Electrolytic water catalytic material, preparation method and application thereof

Abstract

The application belongs to the field of electrolysis of water, and particularly relates to an electrolysis of water catalytic material and a preparation method and application thereof. The electrolysis of water catalytic material provided by the application comprises a foamed nickel substrate, a modified nickel nanosheet array formed on the surface of the foamed nickel substrate, and a transition metal-based hydrotalcite deposited on the surface of the modified nickel nanosheet array. The coexistence of the ultrathin nanosheet array formed by in-situ modification on the foamed nickel substrate and the deposited transition metal-based hydrotalcite produces abundant Schottky heterojunction structures, improves the oxygen evolution performance of the catalytic material under a large current density and the stability under a long period, and the catalytic material does not add noble metals, and has a significant price advantage. On this basis, the application preferably introduces an appropriate amount of Mn in the process of depositing the hydrotalcite, introduces holes in the ultrathin nanosheet array, forms a unique hydrophilic-gasophobic nanosheet array, accelerates the oxygen to separate from the catalyst, and further improves the performance of the catalytic material.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrolysis of water, and particularly relates to an electrolysis of water catalytic material and a preparation method and application thereof. BACKGROUND

[0002] As a highly hydrogen-producing environmentally friendly strategy, electrolysis of water plays a crucial role in resolving the contradiction between the increasingly serious energy crisis caused by the gradual depletion of fossil fuels and the increasingly serious environmental pollution caused by excessive carbon emissions. Moreover, hydrogen energy, as a clean energy with high calorific value and no pollution, is the most promising green energy to replace fossil fuels. Electrolysis of water to produce hydrogen is a pollution-free and highest purity hydrogen production method among many hydrogen production methods. However, in practical applications, higher voltage is often required to drive the electrolysis of water, which leads to great energy waste. Therefore, developing high-efficiency and low-cost catalytic materials is the focus of research. Due to the slow kinetics process, the half-reaction of oxygen evolution reaction in electrolysis of water is widely considered to be the rate-limiting step because it involves a four-electron transfer process. Therefore, developing low-cost and high-efficiency anode catalytic materials is the key to improving the overall performance of electrolysis of water.

[0003] In view of the current domestic and foreign research on catalysts for alkaline electrolysis of water to produce hydrogen, although there are many reported catalysts in the literature, there are few reports on testing under high current density (1 A / cm 2 ) close to industrial conditions, and even fewer performance tests of catalysts assembled into membrane electrodes. Most of the catalysts are studied at low current density (<100 mA / cm 2 ), which has a large gap with the actual industrial working conditions (1000 mA / cm 2 ).

[0004] In current industrial production processes, high-performance catalysts mostly use noble metal ruthenium and iridium oxides as catalysts to improve the performance of the oxygen evolution reaction. However, noble metal ruthenium and iridium oxides are expensive and have a low reserve, which makes the cost of hydrogen production relatively high, limiting the widespread application of this type of catalyst. Ni, Co, Fe, and Mn are the most widely used catalyst materials among transition metals, and due to their unique electronic structure, they are widely used in the design of electrolysis of water catalysts by researchers. Patents CN107881530A and CN110586196A respectively designed a Ni-Co-based and a Ni-Fe-based electrolysis of water catalyst and applied them to the performance evaluation of electrolysis of water. In laboratory low-current density tests, both showed comparable performance to noble metal catalysts (ruthenium and iridium oxides). However, these catalysts have a low operating current density (the current density is usually lower than 100 mA / cm 2However, these advanced non-noble metal catalysts still have some limitations, such as short operation period, which cannot meet the industrial operation requirements, and so on. In addition, due to the limitations of amplification and macroscopic quality manufacturing methods, these advanced non-noble metal catalysts are difficult to be amplified to large-area electrodes, and thus cannot be mass-produced for real commercial applications. Therefore, multifunctional catalyst systems (with large current, high activity and easy amplification production) that can be effectively applied under industrial conditions are crucial for promoting the development of hydrogen energy from the basic to the practical application.

[0005] Under high current density, the mass transfer effect of the oxygen evolution reaction (OER) process involves the adsorption / dissipation of reactants (OH - , H2O) and the formation / detachment of bubbles on the catalyst surface. The high-speed OER process rapidly consumes the reactants near the catalyst surface, and the enhancement of concentration polarization can lead to a decline in catalytic performance. Therefore, it is important to achieve the required reactant concentration on the catalyst surface to enhance the electrochemical reaction under high current density. In addition, under high current density conditions, a large amount of O2 bubbles will be generated on the oxygen evolution electrode, and the disturbance caused by a large amount of bubbles will cause mechanical stress and severe vibration on the catalyst surface, thereby affecting the physical stability of the catalyst and membrane electrode surface, such as structural failure or catalyst loss, which further leads to a decline in catalytic performance. In particular, during the OER process, dissolution occurs on the catalyst surface, especially under high current density and strong oxidation potential, leading to chemical instability of the catalyst. In particular, many catalysts still cannot adapt to the volatility of green electricity (photovoltaic power generation, solar power generation) and cannot be operated for a long period under fluctuating power supply conditions. These factors greatly limit the development of high-performance OER catalysts under high current density. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a water electrolysis catalyst material and a preparation method and application thereof. The catalyst material provided by the present application has good oxygen evolution performance and long-period stability under high current density, and no noble metal is added to the catalyst material, which has a significant price advantage. The preparation method provided by the present application is simple and easy to operate, environmentally friendly, and suitable for industrial production.

[0007] The present application provides a water electrolysis catalyst material, comprising: a foam nickel substrate, a modified nickel nanosheet array formed on the surface of the foam nickel substrate, and a transition metal-based hydrotalcite deposited on the surface of the modified nickel nanosheet array.

[0008] The modified nickel nanosheet array is a sulfur-modified nickel nanosheet array, a selenium-modified nickel nanosheet array, or a phosphorus-modified nickel nanosheet array.

[0009] The transition metal elements in the transition metal-based hydrotalcite include at least two of Ni, Fe, Mn, and Co.

[0010] Preferably, the transition metal element in the transition metal-based hydrotalcite comprises Mn; the modified nickel nanosheet array and the transition metal-based hydrotalcite deposited thereon form a hydrophilic-gas-repellent porous nanosheet array.

[0011] Preferably, the transition metal-based hydrotalcite is a nickel-manganese hydrotalcite.

[0012] The present application provides a preparation method of an electrolytic water catalytic material, comprising the following steps:

[0013] a) modifying the foam nickel substrate in situ by nanosheeting with a modifier, and forming a modified nickel nanosheet array on the surface of the foam nickel substrate after the modification is completed;

[0014] In step a), the modifier is a sulfur source modifier, a selenium source modifier or a phosphorus source modifier; the sulfur source modifier is sulfur and / or a sulfur-containing compound, the selenium source modifier is selenium and / or a selenium-containing compound, and the phosphorus source modifier is phosphorus and / or a phosphorus-containing compound.

[0015] b) placing the foam nickel substrate modified in step a) in a solution of a transition metal source, and depositing the transition metal source in the solution in a hydrotalcite structure on the surface of the modified nickel nanosheet array by electrodeposition to obtain an electrolytic water catalytic material;

[0016] In step b), the transition metal source is at least two of a Ni source, a Fe source, a Mn source and a Co source.

[0017] Preferably, in step a), the ratio of the molar amount of the modifier to the volume of the foam nickel substrate is (5-150) mmol:0.2 cm 3 .

[0018] Preferably, in step a), the modification method is a hydrothermal method, an immersion method or a vapor deposition method.

[0019] Preferably, in step b), the transition metal source is a Ni source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms is 3:(1-9); or the transition metal source is a Ni source and a Co source, the molar ratio of the Ni source in terms of Ni atoms to the Co source in terms of Co atoms is 3:(1-9); or the transition metal source is a Mn source and a Co source, the molar ratio of the Mn source in terms of Mn atoms to the Co source in terms of Co atoms is 3:(1-9); or the transition metal source is a Ni source and a Fe source, the molar ratio of the Ni source in terms of Ni atoms to the Fe source in terms of Fe atoms is 3:(1-9); or the transition metal source is a Ni source, a Fe source and a Co source, the molar ratio of the Ni source in terms of Ni atoms, the Fe source in terms of Fe atoms to the Co source in terms of Co atoms is 3:(1-9):(1-9); or the transition metal source is a Ni source, a Fe source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms, the Fe source in terms of Fe atoms to the Mn source in terms of Mn atoms is 3:(1-9):(1-9); or the transition metal source is a Ni source, a Co source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms, the Co source in terms of Co atoms to the Mn source in terms of Mn atoms is 3:(1-9):(1-9); or the transition metal source is a Co source, a Fe source and a Mn source, the molar ratio of the Co source in terms of Co atoms, the Fe source in terms of Fe atoms to the Mn source in terms of Mn atoms is 3:(1-9):(1-9).

[0020] In step b), the total ion concentration of the transition metal source in the solution is 0.1-3 mol / L.

[0021] Preferably, in step b), the transition metal source is a Ni source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms is 3:(2-4); the total ion concentration of the transition metal source in the solution is 0.5-2 mol / L.

[0022] Preferably, in step b), the deposition potential of the electrodeposition is-0.2--0.01 V; the deposition time of the electrodeposition is 1-60 min.

[0023] The present application provides a method for electrolyzing water, wherein the catalyst used in the electrolysis process is the electrolytic water catalyst material described in the above technical solution or the electrolytic water catalyst material prepared by the preparation method described in the above technical solution.

[0024] Compared with the prior art, the application provides an electrolytic water catalytic material and a preparation method and application thereof. The electrolytic water catalytic material provided by the application comprises a foam nickel substrate, a modified nickel nanosheet array formed on the surface of the foam nickel substrate, and a transition metal-based hydrotalcite deposited on the surface of the modified nickel nanosheet array; the modified nickel nanosheet array is a sulfur-modified nickel nanosheet array, a selenium-modified nickel nanosheet array, or a phosphorus-modified nickel nanosheet array; and the transition metal elements in the transition metal-based hydrotalcite include at least two of Ni, Fe, Mn, and Co. The catalytic material provided by the application produces a rich Schottky heterojunction structure through the coexistence of the ultrathin nanosheet array formed by in-situ modification on the foam nickel substrate and the deposited transition metal-based hydrotalcite, thereby increasing the effective active area of the catalytic material, optimizing the surface structure of the catalytic material, and improving the oxygen evolution performance of the catalytic material under a large current density and the stability of the catalytic material under a long period; and no noble metal is added in the catalytic material, and the catalytic material has a significant price advantage compared with a ruthenium, iridium, or other noble metal catalytic material. On this basis, the catalytic material provided by the application can form a certain number of air-avoiding pores on the surface of the material by introducing an appropriate amount of Mn in the process of depositing the hydrotalcite, so as to construct an ultrahydrophilic-air-avoiding porous nanosheet array on the surface of the material, and further improve the oxygen evolution performance of the catalytic material under a large current density and the stability of the catalytic material under a long period. The preparation method provided by the application comprises the following steps: a) using a modifier to perform in-situ nanosheet modification on a foam nickel substrate, and forming a modified nickel nanosheet array on the surface of the foam nickel substrate after the modification is completed; in step a), the modifier is a sulfur source modifier, a selenium source modifier, or a phosphorus source modifier; the sulfur source modifier is sulfur and / or a sulfur-containing compound, the selenium source modifier is selenium and / or a selenium-containing compound, and the phosphorus source modifier is phosphorus and / or a phosphorus-containing compound; b) placing the foam nickel substrate subjected to the modification treatment in step a) in a solution of a transition metal source, and depositing the transition metal source in the solution in a hydrotalcite structure on the surface of the modified nickel nanosheet array by electrodepositing to obtain an electrolytic water catalytic material; in step b), the transition metal source is at least two of a Ni source, a Fe source, a Mn source, and a Co source. The preparation method provided by the application combines a modification method and an electrodeposition method, and has the advantages of simple operation, good economy, small environmental pollution, and easy realization of large-scale production. Experimental results show that the catalytic material provided by the application has excellent electrocatalytic performance in the process of electrolytic water oxygen evolution, can drive a current density of 1000 mA·cm -2 only with a voltage of not more than 400 mV, and has a performance retention rate of > 90% and good oxygen evolution stability after a test under a condition of 1000 mA·cm -2 for 2000 h. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only a part of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on the drawings provided are within the scope of the present application.

[0026] Figure 1 is an SEM image of the material of Example 3 provided by the present application;

[0027] Figure 2 is an SEM image of the material of Example 4 provided by the present application;

[0028] Figure 3 is a TEM image of the material of Example 4 provided by the present application at different magnifications;

[0029] Figure 4 is a TEM image of the material of Comparative Example 1 provided by the present application;

[0030] Figure 5 is a TEM image of the material of Comparative Example 2 provided by the present application;

[0031] Figure 6 is a linear sweep voltammetry curve diagram corresponding to the materials of different examples and comparative examples provided by the present application;

[0032] Figure 7 is a Tafel slope diagram corresponding to the materials of different examples and comparative examples provided by the present application;

[0033] Figure 8 is a constant current stability test diagram of the material of Example 4 provided by the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present application.

[0035] The present application provides an electrolytic water catalytic material, comprising: a foamed nickel substrate, a modified nickel nanosheet array formed on the surface of the foamed nickel substrate, and a transition metal-based hydrotalcite deposited on the surface of the modified nickel nanosheet array.

[0036] In the electrolytic water catalytic material provided by the application, the porosity of the foam nickel substrate (NF for short) is preferably greater than or equal to 98%; the thickness of the foam nickel substrate is preferably 0.05-0.2 cm, and can be specifically 0.05 cm, 0.06 cm, 0.07 cm, 0.08 cm, 0.09 cm, 0.1 cm, 0.11 cm, 0.12 cm, 0.12 cm, 0.14 cm, 0.15 cm, 0.16 cm, 0.17 cm, 0.18 cm, 0.19 cm or 0.2 cm.

[0037] In the electrolytic water catalytic material provided by the application, the modified nickel nanosheet array (Ni-X for short) is a sulfur-modified nickel nanosheet array (Ni-S for short), a selenium-modified nickel nanosheet array (Ni-Se for short) or a phosphorus-modified nickel nanosheet array (Ni-P for short).

[0038] In the electrolytic water catalytic material provided by the application, the modified nickel nanosheet array is formed by in-situ nanosheet modification of the foam nickel substrate, and the modifier used is a sulfur source modifier, a selenium source modifier or a phosphorus source modifier. The sulfur source modifier is preferably sulfur and / or a sulfur-containing compound, and can be specifically one or more of sulfur powder, thioacetamide, sodium sulfide and thiourea; the selenium source modifier is preferably selenium and / or a selenium-containing compound, and can be specifically selenium powder and / or selenium dioxide; the phosphorus source modifier is preferably phosphorus and / or a phosphorus-containing compound, and can be specifically one or more of potassium hypophosphite, potassium dihydrogen phosphate, red phosphorus and sodium hypophosphite; and the ratio of the molar amount of the modifier to the volume of the foam nickel substrate is preferably (5-150) mmol:0.2 cm 3 , and can be specifically 5 mmol:0.2 cm 3 , 6 mmol:0.2 cm 3 , 7 mmol:0.2 cm 3 , 7.35 mmol:0.2 cm 3 , 8 mmol:0.2 cm 3 , 9 mmol:0.2 cm 3 , 10 mmol:0.2 cm 3 , 15 mmol:0.2 cm 3 , 20 mmol:0.2 cm 3 , 25 mmol:0.2 cm 3 , 30 mmol:0.2 cm 3 , 35 mmol:0.2 cm 3 , 40 mmol:0.2 cm 3 , 45 mmol:0.2 cm 3 , 50 mmol:0.2 cm 3 , 55 mmol:0.2 cm 3, 60 mmol: 0.2 cm 3 , 65 mmol: 0.2 cm 3 , 70 mmol: 0.2 cm 3 , 75 mmol: 0.2 cm 3 , 80 mmol: 0.2 cm 3 , 85 mmol: 0.2 cm 3 , 90 mmol: 0.2 cm 3 , 95 mmol: 0.2 cm 3 , 100 mmol: 0.2 cm 3 , 110 mmol: 0.2 cm 3 , 120 mmol: 0.2 cm 3 , 130 mmol: 0.2 cm 3 , 140 mmol: 0.2 cm 3 , or 150 mmol: 0.2 cm 3 ; the modification method is preferably a hydrothermal method, a soaking method or a vapor deposition method.

[0039] In the electrolytic water catalytic material provided by the application, the transition metal elements in the transition metal-based hydrotalcite (referred to as x LDH) include at least two of Ni, Fe, Mn and Co; and the transition metal-based hydrotalcite can be specifically nickel-manganese hydrotalcite (NiMn LDH), nickel-cobalt hydrotalcite (NiCo LDH), manganese-cobalt hydrotalcite (MnCo LDH), nickel-iron hydrotalcite (NiFe LDH), nickel-iron-cobalt hydrotalcite (NiFeCo LDH), nickel-iron-manganese hydrotalcite (NiFeMn LDH), nickel-cobalt-manganese hydrotalcite (NiCoMn LDH) or cobalt-iron-manganese hydrotalcite (CoFeMn LDH).

[0040] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni to Mn in the nickel-manganese hydrotalcite is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0041] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni to Co in the nickel-cobalt hydrotalcite is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0042] In the electrolytic water catalytic material provided by the application, the molar ratio of Mn to Co in the manganese-cobalt hydrotalcite is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0043] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni to Fe in the nickel-iron hydrotalcite is preferably 3:(1-9), and specifically can be 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0044] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni, Fe and Co in the nickel-iron-cobalt hydrotalcite is preferably 3:(1-9):(1-9), wherein the molar ratio of Ni to Fe is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of Ni to Co is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0045] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni, Fe and Mn in the nickel-iron-manganese hydrotalcite is preferably 3:(1-9):(1-9), wherein the molar ratio of Ni to Fe is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of Ni to Mn is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0046] In the electrolytic water catalytic material provided by the application, the molar ratio of Ni, Co and Mn in the nickel-cobalt-manganese hydrotalcite is preferably 3:(1-9):(1-9), wherein the molar ratio of Ni to Co is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of Ni to Mn is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0047] In the electrolytic water catalytic material provided by the application, the molar ratio of Co, Fe and Mn in the cobalt-iron-manganese hydrotalcite is preferably 3:(1-9):(1-9), wherein the molar ratio of Co to Fe is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of Co to Mn is specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0048] In the electrolytic water catalytic material provided by the present application, the transition metal element in the transition metal-based hydrotalcite is preferably Mn, i.e. manganese-based hydrotalcite. In the present application, by introducing a certain amount of Mn element, the modified nickel nanosheet array and the transition metal-based hydrotalcite deposited thereon form a hydrophilic-gasophobic porous nanosheet array, thereby improving the oxygen evolution performance of the catalytic material under a large current density and the stability under a long period. In the present application, for the electrolytic water catalytic material with manganese-based hydrotalcite deposited on the surface, the performance is optimal when the manganese-based hydrotalcite is nickel-manganese hydrotalcite.

[0049] The present application also provides a preparation method of the electrolytic water catalytic material, comprising the following steps:

[0050] a) modifying the foam nickel substrate in situ by nanosheeting with a modifier, and forming a modified nickel nanosheet array on the surface of the foam nickel substrate after the modification is completed;

[0051] b) placing the foam nickel substrate modified in step a) in a solution of a transition metal source, and depositing the transition metal source in the solution in a hydrotalcite structure on the surface of the modified nickel nanosheet array by electrodeposition to obtain the electrolytic water catalytic material.

[0052] In the preparation method provided by the present application, in step a), the modifier is a sulfur source modifier, a selenium source modifier or a phosphorus source modifier; wherein the sulfur source modifier is preferably sulfur and / or a sulfur-containing compound, and specifically can be one or more of sulfur powder, thioacetamide, sodium sulfide and thiourea; the selenium source modifier is preferably selenium and / or a selenium-containing compound, and specifically can be selenium powder and / or selenium dioxide; the phosphorus source modifier is preferably phosphorus and / or a phosphorus-containing compound, and specifically can be one or more of potassium hypophosphite, potassium dihydrogen phosphate, red phosphorus and sodium hypophosphite; and the ratio of the molar amount of the modifier to the volume of the foam nickel substrate is preferably (5-150) mmol:0.2 cm 3 , and specifically can be 5 mmol:0.2 cm 3 , 6 mmol:0.2 cm 3 , 7 mmol:0.2 cm 3 , 7.35 mmol:0.2 cm 3 , 8 mmol:0.2 cm 3 , 9 mmol:0.2 cm 3 , 10 mmol:0.2 cm 3 , 15 mmol:0.2 cm 3 , 20 mmol:0.2 cm 3 , 25 mmol:0.2 cm 3 , 30 mmol:0.2 cm 3 , 35 mmol:0.2 cm 3 , 40 mmol:0.2 cm3 45 mmol: 0.2 cm 3 50 mmol: 0.2 cm 3 55 mmol: 0.2 cm 3 60 mmol: 0.2 cm 3 65 mmol: 0.2 cm 3 70 mmol: 0.2 cm 3 75 mmol: 0.2 cm 3 80 mmol: 0.2 cm 3 85 mmol: 0.2 cm 3 90 mmol: 0.2 cm 3 95 mmol: 0.2 cm 3 100 mmol: 0.2 cm 3 110 mmol: 0.2 cm 3 120 mmol: 0.2 cm 3 130 mmol: 0.2 cm 3 140 mmol: 0.2 cm 3 or 150 mmol: 0.2 cm 3 .

[0053] In the preparation method provided by the application, in step a), the modification method is preferably a hydrothermal method, a soaking method or a vapor deposition method; wherein the treatment temperature of the hydrothermal method is preferably 200-250°C; the treatment temperature of the soaking method is preferably 10-70°C; and the treatment temperature of the vapor deposition method is preferably 200-350°C.

[0054] In the preparation method provided by the application, in step a), when the modifier used is a sulfur source modifier, the specific operation process of modification preferably comprises: soaking the foamed nickel substrate in a sulfur source modifier solution, washing and drying after taking out, to obtain sulfur-modified foamed nickel (referred to as Ni-S / NF), and a sulfur-modified nickel nanosheet array is formed on the surface of the sulfur-modified foamed nickel. Preferably, the solvent of the sulfur source modifier solution is water; the concentration of the sulfur source modifier solution is preferably 0.5-1.5 mol / L, and can be specifically 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L; the temperature of the soaking is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the time of the soaking is preferably 5-15 h, and can be specifically 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h; the washing mode is preferably alternating water washing and ethanol washing; the drying mode is preferably vacuum drying; the drying temperature is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; and the drying time is preferably 12-48 h, and can be specifically 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h.

[0055] In the preparation method provided by the application, in step a), when the modifier used is a selenium source modifier, the specific operation process of modification preferably comprises: soaking the foamed nickel substrate in a selenium source modifier solution, washing and drying after taking out, to obtain selenium-modified foamed nickel (referred to as Ni-Se / NF), and a selenium-modified nickel nanosheet array is formed on the surface of the selenium-modified foamed nickel. Preferably, the solvent of the selenium source modifier solution is ethanol; the concentration of the selenium source modifier solution is preferably 0.5-1.5 mol / L, and can be specifically 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L; the temperature of the soaking is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the time of the soaking is preferably 5-15 h, and can be specifically 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h; the washing mode is preferably alternating water washing and ethanol washing; the drying mode is preferably vacuum drying; the drying temperature is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; and the drying time is preferably 12-48 h, and can be specifically 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h.

[0056] In the preparation method provided by the application, in step a), when the modifier used is a phosphorus source modifier, the specific operation process of modification preferably comprises: placing the phosphorus source modifier upstream of a tube furnace, placing the foamed nickel substrate downstream of the tube furnace, carrying out vapor deposition in a protective gas atmosphere, washing and drying after taking out, to obtain phosphorus-modified foamed nickel (referred to as Ni-P / NF), and a phosphorus-modified nickel nanosheet array is formed on the surface of the phosphorus-modified foamed nickel. Preferably, the protective gas comprises but is not limited to nitrogen; the temperature of the vapor deposition is preferably 250-350°C, and can be specifically 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C or 350°C; the time of the vapor deposition is preferably 1-5 h, and can be specifically 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h; the washing mode is preferably alternating water washing and ethanol washing; the drying mode is preferably vacuum drying; the drying temperature is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; and the drying time is preferably 12-48 h, and can be specifically 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h.

[0057] In the preparation method provided by the application, in step b), the transition metal source is at least two of a Ni source, a Fe source, a Mn source and a Co source; wherein the Ni source is preferably one or more of nickel acetate, nickel sulfate, nickel carbonate, nickel nitrate and acetylacetone nickel dihydrate; the Fe source is preferably one or more of iron nitrate, iron chloride, iron sulfate, iron acetate and acetylacetone iron; the Mn source is preferably one or more of manganese nitrate, manganese chloride and manganese acetate; and the Co source is preferably one or more of cobalt nitrate, cobalt chloride, cobalt acetate and acetylacetone cobalt.

[0058] In the preparation method provided by the present application, in step b), by adjusting the type and ratio of the transition metal source used, a hydrotalcite structure with different component compositions can be formed by electrodeposition. In the embodiments provided by the present application, the transition metal source can be a Ni source and a Mn source, and the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source can be a Ni source and a Co source, and the molar ratio of the Ni source in terms of Ni atoms to the Co source in terms of Co atoms is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source can be a Mn source and a Co source, and the molar ratio of the Mn source in terms of Mn atoms to the Co source in terms of Co atoms is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source can be a Ni source and a Fe source, and the molar ratio of the Ni source in terms of Ni atoms to the Fe source in terms of Fe atoms is preferably 3:(1-9), and can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source can be a Ni source, a Fe source and a Co source, and the molar ratio of the Ni source in terms of Ni atoms, the Fe source in terms of Fe atoms and the Co source in terms of Co atoms is preferably 3:(1-9):(1-9), wherein the molar ratio of the Ni source in terms of Ni atoms to the Fe source in terms of Fe atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of the Ni source in terms of Ni atoms to the Co source in terms of Co atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source preferably is a Ni source, a Fe source and a Mn source, and the molar ratio of the Ni source in terms of Ni atoms, the Fe source in terms of Fe atoms and the Mn source in terms of Mn atoms is preferably 3:(1-9):(1-9), wherein the molar ratio of the Ni source in terms of Ni atoms to the Fe source in terms of Fe atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.Alternatively, the transition metal source can be a Ni source, a Co source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms, the Co source in terms of Co atoms and the Mn source in terms of Mn atoms is preferably 3:(1-9):(1-9), wherein the molar ratio of the Ni source in terms of Ni atoms and the Co source in terms of Co atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of the Ni source in terms of Ni atoms and the Mn source in terms of Mn atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9; or the transition metal source can be a Co source, a Fe source and a Mn source, the molar ratio of the Co source in terms of Co atoms, the Fe source in terms of Fe atoms and the Mn source in terms of Mn atoms is preferably 3:(1-9):(1-9), wherein the molar ratio of the Co source in terms of Co atoms and the Fe source in terms of Fe atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9, and the molar ratio of the Co source in terms of Co atoms and the Mn source in terms of Mn atoms can be specifically 3:1, 3:2, 3:3, 3:4, 3:5, 3:6, 3:7, 3:8 or 3:9.

[0059] In the preparation method provided by the application, in step b), the total ion concentration of the transition metal source in the solution of the transition metal source is preferably 0.1-3 mol / L, and can be specifically 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L or 3 mol / L.

[0060] In the preparation method provided by the application, in step b), the transition metal source preferably contains a Mn source. In the application, by introducing a certain amount of Mn element, the modified nickel nanosheet array and the transition metal-based hydrotalcite deposited thereon can form a hydrophilic-gas-repellent porous nanoarray, thereby improving the oxygen evolution performance of the catalytic material under a large current density and the stability under a long period. In the application, the transition metal source is most preferably a Ni source and a Mn source, the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms is preferably 3:(2-4), and specifically can be 3:2, 3:2.3, 3:2.5, 3:2.7, 3:3, 3:3.2, 3:3.5, 3:3.7 or 3:4; and the total ion concentration of the transition metal source in the solution is preferably 0.5-2 mol / L, and specifically can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L or 2 mol / L. In the application, when the above transition metal source, molar ratio and concentration are selected, it is easier to form a hydrophilic-gas-repellent porous nanoarray structure on the surface of the catalytic material, thereby improving the oxygen evolution performance of the finally prepared catalytic material under a large current density and the stability under a long period.

[0061] In the preparation method provided by the application, in step b), the volume ratio of the modified foam nickel substrate to the transition metal source solution is preferably 0.2 cm 3 :(30-100) mL, and specifically can be 0.2 cm 3 :30 mL, 0.2 cm 3 :35 mL, 0.2 cm 3 :40 mL, 0.2 cm 3 :45 mL, 0.2 cm 3 :50 mL, 0.2 cm 3 :55 mL, 0.2 cm 3 :60 mL, 0.2 cm 3 :65 mL, 0.2 cm 3 :70 mL, 0.2 cm 3 :75 mL, 0.2 cm 3 :80 mL, 0.2 cm 3 :85 mL, 0.2 cm 3 :90 mL, 0.2 cm 3 :95 mL, or 0.2 cm 3 :100 mL.

[0062] In the preparation method provided by the application, in step b), the deposition potential of the electrodeposition is preferably -0.2 to -0.01 V, and can be specifically -0.2 V, -0.19 V, -0.18 V, -0.17 V, -0.16 V, -0.15 V, -0.14 V, -0.13 V, -0.12 V, -0.11 V, -0.1 V, -0.09 V, -0.08 V, -0.07 V, -0.06 V, -0.05 V, -0.04 V, -0.03 V, -0.02 V or -0.01 V; and the electrodeposition time is preferably 1 to 60 min, and can be specifically 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0063] In the preparation method provided by the application, in step b), after the electrodeposition is completed, the obtained material is washed and dried. The washing mode is preferably alternating water washing and ethanol washing; the drying mode is preferably vacuum drying; the drying temperature is preferably 50 to 80 DEG C, and can be specifically 50 DEG C, 55 DEG C, 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C or 80 DEG C; and the drying time is preferably 12 to 48 h, and can be specifically 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h.

[0064] The application further provides a method for electrolyzing water, wherein the catalyst used in the electrolysis process is the electrolytic water catalyst material described in the above technical solution or prepared by the preparation method described in the above technical solution. The object of the electrolysis is preferably alkaline water (alkali liquor), more preferably potassium hydroxide aqueous solution, the concentration of the potassium hydroxide aqueous solution is preferably 0.1 to 3 mol / L, more preferably 1 mol / L; and the electrolytic water catalyst material is used as an anode catalyst in the electrolysis process.

[0065] The technical solution provided by the application has the following technical advantages:

[0066] 1) The catalyst material does not contain noble metals, and has a significant price advantage compared with noble metal catalyst materials such as ruthenium and iridium, and the raw materials used are widely available and environmentally friendly;

[0067] 2) The coexistence of the ultra-thin nanosheet array formed by in-situ modification on the foam nickel substrate and the deposited transition metal-based hydrotalcite produces a rich Schottky heterojunction structure, increases the effective active area of the catalyst material, optimizes the surface structure of the catalyst material, and improves the oxygen evolution performance of the catalyst material under a large current density and the stability of the catalyst material under a long period.

[0068] 3) In the preferred technical solution, by introducing an appropriate amount of Mn during the deposition of hydrotalcite, a certain number of air-avoiding holes can be formed on the surface of the material, thereby constructing a super-hydrophilic-air-avoiding porous nano array on the surface of the material, and further improving the oxygen evolution performance of the catalytic material under a large current density and the stability under a long period;

[0069] 4) The catalytic material is prepared by combining the modification method with the electrodeposition method, which is simple to operate, good in economy, small in environmental pollution, and easy to realize large-scale production.

[0070] For a clearer understanding, the following examples are described in detail below.

[0071] Example 1

[0072] The Ni-S / NF material is prepared by the following steps:

[0073] The foam nickel (specification: 2 cm x 1 cm x 0.1 cm, porosity: 98%) is immersed in 120 mL of 0.5 mol / L sulfur powder aqueous solution, soaked at 80°C for 4 h, then taken out, and after natural cooling, washed with deionized water and ethanol alternately for 3-8 times, dried in a vacuum oven at 60°C for 24 h, to obtain in-situ ultra-thin nanosheet modified foam nickel, marked as Ni-S / NF.

[0074] Example 2

[0075] The Ni-Se / NF material is prepared by the following steps:

[0076] A 1.0 mol / L concentration of selenium powder ethanol solution 120 mL is prepared, stirred at a temperature of 80°C for 30 min, then the foam nickel (specification: 2 cm x 1 cm x 0.1 cm, porosity: 98%) is immersed in the 80°C solution for 10 h, washed with deionized water and ethanol for 3-8 times after taking out, dried in a vacuum oven at 60°C for 24 h, to obtain in-situ ultra-thin nanosheet modified foam nickel, marked as Ni-Se / NF.

[0077] Example 3

[0078] The Ni-P / NF material is prepared by the following steps:

[0079] 1.0 g of potassium dihydrogen phosphate is placed on the upstream of the tube furnace, and the foam nickel (specification: 2 cm x 1 cm x 0.1 cm, porosity: 98%) is placed on the downstream of the tube furnace, and the temperature is maintained at 350°C in a nitrogen atmosphere, and the gas phase deposition is carried out for 2 h, and the obtained material is washed with deionized water and ethanol alternately for 3-8 times, and dried in a vacuum oven at 60°C for 24 h, to obtain in-situ ultra-thin nanosheet modified foam nickel, marked as Ni-P / NF.

[0080] Example 4

[0081] The NiMn LDH / Ni-P / NF material was prepared by the following steps:

[0082] An electrodeposition electrolyte was prepared, and the molar ratio of metal sources was nNi:nMn = 1:1, and the total ion concentration of metal sources was 1.0 mo / L. Nickel nitrate and manganese nitrate were fully dissolved in 50 mL of deionized water to obtain the electrodeposition electrolyte. The Ni-P / NF prepared in Example 3 (specification: 2 cm x 1 cm x 0.1 cm) was placed into the above electrodeposition electrolyte, and the deposition potential was fixed at -1 V for 7 minutes. Finally, the obtained material was alternately washed with deionized water and ethanol for 3-8 times, and vacuum dried at 60°C for 24 h to obtain a composite catalytic material with super-hydrophilic-gas-repellent porous nano-array, which was marked as NiMn LDH / Ni-P / NF.

[0083] Examples 5-11

[0084] The composition of the electrodeposition solution in Example 4 was changed, and the molar ratio of metal sources in different electrodeposition electrolytes was controlled as follows: nNi:nCo = 1:1, nMn:nCo = 1:1, nNi:nFe = 1:1, nNi:nFe:nCo = 2:3:3, nNi:nFe:nMn = 2:3:3, nNi:nCo:nMn = 2:3:3, nCo:nFe:nMn = 2:3:3, and the total ion concentration of metal sources was 1.0 mo / L. The metal sources used were nickel nitrate, cobalt nitrate, iron nitrate, and manganese nitrate. The rest was the same as Example 4, and a series of composite catalytic materials were prepared.

[0085] Example 12

[0086] The Ni-P / NF in Example 4 was replaced with the Ni-S / NF prepared in Example 1, and the rest was the same as Example 4 to prepare a composite catalytic material.

[0087] Example 13

[0088] The Ni-P / NF in Example 4 was replaced with the Ni-Se / NF prepared in Example 2, and the rest was the same as Example 4 to prepare a composite catalytic material.

[0089] Comparative Example 1

[0090] The molar ratio of metal sources in Example 4 was adjusted to nNi:nMn = 1:0, and the rest was the same as Example 4 to prepare a composite catalytic material.

[0091] Comparative Example 2

[0092] The ratio of the amount of substance of the metal source in Example 4 was adjusted to nNi:nMn = 1:2, and the rest was the same as in Example 4 to prepare a composite catalytic material.

[0093] Comparative Example 3

[0094] A certain commercial yttrium oxide catalytic material.

[0095] Micro-morphology observation

[0096] (1) Scanning electron microscopy (SEM) observation of the Ni-P / NF material prepared in Example 3 and the NiMn LDH / Ni-P / NF material prepared in Example 4, the results are shown in Figures 1-2 , wherein Figure 1 is an SEM image of the material of Example 3 provided by the application, Figure 2 is an SEM image of the material of Example 4 provided by the application. As can be seen from Figure 1 , the micro-morphology of the Ni-P / NF material presents a clear lamellar structure. This staggered two-dimensional nanosheet structure can provide a large number of active sites for the reaction and can accelerate the diffusion speed of oxygen to improve the mass transfer efficiency; as can be seen from Figure 2 , the NiMn LDH / Ni-P / NF material successfully deposited NiMn hydrotalcite lamella on the basis of retaining the original two-dimensional nanostructure, and the size of the lamella is obviously smaller than that of Ni-P / NF.

[0097] (2) High-magnification transmission electron microscopy (TEM) observation of the NiMn LDH / Ni-P / NF material prepared in Example 4, the results are shown in Figure 3 , wherein Figure 3 is a TEM image of the material of Example 4 provided by the application at different magnifications. As can be seen from Figure 3 , the NiMn LDH / Ni-P / NF material has an obvious heterojunction structure, and the NiMn hydrotalcite lamella is obviously distributed with a certain number of uniform air holes.

[0098] (4) High-magnification transmission electron microscopy (TEM) observation of the composite catalytic materials prepared in Comparative Example 1 and Comparative Example 2, the results are shown in Figures 4-5 , wherein Figure 4 is a TEM image of the material of Comparative Example 1 provided by the application, Figure 5 is a TEM image of the material of Comparative Example 2 provided by the application. As can be seen from Figures 4-5 , when the content of the Mn source is 0, the catalyst lamella morphology remains good, and the lamella is neat and dense without air holes; when the content of the Mn source is increased to 2 times that of Example 4, the structure collapses and cannot maintain the lamellar structure, showing small fragment morphology.

[0099] Evaluation of electrocatalytic performance

[0100] Using a Princeton PMC 1000 electrochemical workstation at 1000 mA·cm -2 The electrocatalytic performance of the materials prepared in Examples 1-13 and Comparative Examples 1-3 was tested under high current density conditions. The materials prepared in the above examples and comparative examples were used as anode materials (size: 1cm × 1cm × 0.1cm), mercuric oxide electrodes were used as reference electrodes, carbon rods were used as counter electrodes, 1.0 mol / L KOH aqueous solution was used as the electrolyte, and the test temperature was 25℃. The test results are as follows: Figures 6-8 And as shown in Tables 1 and 2. Among them, Figure 6 Linear scan voltammetry curves corresponding to different embodiments and comparative sample materials provided by the present invention. Figure 7 Tafel slope diagrams for different embodiments and comparative materials provided by the present invention. Figure 8 Table 1 shows the constant current stability test results of the material in Example 4 provided by the present invention. Table 2 shows the electrocatalytic oxygen evolution performance data of the materials in different examples and comparative examples, and Table 3 shows the long-term stability data of the materials in different examples and comparative examples.

[0101] Table 1. Electrocatalytic oxygen evolution performance data of different embodiments and comparative materials.

[0102]

[0103]

[0104] Table 2. Long-term stability data of materials from different embodiments and comparative examples.

[0105]

[0106] Combination Figures 6-7 As shown in Table 1, the oxygen evolution performance of catalysts deposited on Ni-P / NF with different metal types of hydrotalcite varies. Furthermore, catalysts prepared using the same hydrotalcite material, NiMn, as a precursor on different Ni-X / NF substrates also exhibit significant differences in performance. However, all materials with Schottky heterojunctions (Examples 4-13) demonstrate good OER performance, requiring only an overpotential of no more than 400 mV to drive an A·cm⁻¹ flow rate. -2 The current density of Example 4 showed the best performance; it can also be seen that the content of the Mn source has a significant impact on the catalyst performance. When the Mn content is zero or too high, the catalytic performance deteriorates. This is further combined with the above... Figures 2-5 It is evident that the appropriate number and size of pores have a significant impact on catalyst performance.

[0107] Combine Table 2 and Figure 8 It can be seen that at a high current density of 1000 mA·cm -2Under the above-mentioned conditions, the optimal catalyst NiMnLDH / Ni-P / NF (Example 4) was tested for a long time, and the potential showed no rising trend at all, but maintained a slightly downward trend, which indicated that the oxygen evolution stability of the catalyst was very good.

[0108] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. An electrolytic water catalytic material, comprising: A foamed nickel substrate, a modified nickel nanosheet array formed on the surface of the foamed nickel substrate, and a transition metal-based hydrotalcite deposited on the surface of the modified nickel nanosheet array; The modified nickel nanosheet array is a phosphorus-modified nickel nanosheet array; The transition metal-based hydrotalcite is a nickel-manganese hydrotalcite, and the molar ratio of Ni to Mn in the nickel-manganese hydrotalcite is 3:(2-4); The modified nickel nanosheet array and the transition metal-based hydrotalcite deposited thereon form a hydrophilic-gas-repellent porous nanosheet array.

2. A method for preparing the water electrolysis catalytic material according to claim 1, comprising the following steps: a) modifying a foamed nickel substrate in situ by nanosheeting using a modifier, and forming a modified nickel nanosheet array on the surface of the foamed nickel substrate after the modification is completed; In step a), the modifier is a phosphorus source modifier, and the phosphorus source modifier is phosphorus and / or a phosphorus-containing compound; b) placing the foamed nickel substrate modified in step a) in a solution of a transition metal source, and depositing the transition metal source in the solution in a hydrotalcite structure on the surface of the modified nickel nanosheet array by electrodeposition to obtain a water electrolysis catalytic material; In step b), the transition metal source is a Ni source and a Mn source, and the molar ratio of the Ni source in terms of Ni atoms to the Mn source in terms of Mn atoms is 3:(2-4).

3. The preparation method according to claim 2, characterized in that, In step a), the ratio of the molar amount of the modifying agent to the volume of the foamed nickel substrate is (5-150) mmol: 0.2 cm 3 .

4. The preparation method according to claim 2, characterized in that, In step a), the method for modification is a hydrothermal method, an immersion method or a vapor deposition method.

5. The preparation method according to claim 2, characterized in that, In step b), the total ion concentration of the transition metal source in the solution is 0.1-3 mol / L.

6. The preparation method according to claim 5, characterized in that, In step b), the total ion concentration of the transition metal source in the solution is 0.5-2 mol / L.

7. The preparation method according to claim 2, characterized in that, In step b), the deposition potential of the electrodeposition is -0.2 to -0.01 V, and the deposition time of the electrodeposition is 1-60 min.

8. A method of electrolyzing water, characterized by, The catalyst used in the electrolysis process is the water electrolysis catalytic material according to claim 1 or the water electrolysis catalytic material prepared by the method according to any one of claims 2-7.

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