A method for preparing a nickel-tungsten-cobalt ternary metal oxygen evolution electrode by two-step pulse electrodeposition and application thereof

Abstract

This invention discloses a two-step pulse electrodeposition method for preparing a nickel-tungsten-cobalt ternary metal oxygen evolution electrode and its application. Specifically, it addresses the Ni... 2+ Co 2+ With W 6+ The large differences in reduction potential and the mismatch in reduction kinetics lead to elemental segregation in single-step deposition. This invention addresses this problem by employing a two-step pulsed electrodeposition strategy: first depositing a Ni-W metal layer, then depositing a Ni-Co metal layer. This strategy optimizes the plating bath composition and pulse parameters step-by-step to accommodate the reduction requirements of different metal ions. The method includes: pretreatment of the nickel-based substrate; performing a first-step pulsed electrodeposition in a solution containing nickel and tungsten salts; and then performing a second-step pulsed electrodeposition in a solution containing nickel and cobalt salts, followed by drying. This invention, through specific two-step deposition and the periodic regulation of the pulsed current, effectively optimizes the loading and dispersion of nickel, tungsten, and cobalt, resulting in a high-performance oxygen evolution electrode with stable and reliable performance, meeting the application requirements of large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, specifically to a two-step pulse electrodeposition method for preparing a nickel-tungsten-cobalt ternary metal oxygen evolution electrode and its application. Background Technology

[0002] Hydrogen energy, as a highly efficient, clean, and renewable energy carrier, produces only water as a combustion product and does not generate carbon emissions. Therefore, it is regarded as a key component of the future energy system and has enormous development potential.

[0003] Among various hydrogen production pathways, alkaline water electrolysis technology holds the greatest promise for large-scale application due to its mature process and relatively controllable cost. In this technology, the oxygen evolution reaction (OER), as the anodic half-reaction of water splitting, involves a four-electron transfer process with slow kinetics, making it the core bottleneck restricting the overall efficiency of the water electrolysis system. The oxygen evolution electrode, as the direct reaction site of the OER, directly determines the industrial feasibility of alkaline water electrolysis for hydrogen production due to its catalytic activity, structural stability, and preparation cost. However, current commercially available and laboratory-developed oxygen evolution electrodes still have the following significant shortcomings:

[0004] (1) From the perspective of electrode materials, although noble metal-based electrodes (such as RuO2 and IrO2 electrodes) have excellent OER catalytic activity, their high cost (Ir / Ru precious metal price is more than a thousand times that of nickel) and global resource scarcity seriously limit their promotion and application in the field of large-scale hydrogen production; while traditional nickel-based electrodes (such as pure nickel electrodes, Ni-Co binary alloy electrodes, and Ni-W binary alloy electrodes) have abundant raw materials and low cost, but have obvious shortcomings: on the one hand, the intrinsic catalytic activity is insufficient, resulting in a high OER overpotential and unsatisfactory energy conversion efficiency; on the other hand, the binary alloy system lacks the synergistic regulation of multiple components, and problems such as active component agglomeration, surface oxide film peeling, and conductivity decay are prone to occur during long-term operation, making it difficult to meet the requirements of efficient and long-life industrial operation.

[0005] (2) From the perspective of preparation process, although thermal spraying and plasma spraying have strong mass production capabilities, they have defects such as weak bonding between coating and substrate, poor composition uniformity, high temperature damage to substrate, and limited range of applicable transition metals. Although constant current electrodeposition shows advantages in coating density, the "continuous power supply" mode is prone to causing concentration polarization at the electrode interface, resulting in imbalance of metal ion reduction rate, coarse grains in the deposited layer, and composition segregation. Pulse electrodeposition, through the "on-off alternating" power supply mode, can effectively improve the interfacial mass transfer state and shows significant advantages in refining grains, improving the density and composition uniformity of the deposited layer, and has become the core optimization direction for the preparation of nickel-based oxygen evolution electrodes.

[0006] Despite the advantages mentioned above, pulse electrodeposition still faces key technical challenges when applied to the fabrication of Ni-W-Co ternary metal oxygen evolution electrodes:

[0007] In the Ni-W-Co ternary system, the reduction potentials of the three metal ions differ significantly (Ni 2+ Approximately -0.25 V, Co 2+ Approximately -0.28 V, W 6+ At approximately -0.8 V, both v vs RHE, the reduction kinetics differed greatly. Among them, Co 2+ with Ni 2+ The reduction potentials of these materials are close and their kinetic behaviors are similar, making them easy to co-deposit to form nickel-cobalt alloy layers; while W 6+ The reduction potential is relatively negative, and the reduction rate is slow, requiring an induced co-deposition mechanism to co-deposit with nickel. Traditional single-step pulse electrodeposition processes use a single pulse parameter, which is difficult to match the reduction requirements of the three ions simultaneously, easily leading to element-selective deposition and macroscopic segregation—manifested as the electrode surface preferentially enriches the easily deposited Ni / Co components, while the W element is unevenly distributed, or even has no W deposition in some areas, making it difficult to form an ideal Ni-W-Co ternary alloy.

[0008] Therefore, developing a preparation method that specifically addresses the elemental segregation problem during the co-deposition of Ni-W-Co ternary alloys, and achieving uniform distribution of Ni, W, and Co active components through process optimization to construct a dense, firmly bonded, and cost-controllable ternary metal oxygen evolution electrode, is of great significance for improving the efficiency and reducing the cost of alkaline water electrolysis hydrogen production technology and promoting its industrialization. Summary of the Invention

[0009] Regarding the current preparation process of nickel-tungsten-cobalt ternary metal electrodes in alkaline water electrolysis systems, due to Ni... 2+ Co 2+ With W 6+ Significant differences in reduction potential and mismatched reduction kinetics lead to elemental segregation and compositional inhomogeneity in traditional single-step deposition processes, thus weakening the synergistic catalytic effect of ternary alloys. This invention provides a two-step pulse electrodeposition method for preparing nickel-tungsten-cobalt ternary metal oxygen evolution electrodes and its application. This method optimizes pulse parameters and plating bath composition stepwise to specifically adapt to the reduction requirements of different metal ions, effectively solving the problem of preferential deposition of high-reduction-potential ions and insufficient deposition of low-reduction-potential ions in multi-element alloy co-deposition. The nickel-tungsten-cobalt ternary alloy oxygen evolution electrode prepared by this invention has advantages such as low OER overpotential, excellent long-term stability, and low cost, and can be directly applied to alkaline water electrolysis hydrogen production systems, meeting the high-efficiency operation requirements of industrial-grade electrolyzers.

[0010] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0011] A two-step pulse electrodeposition method for preparing nickel-tungsten-cobalt ternary metal electrodes, targeting the catalytic characteristics of the oxygen evolution reaction and Ni 2+ Co 2+ W 6+ To address the co-deposition segregation problem caused by differences in reduction potential and kinetics, a specific deposition sequence was employed: first depositing a nickel-tungsten metal layer, then a nickel-cobalt metal layer. Pulse electrodeposition was then performed sequentially in mixed salt solutions of different components, specifically including the following steps:

[0012] S1. Pretreatment of nickel-based metal substrate materials;

[0013] S2, First step pulse electrodeposition: In a first mixed salt solution containing nickel salt and tungsten salt, the nickel-based metal substrate material pretreated in step S1 is used as the cathode to perform the first step pulse electrodeposition to obtain a nickel-tungsten binary metal electrode precursor.

[0014] S3, Second step pulse electrodeposition: In a second mixed salt solution containing nickel salt and cobalt salt, the nickel-tungsten binary metal electrode precursor obtained in step S2 is used as the cathode to perform the second step pulse electrodeposition to obtain a nickel-tungsten-cobalt ternary metal electrode.

[0015] S4. Clean and dry the nickel-based ternary metal electrode obtained in step S3 to obtain the nickel-based ternary metal oxygen evolution electrode.

[0016] Further, in the first mixed salt solution, the nickel salt is selected from at least one of nickel sulfate, nickel chloride, and nickel nitrate, with a concentration of 20-100 g / L, preferably 20-80 g / L, more preferably 30-80 g / L; the tungsten salt is selected from one of sodium tungstate and ammonium paratungstate, with a concentration of 20-120 g / L, preferably 40-100 g / L; in the second mixed salt solution, the nickel salt is selected from at least one of nickel sulfate, nickel chloride, and nickel nitrate, with a concentration of 20-100 g / L, preferably 20-80 g / L, more preferably 30-80 g / L; the cobalt salt is selected from at least one of cobalt chloride, cobalt sulfate, and cobalt nitrate, with a concentration of 5-60 g / L, preferably 5-30 g / L.

[0017] Further, in step S1, the nickel-based metal substrate material is nickel mesh or nickel foam, wherein the wire diameter of the nickel mesh is 0.027 ~ 0.5 mm and the mesh count is 40 ~ 200 mesh; the thickness of the nickel foam is 0.2 ~ 5 mm and the number of holes is 40 ~ 110 ppi.

[0018] Further, in step S1, the pretreatment specifically involves: ultrasonically cleaning the nickel-based metal substrate material sequentially with anhydrous ethanol and hydrochloric acid solution (0.5~2M) for 10-15 minutes to remove surface oxides and lipids; then ultrasonically cleaning it with deionized water for 10-15 minutes, and placing it in deionized water for later use after ultrasonic cleaning.

[0019] Furthermore, in step S2, the process conditions for the first step of pulse electrodeposition are as follows:

[0020] The electrodeposition temperature is 30 ~ 90℃, preferably 30 ~ 75℃, and more preferably 40 ~ 70℃;

[0021] The single pulse period of the pulsed current is 20 to 500 seconds, preferably 50 to 300 seconds;

[0022] The low-level current is 0, the high-level current is 10~300 mA, preferably 10~250 mA, more preferably 10~150 mA, and the high-level duty cycle is 10%~80%, preferably 10%~60%, more preferably 10%~50%.

[0023] The total pulse electrodeposition time is 1000 ~ 8000 s, preferably 1200 ~ 7000 s, and more preferably 1500 ~ 6000 s.

[0024] Furthermore, in step S3, the process conditions for the second step of pulse electrodeposition are as follows:

[0025] The electrodeposition temperature is 20 ~ 80℃, preferably 30 ~ 75℃, and more preferably 40 ~ 60℃;

[0026] The single pulse period of the pulsed current is 100 ~ 600 s, preferably 200 ~ 400 s;

[0027] The low-level current is 0, the high-level current is 10~300 mA, preferably 10~250 mA, more preferably 10~150 mA, and the high-level duty cycle is 10%~80%, preferably 10%~60%, more preferably 10%~50%.

[0028] The total pulse electrodeposition time is 500 to 4000 s, preferably 1000 to 2000 s.

[0029] The nickel-tungsten-cobalt ternary metal oxygen evolution electrode prepared by the above method has a catalyst layer with a Ni-W-Co ternary alloy structure. Ni, W, and Co elements are uniformly distributed in the nickel matrix in an alloyed form, forming a dense and homogeneous alloy phase. The active components Ni, W, and Co show no macroscopic segregation. In a 1 mol / L KOH alkaline electrolyte and at 100 mA·cm⁻¹, the electrode exhibits good performance. -2 After 10 hours of continuous operation at the current density, the electrode potential remained stable in the range of 1.5~1.6V and the catalytic performance showed no significant decline.

[0030] The aforementioned nickel-tungsten-cobalt ternary metal oxygen evolution electrode is applied to alkaline water electrolysis hydrogen production systems, which can meet the high-efficiency operation requirements of industrial-grade electrolyzers. The raw material cost is reduced by more than 70% compared with RuO2 and IrO2 noble metal-based oxygen evolution electrodes, and large-area, complex-shaped electrodes can be fabricated on a large scale.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) This invention employs a specific deposition sequence of first depositing a nickel-tungsten metal layer and then depositing a nickel-cobalt metal layer, specifically targeting the Ni-W-Co system. 2+ Co 2+ W 6+ The core issues of significant differences in reduction potential between different metal ions (reduction potential range -0.25 to -0.8 V vs RHE) and mismatched reduction kinetics were addressed by optimizing pulse parameters stepwise to suit the deposition requirements of different ions. This overcame the defects of elemental selective segregation and uneven composition distribution that easily occur in traditional single-step co-deposition. The prepared ternary alloy electrode exhibited intrinsic catalytic activity significantly superior to that of binary alloy electrodes in the alkaline water electrolysis oxygen evolution reaction (OER).

[0033] (2) The "on-off alternation" characteristic of the pulsed current generates a non-equilibrium co-deposition effect, effectively reducing the deposition energy barrier of the sparingly soluble element W, promoting its uniform embedding into the nickel-based lattice, and forming a dense Ni-W-Co alloy. The supported layer exhibits excellent mechanical strength, wear resistance, and resistance to alkaline electrolyte erosion. At 100 mA / cm² 2 After 10 hours of continuous operation at industrial-grade current density, the electrode performance showed no significant decrease, ensuring structural integrity and catalytic stability during long-term operation.

[0034] (3) This invention abandons the complex processes such as high-temperature sintering and high-pressure treatment required for the preparation of traditional alloy electrodes, and adopts a mild electrodeposition technology at medium and low temperature and normal pressure, which is safe to operate and has low energy consumption. The process has excellent repeatability, the performance deviation of electrodes prepared in different batches is small, the product quality is stable and controllable, and it is suitable for the dual needs of laboratory research and development and industrial production.

[0035] (4) The nickel-based substrate and raw materials such as nickel salts, tungsten salts, and cobalt salts selected in this invention are all industrial-grade, inexpensive, and readily available non-precious metal materials, completely eliminating the dependence on precious metals such as Ru and Ir, reducing raw material costs by more than 70%. At the same time, the preparation process is simple, with low equipment requirements, and energy consumption is only about 15% of that of the thermal spraying process. This method can directly prepare large-area electrodes and is suitable for the deposition requirements of complex-shaped substrates, making it easy to achieve large-scale continuous production. It has extremely high commercial conversion value in industrial scenarios such as alkaline water electrolysis for hydrogen production and distributed hydrogen production. Attached Figure Description

[0036] Figure 1 This is a comparison of linear sweep voltammetric curves of OER (Optical Emission Reduction) using different current electroplating electrodes in this invention. Test conditions: A three-electrode system was used, with a platinum mesh as the counter electrode, nickel foam as the loading substrate, a mercuric oxide electrode as the reference electrode, and a 1 mol / L potassium hydroxide aqueous solution.

[0037] Figure 2 This is a comparison of the OER linear sweep voltammetric curves of the unary, binary, and ternary metal-supported nickel-based electrodes in this invention. Test conditions: A three-electrode system was used, with a platinum mesh counter electrode, nickel foam substrate, mercuric oxide electrode as the reference electrode, and a 1 mol / L potassium hydroxide aqueous solution. Detailed Implementation

[0038] The technical solution of the present invention will be further described in detail below through specific embodiments, but the present invention is not limited to these embodiments.

[0039] The analysis method in the embodiments of the present invention is as follows:

[0040] Electrochemical performance tests were conducted on nickel-tungsten-cobalt ternary metal catalytic electrode materials using an electrochemical workstation.

[0041] The model of the electrochemical workstation is: Princeton VERSASTAT3A-400.

[0042] Example 1

[0043] The 46-mesh, 0.25 mm diameter nickel mesh was ultrasonically cleaned for 10-15 minutes in anhydrous ethanol and 1 mol / L hydrochloric acid solution, respectively, to remove lipids and surface oxides. Then it was ultrasonically cleaned for 10-15 minutes in deionized water. After ultrasonic cleaning, it was placed in deionized water for later use.

[0044] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 6g, Na2WO4·2H2O: 8g, dissolved in 200mL of deionized water.

[0045] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 100 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 5000 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0046] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: Ni(NO3)2·6H2O: 15g, CoCl2·6H2O: 6g, dissolved in 200 mL of deionized water.

[0047] Using a nickel-tungsten binary metal electrode precursor as the working electrode, the single pulse period was 200 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 800 seconds. The high-level current density was 80 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 45℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0048] Example 2

[0049] 1.5 mm thick, 110 ppi nickel foam was ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and 1 mol / L hydrochloric acid solution to remove lipids and surface oxides. Then it was ultrasonically cleaned with deionized water for 10-15 minutes. After ultrasonic cleaning, it was placed in deionized water for later use.

[0050] Step 1: Pulse electrodeposition: Preparation of electrodeposition solution: NiCl2·6H2O: 12g, H 42 N 10 O 42 W 12 ·xH2O: 8g, dissolved in 200 mL of deionized water.

[0051] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 150 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 4500 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 60℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0052] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: Ni(NO3)2·6H2O: 15g, CoSO4·7H2O: 6g, dissolved in 200 mL of deionized water.

[0053] Using a nickel-tungsten binary metal electrode precursor as the working electrode, the single pulse period was 210 seconds, the high-level duty cycle was 30%, and the total electrodeposition time was 2400 seconds. The high-level current density was 90 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 40℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0054] Example 3

[0055] The 60-mesh, 0.25mm wire diameter nickel mesh was ultrasonically cleaned for 10-15 minutes in anhydrous ethanol and 1mol / L hydrochloric acid solution, respectively, to remove lipids and surface oxides. Then it was ultrasonically cleaned for 10-15 minutes in deionized water. After ultrasonic cleaning, it was placed in deionized water for later use.

[0056] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 14g, Na2WO4·2H2O: 8g, dissolved in 200mL of deionized water.

[0057] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 60 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 6000 seconds. The high-level current density was 30 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0058] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 12g, CoSO4·7H2O: 6g, dissolved in 200mL of deionized water.

[0059] Using a nickel-tungsten bimetallic loaded electrode precursor as the working electrode, the single pulse period was 200 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 1400 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0060] Example 4

[0061] The 150-mesh, 0.05mm wire diameter nickel mesh was ultrasonically cleaned for 10-15 minutes in anhydrous ethanol and 1mol / L hydrochloric acid solution, respectively, to remove lipids and surface oxides. Then it was ultrasonically cleaned for 10-15 minutes in deionized water. After ultrasonic cleaning, it was placed in deionized water for later use.

[0062] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: Ni(NO3)2·6H2O: 12g, Na2WO4·2H2O: 8g, dissolved in 200 mL of deionized water.

[0063] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 200 seconds, the high-level duty cycle was 40%, and the total electrodeposition time was 4600 seconds. The high-level current density was 40 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0064] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: NiSO4·6H2O: 10g, Co(NO3)2·6H2O: 6g, dissolved in 200 mL of deionized water.

[0065] Using a nickel-tungsten binary metal electrode precursor as the working electrode, the single pulse period was 260 seconds, the high-level duty cycle was 60%, and the total electrodeposition time was 1800 seconds. The high-level current density was 70 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0066] Example 5

[0067] The 3mm thick, 75ppi nickel foam was ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and 1mol / L hydrochloric acid solution to remove lipids and surface oxides. Then it was ultrasonically cleaned with deionized water for 10-15 minutes. After ultrasonic cleaning, it was placed in deionized water for later use.

[0068] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 12g, Na2WO4·2H2O: 8g, dissolved in 200mL of deionized water.

[0069] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 100 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 5000 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0070] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 14g, CoCl2·6H2O: 6g, dissolved in 200 mL of deionized water.

[0071] Using a nickel-iron binary metal electrode precursor as the working electrode, the single pulse period was 200 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 1200 seconds. The high-level current density was 80 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0072] Example 6

[0073] The 100-mesh, 0.1mm wire diameter nickel mesh was ultrasonically cleaned for 10-15 minutes in anhydrous ethanol and 1mol / L hydrochloric acid solution, respectively, to remove lipids and surface oxides. Then it was ultrasonically cleaned for 10-15 minutes in deionized water. After ultrasonic cleaning, it was placed in deionized water for later use.

[0074] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 12g, Na2WO4·2H2O: 8g, dissolved in 200mL of deionized water.

[0075] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 150 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 3000 seconds. The high-level current density was 60 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0076] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 14g, CoSO4·7H2O: 6g, dissolved in 200mL of deionized water.

[0077] Using a nickel-tungsten binary metal electrode precursor as the working electrode, the single pulse period was 200 seconds, the high-level duty cycle was 60%, and the total electrodeposition time was 1200 seconds. The high-level current density was 45 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0078] Comparative Example 1

[0079] 1.5 mm thick, 110 ppi nickel foam was ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and 1 mol / L hydrochloric acid solution to remove lipids and surface oxides. Then it was ultrasonically cleaned with deionized water for 10-15 minutes. After ultrasonic cleaning, it was placed in deionized water for later use.

[0080] Prepare the electrodeposition solution: NiSO4·6H2O: 12g, Na2WO4·2H2O: 8g, CoCl2·6H2O: 6g, dissolved in 200mL of deionized water.

[0081] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 200 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 5000 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0082] Comparative Example 2

[0083] The 3mm thick, 75ppi nickel foam was ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and 1mol / L hydrochloric acid solution to remove lipids and surface oxides. Then it was ultrasonically cleaned with deionized water for 10-15 minutes. After ultrasonic cleaning, it was placed in deionized water for later use.

[0084] Step 1: Constant current electrodeposition: Prepare electrodeposition solution: NiCl2·6H2O: 12g, Na2WO4·2H2O: 8g, dissolved in 200 mL of deionized water.

[0085] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode and a nickel metal substrate with the same cathode surface area as the counter electrode. The electrodeposition time was 2000 seconds, and the current density was 50 mA / cm². 2The electrodeposition temperature was 55℃, and the product was washed and dried to obtain a nickel-tungsten binary metal electrode precursor.

[0086] The second step is constant current electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 14g, CoCl2·6H2O: 6g, and dissolve in 200 mL of deionized water.

[0087] Using a nickel-iron binary metal electrode precursor as the working electrode, the single electrodeposition time was 1500 seconds and the current density was 80 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-tungsten-cobalt ternary metal oxygen evolution electrode.

[0088] Comparative Example 3

[0089] The 3mm thick, 75ppi nickel foam was ultrasonically cleaned for 10-15 minutes each with anhydrous ethanol and 1mol / L hydrochloric acid solution to remove lipids and surface oxides. Then it was ultrasonically cleaned with deionized water for 10-15 minutes. After ultrasonic cleaning, it was placed in deionized water for later use.

[0090] Step 1: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 14g, CoCl2·6H2O: 6g, dissolved in 200 mL of deionized water.

[0091] A nickel-based metal substrate was immersed in an electrodeposition solution, serving as the working electrode. Nickel metal of the same cathode surface area was used as the counter electrode. The single pulse period was 200 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 1200 seconds. The high-level current density was 80 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. The electrodeposition temperature was 35℃, followed by washing and drying to obtain a nickel-tungsten binary metal electrode precursor.

[0092] Step 2: Pulse electrodeposition: Prepare the electrodeposition solution: NiCl2·6H2O: 12g, Na2WO4·2H2O: 8g, dissolved in 200mL of deionized water.

[0093] Using a nickel-cobalt binary metal electrode precursor as the working electrode, the single pulse period was 100 seconds, the high-level duty cycle was 50%, and the total electrodeposition time was 5000 seconds. The high-level current density was 50 mA / cm². 2 The low-level current density is 0 mA / cm². 2 The electrodeposition temperature was 50℃. After electrodeposition, the sample was rinsed with deionized water and dried to obtain a nickel-cobalt-tungsten ternary metal oxygen evolution electrode.

[0094] Overpotential tests were performed on the above examples and comparative examples. The test conditions were as follows: a three-electrode system was used, with a platinum mesh as the counter electrode, a mercuric oxide electrode as the reference electrode, and a 1 mol / L potassium hydroxide aqueous solution as the solution. The test results are shown in Table 1.

[0095] Table 1. Comparison of overpotentials between embodiments and comparative examples in this invention.

[0096]

[0097] As shown in Table 1, with 100 mA·cm -2 The oxygen evolution overpotential at current density is the core indicator, reflecting the impact of the two-step pulse electrodeposition process, substrate type, and different metal combinations on the electrode catalytic performance. The specific differences and reasons are as follows:

[0098] The two-step pulse process is significantly superior to the traditional process. Examples 1-6 all adopted two-step pulse electrodeposition, and their oxygen evolution overpotentials were concentrated between 280-319 mV. Among them, the overpotential of Example 5 was as low as 280 mV, showing the best catalytic activity. In contrast, the overpotentials of Comparative Example 1 (one-step pulse process), Comparative Example 2 (two-step constant current process), and Comparative Example 3 (pulse-loaded nickel-cobalt-tungsten composite electrode / NF) reached 350 mV, 335 mV, and 367 mV, respectively, which were all inferior to the examples. Comparative Example 3 adopted a pulse-loaded nickel-cobalt-tungsten composite electrode / NF (metals in the order of nickel, cobalt, and tungsten), and the oxygen evolution overpotential was as high as 367 mV, which was 87 mV higher than the lowest value of Example 5. Even compared with Example 4 (319 mV), which had the highest overpotential among the examples, it was still 48 mV higher. This difference fully demonstrates the core advantage of the present invention, "stepwise deposition + precise metal sequence"—by independently controlling the pulse parameters of the two steps, it can not only match the reduction kinetic requirements of different transition metal ions, but also avoid the failure of active components due to disordered metal deposition sequence. It completely solves the problem of dual element segregation caused by "mismatch of metal ion reduction rate" and "improper metal sequence" in the traditional single-step process, thereby maximizing the increase of the number of active sites, optimizing the distribution of active components, and ultimately significantly reducing the oxygen evolution overpotential.

[0099] Comparing Example 1 (nickel mesh substrate, overpotential 300mV) and Example 5 (nickel foam substrate, overpotential 280mV), the overpotential of the nickel foam substrate was lower under the same metal combination (nickel, tungsten, cobalt). This is because nickel foam has a three-dimensional porous structure, which can provide a larger specific surface area for electrodeposition (increasing the adhesion area of ​​active sites) and optimize the electrolyte permeation and oxygen escape channels, further improving catalytic efficiency.

[0100] Depend on Figure 1 It can be seen that, Figure 1The horizontal axis represents voltage (V vs. RHE), and the vertical axis represents current density (reflecting the catalytic reaction rate; a higher value indicates stronger activity). A detailed analysis follows:

[0101] The correlation between curve position and catalytic activity: Under the same voltage, the current density of the two-step pulse electrodeposition of nickel-tungsten-cobalt samples was significantly higher than that of the one-step pulse electrodeposition of nickel-tungsten-cobalt samples, the two-step pulse electrodeposition of nickel-cobalt-tungsten samples, and the two-step galvanostatic samples; conversely, at the same current density (e.g., 100 mA·cm⁻¹), the catalytic activity was lower. -2 Under these conditions, the two-step pulsed nickel-tungsten-cobalt sample requires the lowest voltage. For example, when the voltage is 1.6V, the current density of the two-step pulsed nickel-tungsten-cobalt sample is better than that of the one-step pulsed, two-step pulsed nickel-cobalt-tungsten, and two-step constant current samples, indicating that the two-step pulsed nickel-tungsten-cobalt sample of the present invention can undergo the oxygen evolution reaction faster under the same energy input and has stronger catalytic activity.

[0102] The two-step pulsed nickel-cobalt-tungsten sample (Comparative Example 3) has the curve furthest to the right and the lowest current density, further verifying the negative impact of reversing the metal deposition sequence on catalytic performance; the two-step constant current nickel-cobalt-cobalt sample has the curve in the middle, which is better than the two-step pulsed nickel-cobalt-tungsten and one-step pulsed nickel-cobalt-cobalt samples, but still has the problem of uneven distribution of active components; the two-step pulsed nickel-cobalt-cobalt sample has the curve furthest to the left, verifying the optimization effect of the step-by-step process on the interface state and deposition layer structure.

[0103] Depend on Figure 2 It can be seen that: the two-step pulse electrodeposition sample at "100 mA·cm" -2 Long-term stability curve under 1M KOH conditions: Within a test duration of 10 hours, the potential remained stable in the range of 1.50-1.53V. Even when electrolyte was added midway, the potential did not fluctuate significantly, indicating that the catalyst has excellent long-term operational stability in the oxygen evolution reaction.

Claims

1. A method for preparing a nickel-tungsten-cobalt ternary metal oxygen evolution electrode using a two-step pulse electrodeposition process, characterized in that, Includes the following steps: S1. Pretreatment of nickel-based metal substrate materials; S2, First step pulse electrodeposition: In a first mixed salt solution containing nickel salt and tungsten salt, the nickel-based metal substrate material pretreated in step S1 is used as the cathode to perform the first step pulse electrodeposition to obtain a nickel-tungsten binary metal electrode precursor. S3, Second step pulse electrodeposition: In a second mixed salt solution containing nickel salt and cobalt salt, the nickel-tungsten binary metal electrode precursor obtained in step S2 is used as the cathode to perform the second step pulse electrodeposition to obtain a nickel-tungsten-cobalt ternary metal electrode. S4. Clean and dry the nickel-tungsten-cobalt ternary metal electrode obtained in step S3 to obtain the nickel-based ternary metal oxygen evolution electrode.

2. The method according to claim 1, characterized in that, In the first mixed salt solution, the nickel salt is selected from at least one of nickel sulfate, nickel chloride, and nickel nitrate, with a concentration of 20-100 g / L, and the tungsten salt is selected from one of sodium tungstate and ammonium paratungstate, with a concentration of 20-120 g / L; in the second mixed salt solution, the nickel salt is selected from at least one of nickel sulfate, nickel chloride, and nickel nitrate, with a concentration of 20-100 g / L, and the cobalt salt is selected from at least one of cobalt chloride, cobalt sulfate, and cobalt nitrate, with a concentration of 5-60 g / L.

3. The method according to claim 1, characterized in that, In step S1, the pretreatment specifically involves ultrasonically cleaning the nickel-based metal substrate material sequentially with anhydrous ethanol, 0.5-2 mol / L hydrochloric acid solution, and deionized water for 10-15 minutes each.

4. The method according to claim 1, characterized in that, In step S2, the process conditions for the first step of pulse electrodeposition are as follows: electrodeposition temperature is 30~90℃, single pulse period of pulse current is 20~500 s, low level current is 0, high level current is 10~300 mA, high level duty cycle is 10%~80%, and total pulse electrodeposition time is 1000~8000 s.

5. The method according to claim 1, characterized in that, In step S3, the process conditions for the second step of pulse electrodeposition are as follows: electrodeposition temperature is 20~80℃, single pulse period of pulse current is 100~600 s, low level current is 0, high level current is 10~300 mA, high level duty cycle is 10%~80%, and total pulse electrodeposition time is 500~4000 s.

6. The nickel-tungsten-cobalt ternary metal oxygen evolution electrode prepared by the method according to any one of claims 1 to 5, characterized in that, The catalyst layer of the nickel-based ternary metal oxygen evolution electrode has a Ni-W-Co ternary alloy structure. Ni, W and Co elements are uniformly distributed in the nickel matrix in an alloyed form, and the active components Ni, W and Co do not exhibit macroscopic segregation.

7. The application of the nickel-tungsten-cobalt ternary metal oxygen evolution electrode according to claim 6, characterized in that, The nickel-tungsten-cobalt ternary metal oxygen evolution electrode is used in an alkaline water electrolysis hydrogen production system.

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