Preparation method and application of electro-catalytic water decomposition electrode with 3D structure

Abstract

The invention discloses a preparation method and application of an electrocatalytic water decomposition electrode with a 3D structure, and the method comprises the following steps: S1, taking foamy copper as a raw material, and preparing a foamy copper / Cu nanowire substrate with the 3D structure through a chemical oxidation method, a calcination method and an electroreduction method in sequence; and S2, placing the foamy copper / Cu nanowire substrate prepared in the step S1 in a mixed electrolyte containing transition metal M < 2 + > salt and rare earth Ln < 3 + > salt through an electro-deposition method, and depositing lamellar M / Ln (OH) 3 on the surface of the foamy copper / Cu nanowire array so as to obtain the foamy copper / Cu nanowire (at) M / Ln (OH) 3 electrode material with a 3D structure. The method is green, environment-friendly, mild and controllable; the prepared catalytic material has a special structure: the catalyst can be directly used as a water decomposition electrode, has double functions of producing hydrogen and oxygen, and can realize efficient complete water decomposition.

Description

Technical Field

[0001] The present invention belongs to the field of new energy materials, and particularly relates to a preparation method and application of a 3D structure electrocatalytic water splitting electrode. Background Art

[0002] With the increasingly serious global energy crisis and environmental pollution problems, it is urgent to develop green and efficient sustainable clean energy. Hydrogen is a clean and efficient energy carrier, and electrocatalytic water splitting is an important way to produce hydrogen industrially. However, water splitting requires overcoming the energy barrier of water decomposition, consuming a large amount of electric energy, which greatly increases the cost of hydrogen production. The use of co-catalysts can greatly reduce the energy barrier of water decomposition and improve the efficiency of catalytic water splitting to produce hydrogen. Currently, the most effective co-catalysts are platinum group noble metals, but their expensive prices greatly limit their large-scale application and increase the cost of hydrogen production. Therefore, the development of efficient and inexpensive non-noble metal co-catalysts has become a research hotspot.

[0003] Transition metals Ni, Co and their compounds have attracted much attention due to their advantages such as rich crust content, easy preparation, high catalytic activity and good stability. However, single metal Ni or Co nanoparticles are prone to agglomeration, resulting in a sharp reduction in active sites. The binding energy between the intrinsic metal Ni / Co and H atoms is not conducive to the adsorption and desorption equilibrium of H atoms. Therefore, the hydrogen evolution activity still has a certain gap with Pt. And under alkaline conditions, the proton concentration is low, and the H-OH bond needs to be broken, and the Volmer reaction kinetics is slow. Rare earth hydroxides are a class of compounds with a lamellar structure, and the unique electronic properties of rare earth elements: large atomic radius and multiple outer electrons (5s, 5p and 4f electrons) can effectively regulate the electronic structure of metal Ni; rare earth hydroxides can also preferentially adsorb the reactant H2O under alkaline conditions, promote the dissociation of water, and improve the hydrogen evolution kinetics of electrolytic water. Loading metal Ni / Co on the lamellar rare earth hydroxide can, on the one hand, greatly improve the dispersion and active sites of metal Ni / Co, and on the other hand, rare earth hydroxide can effectively regulate the electronic structure of metal Ni / Co and promote the Volmer reaction to improve the reaction kinetics.

[0004] To achieve efficient electrocatalytic hydrogen production and oxygen production, the structure and conductivity of the electrode are important factors. The three-dimensional stereoscopic structure can increase the specific surface area of the catalyst and rich active sites, and improve the mass transfer and diffusion rate. Commercially available copper foam has a self-supporting three-dimensional structure. Copper itself has excellent conductivity and low price, making it a good substrate material for electrocatalysts. How to further increase the specific surface area of copper foam and organically and efficiently combine the transition metal / Ln(OH)3 catalytic material with the substrate material to improve the hydrogen production catalytic performance of the electrocatalytic material to achieve industrial low-cost hydrogen production (by-product oxygen production) has become a technical problem to be solved urgently. Summary of the Invention

[0005] Aiming at the deficiencies and problems in the prior art, the present invention aims to provide a preparation method and application of a 3D structure electrocatalytic water splitting electrode.

[0006] The technical solution adopted by the present invention is as follows:

[0007] In the first aspect of the present invention, a preparation method of a 3D structure electrocatalytic water splitting electrode is provided, and the method includes the following steps:

[0008] S1. Using copper foam as a raw material, a copper foam / Cu nanowire substrate with a 3D structure is prepared through a chemical oxidation method - calcination method - electroreduction method in sequence.

[0009] S2. Through the electrodeposition method, the copper foam / Cu nanowire substrate prepared in step S1 is placed in a mixed electrolyte containing a transition metal M 2+ salt and a rare earth Ln 3+ salt, and a layer of M / Ln(OH)3 is deposited on the surface of the copper foam / Cu nanowire substrate, thereby obtaining a copper foam / Cu nanowire@M / Ln(OH)3 electrode material with a 3D structure.

[0010] Further, step S1 specifically includes:

[0011] S11. Through the chemical oxidation method, using ammonium persulfate as an oxidant, copper foam is placed in a mixed solution of ammonium persulfate and sodium hydroxide, and copper foam is fully oxidized to in-situ grow Cu(OH)2 nanowires.

[0012] S12. Through the calcination method, the Cu(OH)2 nanowires prepared in step S11 are placed in a muffle furnace and calcined at 180°C - 200°C for 1h - 2h to generate CuO nanowires.

[0013] S13. Through the electroreduction method, by the constant voltage method for 10min - 40min, the CuO nanowires prepared in step S12 are reduced to Cu nanowires, obtaining a copper foam / Cu nanowire substrate with a 3D structure.

[0014] Further, in step S2, M is any one of Ni and Co metal elements, the transition metal M 2+ salt is any one of nitrate, chloride, and acetate, Ln is any one or more than two rare earth elements among La, Ce, Pr, Nd, and Yb, and the rare earth Ln 3+ salt is a soluble nitrate; the concentration of M 2+ in the electrolyte is 0.1 - 1.0 mol L -1 , and the molar ratio of Ln 3+ / M 2+ is 0.5 - 20%.

[0015] Further, in the electrodeposition method in step S2, constant voltage electrodeposition can be used, and the constant voltage is -1.0 to -1.4 V (vs. Ag / AgCl), and the deposition time is 100 s to 500 s.

[0016] The second aspect of the present invention provides a 3D structure electrocatalytic water splitting electrode prepared by the above method.

[0017] The third aspect of the present invention provides the application of the above 3D structure electrocatalytic water splitting electrode in the electrocatalytic water splitting reaction.

[0018] The present invention has the following advantages:

[0019] 1. The present invention uses a one-step electrodeposition method to prepare a lamellar transition metal M / Ln(OH)3 catalyst with a core-shell structure on a 3D structure of copper foam / copper nanowire substrate. In this catalyst, transition metal nanoparticles are highly dispersed on the rare earth hydroxide lamellae, and there are a large number of defects and vacancies at the heterogeneous interface between the two, providing abundant active sites. This catalyst can be directly used as a water splitting electrode, has the properties of both hydrogen production and oxygen production, and can achieve efficient overall water splitting.

[0020] 2. At a current density of 100 mA cm -2 , the hydrogen production overpotential of the prepared Ni / Pr(OH)3-7.5% catalyst is 266 mV, and the oxygen production overpotential is 220 mV; for the overall water splitting performance, at current densities of 50 and 100 mA cm -2 , the voltages are 1.62 and 1.77 V respectively, and it has extremely high stability. The Ni / Ce(OH)3 and Ni / La(OH)3 prepared by the same method both have higher hydrogen production and oxygen production performance than metallic Ni, reflecting the universality and controllability of this method. Description of the Drawings

[0021] Figure 1 SEM image of the Ni / Pr(OH)3 catalyst prepared in Example 3;

[0022] Figure 2 TEM and HRTEM images of the Ni / Pr(OH)3 catalyst prepared in Example 3;

[0023] Figure 3 Hydrogen production LSV graph of the Ni / Pr(OH)3 catalysts prepared in Examples 1-4;

[0024] Figure 4 Oxygen production LSV graph of the Ni / Pr(OH)3 catalysts prepared in Examples 1-4;

[0025] Figure 5LSV graph of overall water splitting for the Ni / Pr(OH)3-7.5% catalyst prepared in Example 3;

[0026] Figure 6 LSV graph of hydrogen production for the Ni / Ce(OH)3 catalysts prepared in Examples 5-8;

[0027] Figure 7 LSV graph of oxygen production for the Ni / Ce(OH)3 catalysts prepared in Examples 5-8;

[0028] Figure 8 LSV graph of overall water splitting for the Ni / Ce(OH)3-0.5% catalyst prepared in Example 6;

[0029] Figure 9 LSV of oxygen production for the Ni / La(OH)3 catalyst prepared in Example 9. Detailed implementation manners

[0030] The present invention provides a preparation method and application of a 3D structure electrocatalytic water splitting electrode.

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. The present invention will be further described in conjunction with the embodiments without departing from the spirit or basic characteristics of the present invention.

[0032] The technical solutions adopted by the present invention are as follows:

[0033] In the first aspect of the present invention, a preparation method of a 3D structure electrocatalytic water splitting electrode is provided, and the method includes the following steps:

[0034] S1. Using copper foam as a raw material, a foam copper / Cu nanowire substrate (foam copper / copper nanowire array substrate) with a 3D structure is prepared through a chemical oxidation method - calcination method - electroreduction method in sequence;

[0035] S2. Through an electrodeposition method, the foam copper / Cu nanowire substrate prepared in step S1 is placed in a mixed electrolyte containing a transition metal M 2+ salt and a rare earth Ln 3+ salt, and a layer of M / Ln(OH)3 is deposited on the surface of the foam copper / Cu nanowire substrate to obtain a 3D structure foam copper / Cu nanowire@M / Ln(OH)3 electrode material.

[0036] Further, step S1 specifically includes:

[0037] S11. By the chemical oxidation method, using ammonium persulfate as the oxidant, place the copper foam in a mixed solution of ammonium persulfate and sodium hydroxide. Among them, the mixed solution is a solution of 2.28 g (NH4)2S2O8 + 8.00 g NaOH, the volume of the mixed solution is 70 mL to 90 mL, preferably 80 mL, the number of copper foam is 1 to 4 strips, the size of the copper foam is 1 to 3 cm × 1 to 3 cm, and fully oxidize the copper foam to in-situ grow Cu(OH)2 nanowires;

[0038] S12. By the calcination method, put the Cu(OH)2 nanowires prepared in step S11 into a muffle furnace and calcine at 180 °C to 200 °C for 1 h - 2 h to generate CuO nanowires;

[0039] S13. By the electroreduction method, place the CuO nanowires prepared in step S12 in a solution of KHCO3, and reduce them by the constant voltage method for 10 min to 40 min. The constant voltage is set to -0.9 to -1.5 V (vs. Hg / HgO), and the CuO nanowires prepared in step S12 are reduced to Cu nanowires to obtain a 3D-structured copper foam / Cu nanowire substrate.

[0040] Further, in the step S2, M is any one of the metal elements Ni and Co, the transition metal M 2+ The salt is any one of nitrates, chlorides, and acetates, Ln is any one or more of the rare earth elements La, Ce, Pr, Nd, Yb, the rare earth Ln 3+ The salt is a soluble nitrate; M in the electrolyte 2+ The concentration is 0.1 to 1.0 mol L -1 And the molar ratio of Ln 3+ / M 2+ Is 0.5 to 20%, and the pH of the electrolyte is adjusted to 1.0 to 5.0.

[0041] Further, for the electrodeposition method in the step S2, constant voltage electrodeposition can be used, the constant voltage is -1.0 to -1.4 V (vs. Ag / AgCl), and the deposition time is 100 s to 500 s.

[0042] The second aspect of the present invention provides a 3D-structured electrocatalytic water splitting electrode prepared by the above method.

[0043] The third aspect of the present invention provides the application of the above 3D-structured electrocatalytic water splitting electrode in the electrocatalytic water splitting reaction. Specifically: under alkaline conditions, it can be used as a hydrogen production working electrode or an oxygen production working electrode to decompose water for efficient hydrogen production or oxygen production, and at the same time can be used as a hydrogen production and oxygen production electrode (bifunctional electrode) for overall water splitting to produce hydrogen and oxygen.

[0044] Example 1

[0045] A method for preparing a 3D bifunctional electrocatalytic water splitting electrode material is specifically carried out according to the following steps:

[0046] Step 1: Wash a piece of 1×2 cm 2 The copper (CF) foam was immersed in a mixed solution containing 2.28g (NH4)2S2O8 and 8.00g NaOH (80mL) and placed in a refrigerator at 4°C for 2 hours to fully oxidize, producing blue Cu(OH)2 nanowires. The nanowires were then rinsed with deionized water and dried at 80°C. The Cu(OH)2 nanowires were then annealed in a muffle furnace at 200°C for 1 hour to produce CuO nanowires. Finally, the CuO nanowires were electroreduced in a KHCO3 solution at a voltage of -1.02V (vs. Hg / HgO) for 30 minutes to convert the CuO nanowires into Cu nanowires, resulting in a copper foam / copper nanowire substrate.

[0047] Step 2: Place the foam copper / copper nanowire substrate prepared in step 1 into a mixture of NiCl2 and Pr(NO3)3 electrolyte. 2+ The concentration is 0.15 mol L -1 ,Pr 3+ / Ni 2+ The molar ratio is 2.5%, the pH of the solution is adjusted to 3.0 with dilute hydrochloric acid, and nitrogen (N2) is blown into the electrolyte solution for 25 minutes to remove oxygen in the solution. A voltage of -1.2 V (vs Ag / AgCl) is applied and electrodeposition is performed for 300 seconds. A 3D structured foam copper / copper nanowire@Ni / Pr(OH)3 catalytic electrode is obtained by one-step electrodeposition, which is recorded as Ni / Pr(OH)3-2.5%.

[0048] Example 2

[0049] Step 1: Same as step 1 in Example 1

[0050] Step 2: Place the foam copper / copper nanowire substrate prepared in step 1 into a mixture of NiCl2 and Pr(NO3)3 electrolyte. 2+ The concentration is 0.15 mol L -1 ,Pr 3+ / Ni 2+ The molar ratio was 5.0%, the pH of the solution was adjusted to 3.0 with dilute hydrochloric acid, and N2 was blown into the electrolyte solution for 25 minutes to remove oxygen in the solution. A voltage of -1.2 V (vs. Ag / AgCl) was applied, and the electrodeposition was carried out for 300 seconds. A 3D structured foam copper / copper nanowire@Ni / Pr(OH)3 catalytic electrode was obtained by one-step electrodeposition, which was recorded as Ni / Pr(OH)3-5.0%.

[0051] Example 3

[0052] Step 1: The same as Step 1 in Example 1

[0053] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Pr(NO3)3. The concentration of Ni 2+ is 0.15 mol / L -1 , and the Pr 3+ / Ni 2+ molar ratio is 7.5%. The pH of the solution is adjusted to 3.0 with dilute hydrochloric acid, and N2 is bubbled into the electrolyte solution for 25 minutes to remove the oxygen in the solution. Then, a voltage of -1.2 V (vs. Ag / AgCl) is applied, and electrodeposition is carried out for 300 s to obtain a 3D-structured copper foam / copper nanowire@Ni / Pr(OH)3 catalytic electrode by one-step electrodeposition, denoted as Ni / Pr(OH)3-7.5%.

[0054] The electrode obtained in Example 3 was observed by scanning electron microscopy. Figure 1 As shown, a large number of nanowire arrays grow on the copper foam substrate, and there are a large number of voids between the catalyst arrays, which is beneficial to the diffusion of mass transfer. The TEM and HRTEM images ( Figure 2 ) clearly show that the prepared catalyst has an obvious core-shell structure. The inner Cu nanowires can efficiently transport electrons, and the outer Ni / Pr(OH)3 exhibits a lamellar structure. Fine Ni nanoparticles are highly dispersed in the Pr(OH)3 lamellae, and there are a large number of defects and vacancies at the heterointerface between the two, providing rich active sites for the catalyst.

[0055] Example 4

[0056] Step 1: The same as Step 1 in Example 1

[0057] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Pr(NO3)3. The concentration of Ni 2+ is 0.15 mol / L -1 , and the Pr 3+ / Ni 2+ molar ratio is 10.0%. The pH of the solution is adjusted to 3.0 with dilute hydrochloric acid, and N2 is bubbled into the electrolyte solution for 25 minutes to remove the oxygen in the solution. Then, a voltage of -1.2 V (vs. Ag / AgCl) is applied, and electrodeposition is carried out for 300 s to obtain a 3D-structured copper foam / copper nanowire@Ni / Pr(OH)3 catalytic electrode by one-step electrodeposition, denoted as Ni / Pr(OH)3-10.0%.

[0058] Example 5

[0059] Step 1: The same as Step 1 in Example 1

[0060] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Ce(NO3)3, where the concentration of Ni 2+ is 0.15 mol / L -1 , and the Ce 3+ / Ni 2+ molar ratio is 0.25%. Adjust the pH of the solution to 3.0 with dilute hydrochloric acid, purge N2 into the electrolyte solution for 25 minutes to remove the oxygen in the solution, apply a voltage of -1.2 V (vs. Ag / AgCl), and perform electrodeposition for 300 s to obtain a 3D-structured copper foam / copper nanowire@Ni / Ce(OH)3 catalytic electrode by one-step electrodeposition, denoted as Ni / Ce(OH)3-0.25%.

[0061] Example 6

[0062] Step 1: The same as Step 1 of Example 1

[0063] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Ce(NO3)3, where the concentration of Ni 2+ is 0.15 mol / L -1 , and the Ce 3+ / Ni 2+ molar ratio is 0.5%. Adjust the pH of the solution to 3.0 with dilute hydrochloric acid, purge N2 into the electrolyte solution for 25 minutes to remove the oxygen in the solution, apply a voltage of -1.2 V (vs. Ag / AgCl), and perform electrodeposition for 300 s to obtain a 3D-structured copper foam / copper nanowire@Ni / Ce(OH)3 catalytic electrode by one-step electrodeposition, denoted as Ni / Ce(OH)3-0.5%.

[0064] Example 7

[0065] Step 1: The same as Step 1 of Example 1

[0066] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Ce(NO3)3, where the concentration of Ni 2+ is 0.15 mol / L -1 , and the Ce 3+ / Ni 2+ molar ratio is 1.0%. Adjust the pH of the solution to 3.0 with dilute hydrochloric acid, purge N2 into the electrolyte solution for 25 minutes to remove the oxygen in the solution, apply a voltage of -1.2 V (vs. Ag / AgCl), and perform electrodeposition for 300 s to obtain a 3D-structured copper foam / copper nanowire@Ni / Ce(OH)3 catalytic electrode by one-step electrodeposition, denoted as Ni / Ce(OH)3-1.0%.

[0067] Example 8

[0068] Step 1: The same as Step 1 of Example 1

[0069] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and Ce(NO3)3. The Ni 2+ concentration is 0.15 mol L -1 , and the Ce 3+ / Ni 2+ molar ratio is 2.0%. The pH of the solution is adjusted to 3.0 with dilute hydrochloric acid. Nitrogen is bubbled into the electrolyte solution for 25 minutes to remove the oxygen in the solution, and a voltage of -1.2 V (vs. Ag / AgCl) is applied. Electrodeposition is carried out for 300 s, and a 3D-structured copper foam / copper nanowire@Ni / Ce(OH)3 catalytic electrode is obtained by one-step electrodeposition, denoted as Ni / Ce(OH)3-2.0%.

[0070] Example 9

[0071] Step 1: The same as Step 1 of Example 1

[0072] Step 2: Place the copper foam / copper nanowire substrate prepared in Step 1 into a mixed solution of electrolyte NiCl2 and La(NO3)3. The Ni 2+ concentration is 0.15 mol L -1 , and the La 3+ / Ni 2+ molar ratio is 1.0%. The pH of the solution is adjusted to 3.0 with dilute hydrochloric acid. Nitrogen is bubbled into the electrolyte solution for 25 minutes to remove the oxygen in the solution, and a voltage of -1.2 V (vs. Ag / AgCl) is applied. Electrodeposition is carried out for 300 s, and a 3D-structured copper foam / copper nanowire@Ni / Ce(OH)3 catalytic electrode is obtained by one-step electrodeposition, denoted as Ni / La(OH)3-1.0%.

[0073] Application Example 1

[0074] Take the catalysts Ni / Pr(OH)3 obtained in Examples 1-4 as the working electrode for hydrogen production, and conduct LSV hydrogen production tests in 1.0 M KOH solution ( Figure 3 ). The Ni / Pr(OH)3 electrode has a lower hydrogen production overpotential than the Ni electrode. The electrode material Ni / Pr(OH)3-7.5% obtained in Example 3 has the minimum hydrogen production overpotential at current densities of 10 and 100 mA cm -2 , which are 87 and 266 mV respectively.

[0075] Application Example 2

[0076] Take the catalysts Ni / Pr(OH)3 obtained in Examples 1-4 as the working electrode for oxygen production, and conduct LSV oxygen production tests in 1.0 M KOH solution (Figure 4 ) The Ni / Pr(OH)3 electrode has a lower oxygen evolution overpotential than the Ni electrode. The electrode Ni / Pr(OH)3-7.5% obtained in Example 3 -2 has the minimum oxygen evolution overpotential of 220 mV at a current density of 100 mA cm

[0077] Application Example 3

[0078] Using the catalyst Ni / Pr(OH)3-7.5% obtained in Example 3 as a bifunctional catalytic electrode, in 1.0 M KOH solution, a LSV test for overall water splitting was carried out ( Figure 5 ). At current densities of 50 and 100 mA cm -2 , the overall water splitting voltages are 1.62 and 1.77 V respectively, which are higher than the overall water splitting performance of an electrolytic cell composed of commercial Pt and RuO2, fully demonstrating the superiority of the electrode prepared by this method: this 3D structure provides rich active sites and mass transfer diffusion channels for the catalyst; the inner core of Cu nanowires provides a guarantee for electron transport, and the outer shell of lamellar Ni / Pr(OH)3 binary components provides rich OH - adsorption and H adsorption sites, synergistically promoting the water splitting performance; and the addition of rare earth elements improves the dispersion of metallic Ni, changes the electronic structure of Ni, constructs a large number of heterointerfaces and defects, greatly improving the hydrogen production, oxygen production and bifunctional overall water splitting performance under alkaline conditions, and is expected to achieve efficient industrial hydrogen production and oxygen production.

[0079] Application Example 4

[0080] Using the catalysts Ni / Ce(OH)3 obtained in Examples 5-8 as the working electrode for hydrogen production, in 1.0 M KOH solution, a LSV hydrogen production test was carried out ( Figure 6 ). The Ni / Ce(OH)3 electrode has a lower hydrogen evolution overpotential than the Ni electrode. The Ni / Ce(OH)3-0.50% catalytic electrode obtained in Example 6 has a hydrogen evolution overpotential of 286 mV at a current density of 100 mA cm -2 .

[0081] Application Example 5

[0082] Using the catalysts Ni / Ce(OH)3 obtained in Examples 5-8 as the working electrode for oxygen production, in 1.0 M KOH solution, a LSV oxygen production test was carried out ( Figure 7 ). The Ni / Ce(OH)3 electrode has a lower oxygen evolution overpotential than the Ni electrode. The Ni / Ce(OH)3-0.50% catalytic electrode obtained in Example 6 has an overpotential of 200 mV at an oxygen evolution current of 100 mA cm -2 .

[0083] Application Example 6

[0084] Using the catalyst Ni / Ce(OH)3-0.5% obtained in Example 6 as a bifunctional catalytic electrode, in 1.0 M KOH solution, perform a full water splitting LSV test ( Figure 8 ). At current densities of 50 and 100 mA cm -2 , the full water splitting voltages are 1.70 and 1.87 V vs RHE respectively, which are higher than the full water splitting performance of an electrolytic cell composed of commercial Pt and RuO2 (2.06 V), fully demonstrating the superiority of the electrode prepared by this method.

[0085] Application Example 7

[0086] Using the catalyst Ni / La(OH)3-1.0% obtained in Example 9 as the working electrode for oxygen evolution, in 1.0 M KOH solution, perform an LSV oxygen evolution test ( Figure 9 ), the Ni / La(OH)3-1.0% electrode has a lower oxygen evolution overpotential than the Ni electrode. The Ni / La(OH)3-1.0% catalytic electrode obtained in Example 9 has an oxygen evolution overpotential of 250 mV at a current density of 100 mA cm -2 .

[0087] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or change without departing from the present invention shall be included within the scope of the technical solution of the present invention.

Claims

1. A preparation method of an electrode for electrocatalytic water splitting with a 3D structure, characterized in that The method includes the following steps: S1. Using copper foam as the raw material, a copper foam / Cu nanowire substrate with a 3D structure is prepared by sequentially passing through a chemical oxidation method - calcination method - electroreduction method; S2. By means of electrodeposition, place the copper foam / Cu nanowire substrate prepared in step S1 in a mixed electrolyte containing transition metal M 2+ salt and rare earth Ln 3+ salt, and deposit a lamellar M / Ln(OH)3 on the surface of the copper foam / Cu nanowire substrate, thereby obtaining a copper foam / Cu nanowire@M / Ln(OH)3 electrode material with a 3D structure.

2. The preparation method of a 3D-structured electrocatalytic water splitting electrode according to claim 1, wherein, The specific steps of step S1 include: S11. By the chemical oxidation method, using ammonium persulfate as the oxidant, placing the copper foam in a mixed solution of ammonium persulfate and sodium hydroxide, and fully oxidizing the copper foam to in-situ grow Cu(OH)2 nanowires; S12. By the calcination method, putting the Cu(OH)2 nanowires obtained in step S11 into a muffle furnace and calcining at 180°C to 200°C for 1 h - 2 h to generate CuO nanowires; S13. By the electroreduction method, reducing for 10 min to 40 min by the constant voltage method, and reducing the CuO nanowires obtained in step S12 to Cu nanowires to obtain a copper foam / Cu nanowire substrate with a 3D structure.

3. The preparation method of a 3D-structured electrocatalytic water splitting electrode according to claim 1, characterized in that, In the step S2, M is any one of Ni and Co, and the transition metal M 2+ salt is any one of nitrate, chloride, and acetate, Ln is any one or more than two rare earth elements among La, Ce, Pr, Nd, and Yb, and the rare earth Ln 3+ salt is soluble nitrate; in the electrolyte, M 2+ concentration is 0.1 to 1.0 mol / L -1 , while the molar ratio of Ln 3+ / M 2+ is 0.5 to 20%.

4. The preparation method of a 3D-structured electrocatalytic water splitting electrode according to claim 1, characterized in that, In the electrodeposition method in step S2, constant voltage electrodeposition is used, the constant voltage is -1.0 to -1.4 V (vs. Ag / AgCl), and the deposition time is 100 s to 500 s.

5. A 3D structure electrocatalytic water splitting electrode prepared by the preparation method according to any one of claims 1 to 4.

6. Application of a 3D structure electrocatalytic water splitting electrode prepared by the preparation method according to any one of claims 1 to 4 in an electrocatalytic water splitting reaction.

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