydrogen accounts for 30% of the volume fraction of the mixture) is introduced. The temperature is raised to 600 ℃ at a rate of 4 ℃ / min and held for 4 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0061] Example 6

[0062] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0063] (1) Dissolve 3 g of sodium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add copper wire to the solution and let it stand for 20 min. Then take out the copper wire, wash it, and vacuum dry it to obtain copper wire with copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0064] (2) Then, 20 mg of ammonium dimolybdate was dissolved in 45 mL of isopropanol to prepare an ammonium dimolybdate isopropanol solution. 200 mg of nickel acetate was added to the ammonium dimolybdate isopropanol solution and completely dissolved. Then, 100 mg of cobalt phosphate was added to the ammonium dimolybdate isopropanol solution to dissolve it, resulting in a mixed solution. 15 mL of deionized water was added, and the mixture was ultrasonically stirred for 10 min, followed by stirring for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and copper wires with a copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) were added. 2A solvothermal reaction was carried out at a temperature of 160 °C for 18 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0065] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 20% of the volume fraction of the mixed gas), heat it to 700 ℃ at a rate of 5 ℃ / min, and hold it at the temperature for 5 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0066] Example 7

[0067] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0068] (1) Dissolve 3 g of sodium persulfate and 6 g of sodium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 20 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0069] (2) Then, 10 mg of molybdenum chloride was dissolved in 15 mL of isopropanol to prepare a molybdenum chloride isopropanol solution, 300 mg of nickel formate was dissolved in 15 mL of isopropanol to prepare a nickel formate isopropanol solution, and 100 mg of cobalt oxalate was dissolved in 15 mL of isopropanol to prepare a cobalt oxalate isopropanol solution. Then, the molybdenum chloride isopropanol solution, the nickel formate isopropanol solution and the cobalt oxalate isopropanol solution were mixed, 15 mL of deionized water was added, and the mixture was ultrasonically stirred and dispersed. The mixture was ultrasonically stirred for 10 min and then stirred for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and the copper mesh with copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 160 °C for 24 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 36 hours to obtain a primary sample.

[0070] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 50% of the volume fraction of the mixed gas), heat it to 750 ℃ ​​at a rate of 6 ℃ / min, and hold it at the temperature for 3 hours for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0071] Example 8

[0072] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0073] (1) Dissolve 3 g of sodium persulfate and 9 g of potassium hydroxide in 150 mL of deionized water to prepare a solution. Add copper foil to the solution and let it stand for 20 min. Then, take out the copper foil, wash it, and vacuum dry it to obtain copper foil with copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0074] (2) Then, 20 mg of molybdenum acetylacetonate was dissolved in 15 mL of glycerol to prepare a molybdenum acetylacetonate glycerol solution, 200 mg of nickel sulfate was dissolved in 15 mL of glycerol to prepare a nickel sulfate glycerol solution, and 300 mg of cobalt sulfate was dissolved in 15 mL of glycerol to prepare a cobalt sulfate glycerol solution. The molybdenum acetylacetonate glycerol solution, the nickel sulfate glycerol solution, and the cobalt sulfate glycerol solution were then mixed, and 15 mL of deionized water was added. The mixture was ultrasonically stirred and dispersed for 10 min, followed by stirring for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and copper foil with a copper hydroxide nanoarray (surface area of ​​9 cm²) was added. 2 A solvothermal reaction was carried out at a temperature of 100 °C for 24 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 36 hours to obtain a primary sample.

[0075] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixture of hydrogen and argon (hydrogen accounts for 40% of the volume fraction of the mixture), heat it to 800 ℃ at a rate of 7 ℃ / min, and hold it at that temperature for 4 hours to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0076] Example 9

[0077] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0078] (1) Dissolve 6 g of potassium persulfate and 12 g of potassium hydroxide in 150 mL of deionized water to prepare a solution. Add copper wire to the solution and let it stand for 20 min. Then take out the copper wire, wash it, and vacuum dry it to obtain copper wire with copper hydroxide nanoarray (surface area of ​​18 cm²). 2 ).

[0079] (2) Then, 20 mg of sodium molybdate, 200 mg of nickel nitrate, and 100 mg of cobalt sulfate were added sequentially to 45 mL of N,N-dimethylformamide to prepare a mixed solution. After complete dissolution, 15 mL of deionized water was added, and the mixture was ultrasonically stirred for 10 min, followed by stirring for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and copper wires with a copper hydroxide nanoarray (surface area of ​​18 cm²) prepared in step (1) were added. 2 A solvothermal reaction was carried out at a temperature of 180 °C for 6 hours. After natural cooling, the product obtained after the solvothermal reaction was removed, filtered, washed, and vacuum dried for 24 hours to obtain a primary sample.

[0080] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 30% of the volume fraction of the mixed gas), heat it to 900 ℃ at a rate of 8 ℃ / min, and hold it at that temperature for 3 hours to perform high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0081] Example 10

[0082] A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst is prepared by the following method:

[0083] (1) Dissolve 3 g of potassium persulfate and 6 g of potassium hydroxide in 150 mL of deionized water to prepare a solution. Add a copper mesh to the solution and let it stand for 20 min. Then remove the copper mesh, clean it, and vacuum dry it to obtain a copper mesh with a copper hydroxide nanoarray (surface area of ​​9 cm²). 2 ).

[0084] (2) Then, 10 mg of sodium molybdate was dissolved in 15 mL of n-butanol to prepare sodium molybdate n-butanol solution, 200 mg of nickel ammonium bromide was dissolved in 15 mL of n-butanol to prepare nickel ammonium bromide n-butanolamine solution, and 100 mg of cobalt ammonium bromide was dissolved in 15 mL of n-butanol to prepare cobalt ammonium bromide n-butanolamine solution. Then, the sodium molybdate n-butanol solution, nickel ammonium bromide n-butanol solution and cobalt ammonium bromide n-butanol solution were mixed, 15 mL of deionized water was added, and the mixture was ultrasonically stirred and dispersed. The mixture was ultrasonically stirred for 10 min and then stirred for 10 min to obtain a mixed suspension. The mixed suspension was placed in a 100 mL reaction vessel, and the copper mesh with copper hydroxide nanoarray (surface area of ​​9 cm²) prepared in step (1) was added. 2 A solvothermal reaction was carried out at a temperature of 120 °C for 18 hours. After natural cooling, the product obtained after the solvothermal reaction was filtered, washed, and vacuum dried for 36 hours to obtain a primary sample.

[0085] (3) Place the primary sample obtained in step (2) in a tube furnace, introduce a mixed gas of hydrogen and argon (hydrogen accounts for 50% of the volume fraction of the mixed gas), heat it to 1000 ℃ at a rate of 10 ℃ / min, and hold it at the temperature for 1 hour for high-temperature calcination to obtain a molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst.

[0086] The molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalysts prepared in Examples 1-10 were subjected to HER testing in neutral and alkaline solutions, as follows:

[0087] (1) The molybdenum-doped nickel-cobalt-copper lattice stretching alloy catalyst prepared in Examples 1-10 was used as the working electrode and electrochemical tests were performed using an electrochemical workstation.

[0088] (2) The test conditions are as follows: a carbon rod is used as the counter electrode, a reversible hydrogen electrode is used as the reference electrode, and the catalysts prepared in Examples 1-10 are used as working electrodes to form 10 sets of three-electrode test systems. Then, the electrochemical performance of HER is detected in an alkaline medium of 1.0 mol / L potassium hydroxide aqueous solution. The results are shown in Table 1. The electrochemical performance of HER is detected in a neutral medium of 1.0 mol / L PBS solution. The results are shown in Table 2.

[0089] Table 1. Electrochemical performance of HER in alkaline medium with 1.0 mol / L potassium hydroxide

[0090]

[0091] Table 2 Electrochemical performance of HER in neutral medium of 1.0 mol / L PBS solution

[0092]

[0093] As shown in Table 1, when using a 1.0 mol / L potassium hydroxide aqueous solution as the alkaline medium for detection at -10 mA cm⁻¹, -2 At a potential of -100 mA cm⁻¹, the electrochemical hydrogen evolution performance of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in this invention is highest at -35 mV in Example 2 and lowest at -172 mV in Example 1; at a potential of -100 mA cm⁻¹, the electrochemical hydrogen evolution performance of the catalyst is highest at -35 mV in Example 2 and lowest at -172 mV in Example 1. -2 At a potential of -500 mA cm⁻¹, the highest electrochemical hydrogen evolution performance of the catalyst prepared in this invention is -90 mV in Example 2, and the lowest is -217 mV in Example 1; at a potential of -500 mA cm⁻¹, the catalyst exhibits the following performance: -2 At the specified potential, the catalyst prepared in this invention exhibits the highest electrochemical hydrogen evolution performance of -166 mV in Example 2 and the lowest of -367 mV in Example 1. Simultaneously, the minimum Tafel slope is 62.85 mV dec in Example 2. -1The maximum value was 84.86 mV dec in Example 1. -1 According to the performance tests in Table 1, the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in this invention exhibits good HER performance in alkaline media. The test data above show that Example 2 is the optimal embodiment of this invention, while Example 1, due to the absence of molybdenum metal, shows slightly inferior HER performance compared to the other embodiments.

[0094] Table 2 shows that when using a 1.0 mol / L PBS solution as the neutral medium for detection, the results were satisfactory at -10 mA / cm². -2 At a potential of -100 mA cm⁻¹, the electrochemical hydrogen evolution performance of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in this invention was highest at -26 mV in Example 2 and lowest at -135 mV in Example 1; at a potential of -100 mA cm⁻¹, the electrochemical hydrogen evolution performance of the catalyst was highest at -26 mV in Example 2 and lowest at -135 mV in Example -2 At a potential of -500 mA cm⁻¹, the highest electrochemical hydrogen evolution performance of the catalyst prepared in this invention was -123 mV in Example 2, and the lowest was -327 mV in Example 1; at a potential of -500 mA cm⁻¹, the catalyst exhibited the following performance: -2 At the specified potential, the catalyst prepared in this invention exhibits the highest electrochemical hydrogen evolution performance of -255 mV in Example 2 and the lowest of -545 mV in Example 1. Simultaneously, the minimum Tafel slope is 89.92 mV dec in Example 2. -1 The maximum value was 165.75 mV dec in Example 1. -1 According to the performance test results in Table 2, the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in this invention exhibits good HER performance in a neutral medium. Furthermore, the test data above shows that Example 2 is the optimal embodiment of this invention; Example 1, due to the absence of molybdenum metal, shows slightly inferior HER performance compared to the other embodiments.

[0095] Figure 1 The images show the XRD patterns of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalysts prepared in Examples 1-3 of this invention. Figure 1It can be seen that the three diffraction peaks belong to the (111), (200), and (220) crystal planes, respectively, and the corresponding XRD standard cards are Co (PDF#15-0806), Cu (PDF#99-0034), and Ni (PDF#04-0850). Due to the trace doping of the Mo source, the XRD instrument cannot detect the presence of Mo, but the presence of Mo can be determined in the physical characterization experiments of EDS and XPS. The results of large-scale XRD can prove the successful preparation of NiCoCu alloy, which is the same as the record in the literature. At the same time, in the range of 40°-45°, the 2θ values ​​corresponding to the peaks of the three catalysts in Examples 1, 2, and 3 can be clearly seen to be 43.52°, 43.35°, and 43.27°, respectively. According to Bragg's formula, the interplanar spacing of the three catalysts is calculated to be 0.2079nm, 0.2087nm, and 0.2091nm, respectively. The values ​​show that the interplanar spacing increases sequentially, indicating that Mo doping causes tensile strain in the NiCoCu alloy lattice. Based on the interplanar spacing, the stretching degrees of the three catalysts in Examples 1, 2, and 3 can be calculated to be 0%, 0.39%, and 0.58%, respectively. Since no molybdenum metal was added in Example 1, the stretching degree of the catalyst was 0%, while the stretching degrees of the catalysts in Examples 2 and 3 reached 0.39% and 0.58%, respectively, due to the addition of different amounts of molybdenum metal.

[0096] Figure 2 In the image, 'ac' represents a TEM image of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared in Examples 1-3 of this invention. Figure 2 As can be seen from the ac, the lattice fringes of the three catalysts in Example 1, Example 2 and Example 3, as captured by TEM, are 0.2078 nm (111), 0.2086 nm (111) and 0.2093 nm (111), respectively, which are basically consistent with the calculated interplanar spacing values. Compared with Example 1, Example 2 and Example 3 show obvious lattice tensile strain.

[0097] Figure 3 The linear sweep voltammetry (LSV) curves of hydrogen evolution (HER) for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of a commercial Pt / C catalyst in 1.0 mol / L potassium hydroxide solution are shown. The LSV curves demonstrate the electrochemical performance of the catalysts. As shown in Table 1, at the same current density, a smaller overpotential indicates better HER performance of the catalyst. (The data is presented in the table below.) -2 At the specified potential, the overpotential of the catalyst prepared in this invention is close to that of the commercial Pt / C catalyst, indicating that the HER electrochemical performance of the catalyst prepared in this invention is comparable to that of the commercial Pt / C catalyst.

[0098] Figure 4Table 1 presents Tafel slope data for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of a commercial Pt / C catalyst in a 1.0 mol / L potassium hydroxide solution. The Tafel slope is obtained by varying the LSV using a formula. The Tafel slope represents the reaction kinetics; as shown in Table 1, a smaller Tafel slope indicates faster reaction kinetics, while a larger Tafel slope indicates slower reaction kinetics. In alkaline media, the Tafel slope of the catalyst prepared in this invention is close to that of the commercial Pt / C catalyst, indicating that the reaction kinetics of the catalyst prepared in this invention are comparable to those of the commercial Pt / C catalyst.

[0099] Figure 5 The linear sweep voltammetry (LSV) curves of hydrogen evolution (HER) for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of a commercial Pt / C catalyst in 1.0 mol / L PBS solution are shown. The LSV curves demonstrate the electrochemical performance of the catalysts. As shown in Table 1, at the same current density, a smaller overpotential indicates better HER performance of the catalyst. (The data is presented in the table below.) -2 At the specified potential, the overpotential of the catalyst prepared in this invention is close to that of the commercial Pt / C catalyst, indicating that the HER electrochemical performance of the catalyst prepared in this invention is comparable to that of the commercial Pt / C catalyst.

[0100] Figure 6 Table 1 presents Tafel slope data for the catalysts prepared in Examples 1-3 of this invention and 20 wt.% of a commercial Pt / C catalyst in 1.0 mol / L PBS solution. The Tafel slope is obtained by varying the LSV using a formula. The Tafel slope represents the reaction kinetics; as shown in Table 1, a smaller Tafel slope indicates faster reaction kinetics, while a larger Tafel slope indicates slower reaction kinetics. In neutral medium, the Tafel slope of the catalyst prepared in this invention is close to that of the commercial Pt / C catalyst, indicating that the reaction kinetics of the catalyst prepared in this invention are comparable to those of the commercial Pt / C catalyst.

[0101] from Figures 3-6 As can be seen from the description, the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst prepared by the method of the present invention has good HER performance in alkaline and neutral solutions.

[0102] The preparation process of this invention is simple and low-cost. The product prepared by this invention has good catalytic performance for the hydrogen evolution reaction (HER), at -10 / -100 / -500 mA cm⁻¹. -2The catalyst exhibits potentials of -35 / -90 / -166 mV in alkaline media and -26 / -123 / -255 mV in neutral media. The raw material cost of the catalyst prepared by the method of this invention for the same mass is less than 1% of the raw material cost of a 20 wt.% commercial Pt / C catalyst, demonstrating a significant advantage and laying a technological foundation for reducing hydrogen production costs.

[0103] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst, characterized in that, It includes the following steps: 1) Dissolve persulfate and inorganic base in deionized water to prepare a solution. Add copper substrate material to the solution and let it stand for 10-30 minutes. Take out the copper substrate material, clean it and dry it to obtain an intermediate sample. The mass ratio of persulfate to inorganic alkali is 1:2-3; 2) Dissolve the metal precursors molybdenum salt, nickel salt, and cobalt salt in an organic solvent to obtain a mixed solution. Add the mixed solution and the intermediate sample obtained in step 1) to a reaction vessel for a solvothermal reaction at a temperature of 100-180℃ for 6-24 hours. After the reaction is completed, cool to room temperature, remove the reaction liquid from the reaction vessel, filter it, and wash and dry the filter cake to obtain a preliminary sample. The mass ratio of the metal precursor molybdenum salt, metal precursor nickel salt, and metal precursor cobalt salt is 0-2:10-30:5-30. The ratio of the input mass of the cobalt salt precursor to the surface area of ​​the intermediate sample is 5-30:0.9 mg / cm². 2 ; 3) Place the preliminary sample prepared in step 2) in a calcination furnace, introduce a mixed gas of hydrogen and argon, wherein the volume fraction of hydrogen in the mixed gas is 5-60%, and heat it to 400-1000℃ at a heating rate of 2-10℃ / min for high-temperature calcination for 1-5 hours to obtain the molybdenum-doped nickel-cobalt-copper lattice stretched alloy catalyst.

2. The preparation method of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that, The inorganic base in step 1) is potassium hydroxide or sodium hydroxide.

3. The preparation method of the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that, The organic solvent added in step 2) is one or a mixture of two or more of the following: ethanol, ethylene glycol, methanol, isopropanol, glycerol, n-butanol, N,N-dimethylformamide, oleylamine, oleic acid, polyethylene glycol, toluene, acetonitrile, N,N-dimethylacetamide, dimethyl sulfoxide, pyridine, pyrrole, urea, aniline, N-methylaniline, N,N-dimethylaniline, N-ethylaniline, N,N-diethylaniline, diphenylamine, aniline hydrochloride, dioxane, phenylalanine, 2-hydroxypyridine, 2-aminopyridine. 2,6-Diaminopyridine, 2-methylpyridine, 3-aminopyridine, 4-methylpyridine, pentachloropyridine, 3-chloropyridine, 3-fluoropyridine, 3-bromopyridine, 2,3-diaminopyridine, 2-amino-3-chloropyridine, 2-pyrrolidone, 2-pyrrolic acid, 3-acetyl-2,4-dimethylpyridine, hydroxyethylpyrrolidone, 2-acetylpyridine, 1-methylpyridine, tetrahydropyridine, ethyl pyrrolidone-2-carboxylate, 2,4-dimethylpyridine, 4-acetylpyridine, 2-acetylpyridine, N-methylpyridine, or deionized water.

4. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: The persulfate mentioned in step 1) is one of the following: ammonium persulfate, sodium persulfate, or potassium persulfate.

5. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: The copper substrate material mentioned in step 1) is one of the following: copper wire, copper mesh, copper foil, or copper sheet.

6. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: The metal precursor molybdenum salt in step 2) is one of the following: molybdic acid, ammonium molybdate tetrahydrate, ammonium heptamolybdate, ammonium dimolybdate, sodium molybdate, phosphomolybdic acid, ammonium phosphomolybdate, sodium phosphomolybdate, molybdenum chloride, lithium molybdate, potassium molybdate, molybdenum hexacarbonyl, molybdenum acetylacetonate, and molybdenum isopropoxide.

7. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: The nickel salt precursor in step 2) is one of the following: nickel chloride, nickel acetylacetone, nickel acetylacetonate, nickel acetate, nickel bromide, nickel iodide, nickel sulfate, nickel nitrate, nickel sulfate, nickel hypophosphite, nickel nitrate, nickel aminosulfonate, basic nickel carbonate, nickel formate, nickel dicrocene, nickel bis(triphenylphosphine)bromide, and nickel bis(triphenylphosphine)chloride.

8. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: The cobalt salt precursor metal in step 2) is one of the following: cobalt chloride, cobalt acetate, cobalt phosphate, cobalt phthalocyanine, potassium cobalt cyanocyanate, potassium hexacyanocobaltate, cobalt hexaaminochloride, cobalt perchlorate, cobalt nitrate, cobalt fluoride, cobalt iodide, cobalt bromide, sodium cobalt nitrite, cobalt oxalate, cobalt sulfate, cobalt sulfate, ammonium cobalt sulfate, cobalt naphthenate, and cobalt acetylacetonate.

9. The method for preparing the molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst according to claim 1, characterized in that: In step 2), after mixing the three solutions to obtain a mixed solution, deionized water is added, and the mixture is ultrasonically stirred and dispersed to obtain a mixed suspension. The mixed suspension and the intermediate sample obtained in step 1) are then added to a reaction vessel for a solvothermal reaction.

10. A molybdenum-doped nickel-cobalt-copper lattice-stretched alloy catalyst, characterized in that: It is prepared by the preparation method described in any one of claims 1-9.

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