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

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production, and discloses a three-dimensional structure self-supporting electrode and a preparation method and application thereof. The cobalt-molybdenum boride electrode with the three-dimensional structure is prepared by taking foamy copper as a substrate through a cyclic voltammetry / hydrothermal / roasting three-step method. The electrode prepared by the method is applied to alkaline water electrolysis reaction. Wherein the cobalt molybdenum boride electrode is of an urchin-shaped nanosphere structure composed of nanowires, the diameter of nanospheres ranges from 5 microns to 15 mm, and the diameter of the nanowires ranges from 20 nm to 100 nm. The electrode prepared by the method does not need additional binders such as a current collector, Nafion and sugar alcohol, so that the utilization rate of a catalyst on the surface of the electrode is greatly improved; due to the three-dimensional structure of the electrode, sufficient wetting of electrolyte can be guaranteed, and transmission of reactants and products is facilitated; the synergistic effect among the components and the three-dimensional layered porous nano-structure of the electrode can accelerate the decomposition of water. The electrode can be used for preparing a water electrolysis double-effect electrode, a seawater electrolysis double-effect electrode and a carbon dioxide electroreduction reaction anode electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolysis of water, and relates to a three-dimensional structured self-supporting electrode and a preparation method and application thereof. Background Art

[0002] With the rapid development of economy, the demand for energy is increasing day by day. The massive consumption of fossil energy has led to the intensification of greenhouse effect and serious damage to the global ecological environment. According to statistics, the consumption of fossil energy accounts for more than 80% of all energy consumption. In order to reduce the dependence on fossil energy, reduce the emission of polluting gases and prevent further deterioration of the environment, it is an inevitable trend for future development to select and promote clean energy such as hydrogen energy, hydropower, wind energy, solar energy, geothermal energy, biomass energy and tidal energy. However, renewable energy such as hydropower, tidal energy and solar energy has strict requirements on climate and environmental conditions, which limits its further development and large-scale application. Hydrogen as a fuel has many advantages such as high calorific value, basically no pollution, renewable, wide source, and efficiency of more than 90% when used with fuel cells. It is considered to be the best alternative energy to replace fossil fuels.

[0003] The technology of producing hydrogen by electrolysis of water is one of the effective ways to achieve carbon dioxide emission reduction and renewable energy storage. At present, the best performing water electrolysis electrodes are platinum (Pt), iridium dioxide (IrO2) and ruthenium dioxide (RuO2). Therefore, it has become a development trend to use non-precious metals instead of precious metals in the field of water electrolysis. However, the use of different types of metal carriers will also have a certain impact on the catalytic activity of the electrode. Therefore, how to develop safe and green carriers with high loading capacity to increase the loading capacity of transition metal borides has become the key to improving the HER and OER catalytic efficiency of the electrode. At present, most of the methods for preparing borides are to use sodium borohydride as a boron source to prepare nanoborides. However, the performance of the electrodes prepared by these methods still cannot meet the requirements of large-scale use, and the prepared nanoelectrodes require binders, etc., which are sprayed or scraped to coat them on the substrate, which not only reduces the utilization rate of the electrode, but also increases the preparation cost of the electrode. In addition, due to the poor bonding between the electrode and the substrate, it is very easy to fall off during the electrolysis of water. How to improve the bonding between the substrate and the electrode and improve the reaction activity of the electrode is an urgent problem to be solved for boride electrodes. Summary of the invention

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

[0005] The above object of the present invention is achieved through the following technical solutions:

[0006] A three-dimensional self-supporting electrode, the electrode comprises a copper foam as a base layer, a copper oxide layer is formed on the surface of the copper foam by electrochemical etching using cyclic voltammetry, and then a cobalt molybdenum boride is in situ grown on the copper foam with the etched copper oxide layer by a hydrothermal method, and finally a cobalt molybdenum boride electrode is obtained by calcining under inert gas protection, wherein the base layer thickness is 300 μm to 1 mm; the copper oxide loading is 0.1 mg / cm 2 -3 mg / cm 2 The loading of cobalt molybdenum boride electrode is 10mg / cm 2 -60 mg / cm 2 .

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

[0008] The preparation method of the above-mentioned three-dimensional structure self-supporting electrode comprises: ultrasonically treating the copper foam in an HCl solution for 30 minutes, and washing it with acetone or anhydrous ethanol and deionized water in turn; electrochemically etching the copper foam by a cyclic circulation method to obtain a copper oxide layer containing copper hydroxide and oxide, which is recorded as CuO / CF; dissolving cobalt salt, molybdenum salt, boric acid and a stabilizer in deionized water, adding the etched copper foam, and performing a hydrothermal reaction to obtain an electrode A; placing the electrode A in a tubular furnace and passing an inert gas for calcination to obtain a three-dimensional structure self-supporting electrode Co. x Mo y B z @CuO / CF.

[0009] The preparation method of the above three-dimensional structured self-supporting electrode comprises the following specific steps:

[0010] S1: The copper foam is pressed on a tablet press at 0.5 MPa-3 MPa for 30-90 seconds, then placed in an HCl solution for ultrasonic treatment for 15-50 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and then placed in a 30-90°C oven to dry the copper foam for later use, thereby obtaining a clean copper foam substrate;

[0011] S2: placing the copper foam substrate obtained in step S1 in an aqueous solution of any one of NaOH and KOH or two or more thereof, electrochemically etching the copper foam substrate using cyclic voltammetry, washing with deionized water after scanning and drying for 12-36 hours to obtain a copper oxide layer containing copper hydroxide and oxide, recorded as CuO / CF;

[0012] S3: Cobalt salt, molybdenum salt, boric acid and stabilizer are mixed and added to deionized water. Under room temperature, magnetic stirring is performed for 15-35 minutes to form a precursor cobalt-molybdenum mixed solution, which is poured into a reactor. Subsequently, the copper oxide layer etched in S2 is placed in the reactor, and the reactor is placed in a vacuum oven for hydrothermal reaction. After the reaction is completed, the reactor is taken out, and after cooling, it is rinsed with acetone or anhydrous ethanol and deionized water in succession, and then placed in a 60°C vacuum oven for drying 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 sum of cobalt and molybdenum is 0.05-5; the concentration of the stabilizer polyvinyl pyrrolidone (PVP) is 0.1M;

[0013] S4: Place the dried electrode A into a tube furnace and introduce inert gas for calcination to obtain a three-dimensional self-supporting electrode Co x Mo y B z @CuO / CF; 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%, z, i.e., the molar percentage of B, is in the range of 5-40%, and the loading amount of the cobalt-molybdenum boride electrode is 10 mg / cm 2 -60mg / cm 2 .

[0014] Furthermore, in step S1, the ultrasonic treatment is preferably performed for 30 minutes and the drying temperature is 60°C.

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

[0016] Furthermore, the concentration of NaOH or KOH in step S2 is 0.1-3M, preferably 0.5-1.5M; the low potential of the cyclic scan in the cyclic voltammetry 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 scan rate is 20 mV s -1 ~50mV s -1 The scanning number is 1-50 times, preferably 2-10 times, the concentration of KOH in the electrolyte is 0.05M-1.7M, preferably 0.2M-1.1M, and the loading amount of the copper oxide layer is 0.1mg / cm 2 -3mg / cm 2 .

[0017] Further, 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, and the preferred concentration is 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, and the preferred concentration is 0.01M-0.5M; the temperature in the hydrothermal reaction is 100°C-240°C, preferably 140°C-180°C, the hydrothermal time is 12-48h, and the preferred hydrothermal time is 12-21h.

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

[0019] The present invention also claims the use of the electrode prepared by the above preparation method as an anode electrode in water electrolysis for hydrogen evolution, oxygen evolution dual-effect electrode, seawater electrolysis dual-effect electrode, and carbon dioxide electroreduction reaction, and is specifically applied to alkaline water electrolysis or fuel cells.

[0020] The present invention firstly uses cyclic voltammetry to electrochemically etch the substrate, grow more defect sites on its surface, and grow copper oxide, and then uses a hydrothermal method to load cobalt molybdenum boride on the surface to prepare a three-dimensional self-supporting electrode. The defect sites and metal oxides on the surface of the foamed copper can not only improve the dispersion of the electrode, 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 the copper oxide species can anchor the cobalt molybdenum boride on the surface of the copper foam, further enhancing the binding force between the boride and the copper foam, thereby improving the stability of the electrode.

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

[0022] The beneficial effects of the present invention compared with the prior art are:

[0023] The invention provides a three-dimensional copper-based cobalt molybdenum boride electrode. The electrode is based on foamed copper and is prepared by a three-step method of cyclic voltammetry / hydrothermal / calcination.

[0024] The present invention grows cobalt molybdenum boride in situ on electrochemically etched copper foam, and the copper oxide layer of copper hydroxide and oxide grown on the etched copper foam can not only improve the dispersion of the electrode, but also improve 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 the copper oxide species can anchor the boride on the surface of the copper foam, further enhancing the binding force between the cobalt molybdenum boride and the copper foam, thereby improving the stability of the electrode. x Mo y B z It has excellent catalytic activity because the foam copper has a loose and porous structure that can provide more active sites after etching; at the same time, the adsorption strength of Co (d7) is low, and the adsorption strength of Mo (d5) is high. The two alloys can be combined with each other to improve the adsorption strength and the synergistic effect of the strong electron combination between the catalytically active nanoparticles, which gives the composite material higher conductivity, optimal water adsorption energy and faster charge transfer ability, thereby enhancing the catalytic activity of the electrode. The present invention is based on the growth of copper oxide by electrochemical etching on the foam copper by cyclic voltammetry, and doping cobalt, molybdenum and boron to prepare a cobalt molybdenum boride electrode. The sea urchin-shaped nanosphere structure composed of nanowires grown in situ by a hydrothermal method has the characteristics of many surface active sites and a large electrochemical reaction area, and can release gas faster. The electrode formed by the combination of two metals, cobalt and molybdenum, and non-metallic boron can greatly improve the catalytic activity and stability of the electrode.

[0025] Since the preparation process uses cyclic voltammetry, hydrothermal method and roasting method, the entire synthesis steps are simple and convenient, and the raw materials are cheap and widely available, so large-scale production can be carried out.

[0026] The three-dimensional copper-based cobalt-molybdenum boride electrode has good catalytic activity (at a current density of 10 mA cm -2 The overpotential for hydrogen evolution is 105 mV at a current density of 100 mA cm -2 The oxygen evolution overpotential under the condition of 437mV is shown, indicating that the three-dimensional copper-based cobalt-molybdenum boride electrode has good performance in electrocatalytic hydrogen evolution and oxygen evolution reaction under alkaline environment. The preparation process of the present invention is relatively simple, the raw materials are cheap and the reserves are abundant, which is conducive to improving the efficiency of hydrogen production by electrolysis of water and promoting the development of hydrogen energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A hydrogen evolution test of the cobalt molybdenum boride electrode prepared in Example 1, i.e., a linear voltammetric curve in a 1M KOH solution;

[0028] Figure 2 The oxygen evolution test of the cobalt molybdenum boride electrode prepared in Example 1 is a linear voltammetric curve in 1M KOH solution;

[0029] Figure 3 Hydrogen evolution tests at different metal ratios conducted on the cobalt-molybdenum boride electrodes prepared in Example 1, Example 2, Example 3, and Example 4, i.e., linear voltammetric curves in 1M KOH solution;

[0030] Figure 4 Oxygen evolution tests at different metal ratios conducted on the cobalt molybdenum boride electrodes prepared in Example 1, Example 2, Example 3, and Example 4, i.e., linear voltammetric curves in 1M KOH solution;

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

[0032] Figure 6 Oxygen evolution tests at different hydrothermal temperatures performed on the cobalt molybdenum boride electrodes prepared in Example 1, Example 5, Example 6, and Example 7, i.e., linear voltammetric curves in 1M KOH solution;

[0033] Figure 7 Hydrogen evolution tests of cobalt molybdenum boride electrodes prepared in Example 1, Example 8, Example 9, and Example 10 at different hydrothermal times, i.e., linear voltammetric curves in 1M KOH solution;

[0034] Figure 8 Oxygen evolution tests of cobalt molybdenum boride electrodes prepared in Example 1, Example 8, Example 9, and Example 10 at different hydrothermal times, i.e., linear voltammetric curves in 1M KOH solution;

[0035] Fig. 9 The hydrogen evolution test of the cobalt molybdenum boride electrode prepared in Example 1 and Comparative Example 1, Comparative Example 2, and Comparative Example 3, i.e., the linear voltammetric curve in 1M KOH solution;

[0036] Fig.10 The oxygen evolution test of the cobalt molybdenum boride electrode prepared in Example 1 and Comparative Example 1, Comparative Example 2, and Comparative Example 3, i.e., the linear voltammetric curve in 1M KOH solution;

[0037] Fig.11 This is the SEM image of the cobalt molybdenum boride electrode prepared in Example 1. DETAILED DESCRIPTION

[0038] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0039] The present invention provides a three-dimensional structured self-supporting electrode and a preparation method and application thereof. The electrode uses foamed copper as a substrate, and a three-dimensional structured cobalt molybdenum boride electrode is prepared by a three-step method of cyclic voltammetry / hydrothermal / calcination. The electrode prepared by the method is applied to alkaline water electrolysis reaction. The cobalt molybdenum boride electrode is a sea urchin-shaped nanosphere structure composed of nanowires, the diameter of the nanosphere is 5μm to 15mm, and the diameter of the nanowire is 20nm to 100nm. The copper oxide layer not only improves the dispersion of the electrode, but also the synergistic effect of the copper species and the cobalt molybdenum boride can improve the activity of the catalyst; the oxygen-containing functional groups of the copper oxide species can anchor the cobalt molybdenum boride on the surface of the substrate, further improving the binding force between the two, thereby improving the stability of the catalyst. The electrode prepared by the present invention does not require additional binders such as current collectors, Nafion, sugar alcohols, etc., which greatly improves the utilization rate of catalysts on the electrode surface; the three-dimensional structure of the electrode can ensure sufficient wetting of the electrolyte, which is conducive to the transmission of reactants and products; the synergistic effect between the components and the three-dimensional layered porous nanostructure of the electrode can accelerate the decomposition of water. The electrode can be used to prepare a double-effect electrode for water electrolysis, a double-effect electrode for seawater electrolysis, and an anode electrode for carbon dioxide electroreduction reaction.

[0040] The present invention is further described below:

[0041] The present invention provides a three-dimensional cobalt molybdenum boride electrode prepared by a three-step method of cyclic voltammetry, hydrothermal treatment and calcination and a preparation method thereof. The method uses etched copper foam as a substrate to enhance the electrochemical effect of the composite material and improve the water electrolysis performance. The preparation method of the cobalt molybdenum boride electrode comprises:

[0042] The foam copper substrate is pressed on a tablet press at 0.5 MPa-3 MPa for 30-90 seconds, then placed in an HCl solution for ultrasonic treatment for 15-50 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and then placed in a 30-90°C oven to dry the foam copper for later use;

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

[0044] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer and add deionized water. Under room temperature, stir magnetically for 15-35 minutes to form a precursor cobalt-molybdenum mixed solution, pour it into the reactor, then put the pretreated copper oxide layer CuO / CF into the reactor, and then put it into a vacuum oven. After the reaction is completed, take out the reactor and cool it, rinse it with acetone or anhydrous ethanol and deionized water, and put it in a 60°C oven for 6-15 hours to obtain electrode A; the preferred concentration of cobalt salt is 0.01M-1.0M, the preferred concentration of molybdenum salt is 0.01M-0.5M, the preferred temperature of the hydrothermal reaction is 140°C~180°C, and the preferred hydrothermal time is 12-21h;

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

[0046] Example 1

[0047] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0048] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0049] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0050] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0051] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0052] Example 2

[0053] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0054] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0055] Mix 0.03M cobalt salt, 0.07M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0056] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0057] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co3Mo7B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0058] Example 3

[0059] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0060] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0061] Mix 0.07M cobalt salt, 0.03M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0062] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0063] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co7Mo3B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0064] Example 4

[0065] The copper foam was pressed on a tablet press at 1 MPa for 4 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0066] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0067] Mix 0.09M cobalt salt, 0.01M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0068] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0069] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co9Mo1B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0070] Example 5

[0071] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0072] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0073] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0074] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0075] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0076] Example 6

[0077] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0078] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0079] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0080] The precursor cobalt-molybdenum mixed solution and the 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 taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0081] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0082] Example 7

[0083] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0084] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0085] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0086] The precursor cobalt-molybdenum mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0087] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z@CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0088] Example 8

[0089] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0090] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0091] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0092] The precursor cobalt-molybdenum mixed solution and the 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 taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0093] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0094] Example 9

[0095] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0096] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0097] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0098] The precursor cobalt-molybdenum mixed solution and the 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 taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0099] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0100] Example 10

[0101] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0102] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0103] Mix 0.05M cobalt salt, 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor cobalt-molybdenum mixed solution:

[0104] The precursor cobalt-molybdenum mixed solution and the 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 taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0105] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Co5Mo5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0106] Comparative Example 1

[0107] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0108] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0109] Mix 0.05M cobalt salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor mixed solution:

[0110] The precursor mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0111] The precursor A was calcined under nitrogen protection at 300°C to obtain electrode Co5B z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0112] Comparative Example 2

[0113] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0114] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0115] Mix 0.05M molybdenum salt, 0.2M boric acid and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor mixed solution:

[0116] The precursor mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0117] The precursor A was calcined under nitrogen protection at 300°C to obtain the electrode Mo5B. z @CuO / CF, z means the molar content of B ranges from 5 to 40%;

[0118] Comparative Example 3

[0119] The copper foam was pressed on a tablet press at 1 MPa for 45 seconds, then ultrasonically treated in a 1M HCl solution for 30 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and dried for later use;

[0120] The treated copper foam was placed in a 0.5M NaOH aqueous solution and subjected to CV cycle scanning, with a voltage range of -2.0V to 0.2V and 10 scanning cycles. After the scanning, it was rinsed with deionized water or other solvents and then dried for 24 hours; a copper oxide layer containing copper hydroxide and oxide was grown, which was recorded as CuO / CF;

[0121] Mix 0.05M cobalt salt, 0.05M molybdenum salt and 0.1M stabilizer polyvinyl pyrrolidone (PVP) and add deionized water, and stir for 30 minutes to form a precursor mixed solution:

[0122] The precursor mixed solution and the 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 was completed, the reactor was taken out for cooling, and the foamed copper was rinsed with acetone or anhydrous ethanol and deionized water, and placed in a 60°C oven for 10 hours to obtain precursor A:

[0123] The precursor A is calcined under nitrogen protection at 300°C to obtain an electrode Co5Mo5@CuO / CF, wherein the molar content of B is in the range of 5 to 40%.

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

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

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

[0127] from Figure 6 It can be seen that the overpotential of the cobalt molybdenum boride electrode at a hydrothermal temperature of 140 °C is significantly lower than that of the electrodes prepared under other hydrothermal temperature conditions; at a current density of 100 mA cm -2 When the hydrothermal temperature is 140℃, the overpotential of oxygen evolution is only 437mV, 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 oxygen evolution reaction in water electrolysis when the hydrothermal temperature is 140℃.

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

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

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

[0131] from Fig.10 It can be seen that under the same conditions, the overpotential of the cobalt molybdenum boride electrode is significantly lower than that of electrodes made of other metals; at a current density of 100 mA cm -2When the overpotential of oxygen evolution is only 437 mV, it is better than other electrodes, thus proving that the cobalt molybdenum boride electrode has excellent catalytic activity for the oxygen evolution reaction in water electrolysis.

[0132] A scanning electron microscope (model: Quanta 400FEG, manufactured by FEI Company of the United States) was used to take a SEM image of the three-dimensional copper-based doped cobalt-molybdenum metal boride electrode prepared in Example 1. Fig. 9 As shown. Fig. 9 It can be seen that the obtained three-dimensional copper-based doped cobalt-molybdenum metal boride electrode is composed of urchin-shaped nanospheres of cobalt-molybdenum boride nanowires.

[0133] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A three-dimensional self-supporting electrode, characterized in that: The electrode includes a copper foam as a base layer, electrochemically etching using cyclic voltammetry to generate a layer of copper oxide on its surface, then in-situ growing cobalt molybdenum boride on the copper foam with the etched copper oxide layer by a hydrothermal method, and finally calcining under inert gas protection to obtain a cobalt molybdenum boride electrode; the cobalt molybdenum boride electrode is a sea urchin-shaped nanosphere structure composed of nanowires.

2. A three-dimensional self-supporting electrode as claimed in claim 1, characterized in that: The thickness of the substrate layer is 300 μm to 1 mm; the copper oxide loading is 0.1 mg / cm 2 -3 mg / cm 2 The loading of cobalt molybdenum boride electrode is 10mg / cm 2 -60mg / cm 2 .

3. A three-dimensional self-supporting electrode as claimed in claim 1, characterized in that: The cobalt molybdenum boride electrode is a sea urchin-shaped nanosphere structure composed of nanowires, the diameter of the nanosphere is 5 μm to 15 mm, and the diameter of the nanowire is 20 nm to 100 nm.

4. A method for preparing a three-dimensional self-supporting electrode according to any one of claims 1 to 3, characterized in that: include: The copper foam was ultrasonicated in HCl solution for 30 min, and then rinsed with acetone or anhydrous ethanol and deionized water; The copper foam is electrochemically etched by a cyclic method to obtain a copper oxide layer containing copper hydroxide and oxide, which is recorded as CuO / CF. Cobalt salt, molybdenum salt, boric acid and stabilizer are dissolved in deionized water, and the etched copper foam is added to perform a hydrothermal reaction to obtain electrode A. Electrode A is placed in a tubular furnace and calcined by passing inert gas to obtain a three-dimensional structured self-supporting electrode Co. x Mo y B z @CuO / CF.

5. The preparation method according to claim 4, characterized in that: The specific steps are as follows: S1: The copper foam is pressed on a tablet press at 0.5 MPa-3 MPa for 30-90 seconds, then placed in an HCl solution for ultrasonic treatment for 15-50 minutes, rinsed with acetone or anhydrous ethanol and deionized water, and then placed in a 30-90°C oven to dry the copper foam for later use, thereby obtaining a clean copper foam substrate; S2: placing the copper foam substrate obtained in step S1 in an aqueous solution of any one of NaOH and KOH or two or more thereof, electrochemically etching the copper foam substrate using cyclic voltammetry, washing with deionized water after scanning and drying for 12-36 hours to obtain a copper oxide layer containing copper hydroxide and oxide, recorded as CuO / CF; S3: Cobalt salt, molybdenum salt, boric acid and stabilizer are mixed and added to deionized water. Under room temperature, magnetic stirring is performed for 15-35 minutes to form a precursor cobalt-molybdenum mixed solution, which is poured into a reactor. Subsequently, the copper oxide layer etched in S2 is placed in the reactor, and the reactor is placed in a vacuum oven for hydrothermal reaction. After the reaction is completed, the reactor is taken out, and after cooling, it is rinsed with acetone or anhydrous ethanol and deionized water, and then placed in a 60°C vacuum oven for drying 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 sum of cobalt and molybdenum is 0.05-5; the concentration of the stabilizer polyvinyl pyrrolidone is 0.1M; S4: Place the dried electrode A into a tube furnace and introduce inert gas for calcination to obtain a three-dimensional self-supporting electrode Co x Mo y B z @CuO / CF; 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%, z, i.e., the molar percentage of B, is in the range of 5-40%, and the loading amount of the cobalt-molybdenum boride electrode is 10 mg / cm 2 -60 mg / cm 2 .

6. The preparation method according to claim 5, characterized in that: The concentration of NaOH or KOH in step S2 is 0.1-3M; the low potential of the cyclic scan in the cyclic voltammetry is -3.0V to -1.2V, the high potential is 0.2V to 1.2V, and the scan rate is 1mVs -1 ~100mV s -1 The scanning times are 1-50 times, the concentration of KOH in the electrolyte is 0.05M-1.7M, and the loading of the copper oxide layer is 0.1mg / cm 2 -3 mg / cm 2 .

7. The preparation method according to claim 5, 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 0.005M-2.0M.

8. The preparation method according to claim 5, 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 0.005M-1.0M; the temperature in the hydrothermal reaction is 100°C-240°C, and the hydrothermal time is 12-48h.

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

10. Use of the electrode prepared by the method according to any one of claims 5 to 9 as an anode electrode in water electrolysis for hydrogen evolution, oxygen evolution double-effect electrode, seawater electrolysis double-effect electrode, and carbon dioxide electroreduction reaction.

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