High-stability ni-cu@nicofe oxygen evolution electrocatalyst and preparation method thereof

Abstract

The application discloses a high-stability NiCu@NiCoFe oxygen evolution electrocatalyst, which comprises a NiCu substrate and a NiCoFe active layer loaded on the NiCu substrate by an electrodeposition method; the NiCu substrate is in a three-dimensional network framework structure, and a plurality of nanopores are distributed on the framework; and the NiCoFe active layer is composed of NiCoFe nanoparticles deposited on the framework and the nanopore walls of the framework. The application further discloses a preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst. 2 When the electrocatalyst is used as a hydrolysis oxygen production catalyst, the oxygen evolution overpotential on the surface of the NiCu@NiCoFe electrocatalyst can be as low as 239-278 mV, and the electrocatalyst has good catalytic activity.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-stability NiCu@NiCoFe oxygen evolution electrocatalyst, and also relates to a preparation method of the electrocatalyst. BACKGROUND

[0002] Since the 1970s, hydrogen energy has been considered as one of the cleanest and most promising energy sources. Unlike oil and natural gas stored on the earth, hydrogen energy does not exist naturally, and therefore needs to be produced from other resources, and developing an efficient hydrogen production method is a key step for the development of a hydrogen energy economy.

[0003] There are many ways to obtain hydrogen energy, and the water electrolysis technology driven by renewable energy is an environmentally friendly technology for producing high-purity hydrogen. The water electrolysis process involves two half-reactions, namely the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). OER is a key half-reaction in the process of water electrolysis, involving a complex four-electron transfer process, which has a slow kinetic reaction and a high overpotential, limiting the conversion efficiency of hydrogen production by water electrolysis. Developing an efficient OER electrocatalyst is crucial for accelerating the reaction process and improving the conversion efficiency of OER.

[0004] The energy loss of electrochemical reaction is mainly caused by active polarization, ohmic polarization and mass transfer polarization, so in order to design an efficient non-noble metal OER electrocatalyst, the following principles are usually followed: ① good activity to reduce active polarization; ② large specific surface area to increase the number of active sites; ③ good hydrophilicity to avoid the formation of a large number of bubbles on the surface of the electrode material, thereby exacerbating the mass transfer polarization loss; ④ good electrical conductivity to maintain low ohmic polarization loss when operating at high current density; ⑤ corrosion resistance and good electrochemical stability. RuO2 and IrO2 are currently the best OER catalysts in terms of comprehensive performance. However, the scarcity of Ru and Ir limits their large-scale practical application. Although there have been many reports of transition metal-based nanocatalysts, including NiCoFe nanoparticles, which have better catalytic activity than RuO2 and IrO2, most of the nanocatalysts have poor structural stability and catalytic stability in industrial application environments (current density > 200 mA / cm 2 , 30% KOH, 60-80℃), and are prone to aggregation and detachment from the support during intense oxygen evolution. SUMMARY

[0005] The present application aims to provide a high-stability NiCu@NiCoFe oxygen evolution electrocatalyst, which has good catalytic activity; another object of the present application is to provide a preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst.

[0006] Technical solution: The high-stability NiCu@NiCoFe oxygen evolution electrocatalyst disclosed by the application comprises a NiCu substrate and a NiCoFe active layer loaded on the NiCu substrate by electrodepositing; wherein the NiCu substrate is in a three-dimensional network skeleton structure, and a plurality of nanopores are distributed on the skeleton; the NiCoFe active layer is composed of NiCoFe nanoparticles deposited on the skeleton and the nanopore walls of the skeleton.

[0007] NiCoFe has good intrinsic oxygen evolution catalytic performance, but its deposition overpotential is very high, and it cannot obtain a porous and dendritic structure (which can increase the specific surface area and has high structural stability during oxygen evolution), therefore, a porous NiCu dendrite is used as a substrate to provide a large specific surface area and high structural stability for NiCoFe.

[0008] The skeleton structure has three-dimensionally connected micropores with a pore diameter of 0.2-25 μm. The NiCu substrate has a hierarchical porous structure, including three-dimensionally connected micropores and nanopores on the skeleton.

[0009] The skeleton structure of the NiCu substrate grows a large number of dendritic structures (which can increase the specific surface area of the substrate and increase the electrical conductivity), and the size of the dendritic structure is 0.2 μm-8 μm.

[0010] The hierarchical porous structure of the substrate has a large specific surface area, which can provide a large number of attachment sites for the active layer, secondly, the hierarchical porous structure conforms to the change from small to large when the oxygen bubbles overflow during oxygen evolution, and the structure can also remain stable and not collapse under strong oxygen evolution conditions, finally, the hierarchical porous structure is beneficial to the rapid mass transfer of ions, molecules and the like in the pore channel during the oxygen evolution reaction. The dendritic structure can further increase the specific surface area of the hierarchical porous structure, and the electric field enhancement effect of the dendritic tip can further improve the catalytic activity of the active layer of the catalyst.

[0011] The thickness of the NiCoFe active layer is 10-60 nm.

[0012] In the NiCu@NiCoFe electrocatalyst, the loading amount of the NiCoFe active layer on the NiCu substrate is 0.6-20 mg / cm 2 .

[0013] In the NiCu substrate, the content of Ni in the NiCu alloy is 95 at%, and the content of Cu is 5 at%. The substrate is Ni 95 Cu5, which has good electrical conductivity. Under this composition, a porous dendritic structure can be obtained, and when NiCoFe is deposited subsequently, Ni 95 Cu5 has high chemical stability and will not cause corrosion and collapse.

[0014] In the NiCoFe active layer, the content of Ni in NiCoFe is 33-75 at%, the content of Co is 15-50 at%, and the content of Fe is 10-30 at%.

[0015] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst specifically comprises the following steps:

[0016] (1) Place the working electrode in a mixed solution containing NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the concentrations of the respective compounds in the mixed solution are as follows: the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M; through the synergistic effect of the concentrations of the substances in the formula solution and the current density, the present application can effectively inhibit the deposition of copper, so that the substrate grows uniformly during the growth process, and is in a nickel-rich state from the bottom to the top, and has a hierarchical porous structure and a dendritic structure; the nickel-rich state can improve the stability of the substrate in the subsequent active layer plating reaction process; that is, the large deposition current density and the plating solution formula ensure the porous, dendritic structure and Ni 95 Cu5 composition; the higher the current density, the larger the pore structure, and the higher the Ni content; when the current density is too small, the porous structure cannot be formed; the higher the concentration of Ni ions in the formula, the higher the Ni content of the NiCu plating layer; however, pure Ni cannot obtain a porous structure, and low Ni will be severely corroded during the subsequent NiCoFe deposition, resulting in the collapse of the pores;

[0017] (2) Obtain a hierarchical porous NiCu substrate through constant-current electrochemical deposition;

[0018] (3) Wash the NiCu substrate with ultrapure water and then perform vacuum freeze-drying treatment; vacuum freeze-drying can effectively prevent the formation of an amorphous oxide film on the surface of the substrate; if vacuum freeze-drying is not used, an amorphous oxide film is easily formed on the surface of the substrate, which is not conducive to the loading of the active layer and affects the catalytic performance of the product during the subsequent application process; the amorphous oxide film is not conductive;

[0019] (4) Place the NiCu substrate as the working electrode in a mixed solution containing NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the concentrations of the respective compounds in the mixed solution are as follows: the concentration of NiSO4 is 0.03-0.18 M, the concentration of FeSO4 is 0.03-0.09 M, the concentration of CoSO4 is 0.03-0.15 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M; the Ni 2+ , Co2+ and Fe 2+ The concentration influences the composition of NiCoFe, and the composition influences the activity and stability of the catalyst, high Fe has better catalytic activity, but poor catalytic stability, high Co and low Ni have poor catalytic activity, and under the condition of high Ni, low Co and low Fe, the catalytic activity and catalytic stability are both kept in a high state.

[0020] (5) depositing the NiCoFe active layer on the NiCu substrate by the constant current electrochemical deposition method to obtain the NiCu@NiCoFe oxygen evolution electrocatalyst;

[0021] (6) rinsing the NiCu@NiCoFe oxygen evolution electrocatalyst with ultrapure water and freeze-drying, and the vacuum freeze-drying can effectively prevent the formation of amorphous oxide film on the surface of the product.

[0022] In step (2), the current density of the constant current deposition is 4A / cm 2 , and the deposition time is 45s.

[0023] In step (3), the NiCu substrate is soaked with ultrapure water for more than 3 times, and each time is 5min.

[0024] In step (3), the freeze-drying time is more than 2h.

[0025] In step (5), the current density of the constant current deposition is 5-100mA / cm 2 , and the deposition time is 30-1800s.

[0026] In step (6), the NiCu@NiCoFe electrocatalyst is soaked with ultrapure water for more than 3 times, and each time is 5min.

[0027] In step (6), the freeze-drying time is more than 2h.

[0028] Advantages: Compared with the prior art, the electrocatalyst has the following obvious advantages: in the electrocatalyst, the effective load of the NiCoFe active layer on the NiCu substrate can reach 0.6-20mg / cm 2, far higher than the long-time effective load of most nano-catalysts, because the structure of the NiCu substrate of the application can greatly improve the load of the active layer, and the use of electrodeposition makes the active layer load more firmly and not easy to fall off, thereby maintaining a high long-time effective load; due to the high effective load, the reaction active sites are more, and the intrinsic catalytic activity of NiCoFe is high, so when the electro-catalyst of the application is used as a hydrolysis oxygen production catalyst, the oxygen evolution overpotential on the surface of the NiCu@NiCoFe electro-catalyst can be as low as 239-278mV, and the electro-catalyst has good catalytic activity; and the electro-catalyst of the application can work stably (for oxygen evolution reaction under alkaline conditions) under industrial electrolysis water environment (500mA / cm 2 , 60℃, 30%KOH), and has good chemical stability. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the low-magnification (insert) and high-magnification morphology (scanning electron microscope) of the NiCu@NiCoFe electro-catalyst of the application;

[0030] Figure 2 is the energy spectrum of the NiCu@NiCoFe electro-catalyst of Example 1;

[0031] Figure 3 is the linear sweep graph of the oxygen evolution reaction of the NiCu@NiCoFe electro-catalyst of Example 1;

[0032] Figure 4 is the stability test graph of the NiCu@NiCoFe electro-catalyst of Example 1 under 500mA / cm 2 , 60℃, 30%KOH;

[0033] Figure 5 is the energy spectrum of the NiCu@NiCoFe electro-catalyst of Example 2;

[0034] Figure 6 is the linear sweep graph of the oxygen evolution reaction of the NiCu@NiCoFe electro-catalyst of Example 2;

[0035] Figure 7 is the energy spectrum of the NiCu@NiCoFe electro-catalyst of Example 3;

[0036] Figure 8 is the linear sweep graph of the oxygen evolution reaction of the NiCu@NiCoFe electro-catalyst of Example 3;

[0037] Figure 9 is the energy spectrum of the NiCu@NiCoFe electro-catalyst of Example 4;

[0038] Figure 10Linear sweep plot for oxygen evolution reaction of Example 4 NiCu@NiCoFe electrocatalyst;

[0039] Figure 11 Energy dispersive spectroscopy plot for Example 5 NiCu@NiCoFe electrocatalyst;

[0040] Figure 12 Linear sweep plot for oxygen evolution reaction of Example 5 NiCu@NiCoFe electrocatalyst;

[0041] Figure 13 Energy dispersive spectroscopy plot for Example 6 NiCu@NiCoFe electrocatalyst;

[0042] Figure 14 Linear sweep plot for oxygen evolution reaction of Example 6 NiCu@NiCoFe electrocatalyst;

[0043] Figure 15 Energy dispersive spectroscopy plot for Example 7 NiCu@NiCoFe electrocatalyst;

[0044] Figure 16 Linear sweep plot for oxygen evolution reaction of Example 7 NiCu@NiCoFe electrocatalyst;

[0045] Figure 17 Energy dispersive spectroscopy plot for Example 8 NiCu@NiCoFe electrocatalyst;

[0046] Figure 18 Linear sweep plot for oxygen evolution reaction of Example 8 NiCu@NiCoFe electrocatalyst;

[0047] Figure 19 Energy dispersive spectroscopy plot for Example 9 NiCu@NiCoFe electrocatalyst;

[0048] Figure 20 Linear sweep plot for oxygen evolution reaction of Example 9 NiCu@NiCoFe electrocatalyst;

[0049] Figure 21 Energy dispersive spectroscopy plot for Example 10 NiCu@NiCoFe electrocatalyst;

[0050] Figure 22 Linear sweep plot for oxygen evolution reaction of Example 10 NiCu@NiCoFe electrocatalyst;

[0051] Figure 23 Energy dispersive spectroscopy plot for Example 11 NiCu@NiCoFe electrocatalyst;

[0052] Figure 24 Linear sweep plot for oxygen evolution reaction of Example 11 NiCu@NiCoFe electrocatalyst;

[0053] Figure 25 Energy dispersive spectroscopy of NiCu@NiCoFe electrocatalyst for Example 12;

[0054] Figure 26 Linear sweep for oxygen evolution reaction of NiCu@NiCoFe electrocatalyst for Example 12;

[0055] Figure 27 Energy dispersive spectroscopy of NiCu@NiCoFe electrocatalyst for Comparative Example 2;

[0056] Figure 28 Linear sweep for oxygen evolution reaction of NiCu@NiCoFe electrocatalyst for Comparative Example 2;

[0057] Figure 29 Scanning electron microscopy of NiCu@NiCoFe electrocatalyst for Comparative Example 2;

[0058] Figure 30 Energy dispersive spectroscopy of NiCu@NiCoFe electrocatalyst for Comparative Example 3;

[0059] Figure 31 Energy dispersive spectroscopy of NiCu@NiCoFe electrocatalyst for Comparative Example 4;

[0060] Figure 32 Linear sweep for oxygen evolution reaction of NiCu@NiCoFe electrocatalyst for Comparative Example 4;

[0061] Figure 33 Scanning electron microscopy of NiCu@NiCoFe electrocatalyst for Comparative Example 4;

[0062] Figure 34 Transmission electron microscopy of NiCu@NiCoFe electrocatalyst for Example 1;

[0063] Figure 35 Preparation flow chart of the present application. DETAILED DESCRIPTION

[0064] Example 1

[0065] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the present application specifically comprises the following steps:

[0066] (1) Place the working electrode in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is: the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0067] (2) constant current electrochemical deposition, the current density of the constant current deposition is 4 A / cm 2 , the deposition time is 45 s, and a hierarchical porous NiCu substrate is obtained;

[0068] (3) the NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5 min; after cleaning, it is dried in a vacuum freeze dryer for 2 h;

[0069] (4) the NiCu substrate is used as a working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is: the concentration of NiSO4 is 0.15 M, the concentration of FeSO4 is 0.03 M, the concentration of CoSO4 is 0.03 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0070] (5) constant current electrochemical deposition, the current density of the constant current deposition is 20 mA / cm 2 , the deposition time is 900 s, and a NiCoFe active layer is deposited on the NiCu substrate to obtain a NiCu@NiCoFe electrocatalyst;

[0071] (6) the NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5 min; after cleaning, it is dried in a vacuum freeze dryer for 2 h.

[0072] The electrocatalyst prepared in Example 1 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows (as shown in Figure 2 ) that the content of Ni is 71.0 at%, the content of Fe is 11.0 at%, the content of Cu is 3.0 at%, and the content of Co is 15.0 at%; scanning electron microscope observation shows (as shown in Figure 1 ) that the skeleton structure (the skeleton structure is similar to a foam) has a large number of three-dimensionally connected micropores with a pore size in the range of 25 μm, and a plurality of nanopores are also distributed on the skeleton; meanwhile, the skeleton also contains rich dendritic morphology, the dendritic size is in the range of 0.2 μm to 8 μm, and after cleaning and activation, the oxygen evolution overpotential on the surface can be as low as 244 mV, the oxygen evolution potential is taken as the potential applied at a current density of 10 mA / cm 2 (as shown in Figure 3 ), and under industrial electrolytic water conditions (500 mA / cm 2 , 60°C, 30% KOH), a 10-hour stability test is performed, and the catalytic activity remains unchanged (i.e. the overpotential does not increase) (as shown in Figure 4 ). It can be seen from Figure 34 that the NiCu dendrite is coated with a dense NiCoFe active layer.

[0073] Example 2

[0074] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the application specifically comprises the following steps:

[0075] (1) Place the working electrode in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is: the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0076] (2) Perform constant-current electrochemical deposition, and the current density of the constant-current deposition is 4 A / cm 2 , and the deposition time is 45 s to obtain a hierarchical porous NiCu substrate;

[0077] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 min; and after cleaning, dry the NiCu substrate in a vacuum freeze dryer for 2 h;

[0078] (4) Place the NiCu substrate as a working electrode in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is: the concentration of NiSO4 is 0.15 M, the concentration of FeSO4 is 0.03 M, the concentration of CoSO4 is 0.03 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0079] (5) Perform constant-current electrochemical deposition, and the current density of the constant-current deposition is 20 mA / cm 2 , and the deposition time is 30 s to deposit a NiCoFe active layer on the NiCu substrate to obtain a NiCu@NiCoFe electrocatalyst;

[0080] (6) Soak the NiCu@NiCoFe electrocatalyst in ultrapure water for 3 times, each time for 5 min; and after cleaning, dry the NiCu@NiCoFe electrocatalyst in a vacuum freeze dryer for 2 h.

[0081] The electrocatalyst prepared in Example 2 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that Figure 5 , the content of Ni is 94.5 at%, the content of Fe is 0.2 at%, the content of Cu is 5.0 at%, and the content of Co is 0.3 at%. Scanning electron microscope observation shows that Figure 1), a large number of three-dimensionally connected micropores with a pore size in the range of 25 mu m in a skeleton structure (the skeleton structure is similar to a foam), a plurality of nanopores distributed on the skeleton, and abundant dendritic morphologies with a dendritic size of 0.2 mu m to 8 mu m on the skeleton; after cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 261 mV, and the oxygen evolution potential is taken as the current density of 10 mA / cm 2 the applied potential Figure 6 .

[0082] Example 3

[0083] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the application specifically comprises the following steps:

[0084] (1) placing a working electrode in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is that the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0085] (2) performing constant-current electrochemical deposition, the current density of the constant-current deposition is 4 A / cm 2 , and the deposition time is 45 s, so as to obtain a hierarchical porous NiCu substrate;

[0086] (3) immersing the NiCu substrate in ultrapure water for more than 3 times, each time for 5 min; after cleaning, placing the NiCu substrate in a vacuum freeze dryer for drying for 2 h;

[0087] (4) placing the NiCu substrate as a working electrode in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is that the concentration of NiSO4 is 0.15 M, the concentration of FeSO4 is 0.03 M, the concentration of CoSO4 is 0.03 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0088] (5) performing constant-current electrochemical deposition, the current density of the constant-current deposition is 20 mA / cm 2 , and the deposition time is 60 s, so as to deposit a NiCoFe active layer on the NiCu substrate and obtain a NiCu@NiCoFe electrocatalyst;

[0089] (6) immersing the NiCu@NiCoFe electrocatalyst in ultrapure water for 3 times, each time for 5 min; after cleaning, placing the NiCu@NiCoFe electrocatalyst in a vacuum freeze dryer for drying for 2 h.

[0090] The electrocatalyst prepared in Example 3 is composed of Ni, Fe, Cu, and Co. The energy dispersion spectrum component analysis shows that ( Figure 7 ), wherein the Ni content is 93.7at%, the Fe content is 0.6at%, the Cu content is 4.8at%, and the Co content is 0.9at%. Scanning electron microscopy shows that (such as Figure 1 ), the skeleton structure (similar to foam) has a large number of three-dimensionally connected micropores with a pore size of 25μm, and multiple nanopores are distributed on the skeleton; at the same time, the skeleton also contains rich dendrite morphology, with a dendrite size of 0.2μm to 8μm. After cleaning and activation, the oxygen evolution overpotential on its surface can be as low as 252mV, and the oxygen evolution potential is taken as the current density of 10mA / cm 2 The applied potential ( Figure 8 ).

[0091] Example 4

[0092] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the present invention specifically comprises the following steps:

[0093] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3, and (NH4)2SO4; the electrolyte formula was: NiSO4 concentration was 0.2M, CuSO4 concentration was 0.0075M, (NH4)2SO4 concentration was 1.2M, Na3C6H5O7 concentration was 0.3M, and H3BO3 concentration was 0.4M;

[0094] (2) Perform constant current electrochemical deposition with a current density of 4 A / cm 2 , the deposition time was 45 s, and a hierarchically porous NiCu substrate was obtained;

[0095] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 minutes; after cleaning, place it in a vacuum freeze dryer and dry it for 2 hours;

[0096] (4) The NiCu substrate was used as the working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3, and NH4Cl; the electrolyte formula was: NiSO4 concentration was 0.15M, FeSO4 concentration was 0.03M, CoSO4 concentration was 0.03M, NH4Cl concentration was 0.28M, and H3BO3 concentration was 0.4M;

[0097] (5) Perform constant current electrochemical deposition with a current density of 20 mA / cm 2 , the deposition time is 300s, and a NiCoFe active layer is deposited on the NiCu substrate to obtain a NiCu@NiCoFe electrocatalyst;

[0098] (6) The NiCu@NiCoFe electrocatalyst was soaked in ultrapure water for 3 times, each time for 5 min; after washing, it was placed in a vacuum freeze dryer and dried for 2 h.

[0099] The electrocatalyst prepared in Example 4 is composed of Ni, Fe, Cu, and Co. The energy dispersion spectrum component analysis shows that ( Figure 9 ), wherein the Ni content is 83.3at%, the Fe content is 5.5at%, the Cu content is 4.1at%, and the Co content is 7.1at%. Scanning electron microscopy shows that (such as Figure 1 ), the skeleton structure (similar to foam) has a large number of three-dimensionally connected micropores with a pore size of 25μm, and multiple nanopores are distributed on the skeleton; at the same time, the skeleton also contains rich dendrite morphology, with a dendrite size of 0.2μm to 8μm. After cleaning and activation, the oxygen evolution overpotential on its surface can be as low as 246mV, and the oxygen evolution potential is taken at a current density of 10mA / cm 2 The applied potential ( Figure 10 ).

[0100] Example 5

[0101] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the present invention specifically comprises the following steps:

[0102] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3, and (NH4)2SO4; the electrolyte formula was: NiSO4 concentration was 0.2M, CuSO4 concentration was 0.0075M, (NH4)2SO4 concentration was 1.2M, Na3C6H5O7 concentration was 0.3M, and H3BO3 concentration was 0.4M;

[0103] (2) Perform constant current electrochemical deposition with a current density of 4 A / cm 2 , the deposition time was 45 s, and a hierarchically porous NiCu substrate was obtained;

[0104] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 minutes; after cleaning, place it in a vacuum freeze dryer and dry it for 2 hours;

[0105] (4) The NiCu substrate was used as the working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3, and NH4Cl; the electrolyte formula was: NiSO4 concentration was 0.15M, FeSO4 concentration was 0.03M, CoSO4 concentration was 0.03M, NH4Cl concentration was 0.28M, and H3BO3 concentration was 0.4M;

[0106] (5) constant current electrochemical deposition is performed, the current density of the constant current deposition is 20 mA / cm 2 , a NiCoFe active layer is deposited on the NiCu substrate, and a NiCu@NiCoFe electrocatalyst is obtained;

[0107] (6) the NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5 min; and after cleaning, the NiCu@NiCoFe electrocatalyst is dried in a vacuum freeze dryer for 2 h.

[0108] The electrocatalyst prepared in Example 5 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that (as shown in Figure 11 ), the content of Ni is 54.0 at%, the content of Fe is 19.7 at%, the content of Cu is 1.6 at%, and the content of Co is 24.7 at%. Scanning electron microscope observation shows that (as shown in Figure 1 ), a large number of three-dimensionally connected micropores with a pore size in the range of 25 μm are present in the skeleton structure (the skeleton structure is similar to a foam), and a plurality of nanopores are also distributed on the skeleton; meanwhile, the skeleton also contains rich dendritic morphology, the dendritic size is in the range of 0.2 μm to 8 μm, and after activation, the oxygen evolution overpotential on the surface thereof can be as low as 254 mV, and the oxygen evolution potential is taken as the potential applied (as shown in 2 ) at a current density of 10 mA / cm Figure 12 .

[0109] Example 6

[0110] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst according to the application specifically comprises the following steps:

[0111] (1) the working electrode is placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is that the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0112] (2) constant current electrochemical deposition is performed, the current density of the constant current deposition is 4 A / cm 2 , and the deposition time is 45 s, so that a hierarchical porous NiCu substrate is obtained;

[0113] (3) the NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5 min; and after cleaning, the NiCu substrate is dried in a vacuum freeze dryer for 2 h;

[0114] (4) the working electrode of NiCu substrate is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is that the concentration of NiSO4 is 0.15M, the concentration of FeSO4 is 0.03M, the concentration of CoSO4 is 0.03M, the concentration of NH4Cl is 0.28M, and the concentration of H3BO3 is 0.4M;

[0115] (5) constant current electrochemical deposition is carried out, the current density of constant current deposition is 5mA / cm 2 , and the deposition time is 900s, so that the NiCoFe active layer is deposited on the NiCu substrate to obtain the NiCu@NiCoFe electrocatalyst;

[0116] (6) the NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5min; and after cleaning, the NiCu@NiCoFe electrocatalyst is placed in a vacuum freeze dryer for drying for 2h.

[0117] The electrocatalyst prepared in the embodiment 6 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that (as shown in Figure 13 ), the content of Ni is 91.7at%, the content of Fe is 1.4at%, the content of Cu is 4.8at%, and the content of Co is 2.1at%. Scanning electron microscope observation shows that (as shown in Figure 1 ), a large number of three-dimensionally connected micropores with a pore size in the range of 25μm are arranged in the skeleton structure (the skeleton structure is similar to a foam), and a plurality of nanopores are also arranged on the skeleton; meanwhile, the skeleton also contains rich dendritic morphology, the dendritic size is in the range of 0.2μm-8μm, and after cleaning and activation, the oxygen evolution overpotential on the surface can be as low as 247mV, and the oxygen evolution potential is applied at a current density of 10mA / cm 2 . Figure 14

[0118] Embodiment 7

[0119] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst provided by the application specifically comprises the following steps:

[0120] (1) the working electrode is placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is that the concentration of NiSO4 is 0.2M, the concentration of CuSO4 is 0.0075M, the concentration of (NH4)2SO4 is 1.2M, the concentration of Na3C6H5O7 is 0.3M, and the concentration of H3BO3 is 0.4M;

[0121] (2) constant current electrochemical deposition is carried out, the current density of constant current deposition is 4A / cm 2 ​, and the deposition time is 45s, to obtain a hierarchical porous NiCu substrate;

[0122] (3) The NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5min; and after cleaning, the NiCu substrate is dried in a vacuum freeze dryer for 2h;

[0123] (4) The NiCu substrate is used as a working electrode and is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is as follows: the concentration of NiSO4 is 0.15M, the concentration of FeSO4 is 0.03M, the concentration of CoSO4 is 0.03M, the concentration of NH4Cl is 0.28M, and the concentration of H3BO3 is 0.4M;

[0124] (5) Constant current electrochemical deposition is performed, and the current density of the constant current deposition is 10mA / cm 2 , and the deposition time is 900s, to deposit a NiCoFe active layer on the NiCu substrate, to obtain a NiCu@NiCoFe electrocatalyst;

[0125] (6) The NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5min; and after cleaning, the NiCu@NiCoFe electrocatalyst is dried in a vacuum freeze dryer for 2h.

[0126] The electrocatalyst prepared in Example 7 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that (as shown in Figure 15 ), the content of Ni is 72.1at%, the content of Fe is 10.7at%, the content of Cu is 3.1at%, and the content of Co is 14.1at%. Scanning electron microscope observation shows that (as shown in Figure 1 ), a large number of three-dimensionally connected micropores with a pore size in the range of 25μm are present in the skeleton structure (the skeleton structure is similar to a foam), and a plurality of nanopores are also distributed on the skeleton; meanwhile, the skeleton also contains rich dendritic morphology, and the dendritic size is in the range of 0.2μm to 8μm; after cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 249mV, and the oxygen evolution potential is taken as the potential applied (as shown in 2 ). Figure 16

[0127] Example 8

[0128] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the present application specifically comprises the following steps:

[0129] ​(1) The working electrode is placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is: the concentration of NiSO4 is 0.2M, the concentration of CuSO4 is 0.0075M, the concentration of (NH4)2SO4 is 1.2M, the concentration of Na3C6H5O7 is 0.3M, and the concentration of H3BO3 is 0.4M;

[0130] (2) Constant current electrochemical deposition is performed, the current density of the constant current deposition is 4A / cm 2 , and the deposition time is 45s, so as to obtain a hierarchical porous NiCu substrate;

[0131] (3) The NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5min; after cleaning, the NiCu substrate is dried in a vacuum freeze dryer for 2h;

[0132] (4) The NiCu substrate is used as a working electrode and is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is: the concentration of NiSO4 is 0.15M, the concentration of FeSO4 is 0.03M, the concentration of CoSO4 is 0.03M, the concentration of NH4Cl is 0.28M, and the concentration of H3BO3 is 0.4M;

[0133] (5) Constant current electrochemical deposition is performed, the current density of the constant current deposition is 50mA / cm 2 , and the deposition time is 900s, so as to deposit a NiCoFe active layer on the NiCu substrate and obtain a NiCu@NiCoFe electrocatalyst;

[0134] (6) The NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5min; after cleaning, the NiCu@NiCoFe electrocatalyst is dried in a vacuum freeze dryer for 2h.

[0135] The electrocatalyst prepared in Example 8 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that Figure 17 the content of Ni is 36.9at%, the content of Fe is 29.9at%, the content of Cu is 0.4at%, and the content of Co is 32.8at%. Scanning electron microscope observation shows that (as shown in Figure 1 ) the skeleton structure (the skeleton structure is similar to a foam) has a large number of three-dimensionally connected micropores with a pore size in the range of 25μm, and a plurality of nanopores are distributed on the skeleton; meanwhile, the skeleton also contains a large number of dendritic morphologies, the dendritic size is in the range of 0.2μm-8μm, and after cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 253mV, and the oxygen evolution potential is measured at a current density of 10mA / cm 2 . Figure 18 ​

[0136] Example 9

[0137] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the application specifically comprises the following steps:

[0138] (1) Place the working electrode in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is: the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0139] (2) Perform constant-current electrochemical deposition, and the current density of the constant-current deposition is 4 A / cm 2 , and the deposition time is 45 s to obtain a hierarchical porous NiCu substrate;

[0140] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 min; and after cleaning, dry the NiCu substrate in a vacuum freeze dryer for 2 h;

[0141] (4) Place the NiCu substrate as a working electrode in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is: the concentration of NiSO4 is 0.15 M, the concentration of FeSO4 is 0.03 M, the concentration of CoSO4 is 0.03 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0142] (5) Perform constant-current electrochemical deposition, and the current density of the constant-current deposition is 100 mA / cm 2 , and the deposition time is 900 s to deposit a NiCoFe active layer on the NiCu substrate to obtain a NiCu@NiCoFe electrocatalyst;

[0143] (6) Soak the NiCu@NiCoFe electrocatalyst in ultrapure water for 3 times, each time for 5 min; and after cleaning, dry the NiCu@NiCoFe electrocatalyst in a vacuum freeze dryer for 2 h.

[0144] The electrocatalyst prepared in Example 9 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that (as shown in Figure 19 ), the content of Ni is 47.0 at%, the content of Fe is 22.3 at%, the content of Cu is 0.1 at%, and the content of Co is 30.6 at%. Scanning electron microscope observation shows (as shown in Figure 1), a large number of three-dimensionally connected micropores with a pore size in the range of 25 mu m in a skeleton structure (the skeleton structure is similar to a foam), a plurality of nanopores distributed on the skeleton, and abundant dendritic morphologies with a dendritic size of 0.2 mu m to 8 mu m on the skeleton; after cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 255 mV, and the oxygen evolution potential is taken as the current density of 10 mA / cm 2 the applied potential Figure 20 ).

[0145] Example 10

[0146] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the application specifically comprises the following steps:

[0147] (1) placing a working electrode in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is that the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0148] (2) performing constant-current electrochemical deposition, the current density of the constant-current deposition is 4 A / cm 2 , and the deposition time is 45 s, so as to obtain a hierarchical porous NiCu substrate;

[0149] (3) immersing the NiCu substrate in ultrapure water for more than 3 times, each time for 5 min; after cleaning, placing the NiCu substrate in a vacuum freeze dryer for drying for 2 h;

[0150] (4) placing the NiCu substrate as a working electrode in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is that the concentration of NiSO4 is 0.09 M, the concentration of FeSO4 is 0.09 M, the concentration of CoSO4 is 0.03 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0151] (5) performing constant-current electrochemical deposition, the current density of the constant-current deposition is 20 mA / cm 2 , and the deposition time is 900 s, so as to deposit a NiCoFe active layer on the NiCu substrate and obtain a NiCu@NiCoFe electrocatalyst;

[0152] (6) immersing the NiCu@NiCoFe electrocatalyst in ultrapure water for 3 times, each time for 5 min; after cleaning, placing the NiCu@NiCoFe electrocatalyst in a vacuum freeze dryer for drying for 2 h.

[0153] The electrocatalyst prepared in Example 10 is composed of Ni, Fe, Cu and Co, and energy dispersive spectroscopy composition analysis shows that the content of Ni is 74.6 at%, the content of Fe is 13.3 at%, the content of Cu is 3.0 at%, and the content of Co is 9.1 at%. Figure 21 As shown in Figure 2, the skeleton structure (the skeleton structure is similar to a foam) has a large number of three-dimensionally connected micropores with a pore size in the range of 25 μm, and a plurality of nanopores are distributed on the skeleton; meanwhile, the skeleton has rich dendritic morphology, and the dendritic size is in the range of 0.2 μm to 8 μm. Figure 1 After cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 239 mV, and the oxygen evolution potential is taken as the current density of 10 mA / cm 2 The applied potential ( Figure 22 ) is 1.0 V.

[0154] Example 11

[0155] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst according to the application specifically comprises the following steps:

[0156] (1) The working electrode is placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is that the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M;

[0157] (2) Constant-current electrochemical deposition is performed, and the current density of the constant-current deposition is 4 A / cm 2 , and the deposition time is 45 s, so as to obtain a hierarchical porous NiCu substrate;

[0158] (3) The NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5 min; after cleaning, the NiCu substrate is placed in a vacuum freeze dryer for drying for 2 h;

[0159] (4) The NiCu substrate is used as the working electrode and is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is that the concentration of NiSO4 is 0.03 M, the concentration of FeSO4 is 0.03 M, the concentration of CoSO4 is 0.15 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M;

[0160] (5) Constant-current electrochemical deposition is performed, and the current density of the constant-current deposition is 20 mA / cm 2, the deposition time is 900s, and a NiCoFe active layer is deposited on the NiCu substrate to obtain the NiCu@NiCoFe electrocatalyst;

[0161] (6) The NiCu@NiCoFe electrocatalyst was soaked in ultrapure water for 3 times, each time for 5 min; after washing, it was placed in a vacuum freeze dryer and dried for 2 h.

[0162] The electrocatalyst prepared in Example 11 is composed of Ni, Fe, Cu, and Co. The energy dispersion spectrum component analysis shows that ( Figure 23 ), wherein the Ni content is 52.1at%, the Fe content is 7.5at%, the Cu content is 2.7at%, and the Co content is 37.7at%. Scanning electron microscopy shows that (such as Figure 1 ), the skeleton structure (the skeleton structure is similar to foam) has a large number of three-dimensionally connected micropores with a pore size of 25μm, and there are also multiple nanopores distributed on the skeleton; at the same time, the skeleton also contains rich dendrite morphology, with a dendrite size of 0.2μm to 8μm. After cleaning and activation, the oxygen evolution overpotential on its surface can be as low as 278mV, and the oxygen evolution potential is taken at a current density of 10mA / cm 2 The applied potential ( Figure 24 ).

[0163] Example 12

[0164] The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of the present invention specifically comprises the following steps:

[0165] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3, and (NH4)2SO4; the electrolyte formula was: NiSO4 concentration was 0.2M, CuSO4 concentration was 0.0075M, (NH4)2SO4 concentration was 1.2M, Na3C6H5O7 concentration was 0.3M, and H3BO3 concentration was 0.4M;

[0166] (2) Perform constant current electrochemical deposition with a current density of 4 A / cm 2 , the deposition time was 45 s, and a hierarchically porous NiCu substrate was obtained;

[0167] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 minutes; after cleaning, place it in a vacuum freeze dryer and dry it for 2 hours;

[0168] (4) The NiCu substrate is used as the working electrode and is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is as follows: the concentration of NiSO4 is 0.18M, the concentration of FeSO4 is 0.03M, the concentration of CoSO4 is 0.03M, the concentration of NH4Cl is 0.28M, and the concentration of H3BO3 is 0.4M;

[0169] (5) Constant current electrochemical deposition is performed, the current density of the constant current deposition is 20mA / cm 2 , and the deposition time is 900s, so as to deposit a NiCoFe active layer on the NiCu substrate to obtain a NiCu@NiCoFe electrocatalyst;

[0170] (6) The NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5min; and after cleaning, the NiCu@NiCoFe electrocatalyst is dried in a vacuum freeze dryer for 2h.

[0171] The electrocatalyst prepared in Example 12 is composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis shows that the content of Ni is 70.0at%, the content of Fe is 11.5at%, the content of Cu is 2.8at%, and the content of Co is 15.7at%. Figure 25 The scanning electron microscope observation shows that (as shown in Figure 1 ) the skeleton structure (the skeleton structure is similar to a foam) has a large number of three-dimensionally connected micropores with a pore size in the range of 25μm, and a plurality of nanopores are distributed on the skeleton; meanwhile, the skeleton also contains rich dendritic morphology, the dendritic size is in the range of 0.2μm-8μm, and after cleaning and activation, the oxygen evolution overpotential on the surface thereof can be as low as 251mV, and the oxygen evolution potential is taken as the potential applied (as shown in 2 ). Figure 26

[0172] Table 1 is the effective loading amount of the NiCoFe active layer on the NiCu substrate in Examples 1-10

[0173]

[0174] Comparative Example 1

[0175] A preparation method of a NiCu@NiCoFe oxygen evolution electrocatalyst, specifically comprising the following steps:

[0176] ​(1) The working electrode is placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula is: the concentration of NiSO4 is 0.2M, the concentration of CuSO4 is 0.0075M, the concentration of (NH4)2SO4 is 1.2M, the concentration of Na3C6H5O7 is 0.3M, and the concentration of H3BO3 is 0.4M;

[0177] (2) Constant current electrochemical deposition is performed, and the current density of the constant current deposition is 4A / cm 2 , and the deposition time is 45s, to obtain a hierarchical porous NiCu substrate;

[0178] (3) The NiCu substrate is soaked in ultrapure water for more than 3 times, each time for 5min; after cleaning, it is naturally dried in a fume hood for 2h;

[0179] (4) The NiCu substrate is used as the working electrode and is placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula is: the concentration of NiSO4 is 0.09M, the concentration of FeSO4 is 0.09M, the concentration of CoSO4 is 0.03M, the concentration of NH4Cl is 0.28M, and the concentration of H3BO3 is 0.4M;

[0180] (5) Constant current electrochemical deposition is performed, and the current density of the constant current deposition is 20mA / cm 2 , and the deposition time is 900s, to deposit a NiCoFe active layer on the NiCu substrate, to obtain a NiCu@NiCoFe electrocatalyst;

[0181] (6) The NiCu@NiCoFe electrocatalyst is soaked in ultrapure water for 3 times, each time for 5min; after cleaning, it is naturally dried in a fume hood for 2h.

[0182] The NiCu@NiCoFe electrocatalyst prepared by the above method falls off during the activation process. The reason is that the surface of the NiCu substrate is easily oxidized during the natural drying process, resulting in poor adhesion of the deposited NiCoFe coating. In addition, the electrochemical stability of the catalyst decreases, and the oxygen evolution overpotential increases by more than 30mV within one hour.

[0183] Comparative Example 2

[0184] A preparation method of a NiCu@NiCoFe oxygen evolution electrocatalyst, specifically comprising the following steps:

[0185] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3, and (NH4)2SO4; the electrolyte formula was: NiSO4 concentration was 0.2M, CuSO4 concentration was 0.0075M, (NH4)2SO4 concentration was 1.2M, Na3C6H5O7 concentration was 0.3M, and H3BO3 concentration was 0.4M;

[0186] (2) Perform constant current electrochemical deposition with a current density of 4 A / cm 2 , the deposition time was 45 s, and a hierarchically porous NiCu substrate was obtained;

[0187] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 minutes; after cleaning, place it in a vacuum freeze dryer and dry it for 2 hours;

[0188] (4) The NiCu substrate was used as the working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3, and NH4Cl; the electrolyte formula was: NiSO4 concentration was 0.09M, FeSO4 concentration was 0.12M, CoSO4 concentration was 0.03M, NH4Cl concentration was 0.28M, and H3BO3 concentration was 0.4M;

[0189] (5) Perform constant current electrochemical deposition with a current density of 20 mA / cm 2 , the deposition time is 900s, and a NiCoFe active layer is deposited on the NiCu substrate to obtain the NiCu@NiCoFe electrocatalyst;

[0190] (6) The NiCu@NiCoFe electrocatalyst was soaked in ultrapure water for 3 times, each time for 5 min; after washing, it was placed in a vacuum freeze dryer and dried for 2 h.

[0191] The electrocatalyst prepared in Comparative Example 2 is composed of Ni, Fe, Cu, and Co. The energy dispersion spectrum component analysis shows that ( Figure 27 ), wherein the Ni content is 68.2at%, the Fe content is 21.7at%, the Cu content is 2.3at%, and the Co content is 7.8at%. After cleaning and activation, the oxygen evolution overpotential on its surface is 225mV, and the oxygen evolution potential is taken as the current density of 10mA / cm 2 The applied potential ( Figure 28 ), due to the high iron content in the active layer, the coating will not be dense. During the electrochemical test, the iron will continue to corrode and dissolve into the electrolyte. The active layer will fall off during the electrochemical test ( Figure 29 ). The electrochemical stability of the catalyst decreased, and the overpotential increased by more than 10 mV within one hour.

[0192] Comparative Example 3

[0193] A preparation method of a NiCu@NiCoFe oxygen evolution electrocatalyst, specifically comprising the following steps:

[0194] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; the electrolyte formula was: the concentration of NiSO4 was 0.2 M, the concentration of CuSO4 was 0.0075 M, the concentration of (NH4)2SO4 was 1.2 M, the concentration of Na3C6H5O7 was 0.5 M, and the concentration of H3BO3 was 0.7 M;

[0195] (2) Constant current electrochemical deposition was performed, and the current density of the constant current deposition was 4 A / cm 2 , and the deposition time was 45 s, to obtain a hierarchical porous NiCu substrate;

[0196] (3) The NiCu substrate was soaked in ultrapure water for more than 3 times, each time for 5 min; after cleaning, it was placed in a vacuum freeze dryer for drying for 2 h;

[0197] (4) The NiCu substrate was used as the working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; the electrolyte formula was: the concentration of NiSO4 was 0.09 M, the concentration of FeSO4 was 0.09 M, the concentration of CoSO4 was 0.03 M, the concentration of NH4Cl was 0.28 M, and the concentration of H3BO3 was 0.4 M;

[0198] (5) Constant current electrochemical deposition was performed, and the current density of the constant current deposition was 20 mA / cm 2 , and the deposition time was 900 s, to deposit a NiCoFe active layer on the NiCu substrate, to obtain a NiCu@NiCoFe electrocatalyst;

[0199] (6) The NiCu@NiCoFe electrocatalyst was soaked in ultrapure water for 3 times, each time for 5 min; after cleaning, it was placed in a vacuum freeze dryer for drying for 2 h.

[0200] The NiCu@NiCoFe electrocatalyst prepared in Comparative Example 3 was composed of Ni, Fe, Cu and Co, and energy dispersive spectrum composition analysis showed that Figure 30 , the content of Ni was 63.0 at%, the content of Fe was 12.5 at%, the content of Cu was 6.8 at%, and the content of Co was 17.7 at%. Due to the increase of the contents of Na3C6H5O7 and H3BO3, the deposition of Ni was inhibited, the content of Ni in the NiCu substrate decreased, the content of Cu increased, and the NiCu material dissolved in the plating solution, so that the NiCu@NiCoFe electrocatalyst could not be actually obtained.

[0201] Comparative Example 4

[0202] A method for preparing a NiCu@NiCoFe oxygen evolution electrocatalyst comprises the following steps:

[0203] (1) The working electrode was placed in a mixed solution of NiSO4, CuSO4, Na3C6H5O7, H3BO3, and (NH4)2SO4; the electrolyte formula was: NiSO4 concentration was 0.2M, CuSO4 concentration was 0.2M, (NH4)2SO4 concentration was 1.2M, Na3C6H5O7 concentration was 0.3M, and H3BO3 concentration was 0.4M;

[0204] (2) Perform constant current electrochemical deposition with a current density of 4 A / cm 2 , the deposition time was 45 s, and a hierarchically porous NiCu substrate was obtained;

[0205] (3) Soak the NiCu substrate in ultrapure water for more than 3 times, each time for 5 minutes; after cleaning, place it in a vacuum freeze dryer and dry it for 2 hours;

[0206] (4) The NiCu substrate was used as the working electrode and placed in a mixed solution of NiSO4, FeSO4, CoSO4, H3BO3, and NH4Cl; the electrolyte formula was: NiSO4 concentration was 0.09M, FeSO4 concentration was 0.09M, CoSO4 concentration was 0.03M, NH4Cl concentration was 0.28M, and H3BO3 concentration was 0.4M;

[0207] (5) Perform constant current electrochemical deposition with a current density of 20 mA / cm 2 , the deposition time is 900s, and a NiCoFe active layer is deposited on the NiCu substrate to obtain the NiCu@NiCoFe electrocatalyst;

[0208] (6) The NiCu@NiCoFe electrocatalyst was soaked in ultrapure water for 3 times, each time for 5 min; after washing, it was placed in a vacuum freeze dryer and dried for 2 h.

[0209] The electrocatalyst prepared in Comparative Example 4 is composed of Ni, Fe, Cu, and Co. The energy dispersion spectrum component analysis shows that ( Figure 31 ), wherein the Ni content is 67.1at%, the Fe content is 8.1at%, the Cu content is 13.3at%, and the Co content is 11.5at%. After cleaning and activation, the oxygen evolution overpotential on its surface is 236mV, and the oxygen evolution potential is taken as the current density of 10mA / cm 2 The applied potential ( Figure 32). But Cu in the dendritic structure is easy to dissolve in the process of electroplating active layer, leading to the collapse of the catalyst structure, making the active layer and the substrate poor in binding force, easy to fall off Figure 33 ), the overpotential will increase by more than 20 mV within one hour of electrochemical performance test.

Claims

1. A high stability NiCu@NiCoFe oxygen evolution electrocatalyst, characterized in that: The NiCu substrate and the NiCoFe active layer loaded on the NiCu substrate by electrodeposition; wherein the NiCu substrate is a three-dimensional network skeleton structure, and a plurality of nanopores are distributed on the skeleton; the NiCoFe active layer is composed of NiCoFe nanoparticles deposited on the skeleton and the nanopore walls of the skeleton; the skeleton structure has three-dimensionally connected micropores with a pore size of 0.2-25 μm; a large number of dendritic structures are grown on the skeleton structure of the NiCu substrate, and the size of the dendritic structures is 0.2-8 μm; in the NiCu substrate, the content of Ni in the NiCu alloy is 95 at%, and the content of Cu is 5.0 at%; wherein, in the NiCoFe active layer, the content of Ni in the NiCoFe is 33-75 at%, the content of Co is 15-50 at%, and the content of Fe is 10-30 at%.

2. The high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of claim 1, wherein: The thickness of the NiCoFe active layer is 10-60 nm.

3. The high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of claim 1, wherein: The NiCu@NiCoFe electrocatalyst has a NiCoFe active layer on the NiCu substrate, and the loading of the NiCoFe active layer on the NiCu substrate is 0.6-20 mg / cm 2 .

4. The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst of claim 1, characterized in that, Specifically comprising the following steps: (1) placing a working electrode in a mixed solution containing NiSO4, CuSO4, Na3C6H5O7, H3BO3 and (NH4)2SO4; in the mixed solution, the concentrations of the respective compounds are: the concentration of NiSO4 is 0.2 M, the concentration of CuSO4 is 0.0075 M, the concentration of (NH4)2SO4 is 1.2 M, the concentration of Na3C6H5O7 is 0.3 M, and the concentration of H3BO3 is 0.4 M; (2) obtaining a hierarchical porous NiCu substrate by constant current electrochemical deposition; (3) rinsing the NiCu substrate with ultrapure water and then performing vacuum freeze-drying treatment; (4) placing the NiCu substrate as a working electrode in a mixed solution containing NiSO4, FeSO4, CoSO4, H3BO3 and NH4Cl; in the mixed solution, the concentrations of the respective compounds are: the concentration of NiSO4 is 0.03-0.18 M, the concentration of FeSO4 is 0.03-0.09 M, the concentration of CoSO4 is 0.03-0.15 M, the concentration of NH4Cl is 0.28 M, and the concentration of H3BO3 is 0.4 M; (5) depositing a NiCoFe active layer on the NiCu substrate by constant current electrochemical deposition to obtain a NiCu@NiCoFe oxygen evolution electrocatalyst; (6) rinsing the NiCu@NiCoFe oxygen evolution electrocatalyst with ultrapure water and then performing vacuum freeze-drying.

5. The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst according to claim 4, characterized in that: In step (2), the current density of the constant current deposition was 4 A / cm 2 , and the deposition time was 45 s.

6. The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst according to claim 4, characterized in that: In step (3), the NiCu substrate is soaked with ultrapure water for more than 3 times, each time for 5 min; the freeze-drying time is more than 2 h; in step (6), the NiCu@NiCoFe electrocatalyst is soaked with ultrapure water for more than 3 times, each time for 5 min; the freeze-drying time is more than 2 h.

7. The preparation method of the high-stability NiCu@NiCoFe oxygen evolution electrocatalyst according to claim 4, characterized in that: In step (5), the current density of the constant current deposition is 5 to 100 mA / cm 2 , and the deposition time is 30 to 1800 s.

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