Oxygen evolution electrode of nickel-iron-cobalt-based alloy coating and preparation method of oxygen evolution electrode

Abstract

The invention relates to an oxygen evolution electrode of a nickel-iron-cobalt-based alloy coating and a preparation method of the oxygen evolution electrode, the oxygen evolution electrode is composed of a conductive substrate and an alloy coating which is deposited on the surface and takes Ni, Fe and Co as main metal elements and takes at least one of Mn, Cr, Cu, Mo, W, Ti, Al or Zn as an additional metal element, the preparation method adopts a spraying process, and the nickel-iron-cobalt-based alloy coating is deposited on the conductive substrate. The nickel-iron-cobalt-based alloy coating of the oxygen evolution electrode is well combined with the conductive substrate, the microstructure is controllable, the oxygen evolution electrode is suitable for large-area preparation, the structure formed through element synergy and the spraying process has excellent oxygen evolution catalytic activity and stability, the preparation process is flexible, the cost is low, and large-scale production is easy. And an effective way is provided for development of a high-performance and large-size OER catalyst.

Description

Technical Field

[0001] The present invention relates to an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating and a preparation method thereof, and particularly belongs to the technical field of electrocatalytic materials and hydrogen energy. Background Art

[0002] Developing clean and sustainable hydrogen energy is a key strategy for addressing global energy and environmental challenges, and hydrogen production through water electrolysis is an important technological path for producing high-purity hydrogen. The core bottleneck of this technology lies in the need for efficient, stable, and inexpensive electrocatalysts to reduce the energy consumption of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Currently, commercial applications mainly rely on precious metal catalysts such as platinum (Pt), iridium (Ir), and ruthenium (Ru), but their scarcity and high cost severely restrict the large-scale deployment of water electrolysis technology. Therefore, the development of high-performance electrocatalysts based on abundant non-precious metals such as nickel (Ni), iron (Fe), cobalt (Co), and their multi-element or high-entropy alloys has become a research hotspot in this field due to their unique electronic structure and excellent catalytic potential.

[0003] Currently, significant progress has been made in the preparation of Ni-Fe-Co-based multi-element and high-entropy alloy catalysts. However, existing technology routes still face many challenges in preparing large-scale, high-bonding strength electrodes suitable for industrial applications. Existing technologies can be mainly categorized as follows: (1) Wet chemical and in-situ growth methods: For example, the literature (Preparation and Performance Research of Nickel-Iron-Cobalt-Based Transition Metal Composite Electrode Materials, Yang Jie, Wuhan University of Technology) uses hydrothermal, coprecipitation, and electrodeposition methods, and Chinese patent CN109811360A uses a multi-step hydrothermal method to prepare electrodes. Although these methods can construct fine nanostructures at the microscopic level, they generally have problems such as complex process flows, long time consumption, and high costs. More importantly, the nanocoatings prepared by this method are mostly weakly physically or chemically bonded to the substrate, with insufficient bonding strength. They are easily detached under the intense gas erosion of industrial electrolysis, seriously affecting the long-term stability and service life of the electrode.

[0004] (2) Bulk metallurgy combined with chemical etching: For example, the arc melting combined with dealloying technology used in the literature (Preparation of porous nickel-iron-cobalt-based high-entropy alloy electrocatalysts by dealloying and their electrochemical properties, Wang Chunyang, Qingdao University of Science and Technology) produces a monolithic porous electrode rather than a coating. This method cannot functionalize the surface of existing industrial electrode components. In addition, the melting and long-term etching process makes it difficult to prepare large-scale, homogenized electrodes.

[0005] (3) Electrodeposition: For example, in the literature (Preparation and Electrocatalytic Performance of Nickel-Iron-Cobalt-Based High-Entropy Alloys, Bian Haowei, Qingdao University of Science and Technology), a high-entropy alloy coating was prepared by one-step electrodeposition. For complex multi-element systems, it is extremely difficult to achieve precise and uniform composition control over a large area by electrodeposition, and it is difficult to quickly prepare thick and dense coatings. In addition, the composite catalyst reported in the literature (Tunable Built-In Electric Field in Ru Nanoclusters-Based Electrocatalyst Boosts Water Splitting and Simulated Seawater Electrolysis, Adv. Funct. Materials, 2024, 34, 2310690) still relies on the precious metal Ru element, which fails to fundamentally solve the cost problem.

[0006] In summary, whether it is the wet chemical method, the dealloying method or the traditional electrodeposition method, there are obvious deficiencies in meeting the requirements of high performance, low cost, simple process, and easy scalability, especially in the preparation of large-scale industrial electrodes with high mechanical stability and strong matrix binding. Therefore, there is an urgent need in this field for a new preparation strategy that can apply Ni-Fe-Co-based multi-element / high entropy alloy catalysts with controllable composition to the manufacture of large-scale industrial electrodes in an efficient, low-cost and firmly bonded manner with the matrix. The present invention is proposed to solve the bottlenecks and deficiencies of the above-mentioned prior art. Summary of the Invention

[0007] In response to the above situation, the present invention aims to provide a nickel-iron-cobalt-based alloy coated oxygen evolution electrode and a preparation method thereof. Nickel-iron-cobalt-based alloy oxygen evolution electrode, as an electrocatalyst for the oxygen evolution reaction (OER), faces challenges in terms of material composition design optimization, universality and cost-effectiveness of the preparation process, bonding strength between the coating and the conductive substrate, effective regulation of the microstructure, and large-scale production of large-area, high-performance, and long-life catalysts.

[0008] The invention discloses an oxygen evolution electrode with a nickel-iron-cobalt-based alloy coating, which comprises a conductive substrate and an alloy coating deposited on the surface, which comprises Ni, Fe and Co as main metal elements and at least one of Mn, Cr, Cu, Mo, W, Ti, Al or Zn as an additional metal element.

[0009] The average thickness of the alloy coating is 100-500 μm.

[0010] A method for preparing an oxygen evolution electrode with a nickel-iron-cobalt-based alloy coating adopts a spraying process to deposit a nickel-iron-cobalt-based alloy coating on a conductive substrate, specifically comprising the following steps: Step 1: Selection of raw powder A high entropy alloy powder containing Ni, Fe, and Co as main metal elements and at least one of Mn, Cr, Cu, Mo, W, Ti, Al, or Zn as an additional metal element, or a mixture of single-element powders of Ni, Fe, and Co and at least one of single-element powders of Mn, Cr, Cu, Mo, W, Ti, Al, or Zn is selected as the raw material powder for the alloy coating; Step 2: Pretreatment of the conductive substrate The pretreatment of the conductive substrate is to perform cleaning and sandblasting in sequence; Step 3: Surface spraying of conductive substrate The raw material powder is deposited on the surface of the conductive substrate through a spraying process, and then subjected to heat treatment to obtain an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating.

[0011] The spraying process is cold spraying or laser cladding process.

[0012] The raw material powder has an average particle size of 5 to 100 μm and a spherical or nearly spherical shape.

[0013] The cleaning and surface sandblasting treatment are specifically as follows: Cleaning: The conductive substrate was ultrasonically cleaned in acetone and ethanol, followed by rinsing with deionized water and drying. The ultrasonic cleaning parameters were: ultrasonic power 300W, ultrasonic frequency 40KHz, and cleaning time 15 minutes. Surface sandblasting: Use 80-150 mesh aluminum oxide or silicon carbide to sandblast the cleaned conductive substrate at a sandblasting pressure of 0.4 MPa until a uniform and rough textured surface is formed on the surface of the conductive substrate.

[0014] The heat treatment is carried out at a temperature of 400-1100° C. in an inert atmosphere or in a vacuum for 0.5-5 hours.

[0015] The parameters of the cold spraying process are as follows: the spraying distance between the spray gun outlet and the surface of the conductive substrate is 0.5~5cm, the movement speed of the spray gun relative to the conductive substrate is 20~500mm / s, the accelerating gas pressure is 0.8~5.0MPa, the accelerating gas preheating temperature is 300~800℃, and the accelerating gas is nitrogen, helium, argon or a mixture of two or more thereof.

[0016] The parameters of the laser cladding process are: laser power 500-5000W, scanning speed 100-2000mm / min, spot diameter 1-5mm, and powder feeding mode of pre-setting powder or synchronous powder feeding.

[0017] The beneficial effects of this invention are as follows: 1. By expanding the nickel-iron-cobalt-based alloy to multicomponent and high-entropy alloy systems and combining them with a spray coating process, the intrinsic catalytic activity and structural stability of the oxygen evolution reaction (OER) electrocatalyst are significantly improved. The synergistic effect between multiple metal elements optimizes the material's electronic structure and adsorption characteristics for OER intermediates. Simultaneously, the spray coating process forms a catalytic coating that bonds well to the conductive substrate and has a controllable microstructure, resulting in a low oxygen evolution overpotential, high current density, and excellent long-term operational durability.

[0018] 2. The spray coating process provided by this invention offers a high degree of process flexibility and material universality, enabling the efficient preparation of large-area, uniformly thick (Ni-Fe-Co-based) multi-element or high-entropy alloy OER electrocatalytic coatings tailored to specific needs. Cold spraying better preserves the pristine properties of the pre-alloyed powder and enables low-temperature solid-phase deposition, while thermal spraying (laser cladding) facilitates in-situ alloying and metallurgical bonding with the conductive substrate. This diverse approach provides extensive scope for optimizing the microstructure and properties of coatings with varying alloy compositions.

[0019] 3. The method of the present invention is primarily based on abundant non-precious metal elements and utilizes a mature and efficient spray-coating industrial process technology, significantly reducing the preparation cost of high-performance OER electrocatalysts and demonstrating excellent potential for large-scale production. Compared to traditional complex preparation processes or catalyst systems that rely on precious metals, this invention provides a practical and feasible technical approach for developing low-cost, high-performance OER electrode materials that can be widely used in industrial water electrolysis for hydrogen production and related electrochemical energy conversion devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 : Scanning electron microscope image (SEM) of the nickel-iron-cobalt-manganese-chromium alloy coated oxygen evolution electrode prepared in Example 1 of the present invention; Figure 2 : Linear voltammetric sweep curve (LSV) of the nickel-iron-cobalt-manganese-chromium alloy coated oxygen evolution electrode prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] Example 1 Oxygen evolution electrode coated with NiFeCoMnCr high entropy alloy prepared by cold spraying process Selection of raw material powder: Spherical NiFeCoMnCr high entropy alloy powder with equal atomic ratios pre-alloyed by a gas atomization method is selected, and powder with an average particle size of about 20μm is collected by sieving and set aside.

[0022] Conductive substrate pretreatment: A pure nickel plate (purity > 99.5%) with a size of 5 cm × 5 cm and a thickness of 1.5 mm was selected as the conductive substrate.

[0023] The pure nickel plate was cleaned in acetone and anhydrous ethanol by 300W, 40KHz ultrasonic cleaning for 15 minutes, and then 100-mesh aluminum oxide was used as an abrasive and the surface of the pure nickel plate was sandblasted at a sandblasting pressure of 0.4MPa until the surface showed a uniform and rough textured state. Finally, it was blown clean with high-pressure nitrogen.

[0024] Cold spray deposition: A commercial cold spray equipment (PCS 1000) was used, using high-purity nitrogen as both the accelerating and powder-feeding gases. The accelerating gas pressure was set at 1.0 MPa, and the gas preheat temperature was set at 600°C. The spray distance between the spray gun outlet and the pure nickel plate surface was maintained at 1.0 cm. The spray gun was scanned linearly back and forth relative to the substrate at a speed of 50 mm / s. Through multiple scans and an overlap ratio of approximately 40%, a NiFeCoMnCr high-entropy alloy coating with an average thickness of approximately 500 µm was deposited on the substrate surface.

[0025] Subsequent heat treatment: The pure nickel plate with NiFeCoMnCr high entropy alloy coating was heated to 600℃ at a rate of 5℃ / min in a tube furnace protected by argon atmosphere, kept at this temperature for 2 hours, and then cooled to room temperature with the furnace to obtain an oxygen evolution electrode with NiFeCoMnCr high entropy alloy coating deposited on the surface.

[0026] Example 2 Electrode with NiFeCoMnCr high entropy alloy coating prepared by laser cladding process Raw material powder selection: Weigh high-purity spherical Ni, Fe, Co, Mn, and Cr powders with an average particle size of approximately 20 µm and mix them in equal atomic ratios. Place the five metal element powders in a V-type mixer and mix them at low speed under argon for 2 hours to obtain a physically uniform mixed metal powder for later use.

[0027] Conductive substrate pretreatment: The same pure nickel plate as in Example 1 was selected as the conductive substrate, and the same cleaning and sandblasting roughening pretreatment process as in Example 1 was performed.

[0028] Laser cladding deposition: The pretreated pure nickel substrate is fixed on the workbench of the laser cladding equipment. Using a synchronous powder feeding method, the NiFeCoMnCr mixed metal powder is evenly and stably delivered to the laser focal area through a powder feeder (with argon as the carrier gas).

[0029] A fiber laser was used, with a laser power of 800W, a scanning speed of 1200mm / min, and a spot diameter of 2mm. The powder feed rate was matched to the laser parameters. Multi-pass overlapping cladding was performed using a cross-scan pattern, with one horizontal and one vertical pass each. The overlap ratio was controlled at 50% (corresponding to a 1mm spacing between adjacent passes). The entire cladding process was carried out in a flowing argon protective atmosphere to prevent high-temperature oxidation. The resulting NiFeCoMnCr high-entropy alloy coating exhibited a good metallurgical bond with the substrate and a relatively uniform composition, with an average thickness of approximately 500µm.

[0030] Subsequent heat treatment: The pure nickel plate with the laser-clad NiFeCoMnCr high-entropy alloy coating was subjected to homogenization annealing. The process involved holding the plate at 750°C for one hour under argon protection, followed by furnace cooling to further promote composition homogenization and eliminate residual stress, resulting in a NiFeCoMnCr high-entropy alloy-coated oxygen-evolving electrode.

[0031] Example 3 Example 3 As a comparative example, a NiFeCo ternary alloy coating electrode was prepared by cold spraying The preparation method of this embodiment is similar to that of embodiment 1, the main difference being the composition of the raw material powder.

[0032] Raw material powder selection: Spherical NiFeCo ternary alloy powder pre-alloyed by gas atomization method was selected, wherein the atomic ratio of Ni:Fe:Co is about 56:33:11 and the average particle size is about 20μm.

[0033] Conductive substrate pretreatment: The same pure nickel plate as in Example 1 was selected as the conductive substrate, and the same cleaning and sandblasting roughening pretreatment process as in Example 1 was performed.

[0034] Cold spray deposition: Using the same cold spraying equipment and process parameters as in Example 1, a NiFeCo ternary alloy coating with an average thickness of about 500 μm was deposited.

[0035] Subsequent heat treatment: The heat treatment process is the same as that of Example 1.

[0036] Example 4 Example 4 As a comparative example, a NiFeCo ternary alloy coating electrode was prepared by laser cladding method. The preparation method of this embodiment is similar to that of embodiment 2, the main difference being the composition of the raw material powder.

[0037] Raw material powder selection: High-purity spherical Ni powder, Fe powder, and Co powder with an average particle size of about 20 μm were weighed and prepared according to a Ni:Fe:Co atomic ratio of about 56:33:11. The weighed three element powders were physically mixed in the same manner as in Example 2.

[0038] Conductive substrate pretreatment: The same pure nickel plate as in Example 1 was selected as the conductive substrate, and the same cleaning and sandblasting roughening pretreatment process as in Example 1 was performed.

[0039] Laser cladding deposition: The same laser cladding equipment and process parameters as those in Example 2 were used to clad the mixed metal powder on the surface of the conductive substrate to form a NiFeCo ternary alloy coating with an average thickness of approximately 500 μm.

[0040] Subsequent heat treatment: The heat treatment process is the same as that of Example 2.

[0041] Structural and morphological characterization and performance testing 1. Structure and morphology characterization Scanning electron microscope (SEM) analysis was performed on the NiFeCoMnCr high entropy alloy coating oxygen evolution electrode prepared in Example 1. Figure 1 shown.

[0042] from Figure 1 As can be seen, a high-entropy alloy-coated oxygen evolution electrode was successfully fabricated on a pure nickel substrate via a cold spray process. The coating exhibits typical cold spray deposition characteristics: the original powder particles undergo significant plastic deformation and become densely packed together, forming a strong bond interface between the particles. Furthermore, a limited number of micron-sized pores are observed within the dense matrix structure, forming a unique "dense-microporous synergistic" structure.

[0043] 2. Oxygen evolution reaction (OER) electrochemical performance test The electrochemical performance of oxygen evolution reaction (OER) of the oxygen evolution electrodes prepared in Example 1 (cold spraying), Example 2 (laser cladding), Example 3 and Example 4 was tested.

[0044] The tests were all carried out in a standard three-electrode system, with the oxygen evolution electrode prepared in the present invention (exposed area 1 cm²) as the working electrode, a graphite rod as the counter electrode, a Hg / HgO electrode as the reference electrode, and a 1.0 M KOH aqueous solution as the electrolyte.

[0045] Test items include: linear sweep voltammetry (LSV, scan rate 1mV / s), calculation of Tafel slope by LSV curve fitting, electrochemical impedance spectroscopy (EIS, test frequency range, for example, 100kHz~0.1Hz, used to fit the charge transfer resistance Rct), and cyclic voltammetry (CV, tested at different scan rates in the non-Faraday range, used to calculate the double-layer capacitance Cdl).

[0046] ; The electrochemical performance test results show that the NiFeCoMnCr high entropy alloy coating electrode prepared by cold spraying in Example 1 exhibits the best oxygen evolution reaction (OER) catalytic activity. At a current density of 1.5 GHz, the overpotential is only 357 mV, which is significantly lower than the 538 mV of Example 2 using the laser cladding process and the 427 mV and 592 mV of Examples 3 and 4.

[0047] At the same time, the Tafel slope of Example 1 and charge transfer resistance This further confirms its fast reaction kinetics and efficient charge transfer ability, which is better than the oxygen evolution electrodes of Examples 2, 3 and 4.

[0048] On the other hand, the test results of double layer capacitance reveal the effective electrochemical active surface area of ​​the electrode. Example 1 has the highest double layer capacitance value. , much higher than Example 2 Example 3 and Example 4 This indicates that the electrode prepared by the cold spray method has a larger active surface area and can provide more catalytic active sites, which is consistent with the "dense-microporous synergistic" structure observed in its scanning electron microscopy (SEM) analysis, thereby synergistically improving its OER electrocatalytic performance.

Claims

1. An oxygen evolution electrode with a nickel-iron-cobalt based alloy coating, characterized in that: The nickel-iron-cobalt-based alloy coating oxygen evolution electrode consists of a conductive substrate and a surface-deposited alloy coating with Ni, Fe and Co as main metal elements and at least one of Mn, Cr, Cu, Mo, W, Ti, Al or Zn as an additional metal element.

2. The oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 1, characterized in that: The average thickness of the alloy coating is 100-500 μm.

3. A method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating, characterized in that: The preparation method adopts a spraying process to deposit a nickel-iron-cobalt based alloy coating on a conductive substrate, and specifically comprises the following steps: Step 1: Selection of raw powder A high entropy alloy powder containing Ni, Fe, and Co as main metal elements and at least one of Mn, Cr, Cu, Mo, W, Ti, Al, or Zn as an additional metal element, or a mixture of single-element powders of Ni, Fe, and Co and at least one of single-element powders of Mn, Cr, Cu, Mo, W, Ti, Al, or Zn is selected as the raw material powder for the alloy coating; Step 2: Pretreatment of the conductive substrate The pretreatment of the conductive substrate is to perform cleaning and sandblasting in sequence; Step 3: Surface spraying of conductive substrate The raw material powder is deposited on the surface of the conductive substrate through a spraying process, and then subjected to heat treatment to obtain an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating.

4. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 3, wherein: The spraying process is cold spraying or laser cladding process.

5. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 3, wherein: The raw material powder has an average particle size of 5 to 100 μm and a spherical or nearly spherical shape.

6. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 3, wherein: The cleaning and surface sandblasting treatment are specifically as follows: Cleaning: The conductive substrate was ultrasonically cleaned in acetone and ethanol, followed by rinsing with deionized water and drying. The ultrasonic cleaning parameters were: ultrasonic power 300W, ultrasonic frequency 40KHz, and cleaning time 15 minutes. Surface sandblasting: Use 80-150 mesh aluminum oxide or silicon carbide to sandblast the cleaned conductive substrate at a sandblasting pressure of 0.4 MPa until a uniform and rough textured surface is formed on the surface of the conductive substrate.

7. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 3, wherein: The heat treatment is carried out at a temperature of 400-1100° C. in an inert atmosphere or in a vacuum for 0.5-5 hours.

8. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 4, wherein: The parameters of the cold spraying process are as follows: the spraying distance between the spray gun outlet and the surface of the conductive substrate is 0.5~5cm, the movement speed of the spray gun relative to the conductive substrate is 20~500mm / s, the accelerating gas pressure is 0.8~5.0MPa, the accelerating gas preheating temperature is 300~800℃, and the accelerating gas is nitrogen, helium, argon or a mixture of two or more thereof.

9. The method for preparing an oxygen evolution electrode with a nickel-iron-cobalt based alloy coating according to claim 4, wherein: The parameters of the laser cladding process are: laser power 500-5000W, scanning speed 100-2000mm / min, spot diameter 1-5mm, and powder feeding mode of pre-setting powder or synchronous powder feeding.

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