Electrode and its preparation method and application

Abstract

The present invention provides an electrode, a preparation method thereof, and an application thereof. The electrode comprises a nickel substrate and a metal layer coated on the surface of the nickel substrate. The material of the metal layer comprises metallic nickel and a high-entropy alloy. A plurality of etched grooves are distributed on the surface of the metal layer away from the nickel substrate. The coverage of the etched grooves on the surface of the metal layer is 50 to 100%. The presence of the etched grooves on the surface of the metal layer helps to increase the specific surface area of the electrode and provides more active sites for the electrolysis of water. Due to its unique lattice structure, the high-entropy alloy has abundant active sites, and the presence of the etched grooves further increases the number of these active sites, thereby helping to improve the catalytic activity of the electrode. In addition, the etched groove structure is conducive to the formation and detachment of hydrogen and oxygen bubbles, reduces the residence time of bubbles on the electrode surface, optimizes the mass transfer process of the bubbles, and thus helps to improve the efficiency of water electrolysis.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis, and in particular to an electrode, a preparation method thereof, and applications thereof. Background Art

[0002] Driven by renewable electricity, water electrolysis is expected to become an ideal long-term hydrogen production method to achieve "zero carbon" emissions. Compared with traditional alloys, high-entropy alloys (HEAs) can provide more catalytic active sites due to their unique structural characteristics, including lattice distortion and long-range lattice disorder, and therefore have broad application prospects in the field of water electrolysis catalysts. Since the formation of HEAs often requires high-temperature calcination, it is difficult to form the high surface area pore structure required for the catalytic reaction during this process, which limits the exposure of the intrinsic high-activity catalytic reaction active sites and is not conducive to the improvement of catalytic reaction activity. In addition, compared with the Raney nickel-type electrodes widely used in alkaline water electrolysis, there is currently a lack of large-scale processing methods that can effectively integrate HEAs into industrial applications. Summary of the Invention

[0003] The main purpose of the present invention is to provide an electrode and a preparation method and application thereof, so as to solve the problem of low catalytic activity of water electrolysis catalysts in the prior art.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, an electrode is provided, which includes a nickel substrate and a metal layer coated on the surface of the nickel substrate, the material of the metal layer includes metallic nickel and a high-entropy alloy, and a plurality of etched grooves are distributed on the surface of the metal layer away from the nickel substrate, and the coverage of the etched grooves on the surface of the metal layer is 50 to 100%.

[0005] Furthermore, the width of the etched groove is 20 to 50 nm and the depth is 1 to 20 nm; and / or the spacing between adjacent etched grooves is 10 to 50 nm; and / or the plurality of etched grooves are distributed in an array; and / or the surface of the metal layer further contains hydroxyl groups, and the hydroxyl group density in the total surface of the metal layer is 4 to 20 OH / nm 2 ; and / or, the thickness of the metal layer is 20 to 100 μm; and / or, the mass ratio of the nickel metal and the high entropy alloy is 10 to 100:100; and / or, the specific surface area of the electrode is 40 to 180 m 2 / g.

[0006] Furthermore, the elements in the high entropy alloy are selected from any five or more of titanium, vanadium, chromium, manganese, nickel, iron, cobalt, copper, zinc, molybdenum, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

[0007] According to another aspect of the present invention, a method for preparing the aforementioned electrode is provided, which comprises: step S1, smelting and atomizing a high-entropy alloy raw material in sequence to obtain a high-entropy alloy powder; step S2, mixing the high-entropy alloy powder with metal nickel powder to obtain a metal mixture; step S3, coating the metal mixture on the surface of a nickel substrate by plasma spraying to obtain a composite material; step S4, etching the surface of the composite material using a pulsed laser to form a metal layer on the surface of the nickel substrate, thereby obtaining an electrode.

[0008] Furthermore, in the above step S1, the smelting time is 2 to 12 hours; and / or the smelting temperature is 1500 to 2500°C; preferably, the smelting is carried out in a vacuum suspension smelting furnace; the power of the vacuum suspension smelting furnace is 50 to 500kW; and / or the vacuum leakage rate of the vacuum suspension smelting furnace is <1Pa / h; and / or the particle size of the high entropy alloy powder is 100 to 500 mesh; and / or the morphology of the high entropy alloy powder is ellipsoidal.

[0009] Furthermore, in the above step S2, the mixing is ball milling, and the ball milling speed is 150 to 500 rpm; and / or the ball milling time is 0.5 to 10 h; and / or the particle size of the metal nickel powder is 300 to 500 mesh.

[0010] Furthermore, in the above step S3, the power of plasma spraying is 30 to 65 kW; and / or, the gas for plasma spraying is a H2 / Ar mixed gas, and the volume ratio of hydrogen to argon in the H2 / Ar mixed gas is 1:2 to 10; and / or, the flow rate of the H2 / Ar mixed gas is 8 to 15 L / min; preferably, the plasma spraying is vacuum plasma spraying.

[0011] Furthermore, in the above step S4, the power density of the pulsed laser is 5 to 100 J / cm 2 ; and / or, the wavelength of the pulsed laser is 100 to 1200 nm; and / or, the frequency of the pulsed laser is 5 to 100 kHz; and / or, the pulse width of the pulsed laser is 10 to 2000 fs; and / or, the output laser power of the pulsed laser is 1000 to 10000 mW.

[0012] Furthermore, the above-mentioned step S4 also includes placing the etched composite material in a saturated water vapor environment for hydroxylation treatment to obtain an electrode; preferably, the temperature of the hydroxylation treatment is 10 to 60° C.; and / or, the time of the hydroxylation treatment is 0.5 to 10 hours; and / or, the protective gas in the saturated water vapor environment is selected from any one or more of nitrogen, argon and helium; and / or, the mass content of oxygen in the saturated water vapor environment is less than 0.1%.

[0013] According to another aspect of the present invention, there is provided use of the aforementioned electrode in water electrolysis.

[0014] By applying the technical solution of the present invention, the presence of etched grooves on the surface of the metal layer helps to increase the specific surface area of the electrode, providing more active sites for the electrolysis of water. High entropy alloys have abundant active sites due to their unique lattice structure, and the presence of etched grooves further increases the number of these active sites, thereby helping to improve the catalytic activity of the electrode. In addition, the etched groove structure is conducive to the formation and detachment of hydrogen and oxygen bubbles, reduces the residence time of bubbles on the electrode surface, optimizes the mass transfer process of bubbles, thereby helping to improve the efficiency of water electrolysis. The presence of metallic nickel not only helps to improve the bonding force between the metal layer and the nickel substrate, but also makes the metal layer more dense, helps to reduce the shedding of the metal layer during the electrolysis process, and improves the long-term stability of the electrode. Controlling the coverage of the etched grooves on the surface of the metal layer within the above range helps to further increase the catalytic active sites on the electrode surface while maintaining the stability of the electrode structure, thereby helping to improve the catalytic activity of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0016] Figure 1 Shown is a SEM image of the electrode in Example 1 of the present application. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] Term explanation: High entropy alloy refers to an alloy composed of five or more main elements, with the atomic fraction of each element usually greater than 5% and less than 35%, and these elements form an alloy with approximately equal molar ratios.

[0019] As analyzed in the background technology of this application, the existing water electrolysis catalyst has the problem of low catalytic activity. In order to solve the above problem, this application provides an electrode and its preparation method and application.

[0020] In a typical embodiment of the present application, an electrode is provided, which includes a nickel substrate and a metal layer coated on the surface of the nickel substrate, the material of the metal layer includes metallic nickel and a high-entropy alloy, and a plurality of etched grooves are distributed on the surface of the metal layer away from the nickel substrate, and the coverage of the etched grooves on the surface of the metal layer is 50 to 100%.

[0021] The presence of etched grooves on the surface of the metal layer helps to increase the specific surface area of the electrode, providing more active sites for the water electrolysis reaction. Due to its unique lattice structure, high entropy alloys have abundant active sites, and the presence of etched grooves further increases the number of these active sites, thereby helping to improve the catalytic activity of the electrode. In addition, the etched groove structure is conducive to the formation and detachment of hydrogen and oxygen bubbles, reducing the residence time of bubbles on the electrode surface and optimizing the mass transfer process of bubbles, thereby helping to improve the efficiency of water electrolysis. The presence of metallic nickel not only helps to improve the bonding strength between the metal layer and the nickel substrate, but also makes the metal layer more dense, which helps to reduce the shedding of the metal layer during the electrolysis process and improves the long-term stability of the electrode. Controlling the coverage of the etched grooves on the surface of the metal layer within the above range helps to further increase the catalytic active sites on the electrode surface while maintaining the stability of the electrode structure, thereby helping to improve the catalytic activity of the electrode.

[0022] In one embodiment of the present application, the width of the etched groove is 20 to 50 nm and the depth is 1 to 20 nm; and / or the spacing between adjacent etched grooves is 10 to 50 nm; and / or the plurality of etched grooves are distributed in an array; and / or the surface of the metal layer further contains hydroxyl groups, and the hydroxyl density in the total surface of the metal layer is 4 to 20 OH / nm 2 ; and / or, the thickness of the metal layer is 20 to 100 μm; and / or, the mass ratio of the nickel metal and the high entropy alloy is 10 to 100:100; and / or, the specific surface area of the electrode is 40 to 180 m 2 / g.

[0023] Smaller etching groove width and depth can increase the effective surface area of electrode, provide more catalytic active sites, thereby accelerate electrochemical reaction rate. Meanwhile, appropriate etching groove size helps to promote the formation and detachment of gas (hydrogen, oxygen) bubbles, reduces the residence time of gas on electrode surface, optimizes bubble mass transfer process, and further improves the catalytic efficiency of electrode. However, if etching groove width and depth are too small, it may hinder the circulation of electrolyte, increase flow resistance, but be unfavorable for the progress of reaction. Preferably, the width and depth of etching groove are controlled within the above range, which helps to improve the efficiency of water electrolysis. Electrodes rich in hydroxyl groups on the surface can better attract and maintain contact with electrolyte, particularly when the electrode is immersed in electrolyte environment, hydrophilic surface helps uniform distribution and rapid penetration of electrolyte, helps to optimize the charge transfer process of electrode-electrolyte interface. In addition, the presence of hydroxyl groups can stabilize the active metal sites of electrode, helps to reduce the probability of metal sites being oxidized in air, and helps to make the electrode maintain long-term catalytic activity. Too high a hydroxyl density may cause changes in the physical properties of the electrode surface, affecting its mechanical strength and stability. Therefore, controlling the density of hydroxyl groups in the metal layer within the above range helps to further improve the catalytic activity of the electrode. The presence of metallic nickel helps to reduce the resistance of the metal layer and improve the charge transfer efficiency. At the same time, metallic nickel acts as a binder, helping to improve the structural stability of the electrode. Excessive metallic nickel may dilute the active sites of the high-entropy alloy and reduce the catalytic efficiency of the electrode. Therefore, controlling the mass ratio of metallic nickel to high-entropy alloy within the above range helps to further improve the water electrolysis efficiency of the electrode.

[0024] In order to further improve the catalytic activity of the electrode, in one embodiment of the present application, the elements of the above-mentioned high entropy alloy are preferably selected from any five or more of titanium, vanadium, chromium, manganese, nickel, iron, cobalt, copper, zinc, molybdenum, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

[0025] In another typical embodiment of the present application, a method for preparing the aforementioned electrode is provided, which comprises: step S1, smelting and atomizing a high-entropy alloy raw material in sequence to obtain a high-entropy alloy powder; step S2, mixing the high-entropy alloy powder with metal nickel powder to obtain a metal mixture; step S3, coating the metal mixture on the surface of a nickel substrate by plasma spraying to obtain a composite material; step S4, etching the surface of the composite material with a pulsed laser to form a metal layer on the surface of the nickel substrate, thereby obtaining an electrode.

[0026] Melting and atomizing the high entropy alloy raw material helps to obtain high entropy alloy powder with uniform particle size and consistent morphology. Mixing the high entropy alloy powder with metal nickel powder helps to improve the bonding strength between the metal layer and the nickel substrate. The metal mixture is coated on the surface of the nickel substrate by plasma spraying. This process can form a dense and uniform metal layer. Etching the surface of the composite material using a pulsed laser can accurately construct an etched groove structure. This process not only increases the specific surface area of the electrode and provides more catalytic active sites, but also optimizes the formation of bubbles and the multiphase mass transfer process. The present application is based on melting, atomization and plasma spraying to achieve large-area cladding on the surface of the nickel substrate. This method has the advantages of simple process and short preparation cycle, and can be mass-produced.

[0027] Including but not limited to, the nickel substrate is nickel felt with a porosity of 80% or a 46-mesh twill woven nickel mesh.

[0028] Including but not limited to, the morphology of the above-mentioned etched grooves is selected from any one or more of periodic corrugated shape, lattice shape, rod array shape, etched groove row shape, concave point shape, and fish scale shape.

[0029] In one embodiment of the present application, in the above-mentioned step S1, the smelting time is 2 to 12 hours; and / or the smelting temperature is 1500 to 2500°C; preferably, the smelting is carried out in a vacuum suspension smelting furnace; the power of the vacuum suspension smelting furnace is 50 to 500kW; and / or the vacuum leakage rate of the vacuum suspension smelting furnace is <1Pa / h; and / or the particle size of the high entropy alloy powder is 100 to 500 mesh; and / or the morphology of the high entropy alloy powder is ellipsoidal.

[0030] Preferably, the time and temperature of the smelting are controlled within the above range, which helps to promote the full mixing of the high entropy alloy components and the stable formation of the high entropy alloy phase. Selecting to carry out smelting in a vacuum suspension melting furnace helps to reduce the probability of the high entropy alloy being oxidized at high temperatures, helps to improve the purity of the high entropy alloy, and simultaneously, through the suspension melting technology, helps to better achieve the uniform distribution of the high entropy alloy elements. Preferably, the power of the vacuum suspension melting furnace is controlled within the above range, which helps to promote the formation of the high entropy alloy. Smaller particle size helps to improve the bonding force between the powder and the substrate during spraying, and a specific ellipsoidal shape can promote the uniform distribution of the metal layer material. Controlling the particle size of the high entropy alloy powder within the above range helps to form a dense, uniform metal layer in the subsequent plasma spraying process, thereby helping to improve the efficiency and stability of the electrode in the electrochemical reaction.

[0031] In one embodiment of the present application, in the above step S2, the mixing is ball milling mixing, and the ball milling mixing speed is 150 to 500 rpm; and / or the ball milling mixing time is 0.5 to 10 hours; and / or the particle size of the metal nickel powder is 300 to 500 mesh.

[0032] Controlling the rotation speed and time of ball milling mixing within the above ranges helps improve mixing efficiency. Controlling the particle size of the metal nickel powder within the above range helps improve the compatibility and mixing effect of the metal nickel powder and the high entropy alloy powder. The particle size of the nickel powder matches that of the high entropy alloy powder, which can promote uniform mixing of the two during the ball milling process and help reduce the risk of stratification or agglomeration caused by particle size differences. In addition, the fine particle size of the nickel powder helps improve the bonding strength between the metal layer and the substrate, enhances the adhesion of the metal layer, and thus helps improve the stability of the electrode.

[0033] In one embodiment of the present application, in the above step S2, the diameter of the ball milling beads for ball milling mixing is 10 to 30 mm, and the ball milling beads are preferably zircon beads.

[0034] In one embodiment of the present application, in the above step S2, high entropy alloy powder, metallic nickel powder and ethanol are mixed and ball-milled in a wet state, the mass ratio of ethanol to high entropy alloy powder is 1:100~1, and after ball milling, air drying is performed, the drying temperature is 100~200℃, and the drying time is 2~6h.

[0035] In one embodiment of the present application, in the above step S3, the power of plasma spraying is 30 to 65 kW; and / or, the gas for plasma spraying is a H2 / Ar mixed gas, and the volume ratio of hydrogen to argon in the H2 / Ar mixed gas is 1:2 to 10; and / or, the flow rate of the H2 / Ar mixed gas is 8 to 15 L / min; preferably, the plasma spraying is vacuum plasma spraying.

[0036] Controlling the power of plasma spraying within the above range helps to fully melt the metal mixture, while reducing the probability of thermal damage to the nickel substrate and metal layer, helping to improve the uniformity and density of the metal layer, thereby helping to improve the conductivity and mechanical stability of the electrode. Using an H2 / Ar mixed gas as the process gas for plasma spraying, hydrogen can act as a reducing agent, helping to further optimize the surface state of the high-entropy alloy during the spraying process and reduce the formation of oxides, while argon, as an inert gas, can provide a stable plasma environment while reducing the probability of oxidation of the metal layer. Controlling the volume ratio of hydrogen to argon within the above range can both provide sufficient hydrogen to reduce oxidation reactions and maintain stable combustion of the plasma. Controlling the flow rate of the H2 / Ar mixed gas within the above range helps to maintain stable combustion of the plasma while allowing the powder material to be uniformly transported and sprayed. Vacuum plasma spraying technology is preferred because it can maintain an oxygen-free environment throughout the spraying process, further reducing the probability of oxidation of the high-entropy alloy during the thermal spraying process, thereby helping to improve the catalytic activity and bonding strength of the metal layer.

[0037] In one embodiment of the present application, in the above step S4, the power density of the pulsed laser is 5 to 100 J / cm 2 ; and / or, the wavelength of the pulsed laser is 100 to 1200 nm; and / or, the frequency of the pulsed laser is 5 to 100 kHz; and / or, the pulse width of the pulsed laser is 10 to 2000 fs; and / or, the output laser power of the pulsed laser is 1000 to 10000 mW.

[0038] Controlling the power density of the pulsed laser within the above-mentioned range helps control the depth and inner diameter of the etched grooves within an appropriate range, thereby helping to improve the catalytic efficiency of the electrode. Controlling the wavelength of the pulsed laser within the above-mentioned range helps the interaction between the laser and the surface of the high-entropy alloy generate sufficient energy for etching micro-nanostructures, thereby helping to improve etching efficiency. Higher frequencies can speed up processing and improve production efficiency, but they also require precise control to avoid overheating the material and affecting the formation of the etched grooves. Controlling the frequency of the pulsed laser within the above-mentioned range helps to improve the uniformity of the etched grooves and improve processing efficiency. Controlling the pulse width of the pulsed laser within the above-mentioned range helps to provide high energy in a very short time, forming the etched grooves while reducing the impact of thermal diffusion on the surrounding materials, helping to maintain the clarity and structural integrity of the etched grooves. Controlling the output laser power of the pulsed laser helps to control the volume ratio of the etched grooves in the metal layer within an appropriate range, thereby helping to improve the catalytic activity of the electrode.

[0039] In one embodiment of the present application, the above-mentioned step S4 also includes placing the etched composite material in a saturated water vapor environment for hydroxylation treatment to obtain an electrode; preferably, the temperature of the hydroxylation treatment is 10 to 60°C; and / or, the time of the hydroxylation treatment is 0.5 to 10 hours; and / or, the protective gas in the saturated water vapor environment is selected from any one or more of nitrogen, argon and helium; and / or, the mass content of oxygen in the saturated water vapor environment is less than 0.1%.

[0040] Through hydroxylation treatment in a saturated water vapor environment, hydrophilic hydroxyl groups are formed on the electrode surface. The presence of hydroxyl groups helps to improve the hydrophilicity of the electrode, helps to promote contact between the electrolyte and the electrode surface, and helps to reduce the rapid oxidation of the electrode by oxygen in the air, which helps to ensure that the electrode has long-term catalytic activity. Controlling the temperature and time of the hydroxylation treatment within the above range helps to control the mass ratio of hydroxyl groups in the metal layer within an appropriate range, thereby helping to improve the catalytic activity of the electrode.

[0041] In another typical embodiment of the present application, there is provided the use of the above-mentioned electrode in electrolysis of water.

[0042] The electrode of the present application has lower oxygen evolution overpotential and hydrogen evolution overpotential, and has higher catalytic activity in water electrolysis.

[0043] The beneficial effects of the present application will be further illustrated below with reference to embodiments.

[0044] Example 1

[0045] 1) adding metal ingots with equal molar ratios of Ni, Fe, Co, Cu, and Mo elements into a vacuum levitation melting furnace with a power of 200 kW, maintaining the molten state for 6 hours, a smelting temperature of 2000°C, and a vacuum leakage rate of <0.5 Pa / h; then atomizing and pulverizing the metal in a vacuum environment, and screening high-entropy alloy powder with a particle size of 150 to 325 mesh using 150-mesh and 325-mesh stainless steel sieves, wherein the high-entropy alloy powder has an ellipsoidal morphology;

[0046] 2) 2 kg of the high-entropy alloy powder prepared in step 1, 0.5 kg of 325-mesh nickel powder, and 0.5 kg of ethanol were added to a ball mill and ball-milled at a speed of 200 rpm for 6 h using 20 mm zircon beads; after ball milling, the mixture was dried with forced air at a drying temperature of 150° C. for 2 h to obtain a metal mixture;

[0047] 3) Vacuum plasma spraying was used to clad the metal mixture obtained in step 2 on a nickel felt surface having a porosity of 80%. The power of the vacuum plasma spraying was 45 kW, and the process gas for generating the plasma was an H2 / Ar mixture gas with a volume ratio of hydrogen to argon of 1:4. The total flow rate of the H2 / Ar mixture gas was 12 L / min, to obtain a composite material.

[0048] 4) By laser etching, orderly periodic corrugated grooves are etched on the surface of the metal layer. The power density of the pulsed laser is 60J / cm 2 , wavelength is 200nm, frequency is 30kHz, pulse width is 500fs, output laser power is 4000mW, the surface of the prepared electrode has periodic etched grooves, the coverage of the grooves on the surface of the metal layer is 90%, the width of the etched grooves is 30nm, the depth of the etched grooves is 8nm, and the spacing between adjacent etched grooves is 30nm;

[0049] 5) The material prepared in step 4 was placed in a saturated water vapor environment for surface hydroxylation treatment. The saturated water vapor environment temperature was 35°C, the protective gas was argon, the oxygen content was less than 0.01%, and the placement time was 2 hours to obtain an electrode. The total surface hydroxyl density of the metal layer was 10.5OH / nm 2 The thickness of the metal layer is 40 μm and the specific surface area of the electrode is 142 m 2 / g.

[0050] Example 2

[0051] The difference from Example 1 is that ruthenium, rhodium, palladium, osmium, iridium and platinum are used to replace Ni, Fe, Co, Cu and Mo to finally obtain an electrode.

[0052] Example 3

[0053] The difference from Example 1 is that a 46-mesh twill woven nickel mesh is used to replace the nickel felt with a porosity of 80%, and finally an electrode is obtained.

[0054] Example 4

[0055] The difference from Example 1 is that the power density of the pulsed laser is 5 J / cm 2 , wavelength is 100nm, frequency is 5kHz, pulse width is 10fs, output laser power is 1000mW, the coverage of the etched grooves on the metal layer surface is 50%, the spacing between adjacent etched grooves is 50nm, and the electrode is finally obtained with a specific surface area of 71m 2 / g.

[0056] Example 5

[0057] The difference from Example 1 is that the power density of the pulsed laser is 100 J / cm 2 , wavelength is 1200nm, frequency is 100kHz, pulse width is 2000fs, output laser power is 10000mW, the coverage of the etched grooves on the metal layer surface is 100%, the spacing between adjacent etched grooves is 10nm, and the electrode is finally obtained with a specific surface area of 176m 2 / g.

[0058] Example 6

[0059] The difference from Example 1 is that the power density of the pulsed laser is 5 J / cm 2 , and finally an electrode is obtained, the width of the etched groove is 20nm, and the depth of the etched groove is 1nm.

[0060] Example 7

[0061] The difference from Example 1 is that the power density of the pulsed laser is 100 J / cm 2 Finally, an electrode was obtained, the width of the etched groove was 50nm, and the depth of the etched groove was 20nm.

[0062] Example 8

[0063] The difference from Example 1 is that the power density of the pulsed laser is 120 J / cm 2 Finally, an electrode was obtained, the width of the etched groove was 62nm, and the depth of the etched groove was 28nm.

[0064] Example 9

[0065] The difference from Example 1 is that the saturated water vapor environment temperature is 10°C, the placement time is 0.5h, and the electrode is finally obtained. The total surface hydroxyl density of the metal layer is 4OH / nm 2 .

[0066] Example 10

[0067] The difference from Example 1 is that the saturated water vapor environment temperature is 60°C, the placement time is 10 hours, and the electrode is finally obtained. The total surface hydroxyl density of the metal layer is 20OH / nm 2 .

[0068] Example 11

[0069] The difference from Example 1 is that the saturated water vapor environment temperature is 5°C, the placement time is 0.2h, and the electrode is finally obtained, and the total surface hydroxyl density of the metal layer is 0.4OH / nm 2 .

[0070] Example 12

[0071] The difference from Example 1 is that 100-mesh and 200-mesh stainless steel sieves are used to screen out powder with a particle size of 100-200 mesh, the particle size of the metal nickel powder is 300 mesh, and finally an electrode is obtained.

[0072] Example 13

[0073] The difference from Example 1 is that 300-mesh and 500-mesh stainless steel sieves are used to screen out powder with a particle size of 300-500 mesh, the particle size of the metal nickel powder is 500 mesh, and finally an electrode is obtained.

[0074] Example 14

[0075] The difference from Example 1 is that 550-mesh and 650-mesh stainless steel sieves are used to screen out powder with a particle size of 550-650 mesh, and the particle size of the metal nickel powder is 600 mesh, and finally an electrode is obtained.

[0076] Example 15

[0077] The difference from Example 1 is that the mass of 325-mesh nickel powder is 2 kg, and the electrode is finally obtained.

[0078] Example 16

[0079] The difference from Example 1 is that the mass of 325-mesh nickel powder is 0.2 kg, and the electrode is finally obtained.

[0080] Example 17

[0081] The difference from Example 1 is that the mass of 325-mesh nickel powder is 0.1 kg, and the electrode is finally obtained.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that no laser etching is performed, and an electrode is finally obtained.

[0084] Performance Testing

[0085] The electrodes prepared in the examples and comparative examples were cut into a rectangular block with a length of 1.5 cm and a width of 1 cm. After being fixed with an electrode clamp, they were used as working electrodes for oxygen evolution reaction in alkaline electrolyte. In the three-electrode test system, the platinum wire was the counter electrode, the mercury / mercuric oxide electrode was the reference electrode, and the effective area of the working electrode immersed in the electrolyte was 1 cm. 2 , the test system selected 1 mol / L potassium hydroxide as the electrolyte.

[0086] The electrochemical data were tested by linear voltammetry and AC impedance spectroscopy. The linear voltammetry scan rate was 5 mV / s, the AC impedance spectroscopy test potential was 1.53 V (vs. RHE), the AC amplitude was 10 mV, and the frequency range was 10 6 ~10 -1The electrode was applied to an AEM single cell and tested in electrolytic water to reach 1.5A / cm 2 The voltage required for the current density. The test electrode is at 100mA / cm 2 The oxygen evolution overpotential and hydrogen evolution overpotential at current density up to 1.5A / cm 2 The voltage required for the current density and the test results are shown in Table 1.

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1, the electrode of Example 1 has a high 2 The oxygen evolution overpotential at the current density is 209mV, and the hydrogen evolution overpotential is 89mV, which are respectively better than the 370mV of the commercial noble metal oxygen evolution catalyst IrO2 and the 123mV of the hydrogen evolution catalyst Pt / C; the electrode of Example 1 reaches 1.5A / cm in the water decomposition test. 2 The voltage required for the current density is only 1.78V, which is better than the 2.08V of the film electrode made of commercial IrO2 and Pt / C.

[0091] Compared with Example 1, Example 2 uses precious metals as high entropy alloy components, and has better catalytic performance, which proves the versatility of the synthesis method for the selection of metal elements of catalytic materials; Example 3 can also prepare electrodes with similar results after replacing the substrate, which proves the versatility of the synthesis method for the selection of electrode substrates; In Example 4, the pulsed laser has a low degree of surface etching, and the surface has fewer orderly etched grooves, which has a low performance enhancement effect; In Example 5, the pulsed laser has a high degree of surface etching, but it also leads to poor structural orderliness of the etched grooves, which has a low performance enhancement effect; In Example 6, Low laser power results in shallow surface grooves, weak effect on improving the exposed active sites on the surface, and low performance; in Example 7, high laser power results in large surface groove widths, and also destroys orderliness, so the effect of improving surface micro-nanoscale electrolyte flow and bubble overflow is poor, and the performance is low under comprehensive factors; in Example 8, under the condition of excessively high laser power, melting occurs on the surface of the material, the morphology of the grooves becomes disordered and the size is too large, which does not help to improve the specific surface area, so the performance is seriously reduced; in Example 9, the degree of hydroxylation on the surface of the material is insufficient, and the hydrophilicity of the electrode is poor; In Example 10, the degree of hydroxylation on the surface of the material is too high, covering too many active sites and affecting the catalytic reaction process; in Example 11, the degree of hydroxylation on the surface of the material is too low, the electrode surface does not have hydrophilic properties, and the mass transfer process between the electrode and the electrolyte is limited; in Example 12, the particle size of the high entropy alloy powder is too large, resulting in a low degree of melting during the plasma spraying process, making the substrate surface coating not dense and with many gaps; in Example 13, the particle size of the high entropy alloy powder and the nickel powder is too small, resulting in poor fluidity during the powder feeding process of vacuum plasma spraying, discontinuous spraying flame, affecting the coating. density and uniformity; in Example 14, the particle size of the high entropy alloy powder and the nickel powder is too small, resulting in poor process matching with the vacuum plasma spraying process and poor coating cladding effect; in Example 15, the nickel powder used for bonding is added too much, resulting in a decrease in the content of the high entropy alloy as a catalytic active component in the coating and a decrease in catalytic activity; in Example 16, the nickel powder used for bonding is added too little, resulting in weak coating bonding and easy falling off of the high entropy alloy component on the electrode surface; in Example 17, the nickel powder used for bonding is added too little, and the high entropy alloy component on the electrode surface is extremely easy to fall off, resulting in performance degradation.

[0092] Compared with Example 1, the lack of laser etching in Comparative Example 1 results in a smaller specific surface area of the electrode and fewer exposed catalytic active sites. Therefore, the advantage of the high intrinsic catalytic activity of the high entropy alloy cannot be brought into play, resulting in poor catalytic performance.

[0093] Figure 1 This is the SEM image of the electrode in Example 1 of the present application, Figure 1 It can be seen that laser etching can form an etched groove structure with regular morphology.

[0094] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0095] The presence of etched grooves on the surface of the metal layer helps to increase the specific surface area of the electrode, providing more active sites for the water electrolysis reaction. Due to its unique lattice structure, high entropy alloys have abundant active sites, and the presence of etched grooves further increases the number of these active sites, thereby helping to improve the catalytic activity of the electrode. In addition, the etched groove structure is conducive to the formation and detachment of hydrogen and oxygen bubbles, reducing the residence time of bubbles on the electrode surface and optimizing the mass transfer process of bubbles, thereby helping to improve the efficiency of water electrolysis. The presence of metallic nickel not only helps to improve the bonding strength between the metal layer and the nickel substrate, but also makes the metal layer more dense, which helps to reduce the shedding of the metal layer during the electrolysis process and improves the long-term stability of the electrode. Controlling the coverage of the etched grooves on the surface of the metal layer within the above range helps to further increase the catalytic active sites on the electrode surface while maintaining the stability of the electrode structure, thereby helping to improve the catalytic activity of the electrode.

[0096] The above are merely embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An electrode for electrolyzing water, characterized in that The electrode for electrolyzing water includes a nickel substrate and a metal layer coated on the surface of the nickel substrate. The material of the metal layer includes metallic nickel and a high-entropy alloy. A plurality of etched grooves are distributed on the surface of the metal layer away from the nickel substrate. The coverage of the etched grooves on the surface of the metal layer is 50~100%; the width of the etched grooves is 20~50nm and the depth is 1~20nm.

2. The electrode for electrolyzing water according to claim 1, characterized in that The spacing between adjacent etching grooves is 10-50 nm; and / or, the plurality of etching grooves are distributed in an array; and / or, the surface of the metal layer further contains hydroxyl groups, and the hydroxyl group density in the total surface of the metal layer is 4-20 OH / nm 2 ; and / or, the thickness of the metal layer is 20~100μm; and / or, the mass ratio of the metal nickel and the high entropy alloy is 10~100:100; and / or, the specific surface area of the electrode for electrolyzing water is 40~180m 2 / g.

3. The electrode for electrolyzing water according to claim 1 or 2, characterized in that The elements in the high entropy alloy are selected from any five or more of titanium, vanadium, chromium, manganese, nickel, iron, cobalt, copper, zinc, molybdenum, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

4. A method for preparing an electrode for electrolyzing water according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Step S1, melting and atomizing the high entropy alloy raw material in sequence to obtain high entropy alloy powder; Step S2, mixing the high entropy alloy powder with metal nickel powder to obtain a metal mixture; Step S3, coating the metal mixture on the surface of a nickel substrate by plasma spraying to obtain a composite material; Step S4, using a pulsed laser to etch the surface of the composite material to form a metal layer on the surface of the nickel substrate, thereby obtaining the electrode for electrolyzing water.

5. The preparation method according to claim 4, characterized in that In step S1, the smelting time is 2 to 12 hours; and / or the smelting temperature is 1500 to 2500° C.; and / or, the smelting is carried out in a vacuum suspension smelting furnace; the power of the vacuum suspension smelting furnace is 50-500 kW; and / or, the vacuum leakage rate of the vacuum suspension smelting furnace is less than 1 Pa / h; And / or, the particle size of the high entropy alloy powder is 100-500 mesh; and / or, the morphology of the high entropy alloy powder is an ellipsoid.

6. The preparation method according to claim 4 or 5, characterized in that In step S2, the mixing is performed by ball milling, and the rotation speed of the ball milling is 150 to 500 rpm; and / or the time of the ball milling is 0.5 to 10 h; And / or, the particle size of the metallic nickel powder is 300-500 mesh.

7. The preparation method according to claim 4, characterized in that In step S3, the power of the plasma spraying is 30-65 kW; and / or the gas used for the plasma spraying is a H2 / Ar mixed gas, and the volume ratio of hydrogen to argon in the H2 / Ar mixed gas is 1:2-10; and / or the flow rate of the H2 / Ar mixed gas is 8-15 L / min; and / or the plasma spraying is vacuum plasma spraying.

8. The preparation method according to claim 4, characterized in that In step S4, the power density of the pulsed laser is 5-100 J / cm 2 ; and / or, the wavelength of the pulse laser is 100~1200nm; and / or, the frequency of the pulse laser is 5~100kHz; and / or, the pulse width of the pulse laser is 10~2000fs; and / or, the output laser power of the pulse laser is 1000~10000mW.

9. The preparation method according to claim 4, characterized in that The step S4 further includes placing the etched composite material in a saturated water vapor environment for hydroxylation to obtain the water electrolysis electrode; The temperature of the hydroxylation treatment is 10-60° C.; and / or the time of the hydroxylation treatment is 0.5-10 h; and / or the protective gas in the saturated water vapor environment is selected from any one or more of nitrogen, argon and helium; and / or the mass content of oxygen in the saturated water vapor environment is less than 0.1%.

10. Use of the water electrolysis electrode according to any one of claims 1 to 3 in water electrolysis.

Images