Large-area active cathode and preparation method thereof

Abstract

The invention relates to the technical field of preparation and application of electro-catalytic materials, in particular to a large-area active cathode and a preparation method. The large-area active cathode comprises a nickel electrode substrate, a conductive layer which covers the surface of the nickel electrode substrate and contains a NiCo2O4 spinel structure, and a noble metal-containing coating which covers the surface of the conductive layer and consists of ruthenium and platinum, wherein the nickel electrode substrate is a composite body of a planar net and a three-dimensional net made of a nickel material, and the NiCo2O4 spinel structure in the conductive layer is tightly attached to the surface of the nickel substrate; wherein platinum in the precious metal-containing coating layer as an active layer is in an atomic-scale dispersed state in the precious metal-containing coating layer and is embedded into spinel crystal lattices on the surface of the conductive layer, and ruthenium in the precious metal-containing coating layer exists in the precious metal-containing coating layer in the form of ruthenium oxide. The preparation of the high-performance and low-cost large-area chlor-alkali electrolytic cell cathode coating is realized through trace platinum atom doping and spinel synergistic effect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic material preparation and application, and specifically to a large-area active cathode and a preparation method thereof, and more particularly to a stable, high-performance, low-cost chlor-alkali large-area active cathode and a preparation method thereof. Background Art

[0002] As a core pillar of the basic chemical industry, the chlor-alkali industry's electrolysis process consumes over 60% of its total production costs. High cathode hydrogen evolution overpotential is a key bottleneck leading to rising energy consumption. In recent years, researchers have proposed reducing overpotential through surface modification or alloying. For example, Raney Ni and Ni-Mo alloys can reduce overpotential to 140-160mV (at a current density of 2k-3kA / m). 2 ), but suffer from problems such as low mechanical strength of porous structures and poor resistance to reverse current, making active layer delamination and sintering deactivation prone to occur in large-scale industrial applications. Furthermore, while precious metal-based catalysts (such as Pt / Pd-modified electrodes) can significantly enhance intrinsic activity, their high cost and scarcity severely restrict large-scale application.

[0003] Current technical difficulties lie in three dimensions: first, the long-term stability of non-precious metal catalytic systems in high-temperature, strong-alkaline environments is insufficient; second, the uniform coating process for large-area electrodes (>1m²) has yet to be broken through; and third, the low charge transfer efficiency at the multiphase interface of composite electrodes makes it difficult to balance the mass transfer requirements of high-loaded catalysts with conductivity losses.

[0004] Therefore, the development of large-area cathode preparation technology with high intrinsic activity, structural stability and low cost has become a core breakthrough in promoting energy efficiency upgrades in the chlor-alkali industry. Summary of the Invention

[0005] The purpose of the present invention is to provide a stable, high-performance, low-cost large-area chlor-alkali active cathode, which adopts a composite structure nickel substrate to improve the electrode strength and stability. A conductive layer containing NiCo2O4 spinel structure is first covered on the pre-treated nickel electrode substrate to produce Ni 2+ With Co 3+ The bimetallic synergistic effect of Co can reduce the reaction energy barrier by adjusting the electronic structure. 3+ The upward shift of the d-band center may enhance the ability to dissociate water molecules, while the electron-deficient state of the oxygen ligand reduces the hydrogen adsorption energy. The surface of the NiCo2O4 spinel structure is then covered with a precious metal coating composed of ruthenium and platinum. Through staged oxidation, on the one hand, atomic-level dispersion of platinum is achieved to enhance the performance of the conductive layer and improve the corrosion resistance of the surface layer. On the other hand, ruthenium is oxidized to its corresponding oxide form, providing an electrode surface with high intrinsic activity. The specific technical solution is as follows: A large-area active cathode comprises a nickel electrode substrate, a conductive layer containing a NiCo2O4 spinel structure covering the surface of the nickel electrode substrate, and a precious metal coating composed of ruthenium and platinum covering the surface of the conductive layer; wherein the nickel electrode substrate is a composite of a planar mesh and a three-dimensional mesh made of nickel material, and the NiCo2O4 spinel structure in the conductive layer is tightly attached to the surface of the nickel substrate; wherein the platinum in the precious metal coating serving as the active layer is atomically dispersed in the precious metal coating and embedded in the spinel lattice on the surface of the conductive layer, and the ruthenium in the precious metal coating exists in the precious metal coating in the form of ruthenium oxide.

[0006] Wherein, the flat mesh is a nickel stamping mesh or a nickel wire mesh, and the three-dimensional mesh is a nickel stamping mesh with a U-shaped stamping structure.

[0007] Wherein, the plane net is embedded into the surface of the three-dimensional net.

[0008] Cathodic coating at 100 A / m 2 The hydrogen evolution overpotential at the current density is ≤40 mV (Vs NHE), and at 5 kA / m 2 The hydrogen evolution overpotential at the current density is ≤160 mV (Vs NHE), and the hydrogen evolution overpotential at the current density is 3A / cm 2 Under the test conditions of temperature 85±5 ℃, its accelerated test life is ≥3000 hours.

[0009] A method for preparing a large-area active cathode comprises the following steps: first, coating nickel and cobalt elements and then sintering them on the surface of a nickel electrode substrate, thereby forming a conductive layer containing a NiCo2O4 spinel structure on the surface of the nickel electrode substrate; then, applying a ruthenium-platinum precursor to the surface of the conductive layer containing the NiCo2O4 spinel structure by ultrasonic spraying, thereby forming a precious metal coating composed of ruthenium and platinum on the surface of the conductive layer; and then, achieving atomic-level dispersion of platinum in the precious metal coating through two-stage oxidation to improve the utilization rate of the platinum element.

[0010] Preferably, when the ruthenium-platinum precursor is mixed with the metal salt, a complexing agent and a chlorine removal agent are added thereto to improve the stability of the coating solution used to prepare the precious metal coating and to prevent chloride ions from corroding the nickel electrode substrate.

[0011] Preferably, in the precious metal coating composed of ruthenium-platinum, the platinum used is a low-content trace amount of platinum, and the ruthenium sites dominate the HER activity. The electronic modification effect of trace platinum on ruthenium is utilized to enhance the performance of ruthenium oxide and improve the catalytic activity of the large-area active cathode.

[0012] The method for preparing the large-area active cathode for the chlor-alkali industry specifically comprises the following steps: (1) Nickel substrate processing: Use high-conductivity nickel stamping mesh or nickel-based woven mesh as the base material, and perform continuous precision processing through a multi-station progressive stamping die to form an electrode mesh carrier component with a reinforced edge folding structure; (2) Pretreatment of nickel-based electrode mesh: After sandblasting, the nickel-based electrode mesh is soaked in acetone for 10-30 min, fished out and rinsed with pure water, and finally placed in a high-temperature furnace at 400 °C for 15 min, cooled and taken out for use; (3) Preparation of nickel substrate structure: The processed stamped mesh is processed into a three-dimensional mesh with a U-shaped structure, and then a piece of stamped mesh or nickel wire mesh is embedded into the surface of the three-dimensional mesh to form a nickel electrode substrate; (4) Coating liquid preparation: nickel chloride, cobalt chloride, ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water are used as raw materials to prepare the cathode coating liquid, which includes a NiCo2O4 spinel conductive layer and a high-temperature resistant stable high HER active layer coating liquid; the proportions of each layer of electrode coating liquid are as follows: The conductive layer electrode coating liquid is prepared by preparing nickel-cobalt coating liquid with nickel chloride, cobalt chloride, urea and pure water, wherein the molar ratio of nickel, cobalt, urea and pure water is (1-5): (0.5-5): 6: (120-180), and ultrasonic dispersion is performed after preparation; The active layer electrode coating liquid is a ruthenium-platinum coating liquid prepared with ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol and pure water, wherein the molar ratio of ruthenium, platinum, citric acid, urea, hydrochloric acid, ethylene glycol and pure water is 60: (0-1): 100: 100: 70: 60: (7000-8000), and ultrasonic dispersion is performed after preparation; (5) Ultrasonic spraying and staged oxidation: First, the prepared conductive layer coating liquid is fixed on the surface of the pretreated nickel substrate electrode mesh by ultrasonic spraying. The ultrasonic spraying operation adopts a multi-nozzle ultrasonic spraying system with an atomization frequency of 80~100 kHz, a spraying distance of 8~10 cm, and a substrate temperature controlled at 25~35 ℃. 35~40 ml is sprayed per square meter per layer, and the spraying is performed in 2~3 times. After each spraying, it is left to stand for 5~10 minutes. After each layer of spraying, the electrode is transferred to an oven at 80 ℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350 ℃ and maintained for 15 minutes, and finally heated to 450 ℃ and maintained for 10 min, and the final number of conductive layer coating layers is 2~3 layers; the operation of the active layer is consistent with the above operation, and the final number of layers is 3~4 layers to ensure optimal activity while reducing the amount of precious metals, so that the Ru content per square meter is less than 5g and the Pt content per square meter is less than 0.16g; among them, the operation of the last coating of the active layer is: ultrasonic spraying operation uses a multi-nozzle ultrasonic spraying system, the atomization frequency is 80~100 kHz, the spraying distance is 8~10 cm, the substrate temperature is controlled at 25~35℃, 35~40 ml is sprayed per layer, and the spraying is performed in 2~3 times. After each spraying, it is allowed to stand for 5~10 minutes. After each spraying, the electrode is transferred to an oven at 80℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350℃ and maintained for 15 minutes, then programmed to 450℃ at a rate of 5℃ / min and kept at this temperature for 30 minutes, and finally programmed to cool to about 80℃ at a rate of 5℃ / min.

[0013] Preferably, in the conductive layer coating solution, the molar ratio of nickel to cobalt is 3:2.

[0014] Preferably, in the active layer coating solution, the molar ratio of ruthenium to platinum is 60:1.

[0015] The above-mentioned coated electrode is applied to a method for testing the electrocatalytic hydrogen evolution performance of a stable, high-performance, low-cost, large-area chlor-alkali active cathode. A three-electrode system is used, wherein the working electrode is the stable, high-performance, low-cost, large-area chlor-alkali active cathode, the counter electrode is a platinum sheet electrode, the reference electrode is a double salt bridge saturated potassium chloride solution calomel electrode with a Luggin capillary, and the electrolyte is a 1 mol / L or 32 wt% NaOH solution.

[0016] The beneficial effects of the present invention are: First, the present invention provides a large-area active cathode and preparation method. The bimetallic synergistic effect of the NiCo2O4 spinel structure significantly improves the conductivity, reduces the hydrogen adsorption energy by adjusting the electronic structure, and provides a stable and highly conductive HER (hydrogen evolution reaction) cathode coating substrate.

[0017] Second, the present invention provides a large-area active cathode and preparation method, which forms a synergistic effect of trace platinum atom doping + spinel through staged high-temperature oxidation. During its preparation process, only a very small amount of platinum atoms need to be incorporated into the coating to work together with the spinel structure to achieve the purpose of improving the coating performance, thereby significantly enhancing the catalytic efficiency of the cathode without significantly increasing the cost, thereby realizing the high-performance, low-cost preparation of large-area chlor-alkali electrolytic cell cathode coatings; by evenly dispersing trace platinum atoms in the spinel of the conductive layer, the corrosion resistance of the coating in alkaline solutions is also enhanced.

[0018] Third, the present invention provides a large-area active cathode and preparation method, with ruthenium oxide (RuO2) as the main active substance on the surface, providing the main catalytic active sites. The incorporation of platinum atoms further reduces the electrode HER potential while having excellent anti-poisoning ability.

[0019] Fourth, the present invention provides a large-area active cathode and preparation method. During the coating preparation process, staged oxidation is carried out by controlling the temperature and atmosphere conditions, so that platinum can be dispersed at the atomic level on the surface of the NiCo2O4 spinel structure, thereby achieving higher electrocatalytic activity, better electron conduction efficiency and stronger corrosion resistance.

[0020] Fifth, the present invention provides a large-area active cathode and preparation method, and the composite structure of the flat mesh and three-dimensional mesh of the nickel electrode base is beneficial to increasing the electrode strength and specific surface area, reducing the actual current density of the anode, and improving its service life and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Surface SEM image of Example 1; Figure 2 : EDS element scanning diagram of Example 1; Figure 3 : SEM image of the coating cross section of Example 1 after 500 hours of intensive aging; Figure 4 Schematic diagram of the plane network in the active cathode structure; Figure 5 Schematic diagram of the three-dimensional network in the active cathode structure; Figure 6 Schematic diagram of the planar network and three-dimensional network complex in the active cathode structure. DETAILED DESCRIPTION

[0022] The following embodiments are further described in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] like Figures 1 to 6Shown is an overall implementation plan of a large-area active cathode and a preparation method of the present invention, wherein the large-area active cathode includes a nickel electrode substrate, a conductive layer containing a NiCo2O4 spinel structure covering the surface of the nickel electrode substrate, and a precious metal coating composed of ruthenium-platinum covering the surface of the conductive layer; wherein the nickel electrode substrate is a composite of a planar mesh and a three-dimensional mesh made of nickel material, and the NiCo2O4 spinel structure in the conductive layer is tightly attached to the surface of the nickel substrate; wherein the platinum in the precious metal coating serving as an active layer is in an atomically dispersed state in the precious metal coating and is embedded in the spinel lattice on the surface of the conductive layer, and the ruthenium in the precious metal coating exists in the precious metal coating in the form of ruthenium oxide.

[0024] Wherein, the flat mesh is a nickel stamping mesh or a nickel wire mesh, and the three-dimensional mesh is a nickel stamping mesh with a U-shaped stamping structure.

[0025] Wherein, the plane net is embedded into the surface of the three-dimensional net.

[0026] Cathodic coating at 100 A / m 2 The hydrogen evolution overpotential at the current density is ≤40 mV (Vs NHE), and at 5 kA / m 2 The hydrogen evolution overpotential at the current density is ≤160 mV (Vs NHE), and the hydrogen evolution overpotential at the current density is 3A / cm 2 Under the test conditions of temperature 85±5 ℃, its accelerated test life is ≥3000 hours.

[0027] A method for preparing a large-area active cathode comprises the following steps: first, coating nickel and cobalt elements and then sintering them on the surface of a nickel electrode substrate, thereby forming a conductive layer containing a NiCo2O4 spinel structure on the surface of the nickel electrode substrate; then, applying a ruthenium-platinum precursor to the surface of the conductive layer containing the NiCo2O4 spinel structure by ultrasonic spraying, thereby forming a precious metal coating composed of ruthenium and platinum on the surface of the conductive layer; and then, achieving atomic-level dispersion of platinum in the precious metal coating through two-stage oxidation to improve the utilization rate of the platinum element.

[0028] Preferably, when the ruthenium-platinum precursor is mixed with the metal salt, a complexing agent and a chlorine removal agent are added thereto to improve the stability of the coating solution used to prepare the precious metal coating and to prevent chloride ions from corroding the nickel electrode substrate.

[0029] Preferably, in the precious metal coating composed of ruthenium-platinum, the platinum used is a low-content trace amount of platinum, and the ruthenium sites dominate the HER activity. The electronic modification effect of trace platinum on ruthenium is utilized to enhance the performance of ruthenium oxide and improve the catalytic activity of the large-area active cathode.

[0030] The method for preparing the large-area active cathode for the chlor-alkali industry specifically comprises the following steps: (1) Nickel substrate processing: Use high-conductivity nickel stamping mesh or nickel-based woven mesh as the base material, and perform continuous precision processing through a multi-station progressive stamping die to form an electrode mesh carrier component with a reinforced edge folding structure; (2) Pretreatment of nickel-based electrode mesh: After sandblasting, the nickel-based electrode mesh is soaked in acetone for 10-30 min, fished out and rinsed with pure water, and finally placed in a high-temperature furnace at 400 °C for 15 min, cooled and taken out for use; (3) Preparation of nickel substrate structure: The processed stamped mesh is processed into a three-dimensional mesh with a U-shaped structure, and then a piece of stamped mesh or nickel wire mesh is embedded into the surface of the three-dimensional mesh to form a nickel electrode substrate; (4) Coating liquid preparation: nickel chloride, cobalt chloride, ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water are used as raw materials to prepare the cathode coating liquid, which includes a NiCo2O4 spinel conductive layer and a high-temperature resistant stable high HER active layer coating liquid; the proportions of each layer of electrode coating liquid are as follows: The conductive layer electrode coating liquid is prepared by preparing nickel-cobalt coating liquid with nickel chloride, cobalt chloride, urea and pure water, wherein the molar ratio of nickel, cobalt, urea and pure water is (1-5): (0.5-5): 6: (120-180), and ultrasonic dispersion is performed after preparation; The active layer electrode coating liquid is a ruthenium-platinum coating liquid prepared with ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol and pure water, wherein the molar ratio of ruthenium, platinum, citric acid, urea, hydrochloric acid, ethylene glycol and pure water is 60: (0-1): 100: 100: 70: 60: (7000-8000), and ultrasonic dispersion is performed after preparation; (5) Ultrasonic spraying and staged oxidation: First, the prepared conductive layer coating liquid is fixed on the surface of the pretreated nickel substrate electrode mesh by ultrasonic spraying. The ultrasonic spraying operation adopts a multi-nozzle ultrasonic spraying system with an atomization frequency of 80~100 kHz, a spraying distance of 8~10 cm, and a substrate temperature controlled at 25~35 ℃. 35~40 ml is sprayed per square meter per layer, and the spraying is performed in 2~3 times. After each spraying, it is left to stand for 5~10 minutes. After each layer of spraying, the electrode is transferred to an oven at 80 ℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350 ℃ and maintained for 15 minutes, and finally heated to 450 ℃ and maintained for 10 min, and the final number of conductive layer coating layers is 2~3 layers; the operation of the active layer is consistent with the above operation, and the final number of layers is 3~4 layers to ensure optimal activity while reducing the amount of precious metals, so that the Ru content per square meter is less than 5g and the Pt content per square meter is less than 0.16g; among them, the operation of the last coating of the active layer is: ultrasonic spraying operation uses a multi-nozzle ultrasonic spraying system, the atomization frequency is 80~100 kHz, the spraying distance is 8~10 cm, the substrate temperature is controlled at 25~35℃, 35~40 ml is sprayed per layer, and the spraying is performed in 2~3 times. After each spraying, it is allowed to stand for 5~10 minutes. After each spraying, the electrode is transferred to an oven at 80℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350℃ and maintained for 15 minutes, then programmed to 450℃ at a rate of 5℃ / min and kept at this temperature for 30 minutes, and finally programmed to cool to about 80℃ at a rate of 5℃ / min.

[0031] Preferably, in the conductive layer coating solution, the molar ratio of nickel to cobalt is 3:2.

[0032] Preferably, in the active layer coating solution, the molar ratio of ruthenium to platinum is 60:1.

[0033] The above-mentioned coated electrode is applied to a method for testing the electrocatalytic hydrogen evolution performance of a stable, high-performance, low-cost, large-area chlor-alkali active cathode. A three-electrode system is used, wherein the working electrode is the stable, high-performance, low-cost, large-area chlor-alkali active cathode, the counter electrode is a platinum sheet electrode, the reference electrode is a double salt bridge saturated potassium chloride solution calomel electrode with a Luggin capillary, and the electrolyte is a 1 mol / L or 32 wt% NaOH solution.

[0034] The following are several examples formulated according to the overall implementation scheme of a large-area active cathode and a preparation method of the present invention.

[0035] Example 1: 1. Preparation of 32 wt% NaOH solution: Dissolve 64 g of NaOH flakes in 180 ml of ultrapure water. After the solution is completely cooled, transfer it to a 200 ml volumetric flask and make up to volume.

[0036] 2. Preparation of 35 wt% NaOH solution: Dissolve 350 g of NaOH flakes in 950 ml of ultrapure water. After the solution has completely cooled, transfer it to a 1000 ml volumetric flask and make up to volume.

[0037] 3. Preparation of 30 wt% KOH solution: Dissolve 300 g of KOH flakes in 950 ml of ultrapure water. After the solution is completely cooled, transfer it to a 1000 ml volumetric flask and make up to volume.

[0038] 4. Processing and pretreatment of nickel base material for active cathode: Nickel-based electrode mesh processing: Using highly conductive nickel punched sheets or nickel-based woven mesh as the base material, continuous precision processing is performed through a multi-station progressive stamping die to form an electrode mesh carrier component with a reinforced edge folding structure; Pretreatment of nickel-based electrode mesh: After sandblasting, the nickel-based electrode mesh is soaked in acetone for 10-30 minutes, fished out and rinsed with pure water, and finally transferred to a high-temperature furnace at 400°C for 15 minutes, then taken out and cooled for use.

[0039] 5. Preparation of coating solution for coated electrodes: Nickel chloride, cobalt chloride, ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water are used as raw materials to prepare a cathode coating solution. The coating solution includes a NiCo2O4 spinel conductive layer and a high-temperature resistant, stable, and high-HER active layer coating solution. The proportions of the electrode coating solutions for each layer are as follows: The conductive layer electrode coating liquid is prepared by using nickel chloride, cobalt chloride, urea and pure water to prepare a nickel-cobalt coating liquid, wherein the molar ratio of nickel, cobalt, urea and pure water is 3:2:6:(120-180). After the preparation, ultrasonic dispersion is performed; The active layer electrode coating liquid is a ruthenium-platinum coating liquid prepared with ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol and pure water, wherein the molar ratio of ruthenium, platinum, citric acid, urea, hydrochloric acid, ethylene glycol and pure water is 60:1:100:100:70:60:(7000~8000), and ultrasonic dispersion is performed after preparation.

[0040] 6. Ultrasonic spraying and staged oxidation: First, the prepared conductive layer coating liquid is fixed on the surface of the pretreated nickel substrate electrode mesh by ultrasonic spraying. The ultrasonic spraying operation uses a multi-nozzle ultrasonic spraying system with an atomization frequency of 80-100 kHz, a spraying distance of 8-10 cm, and a substrate temperature controlled at 25-35°C. 35-40 ml per square meter per layer is sprayed in 2-3 times. After each spraying, the electrode is allowed to stand for 5-10 minutes. After each layer of spraying, the electrode is transferred to an oven at 80°C and maintained for 5-10 minutes, then transferred to a high-temperature oxidation furnace at 350°C and maintained for 15 minutes, and finally heated to 450°C and maintained for 10 minutes. The final number of conductive layer coating layers is 2-3 layers. The operation of the active layer is consistent with the above operation, and the final number of layers is 3-4 layers, which can reduce the amount of precious metals while ensuring optimal activity (Ru content is less than 5g per square meter, and Pt content is less than 0.16g per square meter). Among them, the last coating operation of the active layer is: ultrasonic spraying operation uses a multi-nozzle ultrasonic spraying system, the atomization frequency is 80~100 kHz, the spraying distance is 8~10 cm, the substrate temperature is controlled at 25~35 ℃, 35~40 ml is sprayed per layer, and the spraying is performed in 2~3 times. After each spraying, it is allowed to stand for 5~10 minutes. After each layer of spraying, the electrode is transferred to an oven at 80 ℃ and maintained for 5~10 minutes, and then transferred to a high-temperature oxidation furnace at 350 ℃ and maintained for 15 minutes. Then, the temperature is programmed to 450 ℃ at a rate of 5 ℃ / min and kept for 30 minutes. Finally, the temperature is programmed to cool to about 80 ℃ at a rate of 5 ℃ / min.

[0041] 7. Application (1) Hydrogen evolution potential test A three-electrode system was used, with the working electrode being a stable, high-performance, low-cost, large-area active cathode for chlor-alkali, the auxiliary electrode being a platinum sheet, and the reference electrode being a double salt bridge saturated potassium chloride solution calomel electrode with a Luggin capillary. The electrocatalyst was reacted in a 32 wt% NaOH electrolyte at a current density of 4000 A / m at 90±2°C. 2 The hydrogen evolution potential is 1.104 V (vs SCE) when . The experimental results are shown in Table 1.

[0042] (2) Strengthening weightlessness performance test The cathode coating electrode is connected to a constant current DC power supply with a current density of 20000 A / m 2 The solution system was 35 wt% NaOH solution, the temperature was 85±5°C, and the experiment was carried out for 4 h. The loss rate of precious metal in the test electrode was 0%. The experimental results are shown in Table 3.

[0043] (3) Cumulative test of electrode aging time The cathode coating electrode is connected to a constant current DC power supply with a current density of 30000 A / m2 The solution system is 30 wt% KOH solution, the temperature is 85±5℃, and the time for the test voltage to rise by 2 V is 3155h. The experimental results are shown in Table 2.

[0044] Example 2: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 1:2:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0045] Example 3: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 5:2:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0046] Example 4: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 3:0.5:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0047] Example 5: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 3:5:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0048] Example 6: Compared with Example 1, the difference is that the molar ratio of ruthenium chloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water in the active layer coating solution is 60:0:100:100:70:60:(7000-8000), and the other preparation methods are the same as those in Example 1.

[0049] Comparative Example 1: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 0:2:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0050] Comparative Example 2: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 10:2:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0051] Comparative Example 3: Compared with Example 1, the difference is that the molar ratio of nickel chloride, cobalt chloride, urea and pure water in the conductive layer coating solution is 3:0:6:(120-180), and the other preparation methods are the same as those in Example 1.

[0052] Comparative Example 4: Compared with Example 1, the difference is that the molar ratio of ruthenium chloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water in the active layer coating solution is 30:0:100:100:70:60:(7000-8000), and the other preparation methods are the same as those in Example 1.

[0053] Summary of experimental results: Table 1 shows the results of Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 in 32 wt% NaOH solution at a current density of 4000 A / m 2 , at a temperature of 90±2℃ Table 1 Hydrogen evolution potential test sample Hydrogen evolution potential test / V vs SCE Example 1 1.104 Example 2 1.208 Example 3 1.255 Example 4 1.224 Example 5 1.267 Example 6 1.215 Comparative Example 1 1.347 Comparative Example 2 1.381 Comparative Example 3 1.389 Comparative Example 4 1.230 Table 2 shows the results of Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 in 35 wt% NaOH solution at a current density of 20,000 A / m 2 , the enhanced weight loss results of the reaction for 4 h at a temperature of 85±5 ℃.

[0054] Table 2 Enhanced weightlessness performance test sample Enhanced weight loss rate / % Example 1 0 Example 2 0.49 Example 3 0.76 Example 4 0.26 Example 5 0.92 Example 6 1.32 Comparative Example 1 1.85 Comparative Example 2 1.57 Comparative Example 3 3.66 Comparative Example 4 1.02 Table 3 shows the results of Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 in 30 wt% KOH solution at a current density of 30,000 A / m 2 , the reaction temperature is 85±5 ℃, and the enhanced aging time is when the voltage is increased by 2 V.

[0055] Table 3 Enhanced life test (accumulated time of hydrogen electrode enhanced aging) sample Simulation test life / h Example 1 3155 Example 2 1709 Example 3 1962 Example 4 1058 Example 5 1437 Example 6 932 Comparative Example 1 519 Comparative Example 2 463 Comparative Example 3 415 Comparative Example 4 681 The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A large-area active cathode, characterized in that: It comprises a nickel electrode substrate, a conductive layer containing a NiCo2O4 spinel structure covering the surface of the nickel electrode substrate, and a precious metal coating composed of ruthenium-platinum covering the surface of the conductive layer; wherein the nickel electrode substrate is a composite of a planar mesh and a three-dimensional mesh made of nickel material, and the NiCo2O4 spinel structure in the conductive layer is tightly attached to the surface of the nickel substrate; wherein the platinum in the precious metal coating serving as an active layer is in an atomically dispersed state in the precious metal coating and is embedded in the spinel lattice on the surface of the conductive layer, and the ruthenium in the precious metal coating exists in the precious metal coating in the form of ruthenium oxide.

2. A large-area active cathode according to claim 1, characterized in that: The flat mesh is a nickel stamping mesh or a nickel wire mesh, and the three-dimensional mesh is a nickel stamping mesh with a U-shaped stamping structure.

3. A large-area active cathode according to claim 1, characterized in that: The plane net is embedded into the surface of the three-dimensional net.

4. A large-area active cathode according to claim 1, characterized in that: Cathodic coating at 100 A / m 2 The hydrogen evolution overpotential at the current density is ≤40 mV (Vs NHE), and at 5 kA / m 2 The hydrogen evolution overpotential at the current density is ≤160 mV (VsNHE), and the hydrogen evolution overpotential at the current density is 3A / cm 2 Under the test conditions of temperature 85±5 ℃, its accelerated test life is ≥3000 hours.

5. A method for preparing a large-area active cathode according to any one of claims 1 to 4, characterized in that: Nickel and cobalt elements are first coated and sintered on the surface of a nickel electrode substrate, thereby forming a conductive layer containing a NiCo2O4 spinel structure on the surface of the nickel electrode substrate; then a ruthenium-platinum precursor is ultrasonically sprayed onto the surface of the conductive layer containing the NiCo2O4 spinel structure, thereby forming a precious metal coating composed of ruthenium and platinum on the surface of the conductive layer; Then, through two-stage oxidation, atomic-level dispersion of platinum in the precious metal coating is achieved to improve the utilization rate of the platinum element.

6. The method for preparing a large-area active cathode according to claim 5, characterized in that: When the ruthenium-platinum precursor is mixed with the metal salt, a complexing agent and a chlorine removal agent are added thereto to improve the stability of the coating solution used to prepare the precious metal coating and to prevent chloride ions from corroding the nickel electrode substrate.

7. The method for preparing a large-area active cathode according to claim 5, characterized in that: In the precious metal coating composed of ruthenium-platinum, the platinum content is a low trace amount of platinum, and the ruthenium sites dominate the HER activity. The electronic modification effect of trace platinum on ruthenium is used to enhance the performance of ruthenium oxide and improve the catalytic activity of large-area active cathodes.

8. The method for preparing a large-area active cathode according to claim 5, characterized in that: The steps include: (1) Nickel substrate processing: Use high-conductivity nickel stamping mesh or nickel-based woven mesh as the base material, and perform continuous precision processing through a multi-station progressive stamping die to form an electrode mesh carrier component with a reinforced edge folding structure; (2) Pretreatment of nickel-based electrode mesh: After sandblasting, the nickel-based electrode mesh is soaked in acetone for 10-30 min, fished out and rinsed with pure water, and finally placed in a high-temperature furnace at 400 °C for 15 min, cooled and taken out for use; (3) Preparation of nickel substrate structure: The processed stamped mesh is processed into a three-dimensional mesh with a U-shaped structure, and then a piece of stamped mesh or nickel wire mesh is embedded into the surface of the three-dimensional mesh to form a nickel electrode substrate; (4) Coating liquid preparation: nickel chloride, cobalt chloride, ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol, and pure water are used as raw materials to prepare the cathode coating liquid, which includes a NiCo2O4 spinel conductive layer and a high-temperature resistant stable high HER active layer coating liquid; the proportions of each layer of electrode coating liquid are as follows: The conductive layer electrode coating liquid is prepared by preparing nickel-cobalt coating liquid with nickel chloride, cobalt chloride, urea and pure water, wherein the molar ratio of nickel, cobalt, urea and pure water is (1-5): (0.5-5): 6: (120-180), and ultrasonic dispersion is performed after preparation; The active layer electrode coating liquid is a ruthenium-platinum coating liquid prepared with ruthenium trichloride, chloroplatinic acid, citric acid, urea, hydrochloric acid, ethylene glycol and pure water, wherein the molar ratio of ruthenium, platinum, citric acid, urea, hydrochloric acid, ethylene glycol and pure water is 60: (0-1): 100: 100: 70: 60: (7000-8000), and ultrasonic dispersion is performed after preparation; (5) Ultrasonic spraying and staged oxidation: First, the prepared conductive layer coating liquid is fixed on the surface of the pretreated nickel substrate electrode mesh by ultrasonic spraying. The ultrasonic spraying operation adopts a multi-nozzle ultrasonic spraying system with an atomization frequency of 80~100 kHz, a spraying distance of 8~10 cm, and a substrate temperature controlled at 25~35 ℃. 35~40 ml is sprayed per square meter per layer, and the spraying is performed in 2~3 times. After each spraying, it is left to stand for 5~10 minutes. After each layer of spraying, the electrode is transferred to an oven at 80 ℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350 ℃ and maintained for 15 minutes, and finally heated to 450 ℃ and maintained for 10 min, and the final number of conductive layer coating layers is 2~3 layers; the operation of the active layer is consistent with the above operation, and the final number of layers is 3~4 layers to ensure optimal activity while reducing the amount of precious metals, so that the Ru content per square meter is less than 5g and the Pt content per square meter is less than 0.16g; among them, the operation of the last coating of the active layer is: ultrasonic spraying operation uses a multi-nozzle ultrasonic spraying system, the atomization frequency is 80~100 kHz, the spraying distance is 8~10 cm, the substrate temperature is controlled at 25~35℃, 35~40 ml is sprayed per layer, and the spraying is performed in 2~3 times. After each spraying, it is allowed to stand for 5~10 minutes. After each spraying, the electrode is transferred to an oven at 80℃ and maintained for 5~10 minutes, then transferred to a high-temperature oxidation furnace at 350℃ and maintained for 15 minutes, then programmed to 450℃ at a rate of 5℃ / min and kept at this temperature for 30 minutes, and finally programmed to cool to about 80℃ at a rate of 5℃ / min.

9. The method for preparing a large-area active cathode according to claim 8, characterized in that: In the conductive layer coating solution, the molar ratio of nickel to cobalt is 3:

2.

10. The method for preparing a large-area active cathode according to claim 8, characterized in that: In the active layer coating solution, the molar ratio of ruthenium to platinum is 60:1.

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