Three-dimensional self-supporting electrode and preparation method and application thereof

Abstract

This invention belongs to the field of water electrolysis for hydrogen production technology, and discloses a three-dimensional self-supporting electrode, its preparation method, and its application. The electrode uses copper foam as a substrate and a three-step method of cyclic voltammetry / hydrothermal treatment / calcination is used to prepare a three-dimensional cobalt-molybdenum-boride electrode. The electrode prepared by this method is applied to alkaline water electrolysis reactions. The cobalt-molybdenum-boride electrode is a sea urchin-like nanosphere structure composed of nanowires, with nanospheres having a diameter of 5 μm to 15 mm and nanowires having a diameter of 20 nm to 100 nm. The electrode prepared by this invention does not require additional binders such as current collectors, Nafion, or sugar alcohols, greatly improving the utilization rate of the catalyst on the electrode surface. The three-dimensional structure of the electrode ensures sufficient wetting of the electrolyte, which is beneficial for the transport of reactants and products. The synergistic effect between the components and the three-dimensional layered porous nanostructure of the electrode can accelerate water decomposition. This electrode can be used to prepare dual-effect electrodes for water electrolysis, dual-effect electrodes for seawater electrolysis, and anode electrodes for carbon dioxide electroreduction reactions.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology. It relates to a three-dimensional self-supporting electrode, its preparation method, and its application. Background Technology

[0002] With rapid economic development, energy demand is increasing daily. The massive consumption of fossil fuels has exacerbated the greenhouse effect and severely damaged the global ecological environment. Statistics show that fossil fuels account for over 80% of all energy consumption. To reduce dependence on fossil fuels, decrease pollutant emissions, and prevent further environmental degradation, choosing and promoting clean energy sources such as hydrogen, hydropower, wind power, solar energy, geothermal energy, biomass energy, and tidal energy is an inevitable trend for future development. However, renewable energy sources such as hydropower, tidal energy, and solar energy have relatively stringent requirements regarding climate and environmental conditions, limiting their further development and large-scale application. Hydrogen, as a fuel, has many advantages, including high calorific value, virtually no pollutant production, renewability, wide availability, and efficiency exceeding 90% when used in conjunction with fuel cells, making it considered the best alternative energy source to fossil fuels.

[0003] Electrolysis of water to produce hydrogen is an effective way to achieve carbon dioxide emission reduction and renewable energy storage. Currently, the best-performing water electrolysis electrodes are platinum (Pt), iridium dioxide (IrO2), and ruthenium dioxide (RuO2). Therefore, using non-precious metals instead of precious metals in water electrolysis is becoming a development trend. However, using different types of metal supports can also affect the catalytic activity of the electrode. Therefore, developing safe and green supports with high loading capacity to increase the loading of transition metal borides is key to improving the catalytic efficiency of HER and OER electrodes. Currently, most methods for preparing borides use sodium borohydride as the boron source to prepare nano-borides. However, the electrode performance prepared by these methods still does not meet the requirements for large-scale use. Furthermore, the prepared nano-electrodes require binders, which are applied by spraying or scraping onto the substrate, reducing electrode utilization and increasing preparation costs. Additionally, the poor bonding between the electrode and the substrate makes them prone to detachment during water electrolysis. Improving the bonding between the substrate and the electrode and enhancing the electrode's reactivity are urgent problems to be solved for boride electrodes. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a three-dimensional self-supporting electrode, its preparation method, and its application. The electrode prepared by this invention does not require additional binders or current collectors, which greatly improves the overall performance of the electrode. The electrode has a through-hole three-dimensional structure, which can ensure sufficient wetting of the electrolyte and is conducive to the transport of reactants and products.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution:

[0006] A three-dimensional self-supporting electrode comprises a copper foam substrate, a copper oxide layer formed on the substrate by electrochemical etching using cyclic voltammetry, followed by in-situ growth of cobalt-molybdenum boride on the etched copper oxide layer using a hydrothermal method, and finally calcination under inert gas protection to obtain a cobalt-molybdenum boride electrode. The substrate thickness is 300 μm to 1 mm; the copper oxide loading is 0.1 mg / cm³. 2 -3 mg / cm 2 The loading of cobalt-molybdenum-boron oxide electrodes is 10 mg / cm³. 2 -60 mg / cm 2 .

[0007] The cobalt-molybdenum-boron compound electrode is a sea urchin-shaped nanosphere structure composed of nanowires, with the nanospheres having a diameter of 5 μm to 15 mm and the nanowires having a diameter of 20 nm to 100 nm.

[0008] The preparation method of the above-mentioned three-dimensional self-supporting electrode includes: ultrasonicating copper foam in HCl solution for 30 min, and rinsing it successively with acetone or anhydrous ethanol and deionized water; electrochemically etching the copper foam using a cyclic etching method to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF; dissolving cobalt salt, molybdenum salt, boric acid and stabilizer in deionized water, adding the etched copper foam, and performing a hydrothermal reaction to obtain electrode A; placing electrode A in a tube furnace and calcining it under an inert gas to obtain the three-dimensional self-supporting electrode Co. x Mo y B z @CuO / CF.

[0009] The specific steps for fabricating the aforementioned three-dimensional self-supporting electrode are as follows:

[0010] S1: Press the copper foam into tablets at 0.5MPa-3MPa for 30-90s on a tablet press, then sonicate it in HCl solution for 15-50min, rinse it with acetone or anhydrous ethanol and deionized water, and then dry the copper foam in an oven at 30-90℃ for later use to obtain a clean copper foam substrate.

[0011] S2: Place the copper foam substrate obtained in step S1 in any one or more aqueous solutions of NaOH and KOH, and perform electrochemical etching on the copper foam substrate using cyclic voltammetry. After scanning, wash with deionized water and dry for 12-36 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0012] S3: Cobalt salt, molybdenum salt, boric acid, and stabilizer are mixed and added to deionized water. Under room temperature, the mixture is magnetically stirred for 15-35 minutes to form a precursor cobalt-molybdenum mixed solution. This solution is then poured into a reaction vessel. Subsequently, the copper oxide layer etched in S2 is placed into the reaction vessel, which is then placed in a vacuum oven for hydrothermal reaction. After the reaction is complete, the reaction vessel is removed and allowed to cool. It is then rinsed with acetone or anhydrous ethanol and deionized water, and finally dried in a 60°C vacuum oven for 6-15 hours to obtain electrode A. The molar ratio of cobalt salt to molybdenum salt is 0.1-10, and the molar ratio of boron to the total of cobalt and molybdenum is 0.05-5. The concentration of the stabilizer polyvinylpyrrolidone (PVP) is 0.1M.

[0013] S4: Place the dried electrode A into a tube furnace and calcine it with inert gas to obtain the three-dimensional self-supporting electrode Co. x Mo y B z @CuO / CF; x, i.e., the molar percentage of Co, ranges from 30-45%, y, i.e., the molar percentage of Mo, ranges from 30-45%, z, i.e., the molar percentage of B, ranges from 5-40%, and the loading of the cobalt-molybdenum-boron compound electrode is 10 mg / cm³. 2 -60mg / cm 2 .

[0014] Furthermore, in step S1, it is preferable to perform ultrasonic treatment for 30 minutes and drying at a temperature of 60°C.

[0015] Furthermore, the HCl concentration in step S1 is 0.2-3M, preferably 0.5-1.2M.

[0016] Furthermore, in step S2, the concentration of NaOH or KOH is 0.1-3M, preferably 0.5-1.5M; in the cyclic voltammetry, the low potential of the cyclic scan is -3.0V to -1.2V, the high potential is 0.2V to 1.2V, and the scan rate is 1mV / s. -1 ~100mV s -1 The preferred scanning speed is 20 mV / s. -1 ~50mV s -1 The number of scans is 1-50, with an optimal number of scans of 2-10; the concentration of KOH in the electrolyte is 0.05M-1.7M, with an optimal concentration of 0.2M-1.1M; and the loading of the copper oxide layer is 0.1 mg / cm³. 2 -3mg / cm 2 .

[0017] Furthermore, the cobalt salt in step S3 is any one or more of cobalt carbonate, cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate, and the concentration of the cobalt salt is 0.005M-2.0M, preferably 0.01M-1.0M; the molybdenum salt is any one or more of sodium molybdate, cobalt molybdate, nickel molybdate, manganese molybdate, bismuth molybdate, ammonium molybdate, magnesium molybdate, and zinc molybdate, and the concentration of the molybdenum salt is 0.005M-1.0M, preferably 0.01M-0.5M; the temperature in the hydrothermal reaction is 100℃-240℃, preferably 140℃-180℃, and the hydrothermal time is 12-48h, preferably 12-21h.

[0018] Furthermore, the inert gas in step S4 is any one or both of nitrogen and argon. During the calcination process, the heating rate is controlled at 2℃ / min-5℃ / min, the calcination temperature is 200℃-800℃, and the calcination time is 2-8h, preferably 400℃-600℃, and preferably 3-6h; x, i.e., the molar percentage of Co, is in the range of 30-45%, y, i.e., the molar percentage of Mo, is in the range of 30-45%, and z, i.e., the molar percentage of B, is in the range of 5-40%.

[0019] This invention also claims protection for the application of the electrodes prepared by the above-described method as anode electrodes in hydrogen evolution and oxygen evolution dual-effect electrodes for water electrolysis, seawater electrolysis dual-effect electrodes, and carbon dioxide electroreduction reactions. Specifically, they are applied to alkaline water electrolysis or fuel cells.

[0020] This invention first utilizes cyclic voltammetry to electrochemically etch a substrate, growing more defect sites and copper oxide on its surface. Then, a hydrothermal method is used to load cobalt-molybdenum boride onto the surface, fabricating a three-dimensional self-supporting electrode. The defect sites and metal oxides on the foamed copper surface not only improve the electrode's dispersion, but also the copper oxide and Co... x Mo y B z The synergistic effect can further enhance the activity of the electrode; the oxygen-containing functional groups of copper oxide species can anchor cobalt-molybdenum borides on the surface of copper foam, further improving the bonding force between the borides and copper foam, thereby improving the stability of the electrode.

[0021] The electrode prepared by this invention does not require additional binders or current collectors, which greatly improves the overall performance of the electrode; the electrode has a through-hole three-dimensional structure, which can ensure sufficient wetting of the electrolyte and facilitate the transport of reactants and products.

[0022] The advantages of this invention compared to the prior art are:

[0023] The present invention provides a three-dimensional copper-based cobalt-molybdenum boride electrode, which is prepared by a three-step method of cyclic voltammetry / hydrothermal treatment / calcination using copper foam as a substrate.

[0024] This invention involves in-situ growth of cobalt-molybdenum boride onto electrochemically etched copper foam. The copper hydroxide and oxide layer grown on the etched copper foam not only improves electrode dispersion but also... x Mo y B z The synergistic effect can further enhance the activity of the electrode; the oxygen-containing functional groups of copper oxide species can anchor borides to the surface of copper foam, further improving the bonding force between cobalt-molybdenum borides and copper foam, thereby improving the stability of the electrode. The Co loaded on copper foam... x Mo y B z The excellent catalytic activity is attributed to the porous structure of copper foam, which provides more active sites after etching. Simultaneously, Co(d7) exhibits low adsorption strength while Mo(d5) has high adsorption strength; the two alloys can combine to enhance adsorption strength and catalytic activity. The synergistic effect of strong electron interaction between nanoparticles endows the composite material with higher conductivity, optimal water adsorption energy, and faster charge transfer capability, thereby enhancing the electrode's catalytic activity. This invention, based on the growth of copper oxide on copper foam through electrochemical etching using cyclic voltammetry, prepares a cobalt-molybdenum-boron electrode by doping with cobalt, molybdenum, and boron. The urchin-like nanosphere structure composed of nanowires, grown in situ using a hydrothermal method, features numerous surface active sites and a large electrochemical reaction area, enabling faster gas release. The electrode formed by the combination of cobalt and molybdenum, two metals and non-metallic boron, significantly improves the electrode's catalytic activity and stability.

[0025] Because the preparation process uses cyclic voltammetry, hydrothermal method, and calcination method, the entire synthesis steps are simple and convenient, and the raw materials are inexpensive and widely available, making it possible to carry out large-scale production.

[0026] The three-dimensional copper-based cobalt-molybdenum-boron compound electrode exhibits excellent catalytic activity (at a current density of 10 mA cm⁻¹). -2 The hydrogen evolution overpotential is 105 mV at a current density of 100 mA cm⁻¹. -2 The oxygen evolution overpotential was 437 mV, indicating that the three-dimensional copper-based cobalt-molybdenum-boron compound electrode exhibits good electrocatalytic performance in hydrogen evolution and oxygen evolution reactions under alkaline conditions. The preparation process of this invention is relatively simple, and the raw materials are inexpensive and abundant, which is beneficial for improving the efficiency of hydrogen production through water electrolysis and promoting the development of hydrogen energy. Attached Figure Description

[0027] Figure 1 The hydrogen evolution test performed on the cobalt-molybdenum-boron electrode prepared in Example 1 is shown as a linear voltammetry curve in 1M KOH solution.

[0028] Figure 2 The oxygen evolution test performed on the cobalt-molybdenum-boron electrode prepared in Example 1 is shown as a linear voltammetric curve in 1M KOH solution.

[0029] Figure 3 Hydrogen evolution tests were performed on the cobalt-molybdenum-boron oxide electrodes prepared in Examples 1, 2, 3, and 4 at different metal ratios, i.e., linear voltammetric curves in 1M KOH solution.

[0030] Figure 4 Oxygen evolution tests were performed on the cobalt-molybdenum-boron oxide electrodes prepared in Examples 1, 2, 3, and 4 at different metal ratios, i.e., linear voltammetric curves in 1M KOH solution.

[0031] Figure 5 Hydrogen evolution tests were performed on the cobalt-molybdenum boride electrodes prepared in Examples 1, 5, 6 and 7 at different hydrothermal temperatures, i.e., linear voltammetric curves in 1M KOH solution.

[0032] Figure 6 The oxygen evolution tests at different hydrothermal temperatures of the cobalt-molybdenum-boron oxide electrodes prepared in Examples 1, 5, 6, and 7 are shown in the linear voltammetric curves in 1M KOH solution.

[0033] Figure 7 Hydrogen evolution tests were performed on the cobalt-molybdenum-boron oxide electrodes prepared in Examples 1, 8, 9, and 10 for different hydrothermal durations, i.e., linear voltammetric curves in 1M KOH solution;

[0034] Figure 8 Oxygen evolution tests were performed on the cobalt-molybdenum-boron oxide electrodes prepared in Examples 1, 8, 9, and 10 for different hydrothermal durations, i.e., linear voltammetric curves in 1M KOH solution;

[0035] Figure 9 The hydrogen evolution test of the cobalt-molybdenum-boron electrode prepared in Example 1 and Comparative Examples 1, 2, and 3 is shown in the linear voltammetry curve in 1M KOH solution.

[0036] Figure 10 The oxygen evolution test of the cobalt-molybdenum-boron electrode prepared in Example 1 and Comparative Examples 1, 2, and 3 is shown in the linear voltammetric curves in 1M KOH solution.

[0037] Figure 11 This is a SEM image of the cobalt-molybdenum boride electrode prepared in Example 1. Detailed Implementation

[0038] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0039] This invention provides a three-dimensional self-supporting electrode, its preparation method, and its application. The electrode uses copper foam as a substrate and a three-step method of cyclic voltammetry / hydrothermal treatment / calcination is used to prepare a three-dimensional cobalt-molybdenum boride electrode. The electrode prepared by this method is applied to alkaline water electrolysis. The cobalt-molybdenum boride electrode is a sea urchin-like nanosphere structure composed of nanowires, with nanospheres having a diameter of 5 μm to 15 mm and nanowires having a diameter of 20 nm to 100 nm. The copper oxide layer not only improves the electrode's dispersion, but the synergistic effect of copper species and cobalt-molybdenum boride can enhance the catalyst activity; the oxygen-containing functional groups of copper oxide species can anchor the cobalt-molybdenum boride to the substrate surface, further improving the binding force between the two, thereby improving the catalyst's stability. The electrode prepared by this invention does not require additional binders such as current collectors, Nafion, or sugar alcohols, greatly improving the utilization rate of the catalyst on the electrode surface; the three-dimensional structure of the electrode ensures sufficient wetting of the electrolyte, which is beneficial for the transport of reactants and products; the synergistic effect between the components and the three-dimensional layered porous nanostructure of the electrode can accelerate water decomposition. This electrode can be used to prepare dual-effect electrodes for water electrolysis, dual-effect electrodes for seawater electrolysis, and anode electrodes for carbon dioxide electroreduction reactions.

[0040] The present invention will be further described below:

[0041] This invention provides a three-dimensional cobalt-molybdenum boride electrode prepared by a three-step method involving cyclic voltammetry, hydrothermal treatment, and calcination, and the method thereof. This method uses etched copper foam as a substrate, which enhances the electrochemical effect of the composite material and improves its water electrolysis performance. The preparation method of the cobalt-molybdenum boride electrode includes:

[0042] The copper foam substrate is compressed into tablets at 0.5MPa-3MPa for 30-90s on a tablet press, then placed in an HCl solution for ultrasonic treatment for 15-50min. After rinsing with acetone or anhydrous ethanol and deionized water, the copper foam is dried in an oven at 30-90℃ for later use.

[0043] The treated copper foam was placed in one or more aqueous solutions of NaOH and KOH, and CV cyclic scanning was performed. After scanning, it was rinsed with solvents such as deionized water and dried for 12-36 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF. The concentration of KOH in the electrolyte was 0.05M-1.7M, preferably 0.2M-1.1M; the molar ratio of cobalt salt to molybdenum salt was 0.1-10, and the molar ratio of boron to the sum of cobalt and molybdenum was 0.05-5; the concentration of the stabilizer polyvinylpyrrolidone (PVP) was 0.1M; and the loading of the copper oxide layer was 0.1 mg / cm³. 2 -3 mg / cm 2 ;

[0044] 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer were mixed and added to deionized water. The mixture was magnetically stirred for 15-35 minutes at room temperature to form a precursor cobalt-molybdenum mixed solution, which was then poured into a reaction vessel. A pretreated copper oxide layer (CuO / CF) was then placed into the reaction vessel, which was subsequently placed in a vacuum oven. After the reaction was complete, the reaction vessel was removed, cooled, and rinsed with acetone or anhydrous ethanol and deionized water. It was then placed in a 60℃ oven for 6-15 hours to obtain electrode A. The preferred concentration of cobalt salt was 0.01M-1.0M, the preferred concentration of molybdenum salt was 0.01M-0.5M, the preferred hydrothermal reaction temperature was 140℃-180℃, and the preferred hydrothermal time was 12-21 hours.

[0045] The dried electrode A is placed in a tube furnace and calcined under an inert gas to obtain a three-dimensional self-supporting electrode Co. x Mo y B z @CuO / CF; x represents the molar percentage of Co, ranging from 30-45%; y represents the molar percentage of Mo, ranging from 30-45%; and z represents the molar percentage of B, ranging from 5-40%.

[0046] Example 1

[0047] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0048] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0049] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0050] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0051] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0052] Example 2

[0053] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0054] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0055] Mix 0.03M cobalt salt, 0.07M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 min to form a cobalt-molybdenum precursor mixed solution.

[0056] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0057] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co3Mo7B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0058] Example 3

[0059] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0060] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0061] Mix 0.07M cobalt salt, 0.03M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water, stirring for 30 min to form a cobalt-molybdenum precursor solution.

[0062] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0063] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co7Mo3B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0064] Example 4

[0065] Copper foam was compressed into tablets at 1 MPa for 4 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0066] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0067] Mix 0.09M cobalt salt, 0.01M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water, stirring for 30 min to form a cobalt-molybdenum precursor solution.

[0068] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0069] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co9Mo1B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0070] Example 5

[0071] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0072] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0073] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0074] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 120°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0075] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0076] Example 6

[0077] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0078] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0079] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0080] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 160°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0081] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0082] Example 7

[0083] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0084] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0085] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0086] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 180°C for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0087] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z@CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0088] Example 8

[0089] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0090] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0091] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0092] A cobalt-molybdenum mixed solution of precursors and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 6 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0093] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0094] Example 9

[0095] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0096] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0097] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0098] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 12 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0099] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0100] Example 10

[0101] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0102] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0103] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water. Stir for 30 minutes to form a cobalt-molybdenum precursor solution.

[0104] A cobalt-molybdenum precursor solution and a pretreated copper oxide layer (CuO / CF) were placed in a reactor and reacted in a vacuum oven at 140°C for 24 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and finally placed in a 60°C oven for 10 hours to obtain precursor A.

[0105] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0106] Comparative Example 1

[0107] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0108] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0109] Mix 0.05M cobalt salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water, stirring for 30 min to form a precursor mixture solution.

[0110] The precursor mixture and the pretreated copper oxide layer CuO / CF were placed in a reactor and reacted in a vacuum oven at 140℃ for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60℃ oven for 10 hours to obtain precursor A.

[0111] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Co5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0112] Comparative Example 2

[0113] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0114] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0115] Mix 0.05M molybdenum salt, 0.2M boric acid, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water, stirring for 30 min to form a precursor mixture solution.

[0116] The precursor mixture and the pretreated copper oxide layer CuO / CF were placed in a reactor and reacted in a vacuum oven at 140℃ for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60℃ oven for 10 hours to obtain precursor A.

[0117] Precursor A was calcined at 300°C under nitrogen protection to obtain electrode Mo5B. z @CuO / CF, where z represents the molar percentage of B, ranges from 5% to 40%.

[0118] Comparative Example 3

[0119] Copper foam was compressed into tablets at 1 MPa for 45 seconds on a tablet press, then placed in a 1 M HCl solution and sonicated for 30 minutes. After being rinsed with acetone or anhydrous ethanol and deionized water, it was dried for later use.

[0120] The treated copper foam was subjected to CV cyclic scanning in a 0.5M NaOH aqueous solution with a voltage range of -2.0V to 0.2V and 10 scan cycles. After scanning, the foam was rinsed with solvents such as deionized water and then dried for 24 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF.

[0121] Mix 0.05M cobalt salt, 0.05M molybdenum salt, and 0.1M stabilizer polyvinylpyrrolidone (PVP) and add to deionized water, stirring for 30 min to form a precursor mixture solution.

[0122] The precursor mixture and the pretreated copper oxide layer CuO / CF were placed in a reactor and reacted in a vacuum oven at 140℃ for 18 hours. After the reaction, the reactor was removed and cooled. The copper foam was then rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60℃ oven for 10 hours to obtain precursor A.

[0123] Precursor A was calcined under nitrogen protection at 300°C to obtain electrode Co5Mo5@CuO / CF, where the molar content percentage of B ranged from 5% to 40%.

[0124] from Figure 3 It can be seen that the overpotential of the cobalt-molybdenum boride electrode is significantly lower when the ratio of cobalt to molybdenum is 5:5 than that of electrodes prepared under other metal ratios; at a current density of 10 mA cm⁻¹ -2 At this time, its hydrogen evolution overpotential is only 105mV, which is better than that of cobalt-molybdenum boride electrodes prepared under other cobalt-molybdenum metal ratios, thus proving that the cobalt-molybdenum boride electrode has the best catalytic activity for the hydrogen evolution reaction of water electrolysis when the metal cobalt-molybdenum ratio is 5:5.

[0125] from Figure 4 It can be seen that the overpotential of the cobalt-molybdenum boride electrode is significantly lower when the ratio of cobalt to molybdenum is 5:5 than that of electrodes prepared under other metal ratios; at a current density of 100 mA cm⁻¹ -2 At this time, its oxygen evolution overpotential is only 437mV, which is better than that of cobalt-molybdenum boride electrodes prepared under other cobalt-molybdenum metal ratios, thus proving that the cobalt-molybdenum boride electrode has the best catalytic activity for the oxygen evolution reaction of water electrolysis when the metal cobalt-molybdenum ratio is 5:5.

[0126] from Figure 5It can be seen that the overpotential of the cobalt-molybdenum-boron compound electrode at a hydrothermal temperature of 140℃ is significantly lower than that of electrodes prepared under other hydrothermal temperature conditions; at a current density of 10 mA cm⁻¹ -2 At this temperature, the hydrogen evolution overpotential is only 105 mV, which is better than that of cobalt-molybdenum-boride electrodes prepared under other hydrothermal temperature conditions, thus proving that the cobalt-molybdenum-boride electrode has the best catalytic activity for the hydrogen evolution reaction of water electrolysis at a hydrothermal temperature of 140 °C.

[0127] from Figure 6 It can be seen that the overpotential of the cobalt-molybdenum-boron compound electrode at a hydrothermal temperature of 140℃ is significantly lower than that of electrodes prepared under other hydrothermal temperature conditions; at a current density of 100 mA cm⁻¹ -2 At this temperature, the oxygen evolution overpotential is only 437 mV, which is better than that of cobalt-molybdenum-boride electrodes prepared under other hydrothermal temperature conditions, thus proving that the cobalt-molybdenum-boride electrode has the best catalytic activity for the oxygen evolution reaction of water electrolysis at a hydrothermal temperature of 140℃.

[0128] from Figure 7 It can be seen that the overpotential of the cobalt-molybdenum-boron compound electrode prepared under hydrothermal conditions of 18 h is significantly lower than that of electrodes prepared under other hydrothermal durations; at a current density of 10 mA cm⁻¹ -2 When the hydrogen evolution overpotential is only 105 mV, it is superior to the cobalt-molybdenum-boride electrode prepared under other hydrothermal conditions, thus proving that the cobalt-molybdenum-boride electrode has the best catalytic activity for the hydrogen evolution reaction of water electrolysis when the hydrothermal time is 18 h.

[0129] from Figure 8 It can be seen that the overpotential of the cobalt-molybdenum-boron compound electrode prepared under hydrothermal conditions of 18 h is significantly lower than that of electrodes prepared under other hydrothermal durations; at a current density of 100 mA cm⁻¹ -2 At this time, its oxygen evolution overpotential is only 437mV, which is better than that of cobalt-molybdenum-boride electrodes prepared under other hydrothermal duration conditions, thus proving that the cobalt-molybdenum-boride electrode has the best catalytic activity for the oxygen evolution reaction of water electrolysis when the hydrothermal duration is 18h.

[0130] from Figure 9 It can be seen that, under the same conditions, the overpotential of the cobalt-molybdenum-boron compound electrode is significantly lower than that of electrodes made of other metals; at a current density of 10 mA cm⁻¹ -2 At that time, its hydrogen evolution overpotential was only 105 mV, which is better than other electrodes, thus proving that the cobalt-molybdenum boride electrode has excellent catalytic activity for the hydrogen evolution reaction of water electrolysis.

[0131] from Figure 10 It can be seen that, under the same conditions, the overpotential of the cobalt-molybdenum-boron compound electrode is significantly lower than that of electrodes made of other metals; at a current density of 100 mA cm⁻¹ -2At that time, its oxygen evolution overpotential was only 437mV, which is better than other electrodes, thus proving that the cobalt-molybdenum-boron electrode has excellent catalytic activity for the oxygen evolution reaction of water electrolysis.

[0132] The three-dimensional copper-based cobalt-molybdenum metal boride electrode prepared in Example 1 was obtained using a scanning electron microscope (Quanta 400FEG, manufactured by FEI Corporation, USA). (SEM images are shown below.) Figure 9 As shown. From Figure 9 As can be seen from the image, the obtained three-dimensional copper-based doped cobalt-molybdenum metal boride electrode is composed of urchin-shaped nanospheres of cobalt-molybdenum boride made of nanowires.

[0133] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A three-dimensional self-supporting electrode, characterized in that, The electrode comprises a copper oxide layer containing copper hydroxide and oxides grown on a copper foam substrate by electrochemical etching using cyclic voltammetry. Subsequently, cobalt-molybdenum boride is grown in situ on the etched copper foam substrate using a hydrothermal method. Finally, the electrode is calcined under inert gas protection to obtain the cobalt-molybdenum boride electrode. The cobalt-molybdenum boride electrode has a urchin-like nanosphere structure composed of nanowires. The substrate thickness ranges from 300 μm to 1 mm, and the copper oxide loading is 0.1 mg / cm³. 2 -3 mg / cm 2 The loading capacity of the cobalt-molybdenum-boron electrode is 10 mg / cm³. 2 -60mg / cm 2 ; The cobalt-molybdenum-boron compound electrode is a sea urchin-like nanosphere structure composed of nanowires. The diameter of the nanospheres ranges from 5 μm to 15 mm, and the diameter of the nanowires ranges from 20 nm to 100 nm.

2. A method for fabricating a three-dimensional self-supporting electrode as described in any one of claims 1, characterized in that, include: The copper foam was sonicated in HCl solution for 30 min, and then rinsed with acetone or anhydrous ethanol and deionized water. Electrochemical etching of copper foam using a cyclic etching method yields a copper oxide layer containing copper hydroxide and oxides, denoted as CuO / CF. Cobalt salt, molybdenum salt, boric acid, and a stabilizer are dissolved in deionized water, and the etched copper foam is added, followed by a hydrothermal reaction to obtain electrode A. Electrode A is then placed in a tube furnace and calcined under an inert gas atmosphere to obtain a three-dimensional self-supporting electrode Co. x Mo y B z @CuO / CF.

3. The preparation method according to claim 2, characterized in that, The specific steps are as follows: S1: Press the copper foam into tablets at 0.5 MPa-3 MPa for 30-90s on a tablet press, then sonicate it in HCl solution for 30min, rinse it with acetone or anhydrous ethanol and deionized water, and then dry the copper foam in an oven at 30-90℃ for later use to obtain a clean copper foam substrate. S2: Place the copper foam substrate obtained in step S1 in an aqueous solution of either NaOH or KOH, and perform electrochemical etching on the copper foam substrate using cyclic voltammetry. After scanning, wash with deionized water and dry for 12-36 hours to obtain a copper oxide layer containing copper hydroxide and oxide, denoted as CuO / CF. S3: Cobalt salt, molybdenum salt, boric acid, and stabilizer are mixed and added to deionized water. Under room temperature, the mixture is magnetically stirred for 15-35 min to form a precursor cobalt-molybdenum mixed solution. This solution is then poured into a reaction vessel. Subsequently, the copper oxide layer etched in S2 is placed into the reaction vessel, which is then placed in a vacuum oven for hydrothermal reaction. After the reaction is complete, the reaction vessel is removed and allowed to cool. It is then rinsed with acetone or anhydrous ethanol and deionized water, and finally dried in a 60℃ vacuum oven for 6-15 h to obtain electrode A. The molar ratio of cobalt salt to molybdenum salt is 0.1-10, and the molar ratio of boron to the total of cobalt and molybdenum is 0.05-5. The concentration of the stabilizer polyvinylpyrrolidone is 0.1M. S4: Place the dried electrode A into a tube furnace and calcine it with inert gas to obtain the three-dimensional self-supporting electrode Co. x Mo y B z @CuO / CF; x represents the molar percentage of Co ranging from 30-45%, y represents the molar percentage of Mo ranging from 30-45%, z represents the molar percentage of B ranging from 5-40%, and the loading of the cobalt-molybdenum-boron compound electrode is 10 mg / cm³. 2 -60 mg / cm 2 .

4. The preparation method according to claim 3, characterized in that, In step S2, the concentration of NaOH or KOH is 0.1-3M; in the cyclic voltammetry, the low potential of the cyclic scan is -3.0 V to -1.2 V, the high potential is 0.2 V to 1.2 V, and the scan rate is 1 mV / s. -1 ~100 mV s -1 The number of scans ranged from 1 to 50, the concentration of KOH in the electrolyte was 0.05 M to 1.7 M, and the loading of the copper oxide layer was 0.1 mg / cm³. 2 -3 mg / cm 2 .

5. The preparation method according to claim 4, characterized in that, The cobalt salt in step S3 is any one or more of cobalt carbonate, cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate, and the concentration of the cobalt salt is 0.005 M-2.0 M.

6. The preparation method according to claim 4, characterized in that, The molybdenum salt in step S3 is any one or more of sodium molybdate, cobalt molybdate, nickel molybdate, manganese molybdate, bismuth molybdate, ammonium molybdate, magnesium molybdate, and zinc molybdate, and the concentration of the molybdenum salt is 0.005 M-1.0 M; the temperature in the hydrothermal reaction is 100℃-240℃, and the hydrothermal time is 12-48 h.

7. The preparation method according to claim 4, characterized in that, In step S4, the heating rate is controlled at 2℃ / min-5℃ / min during calcination, the calcination temperature is 200℃-800℃, and the calcination time is 2-8h; the molar percentage range of x (Co) is 30-45%, the molar percentage range of y (Mo) is 30-45%, and the molar percentage range of z (B) is 5-40%.

8. The application of the electrode prepared by any one of the preparation methods of claims 2-7 in the dual-effect electrode for hydrogen and oxygen evolution in water electrolysis.

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