An electrolytic water oxygen evolution catalyst coating material, a preparation method and application thereof

Abstract

The application discloses an electrolytic water oxygen evolution catalyst coating material, a preparation method and application thereof, and relates to the technical field of electrolytic water catalysis. The electrolytic water oxygen evolution catalyst coating comprises a metal nickel framework, a spinel type manganese cobalt oxide and a spinel type nickel cobalt oxide. The metal nickel framework has a porous structure, which is beneficial to the contact of the electrode and the electrolyte and the escape of gas. The metal oxide can expose more active sites. The metal framework in the substrate and the coating can enhance the conductivity of the entire electrode system. The electrolytic water oxygen evolution catalyst coating material has the advantages of low preparation cost, high catalytic activity and good stability, and is beneficial to improving the hydrogen production efficiency of electrolytic water and promoting the wide use of hydrogen energy.

Description

A coating material for an oxygen evolution catalyst in water electrolysis, its preparation method and application Technical Field

[0001] This invention relates to the field of water electrolysis catalysis technology, and more specifically, to a coating material for an oxygen evolution catalyst in water electrolysis, its preparation method, and its application. Background Technology

[0002] The combustion of fossil fuels has provided a large amount of energy for human survival and production. However, fossil fuels themselves face an increasing crisis of depletion, and the carbon dioxide produced during combustion is a major contributor to the greenhouse effect. Other byproducts, such as sulfur dioxide and nitrogen oxides, are also major sources of air pollution. Hydrogen, as a clean fuel with high energy density and zero carbon emissions, is one of the options to replace high-carbon fossil fuels. It can be used in fuel cells to convert chemical energy into electrical energy, and can also be used as a raw material for high-value-added products such as electronics, non-ferrous metal smelting, and semiconductors. Compared with traditional hydrogen production technologies such as hydrogen production from fossil fuels like coal and natural gas, and hydrogen extraction from industrial byproducts such as coke oven gas and chlor-alkali industry tail gas, hydrogen production through water electrolysis is a clean and sustainable method. In particular, combining hydrogen production with renewable energy sources such as hydropower, wind power, and solar power can consume surplus electricity that is not connected to the grid in a timely manner, thus both easing the pressure on the power grid and reducing the amount of water, wind, and solar power that is wasted.

[0003] Water electrolysis involves two half-reactions: hydrogen evolution and oxygen evolution. The main factor affecting the efficiency of water electrolysis is the four-electron oxygen evolution reaction, a slow kinetic process that leads to a large overpotential. Therefore, even though the theoretical voltage for water decomposition at room temperature is 1.23V, the actual voltage applied for water electrolysis needs to be significantly higher. Highly efficient catalysts can effectively reduce the overpotential of water electrolysis. Currently, the most effective catalysts are mainly noble metals such as Pt, Ru, and Ir and their oxides. However, the scarcity and high price of these noble metals severely limit their application. Therefore, developing efficient and economically viable non-noble metal catalysts is an effective means to promote the commercial application of water electrolysis.

[0004] Current research has revealed that transition metals and their oxides, sulfides, phosphides, and selenides all possess certain catalytic activities, with some materials exhibiting catalytic activity approaching that of noble metal catalysts. However, the synthesis methods for these catalysts are mostly hydrothermal and electrodeposition-based, making the preparation processes relatively complex and difficult to master, hindering large-scale mass production. Therefore, finding a highly efficient, low-cost, and simple-to-produce water electrolysis catalyst and electrode is an urgent goal.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a coating material for an oxygen evolution catalyst in water electrolysis and its preparation method, aiming to prepare an oxygen evolution catalyst for water electrolysis that is low in cost, has high catalytic activity, and good stability.

[0007] Another objective of this invention is to provide an oxygen evolution electrode for water electrolysis that has low preparation cost and high efficiency in producing hydrogen through water electrolysis.

[0008] A third objective of this invention is to provide the application of the above-mentioned oxygen evolution electrode in water electrolysis for hydrogen production.

[0009] This invention is implemented as follows:

[0010] In a first aspect, the present invention provides a coating material for an oxygen evolution catalyst in water electrolysis, comprising a substrate and a coating attached to the substrate. The coating comprises a metallic nickel framework, spinel-type manganese cobalt oxide, and spinel-type nickel cobalt oxide. The metallic nickel framework has a porous structure, and some of the spinel-type manganese cobalt oxide and spinel-type nickel cobalt oxide are loaded on the metallic nickel framework.

[0011] In an optional embodiment, the total amount of spinel-type manganese cobalt oxide and spinel-type nickel cobalt oxide is in a mass ratio of 4.5 to 5.0 to the metallic nickel framework.

[0012] Preferably, the substrate is at least one of nickel sheet, nickel-based alloy, nickel-plated metal sheet, and stainless steel sheet;

[0013] Preferably, the coating has a sheet-like nanoflower porous structure;

[0014] Preferably, the coating thickness is 30μm to 200μm, and the substrate thickness is 0.15mm to 2.0mm.

[0015] Secondly, the present invention provides a method for preparing an electrolytic oxygen evolution catalyst coating material in the foregoing embodiments, comprising: mixing spinel oxide powder, nickel powder and pore-forming powder to prepare a powder to be sprayed, and using the powder to be sprayed to form a mixed coating on a substrate; chemically etching the mixed coating; wherein the spinel oxide powder includes spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder.

[0016] In an optional embodiment, the mass ratio of the spinel oxide powder, the nickel powder, and the pore-forming agent is 4.5–5.0:0.9–1.0:0.2–5.0, and the mass ratio of the spinel-type manganese cobalt oxide powder and the spinel-type nickel cobalt oxide powder is 1–0.5:0–0.5.

[0017] In an optional embodiment, the preparation process of the powder to be sprayed includes: mixing spinel oxide powder, nickel powder and pore-forming agent, drying at a temperature of 60°C to 100°C, and drying for 6 hours to 36 hours.

[0018] In an optional embodiment, an atmospheric plasma spraying method is used to form a hybrid coating on the substrate;

[0019] Preferably, during atmospheric plasma spraying, the controlled current is 400A to 600A, the spraying distance is 80mm to 200mm, the main gas flow rate is 50splm to 80splm, the auxiliary gas flow rate is 5splm to 20splm, the substrate preheating temperature is 100℃ to 400℃, the spray gun power is 30kW to 50kW, the powder feeding rate is 15g / min to 50g / min, the spraying overlap is 5mm to 20mm, the number of spraying passes is 2 to 10, and the spraying speed is 300mm / s to 600mm / s.

[0020] In an optional embodiment, the substrate is pretreated before spraying, and the pretreatment includes a first washing, sandblasting, a second washing, and drying in sequence.

[0021] Preferably, the first washing is ultrasonic washing with an organic solvent and water in sequence; more preferably, ultrasonic washing with an organic solvent is washing with gasoline, acetone and anhydrous ethanol in sequence.

[0022] Preferably, the solvent used for the secondary washing is selected from at least one of water and anhydrous ethanol.

[0023] In an optional embodiment, the solution used for chemical etching contains an inorganic base and a ligand, wherein the inorganic base is selected from at least one of sodium hydroxide and potassium hydroxide, and the ligand is selected from at least one of potassium sodium tartrate, sodium citrate, and fluoride.

[0024] Preferably, in the solution, the mass fraction of the ligand is 3% to 30%, and the mass fraction of the inorganic base is 10% to 50%.

[0025] Preferably, the corrosion time using alkaline solution is 5h to 40h.

[0026] Thirdly, the present invention provides an electrolytic oxygen evolution electrode for water, which is prepared from any of the electrolytic oxygen evolution catalyst coating materials in the foregoing embodiments or the electrolytic oxygen evolution catalyst coating materials prepared by any of the preparation methods in the foregoing embodiments.

[0027] Fourthly, the present invention provides the application of the oxygen evolution electrode of the aforementioned embodiments in the electrolysis of water to produce hydrogen.

[0028] This invention offers the following advantages: the oxygen evolution catalyst coating for water electrolysis comprises a metallic nickel framework, spinel-type manganese cobalt oxide, and spinel-type nickel cobalt oxide. The metallic nickel framework exhibits a porous structure, which facilitates the contact between the electrode and the electrolyte and the escape of gas. The metal oxides expose more active sites, and the metallic framework in the substrate and coating enhances the conductivity of the entire electrode system. This oxygen evolution catalyst coating material for water electrolysis has advantages such as low preparation cost, high catalytic activity, and good stability, which is beneficial for improving the efficiency of hydrogen production through water electrolysis and promoting the widespread use of hydrogen energy. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 shows the XRD pattern of the catalyst prepared in Example 1;

[0031] Figure 2 is a SEM image of the catalyst prepared in Example 1;

[0032] Figure 3 is a polarization curve of the catalyst prepared in Example 1;

[0033] Figure 4 shows the polarization curve of the catalyst prepared in Example 2;

[0034] Figure 5 shows the polarization curve of the catalyst prepared in Example 3;

[0035] Figure 6 shows the oxygen evolution performance test results of the sample obtained in Example 3 after stability testing. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0037] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0038] S1. Preparation of powder to be sprayed

[0039] The powder to be sprayed is prepared by mixing spinel oxide powder, nickel powder, and a pore-forming agent. The spinel oxide powder includes spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder. The raw materials can be mixed evenly using conventional methods, and the mixing method is not limited, such as ordinary stirring, ball milling, etc.

[0040] In some embodiments, the mass ratio of spinel oxide powder, nickel powder, and pore-forming agent is 4.5–5.0:0.9–1.0:0.2–5.0, and the mass ratio of spinel-type manganese cobalt oxide powder to spinel-type nickel cobalt oxide powder is 1–0.5:0–0.5. It is preferable that the raw materials are within the above ranges; exceeding these ranges may reduce catalytic activity to some extent.

[0041] Specifically, the mass ratio of spinel oxide powder, nickel powder, and pore-forming agent can be 4.5:0.9:0.2, 4.6:0.92:0.5, 4.7:0.94:1.0, 4.8:0.96:2.0, 4.8:0.97:3.0, 4.9:0.98:4.0, 5.0:1.0:5.0, etc. The mass ratio of spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder can be 1:0, 0.9:0.1, 0.8:0.2, 0.6:0.4, 0.5:0.5, etc.

[0042] In some embodiments, the preparation process of the powder to be sprayed includes: mixing spinel oxide powder, nickel powder and a pore-forming agent, and drying them at a temperature of 60°C to 100°C for a time of 6 hours to 36 hours. Drying removes moisture to meet the requirements of subsequent spraying.

[0043] Specifically, the mixing process can be carried out in a general reagent bottle using a stirrer for mechanical stirring; the drying process can be carried out in a general forced-air drying oven, but is not limited to this.

[0044] S2, Substrate Pretreatment

[0045] The substrate is pretreated before spraying to achieve surface cleanliness and create a certain roughness to facilitate the subsequent coating formation.

[0046] The substrate is at least one of nickel sheet, nickel-based alloy and stainless steel sheet, and can be any one or more of the above.

[0047] The pretreatment process includes a first wash, sandblasting, a second wash, and drying. The first wash removes organic impurities, such as oil, from the substrate surface; sandblasting increases the roughness of the substrate to allow powder to deposit better on the surface, although there are no particularly fine requirements for the specific roughness; the second wash removes impurities from the sandblasting process; and drying removes the solvents used in the second wash.

[0048] In some embodiments, a single wash involves ultrasonic cleaning with an organic solvent and water sequentially. The organic solvent is used first to effectively remove organic impurities, followed by a water wash. Preferably, the ultrasonic cleaning with an organic solvent involves sequentially washing with gasoline, acetone, and anhydrous ethanol. Using multiple organic solvents can improve the removal efficiency of organic impurities.

[0049] Specifically, the sanding process depends on the type of substrate. If the substrate is a nickel-based material, which is soft, then a finer grit is used; if the substrate is stainless steel, then a larger grit is used.

[0050] In some embodiments, the solvent used for the secondary washing is selected from at least one of water and anhydrous ethanol. Since the ultrasonic washing process with water is partially exothermic, anhydrous ethanol is preferred, but water can be used for cost reasons.

[0051] S3, Spraying

[0052] A hybrid coating can be formed on a substrate using the powder to be sprayed. This can be achieved using atmospheric plasma spraying, but is not limited to this method.

[0053] In some embodiments, during atmospheric plasma spraying, the controlled current is 400A to 600A, the spraying distance is 80mm to 200mm, the auxiliary gas flow rate is 5splm to 20splm, and the main gas flow rate is 50splm to 80splm. The current, spraying distance, and working gas flow rate have a certain impact on the spraying effect and should ideally be controlled within the above ranges.

[0054] The main gas can be argon or nitrogen;

[0055] The auxiliary gas can be hydrogen or helium;

[0056] It should be noted that using a high current will result in better melting and easier spraying. The current should be controlled between 400A and 600A, such as 400A, 450A, 500A, 550A, 600A, etc.

[0057] It should be noted that the spraying distance should ideally be controlled between 80mm and 200mm, such as 80mm, 90mm, 120mm, 140mm, 160mm, 180mm, 200mm, etc. If the spraying distance is too short, the coating may not melt before being sprayed on, resulting in an inability to form a coating; if the spraying distance is too long, the coating may melt and cool down before contacting the substrate, making it difficult to adhere.

[0058] It should be noted that regarding the flow control of the working gases, the auxiliary gas flow rate should be 5-20 splm, and the main gas flow rate should be 50-80 splm. For example, the auxiliary gas flow rate can be 5 splm, 8 splm, 10 splm, 13 splm, 15 splm, 17 splm, or 20 splm, while the main gas flow rate can be 50 splm, 60 splm, 70 splm, or 80 splm. The auxiliary gas affects the spraying speed, and the main gas is used to heat the powder. If either working gas exceeds the above range, it may result in insufficient spraying temperature or speed, affecting the coating effect.

[0059] Furthermore, during atmospheric plasma spraying, the substrate preheating temperature is controlled at 100℃~400℃, the spray gun power at 30kW~50kW, the powder feed rate at 15g / min~50g / min, the spray overlap at 5mm~20mm, the number of spray passes at 2~10, and the spraying speed at 300mm / s~600mm / s. The powder feed rate and the number of spray passes are coordinated; if the powder feed rate is high, the number of spray passes can be slightly less, and if the powder feed rate is low, the number of spray passes can be slightly more.

[0060] Specifically, the substrate preheating temperature can be 100℃, 180℃, 250℃, 300℃, 350℃, 400℃, etc., the spray gun power can be 30kW, 35kW, 40kW, 45kW, 50kW, etc., the powder feeding rate can be 15g / min, 20g / min, 25g / min, 30g / min, 35g / min, 40g / min, 45g / min, 50g / min, etc., the spray overlap can be 5mm, 8mm, 10mm, 15mm, 20mm, etc., the number of spray passes can be 2, 3, 5, 7, 10, etc., and the spraying speed can be 300mm / s, 400mm / s, 500mm / s, 600mm / s, etc.

[0061] S4, Chemical Corrosion

[0062] A porous, self-supporting manganese-cobalt spinel catalyst coating was prepared by chemically etching the mixed coating with an etchant to dissolve the pore-forming agent in the coating. This coating and electrode do not require any high-temperature or high-pressure environment or other binders during the preparation process, and they have high bonding strength.

[0063] In some embodiments, the solution used for chemical corrosion contains dissolved inorganic base and ligand, and the introduction of ligand can increase corrosion efficiency. The inorganic base is selected from at least one of sodium hydroxide and potassium hydroxide, and can be any one or two of the above; the ligand is selected from at least one of potassium sodium tartrate, sodium citrate, and fluoride, and can be any one or more of the above, and the fluoride can be sodium fluoride, etc.

[0064] Furthermore, in the etching solution, the mass fraction of the ligand is 3%–30%, and the mass fraction of the inorganic alkali is 10%–50%; the etching time is 0.5 h–40 h. The pore-forming agent in the coating is fully dissolved by controlling the alkali concentration and etching time. Specifically, the mass fraction of the ligand can be 3%, 5%, 10%, 15%, 20%, 25%, 30%, etc., the mass fraction of the inorganic alkali can be 10%, 20%, 30%, 40%, 50%, etc., and the etching time can be 0.5 h, 1.0 h, 10 h, 20 h, 30 h, 40 h, etc.

[0065] It should be added that, compared with the prior art, the preparation method provided in this embodiment of the invention uses manganese cobalt spinel powder as the main raw material in the spraying process, which is inexpensive; the etching solution is a potassium hydroxide solution of potassium sodium tartrate, which can be reused repeatedly. The catalyst coating and electrode preparation process is simple, clear, low-cost, and controllable, making it easy for large-scale industrial production, which is conducive to improving the efficiency of hydrogen production by water electrolysis and promoting the widespread use of hydrogen energy.

[0066] This invention also provides a coating material for an oxygen evolution catalyst in water electrolysis, comprising a substrate and a coating attached to the substrate. The coating comprises a metallic nickel framework, spinel-type manganese cobalt oxide, and spinel-type nickel cobalt oxide. The metallic nickel framework has a porous structure, and some of the spinel-type manganese cobalt oxide and spinel-type nickel cobalt oxide are supported on the metallic nickel framework. This coating material can be prepared by the above-described method. It has a large surface area, providing more active sites for the oxygen evolution reaction, and exhibits high electrocatalytic activity, good stability, and good conductivity.

[0067] In an optional embodiment, the mass ratio of spinel-type manganese cobalt oxide, spinel-type nickel cobalt oxide, and metallic nickel framework is 4.5 to 5.0. The chemical formula of the spinel-type manganese cobalt oxide is not fixed, and can be MnCo2O4, and the chemical formula of the spinel-type nickel cobalt oxide is also not fixed, and can be NiCo2O4.

[0068] It should be added that, theoretically, nickel, cobalt, and manganese oxides may also exist, but the test results showed that no nickel, cobalt, or manganese oxides were detected.

[0069] In some embodiments, the coating has a sheet-like nanoflower porous structure, and the sheet-like structure of the metal oxide can expose more active sites.

[0070] In some embodiments, the coating thickness is 30μm to 200μm, and the substrate thickness is 0.15mm to 2.0mm. Specifically, the coating thickness can be 30μm, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, etc.; the substrate thickness can be 0.15mm, 0.2mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, etc.

[0071] This invention provides an electrolytic oxygen evolution electrode for water electrolysis, which is prepared from the above-mentioned electrolytic oxygen evolution catalyst coating material and has the advantages of high catalytic activity and good stability.

[0072] Electrochemical testing showed that the electrode prepared in this embodiment of the invention exhibited a current density of 10 mA / cm² in the electrocatalytic oxygen evolution reaction. 2 The overpotential was 290mV, and the catalytic electrode had good stability, retaining 95% of the initial current after 20 hours during the chronoamperometry test.

[0073] Furthermore, the coated electrode has abundant raw materials, controllable preparation conditions, and high bonding strength; at a current density of 10 mA / cm², it can achieve this. 2 and 100mA / cm 2 At these times, the oxygen evolution overpotentials were 312 mV and 335 mV, respectively, demonstrating excellent electrocatalytic performance. This coated electrode, with its high catalytic activity, excellent catalytic stability, and strong practical applicability, greatly promotes the energy conversion efficiency of water electrolysis and is a novel oxygen evolution catalytic electrode.

[0074] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0075] Example 1

[0076] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0077] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder, and metallic aluminum powder according to a mass ratio of 4.5:1:0.2. Transfer them to a reagent bottle and mechanically mix for 12 hours. Place the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 70°C for 12 hours to dry it, ensuring good flowability of the powder used for spraying.

[0078] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0079] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0080] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate surface temperature to 150°C. The flow rates of the working gases Ar and H2 are 60 slpm and 20 slpm, respectively, and the preheating gun speed is 500 mm / s. -1 The preheating distance is 120mm and the preheating overlap is 5mm.

[0081] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are as follows: the working gases are Ar and H2, with an Ar flow rate of 60 slpm and an H2 flow rate of 12 slpm; the powder feed rate is 20 g / min. -1 The carrier air flow rate is 2 slpm, the spray overlap is 4 mm, the current is 400A, the spray distance is 110 mm, and the spray gun speed is 500 mm / s. -1 The number of spray coats is 4.

[0082] (6) The perforated nickel sheet with a mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 4 wt.% C4O6H4KNa, and the etching time was 4 h.

[0083] (7) Rinse the corroded nickel sheet three times with deionized water and dry it with cold air.

[0084] Example 2

[0085] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0086] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder, and metallic aluminum powder according to a mass ratio of 5:1:0.3. Transfer them to a reagent bottle and mechanically mix for 8 hours. Place the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 70°C for 6 hours to dry it, ensuring good flowability of the powder used for spraying.

[0087] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0088] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0089] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate surface temperature to 180°C. The flow rates of the working gases Ar and H2 are 60 slpm and 20 slpm, respectively, and the preheating gun speed is 480 mm / s. -1 The preheating distance is 120mm and the preheating overlap is 5mm.

[0090] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are as follows: the working gases are Ar and H2, with an Ar flow rate of 60 slpm and an H2 flow rate of 12 slpm; the powder feed rate is 25 g / min. -1 The carrier gas flow rate is 3 slpm, the current is 450A, the spraying distance is 120mm, and the spray gun speed is 500mm / s. -1 The overlap of the spray coating is 5mm, and the number of spray coats is 5.

[0091] (6) The prepared perforated nickel sheet with mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 4 wt.% sodium citrate, and the etching time was 6 h.

[0092] (7) Rinse the corroded nickel sheet three times with deionized water and dry it with cold air.

[0093] Example 3

[0094] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0095] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder, and metallic aluminum powder according to a mass ratio of 6:1:1. Transfer them to a reagent bottle and mechanically mix for 8 hours. Place the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 70°C for 6 hours to dry it, ensuring good flowability of the powder used for spraying.

[0096] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0097] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0098] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate temperature to 200°C. The flow rates of the working gases Ar and H2 are 60 slpm and 10 slpm, respectively, and the preheating gun speed is 450 mm / s. -1 The preheating distance is 120mm and the preheating overlap is 5mm.

[0099] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are: working gases are Ar and H2, with an Ar flow rate of 55 slpm and an H2 flow rate of 8 slpm; the powder feed rate is 30 g / min. -1 The carrier gas flow rate is 3 slpm, the current is 600A, the spraying distance is 110mm, and the spray gun speed is 500mm / s. -1 The overlap of the coating is 6mm, and the number of coating passes is 5.

[0100] (6) The perforated nickel sheet with a mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 4 wt.% C4O6H4KNa, and the etching time was 6 h.

[0101] (7) Rinse the corroded nickel sheet three times with deionized water and dry it with cold air.

[0102] Example 4

[0103] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0104] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder and metallic zinc powder according to a mass ratio of 5:1:2, transfer them to a reagent bottle, mechanically mix for 8 hours, put the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 70°C for 6 hours to dry it, ensuring good flowability of the powder used for spraying.

[0105] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0106] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0107] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate temperature to 250°C. The flow rates of the working gases Ar and H2 are 60 slpm and 10 slpm, respectively, and the preheating gun speed is 400 mm / s. -1 The preheating distance is 110mm and the preheating overlap is 5mm.

[0108] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are as follows: the working gases are Ar and H2, with an Ar flow rate of 50 slpm and an H2 flow rate of 12 slpm; the powder feed rate is 20 g / min. -1 The carrier gas flow rate is 3 slpm, the current is 550A, the spraying distance is 110mm, and the spray gun speed is 500mm / s. -1 The overlap of the spray coating is 5mm, and the number of spray coats is 3.

[0109] (6) The perforated nickel sheet with a mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 4 wt.% C4O6H4KNa, and the etching time was 4 h.

[0110] (7) Rinse the corroded nickel sheet three times with deionized water and dry it with cold air.

[0111] Example 5

[0112] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0113] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8: 0.2), metallic nickel powder, and metallic aluminum powder according to a mass ratio of 5.5:0.9:0.4. Transfer them to a reagent bottle and mechanically mix for 8 hours. Place the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 80°C for 12 hours to dry it, ensuring good flowability of the powder used for spraying.

[0114] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0115] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0116] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate temperature to 250°C. The flow rates of the working gases Ar and H2 are 60 slpm and 10 slpm, respectively, and the preheating gun speed is 400 mm / s. -1 The preheating distance is 110mm and the preheating overlap is 5mm.

[0117] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are as follows: the working gases are Ar and H2, with an Ar flow rate of 70 slpm and an H2 flow rate of 10 slpm; the powder feed rate is 40 g / min. -1 The carrier air flow rate is 3.5 slpm, the spray overlap is 6mm, the current is 600A, the spray distance is 160mm, and the spray gun speed is 500mm / s. -1 Spray 5 coats.

[0118] (6) The perforated nickel sheet with a mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 5 wt.% C4O6H4KNa, and the etching time was 6 h.

[0119] Rinse the corroded nickel sheet three times with deionized water and dry with cold air.

[0120] Example 6

[0121] This invention provides a method for preparing a coating material for an oxygen evolution catalyst in water electrolysis, comprising the following steps:

[0122] (1) Weigh spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder and metallic zinc powder according to a mass ratio of 4.5:1:3, transfer them to a reagent bottle, mechanically mix for 12 hours, put the reagent bottle containing the mixed powder into a forced-air drying oven and keep it at 80°C for 12 hours to dry it, ensuring good flowability of the powder used for spraying.

[0123] (2) Perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0124] (3) Sandblasting is performed on the punched nickel sheet after cleaning in step (2). 120# white corundum sand is selected and the air pressure is controlled at 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0125] (4) The punched nickel sheet processed in step (3) is preheated using a plasma spray gun twice to bring the substrate temperature to 300°C. The flow rates of the working gases Ar and H2 are 60 slpm and 10 slpm, respectively, and the preheating gun speed is 400 mm / s. -1 The preheating distance is 100mm and the preheating overlap is 4mm.

[0126] (5) The mixed powder is sprayed onto the roughened substrate surface using an atmospheric plasma spraying process. Specific spraying parameters are as follows: the working gases are Ar and H2, with an Ar flow rate of 65 slpm and an H2 flow rate of 12 slpm; the powder feed rate is 25 g / min. -1 The carrier gas flow rate is 2.5 slpm, the current is 500A, the spraying distance is 100mm, and the spray gun speed is 500mm / s. -1 The overlap of the spray coating is 5mm, and 3 coats are applied.

[0127] (6) The perforated nickel sheet with a mixed coating was etched using an alkaline solution. The alkaline solution consisted of an aqueous solution with concentrations of 20 wt.% KOH and 4 wt.% sodium fluoride, and the etching time was 6 h.

[0128] Rinse the corroded nickel sheet three times with deionized water and dry with cold air.

[0129] Example 7

[0130] The only difference from Example 1 is that in step (1), spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8: 0.2), metallic nickel powder, and metallic aluminum powder are weighed in a mass ratio of 4.5:1:0.6.

[0131] Example 8

[0132] The only difference from Example 1 is that in step (1), spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder, and metallic aluminum powder are weighed according to a mass ratio of 4.5:1:1.

[0133] Example 9

[0134] The only difference from Example 1 is that in step (1), spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8: 0.2), nickel powder and aluminum powder are weighed in a mass ratio of 4.5:1:1.4.

[0135] Example 10

[0136] The only difference from Example 1 is that in step (1), spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2), metallic nickel powder, and metallic aluminum powder are weighed in a mass ratio of 4.5:1:1.8.

[0137] Comparative Example 1

[0138] The only difference in Example 1 is that only spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8: 0.2) is weighed in step (1).

[0139] Comparative Example 2

[0140] The only difference in Example 1 is that aluminum powder is not weighed in step (1), and the ratio of spinel powder (manganese cobalt spinel: nickel cobalt spinel = 0.8:0.2) and metallic nickel powder remains unchanged.

[0141] Comparative Example 3

[0142] The only difference in Example 1 is that no coating is deposited on the substrate. The specific steps are as follows:

[0143] (1) A perforated nickel sheet (φ30mm×1.5mm) was selected as the substrate and ultrasonically treated with gasoline, acetone, anhydrous ethanol and deionized water respectively to remove organic impurities on the surface of the substrate.

[0144] (2) Sandblasting is performed on the punched nickel sheet after cleaning in step (1). 120# white corundum sand is selected, and the air pressure is controlled at 1 atm and 1 kg. The nickel sheet is sandblasted on one side to roughen the surface of the substrate. Compressed air is used to remove the residual sand and gravel on the surface. Then the substrate is ultrasonically treated with anhydrous ethanol for 10 min.

[0145] Experimental Example 1

[0146] The SEM images, XPS images, and oxygen evolution performance of the material prepared in Example 1 are shown in Figures 1-3. The oxygen evolution performance of the samples obtained in Examples 2-3 are shown in Figures 4 and 5. The oxygen evolution performance of the sample obtained in Example 3 after stability testing is shown in Figure 6.

[0147] Oxygen evolution performance test method: The three-electrode method was adopted, with the experimental sample as the working electrode, a platinum sheet as the counter electrode, and Hg / HgO as the reference electrode. The oxygen evolution performance was analyzed using an electrochemical workstation. During the test, the scan rate was 20mV / s from 0.6V to 1.6V. The current change value between the sample and the platinum sheet was collected using the electrochemical workstation. The oxygen evolution performance of the sample was obtained after the scan was completed, and the oxygen evolution performance curve was plotted using graphing software.

[0148] As can be seen from Figure 1, the surface layer of the coating has a nano-petal-like morphology, which can give the sample a large surface area. At the same time, the petal-like structure is tightly bound and not easy to fall off. Furthermore, finer texture structures can be seen on the surface of the petal-like structure, which further increases the surface area of ​​the sample.

[0149] As shown in Figure 2, the petal-like structure on the sample surface is mainly composed of three transition metals: Ni, Co, and Mn. Combined with the original powder, which consists of nickel, manganese cobalt spinel, and aluminum, after etching to remove the aluminum, the sample is left with nickel and manganese cobalt spinel phases. Nickel provides physical support and conductivity for manganese cobalt spinel, while manganese cobalt spinel provides active sites for the oxygen evolution reaction. Therefore, the three elements Ni, Co, and Mn in the sample combine to form a highly catalytically active phase, namely, the metallic nickel composite spinel phase.

[0150] As can be seen from Figures 3-6, by appropriately adjusting the mass ratio of nickel, manganese cobalt spinel and aluminum, and by controlling the spraying process parameters, the oxygen evolution performance of the coated samples can be significantly improved, and the resulting samples exhibit excellent oxygen evolution stability.

[0151] Experimental Example 2

[0152] The properties of the materials prepared in the examples and comparative examples were tested using conventional methods, and the results are shown in Table 1.

[0153] Table 1 shows the performance test results of the materials obtained in the examples and comparative examples.

[0154]

[0155]

[0156] As shown in Table 1, the addition of manganese cobalt spinel can effectively improve the catalytic activity of the electrode coating. However, when manganese cobalt spinel is used alone, the oxygen evolution reaction under a large current is limited. This is because manganese cobalt spinel has poor conductivity, which limits the electrolysis reaction. The addition of nickel can effectively improve its conductivity. Further addition of aluminum to create pores can significantly improve the catalytic activity of the electrode sample, thereby effectively reducing its overpotential.

[0157] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coating material for an oxygen evolution catalyst in water electrolysis, characterized in that, The invention includes a substrate and a coating attached to the substrate. The coating includes a nickel skeleton, spinel-type manganese cobalt oxide, and spinel-type nickel cobalt oxide. The nickel skeleton has a porous structure, and some of the spinel-type manganese cobalt oxide and the spinel-type nickel cobalt oxide are loaded on the nickel skeleton. The preparation method of the electrolytic oxygen evolution catalyst coating material includes: mixing spinel oxide powder, nickel powder and pore-forming powder to prepare a powder to be sprayed; using the powder to be sprayed to form a mixed coating on the substrate; chemically etching the mixed coating; wherein the spinel oxide powder includes spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder; forming the mixed coating on the substrate using atmospheric plasma spraying; the mass ratio of the spinel oxide powder, the nickel powder and the pore-forming agent is 4.5~5.0:0.9~1.0:0.2~5.0, and the mass ratio of spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder is 0.9~0.5:0.1~0.

5.

2. The coating material for the oxygen evolution catalyst in water electrolysis according to claim 1, characterized in that, The total amount of the spinel-type manganese cobalt oxide and the spinel-type nickel cobalt oxide is in a mass ratio of 4.5 to 5.0 to the mass of the metallic nickel framework.

3. The coating material for the oxygen evolution catalyst in water electrolysis according to claim 1, characterized in that, The substrate is at least one of nickel sheet, nickel-based alloy, nickel-plated metal sheet, and stainless steel sheet.

4. The coating material for the oxygen evolution catalyst in water electrolysis according to claim 3, characterized in that, The coating has a sheet-like nanoflower porous structure.

5. The coating material for the oxygen evolution catalyst in water electrolysis according to claim 4, characterized in that, The coating thickness is 30μm~200μm, and the substrate thickness is 0.15mm~2.0mm.

6. A method for preparing the coating material of the water electrolysis oxygen evolution catalyst as described in any one of claims 1-5, characterized in that, include: Spinel oxide powder, nickel powder and pore-forming powder are mixed to prepare a powder to be sprayed, and the powder to be sprayed is used to form a mixed coating on the substrate; The mixed coating is chemically etched; wherein the spinel oxide powder includes spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder; the mixed coating is formed on the substrate by atmospheric plasma spraying; the mass ratio of the spinel oxide powder, the nickel powder and the pore-forming agent is 4.5~5.0:0.9~1.0:0.2~5.0, and the mass ratio of spinel-type manganese cobalt oxide powder and spinel-type nickel cobalt oxide powder is 0.9~0.5:0.1~0.

5.

7. The preparation method according to claim 6, characterized in that, The preparation process of the powder to be sprayed includes: mixing the spinel oxide powder, the nickel powder and the pore-forming agent, drying them at a temperature of 60℃~100℃ for a time of 6h~36h.

8. The preparation method according to claim 6, characterized in that, During the atmospheric plasma spraying process, the controlled current is 400A to 600A, the spraying distance is 80mm to 200mm, the main gas flow rate is 50splm to 80splm, the auxiliary gas flow rate is 5splm to 20splm, the substrate preheating temperature is 100℃ to 400℃, the spray gun power is 30kW to 50kW, the powder feeding rate is 15g / min to 50g / min, the spraying overlap is 5mm to 20mm, and the spraying speed is 300mm / s to 600mm / s.

9. The preparation method according to claim 8, characterized in that, The substrate is pretreated before spraying, and the pretreatment includes a first washing, sandblasting, a second washing, and drying in sequence.

10. The preparation method according to claim 9, characterized in that, The first wash involves ultrasonic washing using an organic solvent and water in sequence.

11. The preparation method according to claim 10, characterized in that, Ultrasonic cleaning using the organic solvent involves sequentially washing with gasoline, acetone, and anhydrous ethanol.

12. The preparation method according to claim 9, characterized in that, The solvent used for the secondary washing is selected from at least one of water and anhydrous ethanol.

13. The preparation method according to claim 6, characterized in that, The solution used for chemical corrosion contains an inorganic base and a ligand, wherein the inorganic base is selected from at least one of sodium hydroxide and potassium hydroxide, and the ligand is selected from at least one of sodium potassium tartrate, sodium citrate, and sodium bicarbonate.

14. The preparation method according to claim 13, characterized in that, In the solution, the ligand has a mass fraction of 3% to 30%, and the inorganic base has a mass fraction of 10% to 50%.

15. The preparation method according to claim 13, characterized in that, The time for corrosion using alkaline solution is 5 to 40 hours.

16. An oxygen evolution electrode for water electrolysis, characterized in that, It is prepared from the water electrolysis oxygen evolution catalyst coating material according to any one of claims 1-5 or the preparation method according to any one of claims 6-15.

17. The application of the water electrolysis oxygen evolution electrode according to claim 16 in water electrolysis for hydrogen production.

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