A Ni-Fe coating based on solid-state deposition technology and its preparation method and application

Abstract

The present invention relates to a Ni-Fe coating based on solid-state deposition technology and its preparation method and application, belonging to the field of coating technology. The preparation method of the present invention adopts solid-state deposition technology to deposit a mixed powder of Ni and Fe on the surface of a substrate to obtain the Ni-Fe coating; the mass proportion of Ni and Fe in the mixed powder is not less than 30%; the total pressure of the gas in the solid-state deposition technology is 3MPa-4MPa; the temperature of the gas is 700℃-900℃. During the preparation process of the Ni-Fe coating of the present invention, the coating is not easily oxidized, and the finished product area is large, providing more hydrogen channels and reaction sites in practical applications, thereby improving the reaction activity, making the electrode and the electrolyte better in contact, and thus reducing the overpotential. At the same time, the preparation process alleviates the influence of high temperature on the substrate and coating materials, which can not only avoid the oxidation failure and reduced conductivity of the coating material and the substrate material due to high temperature, but also make the combination of the coating and the substrate more firm, effectively extending the working life of the electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a Ni-Fe coating based on solid-state deposition technology, and a preparation method and application thereof. Background Art

[0002] Coal and oil are crucial components of current socioeconomic development. However, overexploitation and consumption of traditional fossil fuels have resulted in significant greenhouse gas emissions, leading to severe environmental pollution and an energy crisis. The research, development, and application of clean, efficient, and renewable energy sources is one of the key solutions to these challenges. The establishment of the "carbon neutrality and carbon peak" policy has clarified the strategic role of hydrogen within the new energy sector and presented significant opportunities for the hydrogen production industry. Among the various hydrogen production technologies, renewable energy-powered water electrolysis holds great promise for scaling up hydrogen production, achieving zero CO2 emissions, reducing fossil fuel use, and improving energy conversion efficiency. Alkaline water electrolysis is one of the most mature hydrogen production technologies and has been widely used due to its high hydrogen production density and simple preparation process. Currently, the commercially available platinum (Pt) electrode for water electrolysis is both expensive and scarce, hindering the large-scale practical application of alkaline water electrolysis. Therefore, the development of highly active, low-cost electrodes is crucial. Researchers have attempted to incorporate nickel (Ni) into Pt and have found that nickel can cleave the H-OH bonds (hydrogen bonds) in water molecules, making it a high-performance electrode material for water electrolysis.

[0003] Currently, there are patents for the preparation of cathode coatings for hydrogen production by electrolysis of water. Patent CN113481534A uses an electro-deposition method to prepare electrode materials. The preparation method is simple and easy to operate, but the uniformity of the particle size obtained by deposition is poor and uncontrolled. Oxidation is prone to occur during the preparation of the electrode, which in turn has a certain impact on the catalytic activity. Patent CN114318400A uses a hydrothermal method to prepare the electrode coating. The resulting coating particles have good dispersion, but the bonding performance between the coating and the substrate is poor, which is not conducive to the stable service of the coating, and it is impossible to prepare the electrode coating on a large scale. Studies have shown that under alkaline electrolyte conditions, oxidation and peeling of the cathode coating for hydrogen production by electrolysis of water will reduce its activity and stability.

[0004] Solid-state deposition is a promising technology for preparing coatings on metals and composite materials. Its principle is that solid powder particles are accelerated to high speeds in a supersonic jet of compressed gas. After colliding with the substrate in a completely solid state, they produce localized plastic deformation, enabling uniform and efficient deposition over large areas. This technology offers numerous advantages, including no oxidation, no phase change, and a metallurgical bond interface that not only maintains the physical and chemical properties of the raw materials but also achieves high bonding strength, significantly enhancing the durability and catalytic activity of electrodes used for hydrogen production from water electrolysis.

[0005] In view of the problems that the existing alkaline water electrolysis hydrogen production cathode coating materials are high in cost, the preparation process easily causes the coating to oxidize, the coating is easy to fall off and it is not convenient to prepare on a large scale, it is very important to prepare a large-area Ni-Fe water electrolysis hydrogen production cathode coating with high catalytic activity, high bonding strength, no oxidation based on solid-state deposition technology, and thereby promote the commercial application of water electrolysis hydrogen production. Summary of the Invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the problems in the prior art of water electrolysis hydrogen production, such as low catalytic activity, easy oxidation, the use of precious metal materials, and the inability to prepare on a large scale.

[0007] In order to solve the above technical problems, the present invention provides a Ni-Fe coating based on solid-state deposition technology and a preparation method and application thereof.

[0008] The first object of the present invention is to provide a method for preparing a Ni-Fe coating, wherein a mixed powder of Ni and Fe is deposited on the surface of a substrate using a solid-state deposition technique to obtain the Ni-Fe coating; the mass proportions of Ni and Fe in the mixed powder are not less than 30%; the total pressure of the gas in the solid-state deposition technique is 3MPa-4MPa; and the temperature of the gas is 700°C-900°C.

[0009] In one embodiment of the present invention, if the mass ratio of Ni and Fe in the mixed powder exceeds the specified range, the less abundant powder will tend to play a lesser role in the water electrolysis process, resulting in reduced water electrolysis efficiency. The total pressure affects the speed at which particles impact the substrate, while the gas temperature affects the temperature at which particles impact the substrate. The speed and temperature of the impact on the substrate affect the powder deposition effect. If the pressure is below the specified range, the powder deposition efficiency is low, a large amount of powder is wasted, and the coating will be uneven. Above the specified temperature, the powder faces the risk of micro-melting oxidation.

[0010] In one embodiment of the present invention, the particle size of Ni powder and Fe powder are both 5-80 μm. Particle size affects not only the particle impact temperature but also the impact velocity. If the particle size is too large, it is easy to rebound during deposition.

[0011] In one embodiment of the present invention, the substrate surface is polished with 80-grit sandpaper. Polishing the substrate surface increases the substrate surface roughness, improving the efficiency of powder deposition on the substrate. It also removes impurities from the substrate surface, preventing the incorporation of non-designed system materials into the coating.

[0012] In one embodiment of the present invention, the material of the substrate is a nickel-based metal plate.

[0013] In one embodiment of the present invention, the spraying distance of the spray gun in the solid-state deposition technology is 30 mm-50 mm, the moving speed is 300 mm / s-700 mm / s, and the powder feeding speed is 5 r / min-9 r / min.

[0014] In one embodiment of the present invention, the gases are nitrogen and helium.

[0015] The second object of the present invention is to provide a Ni-Fe coating prepared by the method described above.

[0016] In one embodiment of the present invention, the thickness of the Ni-Fe coating is 0.2 mm to 0.5 mm.

[0017] A third object of the present invention is to provide an application of the Ni-Fe coating in hydrogen production by water electrolysis. The technical solution of the present invention has the following advantages over the prior art:

[0018] (1) The Ni-Fe coating described in the present invention uses Ni-Fe mixed metal powder as the coating raw material, which is non-precious metal with abundant resource reserves, and greatly reduces the preparation cost of the cathode coating for hydrogen production by electrolysis of water.

[0019] (2) During the preparation process of the Ni-Fe coating of the present invention, the coating is not easily oxidized, and the finished product has a large area, providing more hydrogen channels and reaction sites in practical applications. This improves the reaction activity, enables better contact between the electrode and the electrolyte, and thus reduces the overpotential. At the same time, the preparation process alleviates the impact of high temperature on the substrate and coating materials, which can not only avoid the oxidation failure and reduced conductivity of the coating and substrate materials due to high temperature, but also make the bonding between the coating and the substrate more firm, effectively extending the working life of the electrode.

[0020] (3) The Ni-Fe coating of the present invention has great application prospects in hydrogen production by water electrolysis. Electrocatalysts require moderate strength because stronger binding will hinder the discharge of the produced gas, while weaker binding will make the intermediate difficult to stabilize. D-block element metals such as Fe usually have moderate absorption of main group elements because they have unpaired electrons in their outermost s orbital and the second outermost d orbital. In addition, the appropriate geometric configuration of the electrocatalyst will significantly improve the catalytic activity. If the lattice spacing is too large, the absorption of diatomic reactants and the formation of diatomic products will be inhibited; if the atoms are arranged too closely, strong reactant repulsion will occur. The Ni-Fe material system has a moderate absorption affinity for the reaction intermediates and is well matched with the reaction coordination. It can promote the hydrogen evolution reaction, reduce the energy consumption of water electrolysis, that is, reduce the overpotential, and improve the hydrogen production efficiency, that is, reduce the Tafel slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 Schematic diagram of the solid-state deposition system used in the present invention.

[0023] Figure 2 This is a physical picture of the large-area electrode coating prepared in Example 1 of the present invention.

[0024] Figure 3 This is a microstructure diagram of the large-area electrode coating prepared in Example 1 of the present invention.

[0025] Figure 4 This is a pore image of the large-area electrode coating prepared in Example 1 of the present invention detected by optical microscopy.

[0026] Figure 5 This is a three-dimensional contour surface image of the large-area electrode coating prepared in Example 1 of the present invention.

[0027] Figure 6 This is the detection distribution diagram of various components of the large-area electrode coating prepared in Example 1 of the present invention.

[0028] Figure 7 These are the linear scan curves and Tafel slope diagrams of hydrogen evolution of the large-area electrode coatings prepared in Examples 1-3 of the present invention; wherein, (a) is the linear scan curve of hydrogen evolution, and (b) is the Tafel slope diagram.

[0029] Figure 8 The hydrogen evolution linear scan curve and Tafel slope diagram of the coating prepared in Comparative Examples 1-2 of the present invention; wherein, (a) is the hydrogen evolution linear scan curve, and (b) is the Tafel slope diagram.

[0030] Figure 9 This is a stability test diagram of the large-area electrode coating prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0032] Example 1

[0033] Reference Figure 1 As shown, a Ni-Fe coating based on solid-state deposition technology and a preparation method thereof specifically include the following steps:

[0034] (1) Preparation of raw materials: nickel powder and iron powder with particle diameters of 5-80 μm are prepared, and the nickel powder and iron powder are mixed in a mass ratio of 1:1 to obtain Ni-Fe mixed powder.

[0035] (2) Preparation of coating: The selected nickel substrate is a rectangular parallelepiped with a length of 120 mm, a width of 50 mm, and a height of 2 mm. Before spraying, the substrate is rinsed with deionized water, cleaned with acetone in an ultrasonic bath for 10 minutes, and then dried. The substrate is fixed vertically 30 mm in front of the nozzle. The working gas is a mixture of nitrogen and helium. The total pressure of the gas heater is 3 MPa, and the gas temperature is set at 700 ° C. The powder feeder has a powder feeding speed of 7 r / min. At a lateral speed of 500 mm / s and a lateral step length of 5 mm, the solid particles are deposited on the substrate surface through the spray gun once, and a Ni-Fe coating with a thickness of 0.3 mm is obtained.

[0036] Example 2

[0037] A Ni-Fe coating based on solid-state deposition technology and a preparation method thereof, specifically comprising the following steps:

[0038] (1) Preparation of raw materials: nickel powder and iron powder with particle diameters of 5-80 μm are prepared, and the nickel powder and iron powder are mixed in a mass ratio of 1:1 to obtain Ni-Fe mixed powder.

[0039] (2) Preparation of coating: The selected nickel substrate is a rectangular parallelepiped with a length of 120 mm, a width of 50 mm, and a height of 2 mm. Before spraying, the substrate is rinsed with deionized water, cleaned with acetone in an ultrasonic bath for 10 minutes, and then dried. The substrate is fixed vertically 30 mm in front of the nozzle. The working gas is a mixture of nitrogen and helium. The total pressure of the gas heater is 3 MPa, and the gas temperature is set at 800 ° C. The powder feeder has a powder feeding speed of 7 r / min. At a lateral speed of 500 mm / s and a lateral step length of 5 mm, the solid particles are deposited on the substrate surface through spraying with a spray gun once, and a Ni-Fe coating with a thickness of 0.3 mm is obtained.

[0040] Example 3

[0041] A Ni-Fe coating based on solid-state deposition technology and a preparation method thereof, specifically comprising the following steps:

[0042] (1) Preparation of raw materials: nickel powder and iron powder with particle diameters of 5-80 μm are prepared, and the nickel powder and iron powder are mixed in a mass ratio of 1:1 to obtain Ni-Fe mixed powder.

[0043] (2) Preparation of coating: The selected nickel substrate is a rectangular parallelepiped with a length of 120 mm, a width of 50 mm, and a height of 2 mm. Before spraying, the substrate is rinsed with deionized water, cleaned with acetone in an ultrasonic bath for 10 minutes, and then dried. The substrate is fixed vertically 30 mm in front of the nozzle. The working gas is a mixture of nitrogen and helium. The total pressure of the gas heater is 3 MPa, and the gas temperature is set at 900 ° C. The powder feeder has a powder feeding speed of 7 r / min. At a lateral speed of 500 mm / s and a lateral step length of 5 mm, the solid particles are deposited on the substrate surface by spraying through the spray gun once, and a Ni-Fe coating with a thickness of 0.3 mm is obtained.

[0044] Comparative Example 1

[0045] (1) Preparation of raw materials: nickel powder and iron powder with particle diameters of 5-80 μm are prepared, and the nickel powder and iron powder are mixed in a mass ratio of 1:1 to obtain Ni-Fe mixed powder.

[0046] (2) Preparation of coating: The selected nickel substrate is a rectangular parallelepiped with a length of 120 mm, a width of 50 mm, and a height of 2 mm. Before spraying, the substrate is rinsed with deionized water, cleaned with acetone in an ultrasonic bath for ten minutes, and then dried. The substrate is fixed vertically 30 mm in front of the nozzle. The working gas is a mixture of nitrogen and helium. The total pressure of the gas heater is 5 MPa, and the gas temperature is set at 700 ° C. The powder feeder has a powder feeding speed of 7 r / min. At a lateral speed of 500 mm / s and a lateral step length of 5 mm, the solid particles are deposited on the substrate surface through the spray gun once, and a Ni-Fe coating with a thickness of 0.3 mm is obtained.

[0047] Comparative Example 2

[0048] (1) Preparation of raw materials: nickel powder and iron powder with particle diameters of 5-80 μm are prepared, and the nickel powder and iron powder are mixed in a mass ratio of 1:4 to obtain Ni-Fe mixed powder.

[0049] (2) Preparation of solid deposition coating: The selected nickel substrate is a rectangular parallelepiped with a length of 120 mm, a width of 50 mm, and a height of 2 mm. Before spraying, the substrate is rinsed with deionized water, cleaned with acetone in an ultrasonic bath for ten minutes, and then dried. The substrate is fixed vertically 30 mm in front of the nozzle. The working gas is a mixture of nitrogen and helium with a total pressure of 3 MPa and a gas temperature of 800°C. The powder feeder has a powder feeding speed of 7 r / min. At a lateral speed of 500 mm / s and a lateral step length of 5 mm, the solid particles are deposited on the substrate surface by spraying once through the spray gun to obtain a Ni-Fe coating with a thickness of 0.3 mm.

[0050] Test Example 1

[0051] The Ni-Fe coating prepared in Example 1 was characterized by using an EDS spectrometer to test the element ratio of the coating; a cross-section of the coating was photographed using an optical microscope, and the volume porosity was calculated using ImageJ software; a 1000 μm × 1000 μm surface was scanned on the coating surface using a three-dimensional surface profiler, and the 3D surface area of ​​the area was calculated using Vision64 software. The coating spraying parameters with the highest porosity and the largest 3D surface area were selected and sprayed repeatedly. The results are shown in FIG. Figure 2-6 shown.

[0052] from Figure 2-6 It can be seen that the solid-state deposition technology used in Example 1 has no oxidation reaction in the coating during the preparation process, and can spray a large area of ​​uniform and efficient deposition of the electrolysis water hydrogen production cathode coating. The coating prepared in Example 1 has a high porosity (8.28% ± 1.29%) and a large 3D surface area (14.136 mm 2 ), the elements in the coating are distributed very evenly, and the ratio reaches the preset element mass ratio, and the elements do not change and no oxidation occurs.

[0053] Test Example 2

[0054] The electrode performance test of the Ni-Fe coating prepared in Examples 1-3 and Comparative Examples 1-2 was conducted. The samples were transferred to deionized water and cleaned in an ultrasonic bath for 10 minutes. Then, they were transferred to a potassium hydroxide solution (pH = 13.9 ± 0.1) and activated for 3 hours. Electrochemical testing was performed using the three-electrode method. The treated sample was used as the working electrode, the graphite electrode was used as the auxiliary electrode, and mercuric oxide (Hg / HgO) was used as the reference electrode. The current density was set to -10 mA / cm 2 , test its hydrogen evolution linear scan curve and Tafel slope, the results are as follows Figure 7-8 shown.

[0055] from Figure 7 (a) is the linear scan curve for hydrogen evolution. It can be seen that increasing the spray gun chamber temperature from 700°C to 900°C results in lower overpotentials for the prepared cathode coatings for hydrogen production by electrolysis of water, i.e., the absolute values ​​of the data marked in the figure. Example 1, i.e., the Ni-Fe coating prepared at a gas temperature of 700°C, has the best water electrolysis performance, with an overpotential of -214mV; Example 2, i.e., the Ni-Fe coating prepared at a gas temperature of 800°C, has the highest overpotential as low as -224mV; Example 3, i.e., the Ni-Fe coating prepared at a gas temperature of 900°C, has moderate water electrolysis performance, with an overpotential of -220mV. Figure 7(b) Tafel slopes for Examples 1-3. The results indicate that the coatings prepared by the present invention have low Tafel slopes, demonstrating excellent electrocatalytic performance. The Tafel slope of the Ni-Fe coating in Example 1 is 75 mV / dec; the highest Tafel slope for the Ni-Fe coating in Example 2 is 78 mV / dec; and the lowest Tafel slope for the Ni-Fe coating in Example 3 is 73 mV / dec.

[0056] Depend on Figure 8 It can be seen that when the spray gun chamber pressure is increased from 3MPa to 5MPa, the overpotential and Tafel slope of the prepared water electrolysis hydrogen production cathode coating are increased. The overpotential of Comparative Example 1 is -338mV and the Tafel slope is 103mV / dec, which is much lower than the performance of Example 1. When the element mass ratio of Ni-Fe is changed to 1:4, the overpotential and Tafel slope of the prepared water electrolysis hydrogen production cathode coating are also increased. The overpotential of Comparative Example 2 is -297mV and the Tafel slope is 71mV / dec. Compared with the water electrolysis performance of Example 2, it can be concluded that if the mixed powder exceeds the appropriate ratio range, the electrocatalytic performance of the coating will also deteriorate.

[0057] Test Example 3

[0058] The Ni-Fe coating prepared in Example 3 was tested for stability, and the results were as follows: Figure 9 As shown. Figure 9 It can be seen that the Ni-Fe coating of Example 3 can 2 The current density was stable over 500 linear scans without obvious performance degradation, indicating that the electrode has good catalytic stability and a long working life.

[0059] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a Ni-Fe coating, characterized in that: A solid-state deposition technique is used to deposit a mixed powder of Ni and Fe on the surface of a substrate to obtain the Ni-Fe coating; the mass proportions of Ni and Fe in the mixed powder are both not less than 30%; the particle sizes of the Ni powder and the Fe powder are both 5-80 μm; the total pressure of the gas in the solid-state deposition technique is 3 MPa-4 MPa; the gas temperature is 700° C.-900° C., the spraying distance of the spray gun is 30 mm-50 mm, the moving speed is 300 mm / s-700 mm / s, and the powder feeding speed is 5 r / min-9 r / min; the gases are nitrogen and helium.

2. The method for preparing the Ni-Fe coating according to claim 1, wherein The surface of the substrate is polished with 80-grit sandpaper.

3. The method for preparing the Ni-Fe coating according to claim 1, wherein The material of the substrate is a nickel-based metal plate.

4. A Ni-Fe coating prepared by the method according to any one of claims 1 to 3.

5. The Ni-Fe coating according to claim 4, characterized in that The thickness of the Ni-Fe coating is 0.2 mm to 0.5 mm.

6. Use of the Ni-Fe coating according to claim 4 or 5 in hydrogen production by water electrolysis.

Images