Porous nickel-iron alloy integrated electrode and preparation method and application thereof

Abstract

The invention relates to a porous nickel-iron alloy integrated electrode and a preparation method and application thereof, and belongs to the technical field of electrochemistry. The preparation method comprises the following steps: carrying out cleaning pretreatment on a stainless steel mesh substrate; then electro-deposition is carried out in a solution containing ferric salt and nickel salt, and a nickel-iron alloy layer is formed; carrying out secondary electro-deposition in a solution containing zinc salt, and carrying out high-temperature calcination treatment to obtain a nickel-iron-zinc alloy; and finally, the zinc component is removed through selective corrosion of an alkaline solution, and the nickel-iron alloy integrated electrode with the porous structure is formed on the stainless steel mesh. The method is controllable in process, and a porous structure which is high in specific surface area and beneficial to mass transfer is effectively constructed through step-by-step electro-deposition, calcination and corrosion treatment. The obtained integrated electrode can be directly used as an alkaline water electrolysis oxygen evolution reaction (OER) anode, shows high electrocatalytic activity and stability, and is suitable for the fields of water electrolysis hydrogen production and the like.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical technology and relates to a porous nickel-iron alloy integrated electrode, its preparation method and application. Background Technology

[0002] Hydrogen energy, due to its high energy density and pollution-free combustion products, is considered an ideal carrier for achieving a green transformation of the energy structure. Among various hydrogen production technologies, alkaline water electrolysis is a mature process with great potential for large-scale production, making it one of the most promising green hydrogen production pathways for industrialization. The core reactions of this technology are the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The OER involves a four-electron coupled proton transfer process, which is kineticly slow and requires a high overpotential, making it a key factor limiting the overall energy efficiency improvement and cost reduction of the electrolyzer. Therefore, developing highly active, highly stable, and low-cost OER electrocatalysts is a core requirement for promoting the large-scale application of alkaline water electrolysis technology.

[0003] Currently, the best-performing OER catalysts still rely on noble metal oxides such as iridium (Ir) and ruthenium (Ru), but their scarcity and high price are major obstacles to commercial application. Catalysts based on abundant transition metals, especially nickel (Ni)-based and iron (Fe)-based materials, have become the most attractive alternative catalysts. Numerous studies have confirmed that there is a unique synergistic effect of electronic structure between Ni and Fe, which can significantly optimize the adsorption energy of OER intermediates, enabling nickel-iron alloys and their hydroxides to exhibit excellent intrinsic activity in alkaline media. However, nickel-iron catalysts prepared by conventional methods often have a dense or micron-sized particle structure with limited specific surface area, insufficient exposure of active sites, and large resistance to charge and reactant mass transfer, resulting in their apparent catalytic performance failing to meet expectations.

[0004] To overcome the aforementioned limitations, constructing a three-dimensional, interconnected porous structure is widely recognized as an effective strategy. This structure not only significantly increases the electrochemical active area and exposes numerous edge and defect active sites, but its continuous channels and framework also facilitate electrolyte permeation, rapid bubble desorption, and efficient electron transport. Dealloying is a common technique for preparing porous metals, but it requires the preparation of a uniform precursor alloy, and the subsequent corrosion process needs precise control to preserve the ideal porous framework. In existing technologies, achieving a robust and integrated porous structure with a conductive substrate (such as a metal mesh) remains challenging: direct coating or loading of porous powders easily leads to high contact resistance, weak bonding, and easy detachment; while nanomaterial catalysts grown directly on the substrate struggle to simultaneously achieve high porosity, uniform and efficient alloying of bimetallic components, and effective bonding with the substrate. Especially for systems like nickel-iron alloys, which require high-temperature treatment to form the ideal alloy phase and active structure, how to construct a robust, compositionally controllable, and pore-structure-optimized porous nickel-iron alloy catalyst layer on the substrate under mild conditions or through reasonable process design remains a significant technical challenge. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a porous nickel-iron alloy integrated electrode, its preparation method, and its application. This invention prepares a highly active and stable oxygen evolution reaction catalyst with a porous structure through electrodeposition and chemical etching methods, which is used for alkaline water electrolysis.

[0006] Based on the above technical concept, this invention achieves in-situ construction of a robust three-dimensional porous nickel-iron alloy integrated electrode by sequentially performing nickel-iron alloy electrodeposition, zinc electrodeposition, high-temperature alloying calcination, and selective corrosion with alkaline solution on a stainless steel mesh substrate. This method utilizes zinc as a sacrificial pore-forming template element, which, through high-temperature calcination, forms a uniform precursor alloy with the pre-deposited nickel-iron, followed by mild corrosion selectively removing zinc, thereby directly generating a stable porous nickel-iron framework on the substrate surface. This process not only avoids the cumbersome coating process of powdered catalysts, ensuring excellent conductivity and mechanical stability of the electrode, but also effectively adjusts the pore size and porosity of the porous structure by controlling the electrodeposition parameters and corrosion conditions, providing a flexible means to optimize mass transfer and catalytic performance. The prepared integrated electrode exhibits high activity, high stability, and low energy consumption in alkaline water electrolysis OER reactions, providing a novel and practical technical path for developing low-cost, high-performance water electrolysis anodes.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] Firstly, a method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0009] (1) Clean the stainless steel mesh with anhydrous ethanol, alkaline solution, acidic solution and deionized water for 5-10 minutes respectively.

[0010] (2) The stainless steel mesh obtained in step (1) is electrodeposited in a mixed solution containing iron salt, nickel salt and ammonium chloride. The electrodeposition method is constant current method, and the current density is 1-10 mA cm⁻¹. -2 The reaction time is 1-5 hours; after the reaction is completed, the nickel-iron alloy electrocatalyst material grown on a stainless steel mesh is obtained after soaking, washing and drying.

[0011] (3) The electrocatalyst material obtained in step (2) is electrodeposited in a solution containing zinc salt. The electrodeposition method is a constant current method with a current density of 1-100 mA cm⁻¹. -2 The reaction time is 1-5 hours. After the reaction is completed, the electrocatalyst material is soaked, washed and dried, and then calcined at high temperature to obtain nickel-iron-zinc alloy electrocatalyst material grown on stainless steel mesh.

[0012] (4) The electrocatalyst material obtained in step (3) is etched in an alkaline solution. After soaking, washing and drying, a porous nickel-iron alloy electrocatalyst material is obtained.

[0013] Preferably, in step (1), the alkaline solution is a potassium hydroxide solution and the acidic solution is a hydrochloric acid solution.

[0014] Preferably, in step (2) of this invention, the iron salt is FeSO4·7H2O, and the nickel salt is NiCl2·6H2O and NiSO4·6H2O, which are added simultaneously.

[0015] In a preferred embodiment of the present invention, the soaking and washing in step (2) involves washing with deionized water and anhydrous ethanol 3-8 times in sequence.

[0016] Preferably, the zinc salt mentioned in step (3) of this invention is a mixed solution of ZnSO4·7H2O and Na2SO4.

[0017] In a preferred embodiment of the present invention, the soaking and washing in step (3) involves washing with deionized water and anhydrous ethanol 3-8 times in sequence.

[0018] Preferably, in step (3) of this invention, the calcination temperature is 300-800 ℃ and the time is 1-4 h.

[0019] Preferably, the alkaline solution in step (4) of this invention is potassium hydroxide, the corrosion temperature is 20-60 ℃, and the corrosion time is 2-10 h.

[0020] Preferably, in step (4) of this invention, the soaking and washing are performed by washing with deionized water and anhydrous ethanol 3-8 times in sequence.

[0021] Secondly, the present invention provides a porous nickel-iron alloy integrated electrode, which is obtained by the preparation method provided in the first aspect of the present invention, and the electrode has a porous microstructure.

[0022] Meanwhile, the porous nickel-iron alloy electrocatalyst material prepared by the method of the present invention falls within the protection scope of the present invention.

[0023] Thirdly, the present invention provides the application of the obtained porous nickel-iron alloy integrated electrode as an oxygen evolution anode in the alkaline water electrolysis process.

[0024] The technical features and beneficial effects of this invention are as follows:

[0025] 1. This invention employs a combination of electrodeposition and chemical etching, which is simple and mild. Through constant current deposition, low-temperature calcination, and chemical etching, the porous nickel-iron alloy can be controlled and prepared with low energy consumption and is easy to scale up.

[0026] 2. The prepared catalyst has a unique porous structure, which significantly increases the electrochemical active area and exposes more active sites, giving it both high catalytic activity and excellent structural stability in alkaline oxygen evolution reaction.

[0027] 3. This method is highly versatile and can be adapted to different metal alloy systems by adjusting the electrodeposition and corrosion parameters. It provides a new approach for developing high-performance, low-cost electrocatalysts and has broad application prospects in the fields of industrial water electrolysis for hydrogen production and energy conversion. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the porous nickel-iron alloy integrated electrode prepared in Example 1.

[0029] Figure 2 This is an elemental distribution diagram of the porous nickel-iron alloy integrated electrode prepared in Example 1.

[0030] Figure 3 This is a scanning electron microscope image of the stainless steel mesh in Comparative Example 1.

[0031] Figure 4 This is a scanning electron microscope image of the commercial anode catalyst in Comparative Example 2.

[0032] Figure 5 The linear current-voltage (LSV) curves of the porous nickel-iron alloy integrated electrodes prepared in Examples 1 and 2-3 are shown.

[0033] Figure 6These are LSV diagrams of the porous nickel-iron alloy integrated electrodes prepared in Examples 1 and 4-5, and the electrodes in Comparative Examples 1-2.

[0034] Figure 7 This is a Tafel slope diagram of the porous nickel-iron alloy integrated electrode prepared in Examples 1 and 2-3.

[0035] Figure 8 These are Tafel slope diagrams of the porous nickel-iron alloy integrated electrodes prepared in Examples 1 and 4-5, and the electrodes in Comparative Examples 1-2.

[0036] Figure 9 These are impedance diagrams of the porous nickel-iron alloy integrated electrodes prepared in Examples 1 and 2-3.

[0037] Figure 10 The impedance diagrams are of the porous nickel-iron alloy integrated electrodes prepared in Examples 1 and 4-5, and the electrodes in Comparative Examples 1-2.

[0038] Figure 11 This is a double-layer capacitance diagram of the porous nickel-iron alloy integrated electrode prepared in Examples 1 and 2-3.

[0039] Figure 12 The diagram shows the double-layer capacitance of the porous nickel-iron alloy integrated electrode prepared in Examples 1 and 4-5, and the electrode in Comparative Examples 1-2.

[0040] Figure 13 This is the stability test curve of Example 1 in potassium hydroxide solution. Detailed Implementation

[0041] The present invention will be further described below through specific embodiments, but is not limited thereto.

[0042] Example 1

[0043] A method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0044] (1) Clean the stainless steel mesh with anhydrous ethanol, 1 M potassium hydroxide solution, 1 M hydrochloric acid solution and deionized water by ultrasonic cleaning for 5-10 minutes respectively;

[0045] (2) The stainless steel mesh obtained in (1) is electrodeposited in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl at a current density of 1-10 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionization 3-8 times and dried in a drying oven at 60 ℃ for 12 h to obtain nickel-iron alloy material grown on stainless steel mesh.

[0046] (3) The electrode obtained in (2) is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 at a current density of 1-100 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times, dried in a drying oven at 60 ℃ for 12 h, and calcined in a tube furnace at 550 ℃ for 3 h in an Ar-H2 mixed gas to obtain nickel-iron-zinc alloy material grown on stainless steel mesh.

[0047] (4) The electrode obtained in (3) is etched in 1 M KOH solution at 50 °C. After immersion etching for 3 h, it is washed with deionized water 3-8 times and dried in a drying oven at 60 °C for 12 h to obtain a porous nickel-iron alloy integrated electrode.

[0048] The scanning electron microscope image of the porous nickel-iron alloy integrated electrode prepared in this embodiment is shown below. Figure 1 As shown, there is a porous layer with a thickness of 22 micrometers on the stainless steel mesh, which includes nanoscale and microscale pores. Figure 2 The figure shows the elemental distribution, which indicates that Ni, Fe, and a small amount of zinc are evenly distributed in the porous structure.

[0049] Figure 5 and Figure 6 The linear voltammetric curve of the oxygen evolution reaction (OER) of the porous nickel-iron alloy integrated electrode prepared in this embodiment in 1 M potassium hydroxide solution is shown in the figure. As shown, the catalyst exhibits an OER overpotential of only 268 mV at a current density of 300 mA·cm⁻², demonstrating excellent OER catalytic activity and making it suitable for efficient water electrolysis systems.

[0050] Figure 7 and Figure 8 The Tafel curve for the porous nickel-iron alloy integrated electrode prepared in this embodiment has a slope of 53.6 mV dec. -1 This indicates that the material possesses good reaction kinetics characteristics during the oxygen evolution process.

[0051] Figure 9 and Figure 10 The electrochemical impedance spectroscopy of the porous nickel-iron alloy integrated electrode prepared in this embodiment shows that its low charge transfer impedance indicates that the catalyst has high electronic conduction efficiency, which is beneficial to improving the reaction rate.

[0052] Figure 11 and Figure 12 The double-layer capacitance curve of the porous nickel-iron alloy integrated electrode prepared in this embodiment shows a capacitance value of 29.8 mF·cm⁻², reflecting that the material has a large electrochemically active specific surface area, providing abundant active sites for catalytic reactions and further enhancing its catalytic performance.

[0053] Figure 13 The stability test curve of this embodiment in potassium hydroxide solution shows that the voltage hardly changed after 100 hours of continuous operation, indicating its excellent electrochemical stability.

[0054] Example 2

[0055] A method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0056] (1) Clean the stainless steel mesh with anhydrous ethanol, 1 M potassium hydroxide solution, 1 M hydrochloric acid solution and deionized water by ultrasonic cleaning for 5-10 minutes respectively.

[0057] (2) The stainless steel mesh obtained in (1) is electrodeposited in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl at a current density of 1-10 mA cm⁻¹. -2 The reaction time was 1.5 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times and dried in a drying oven at 60 ℃ for 12 h to obtain nickel-iron alloy material grown on stainless steel mesh.

[0058] (3) The electrode obtained in (2) is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 at a current density of 1-100 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times, dried in a drying oven at 60 ℃ for 12 h, and calcined in a tube furnace at 550 ℃ for 3 h in an Ar-H2 mixed gas to obtain a nickel-iron-zinc alloy electrocatalyst material grown on a stainless steel mesh.

[0059] (4) The electrode obtained in (3) is etched in 1 M KOH solution at 50 °C for 3 h, washed with deionized water 3-8 times, and dried in a drying oven at 60 °C for 12 h to obtain a porous nickel-iron alloy integrated electrode.

[0060] The porous nickel-iron alloy integrated electrode prepared in Example 2 was tested for oxygen evolution reaction performance in a 1 M potassium hydroxide electrolyte. Figure 5 As shown, the catalyst requires an overpotential of 298 mV at a current density of 300 mA·cm⁻², indicating that it still possesses good electrocatalytic oxygen evolution activity. The corresponding Tafel slope is 89.8 mV dec. -1 ( Figure 7 This reflects a decrease in reaction kinetics compared to Example 1. Electrochemical impedance spectroscopy results show that the charge transfer resistance is greater than that of Example 1 (…). Figure 9This indicates that the electron conductivity is lower than that of Example 1. Figure 11 The diagram shows the double-layer capacitance of the porous nickel-iron alloy integrated electrode prepared in this embodiment. The active area was further evaluated by the double-layer capacitance test. The catalyst capacitance value in this embodiment is 25.7 mF·cm⁻², which is lower than that in Example 1. The electrochemical active area is reduced, resulting in a decrease in the number of reactive active sites.

[0061] Example 3

[0062] A method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0063] (1) Clean the stainless steel mesh with anhydrous ethanol, 1 M potassium hydroxide solution, 1 M hydrochloric acid solution and deionized water by ultrasonic cleaning for 5-10 minutes respectively.

[0064] (2) The stainless steel mesh obtained in (1) is electrodeposited in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl at a current density of 1-10 mA cm⁻¹. -2 The reaction time was 2.5 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times and dried in a drying oven at 60 ℃ for 12 h to obtain nickel-iron alloy material grown on stainless steel mesh.

[0065] (3) The electrode obtained in (2) is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 at a current density of 1-100 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times, dried in a drying oven at 60 ℃ for 12 h, and calcined in a tube furnace at 550 ℃ for 3 h in an Ar-H2 mixed gas to obtain a nickel-iron-zinc alloy electrocatalyst material grown on a stainless steel mesh.

[0066] (4) The electrode obtained in (3) is etched in 1 M KOH solution at 50 °C for 3 h, washed with deionized water 3-8 times, and dried in a drying oven at 60 °C for 12 h to obtain a porous nickel-iron alloy integrated electrode.

[0067] The porous nickel-iron alloy integrated electrode prepared in Example 3 was subjected to OER performance testing in a 1 M potassium hydroxide solution, and the corresponding LSV curve is shown below. Figure 5 As shown, this electrode requires an oxygen evolution overpotential of 270 mV to reach 300 mA cm⁻¹. -2 The current density was higher than that in Example 1 but lower than that in Example 2, indicating that a certain amount of NiFe helps to improve the OER activity. Figure 7The Tafel curve for the porous nickel-iron alloy integrated electrode prepared in Example 3 is shown, with a Tafel slope of 79.2 mV dec. -1 The charge transfer impedance is between that of Example 1 and Example 2 ( Figure 9 The double-layer capacitance is 29.3 mF cm⁻¹. -2 ( Figure 11 The value is very close to the double-layer capacitance value of Example 1, indicating that they have similar electrochemical active areas.

[0068] Example 4

[0069] A method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0070] (1) Clean the stainless steel mesh with anhydrous ethanol, 1 M potassium hydroxide solution, 1 M hydrochloric acid solution and deionized water by ultrasonic cleaning for 5-10 minutes respectively.

[0071] (2) The stainless steel mesh obtained in (1) is electrodeposited in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl at a current density of 1-10 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionization 3-8 times and dried in a drying oven at 60 ℃ for 12 h to obtain nickel-iron alloy material grown on stainless steel mesh.

[0072] (3) The electrode obtained in (2) is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 at a current density of 1-100 mA cm⁻¹. -2 The reaction time was 1.5 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times, dried in a drying oven at 60 ℃ for 12 h, and calcined in a tube furnace at 550 ℃ for 3 h in an Ar-H2 mixed gas to obtain nickel-iron-zinc alloy electrocatalyst material grown on stainless steel mesh.

[0073] (4) The electrode obtained in (3) is etched in 1 M KOH solution at 50 °C for 2 h, washed with deionized water 3-8 times, and dried in a drying oven at 60 °C for 12 h to obtain a porous nickel-iron alloy integrated electrode.

[0074] The LSV curve of the porous nickel-iron alloy integrated electrode prepared in Example 4 is as follows: Figure 6 As shown, the electrode exhibits a current density of 300 mAcm under 1 M potassium hydroxide conditions. -2 The oxygen evolution overpotential was 305 mV, higher than that of Examples 1-3, indicating a decrease in its oxygen evolution catalytic performance. The Tafel slope of Example 4 was 98.8 mV dec.-1 ( Figure 8 ), charge transfer impedance increases ( Figure 10 The values ​​were all higher than those in Examples 1-3, reflecting that the porous layer reduced the kinetics of the catalytic reaction. The double-layer capacitance was 21.1 mFcm. -2 ( Figure 12 The values ​​were all lower than those in Examples 1-3, indicating that their electrochemical active area was relatively low.

[0075] Example 5

[0076] A method for preparing a porous nickel-iron alloy integrated electrode includes the following steps:

[0077] (1) Clean the stainless steel mesh with anhydrous ethanol, 1 M potassium hydroxide solution, 1 M hydrochloric acid solution and deionized water by ultrasonic cleaning for 5-10 minutes respectively.

[0078] (2) The stainless steel mesh obtained in (1) is electrodeposited in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl at a current density of 1-10 mA cm⁻¹. -2 The reaction time was 2 h. After the reaction was completed, the obtained catalyst was cleaned with deionization 3-8 times and dried in a drying oven at 60 ℃ for 12 h to obtain nickel-iron alloy material grown on stainless steel mesh.

[0079] (3) The electrode obtained in (2) is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 at a current density of 1-100 mA cm⁻¹. -2 The reaction time was 2.5 h. After the reaction was completed, the obtained catalyst was cleaned with deionizer 3-8 times, dried in a drying oven at 60 ℃ for 12 h, and calcined in a tube furnace at 550 ℃ for 3 h in an Ar-H2 mixed gas to obtain nickel-iron-zinc alloy electrocatalyst material grown on stainless steel mesh.

[0080] (4) The electrode obtained in (3) is etched in 1 M KOH solution at 50 °C for 5 h, washed with deionized water 3-8 times, and dried in a drying oven at 60 °C for 12 h to obtain a porous nickel-iron alloy integrated electrode.

[0081] The oxygen evolution performance curve of the porous nickel-iron alloy integrated electrode prepared in Example 5 is shown below. Figure 6 As shown, this electrode operates at a current density of 300 mA cm⁻¹. -2 The oxygen evolution overpotential is 273 mV. Figure 8 The Tafel curve corresponding to Example 5 has a Tafel slope of 70.9 mV dec. -1The charge transfer impedance was improved compared to Example 1 but decreased compared to Example 4, indicating that the porous layer with a thickness of approximately 22 μm facilitates electron transport. Figure 10 Furthermore, its double-layer capacitance is 29.2 mF cm⁻¹. -2 ( Figure 12 The value is very close to the double-layer capacitance of Example 1, indicating that it has a relatively large electrochemical active area.

[0082] Example 6

[0083] Unlike Examples 1-5, in this example, the electrodeposition reaction time of the stainless steel mesh in step (2) in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl is 1 h;

[0084] In step (3), the electrode is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 for 1 h; after the reaction is completed, the resulting catalyst is calcined in a tube furnace at 300 °C for 4 h.

[0085] Step (4) involves etching the electrode in a 1 M KOH solution at 20 °C for 10 h.

[0086] The porous nickel-iron alloy integrated electrode obtained in this embodiment exhibits the same high catalytic activity and excellent structural stability as in Examples 1-5 during the alkaline oxygen evolution reaction.

[0087] Example 7

[0088] Unlike Examples 1-6, in this example, the electrodeposition reaction time of the stainless steel mesh in step (2) in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl is 5 h;

[0089] In step (3), the electrode is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 for 5 h. After the reaction is completed, the resulting catalyst is calcined in a tube furnace at 800 °C for 1 h.

[0090] Step (4) involves etching the electrode in a 1 M KOH solution at 60 °C for 2 h.

[0091] The porous nickel-iron alloy integrated electrode obtained in this embodiment exhibits the same high catalytic activity and excellent structural stability as in Examples 1-6 during the alkaline oxygen evolution reaction.

[0092] Example 8

[0093] Unlike Examples 1-7, in this example, the electrodeposition reaction time of the stainless steel mesh in step (2) in a mixed solution containing FeSO4·7H2O, NiCl2·6H2O, NiSO4·6H2O and NH4Cl is 3 h;

[0094] In step (3), the electrode is electrodeposited in a solution containing ZnSO4·7H2O and Na2SO4 for 3 hours; after the reaction is completed, the resulting catalyst is calcined in a tube furnace at 700 °C for 2 hours.

[0095] Step (4) involves etching the electrode in a 1 M KOH solution at 40 °C for 6 h.

[0096] The porous nickel-iron alloy integrated electrode obtained in this embodiment exhibits the same high catalytic activity and excellent structural stability as in Examples 1-7 during the alkaline oxygen evolution reaction.

[0097] Comparative Example 1

[0098] A stainless steel mesh electrocatalyst material was purchased directly from a metal mesh manufacturer.

[0099] The scanning electron microscope image of Comparative Example 1 is shown below. Figure 3 As shown in the scanning electron microscope image, the surface of the stainless steel mesh exhibits a dense planar structure, accompanied by a small number of microscopic defects such as pores and impurities.

[0100] Figure 6 The LSV plot of electrode 1 in this comparative example is shown; Figure 8 The Tafel slope plot of electrode 1 in this comparative example is shown; Figure 10 The impedance diagram of electrode 1 in this comparative example is shown; Figure 12 The double-layer capacitance diagram of the electrode in Comparative Example 1 is shown. As can be seen from the figure, the stainless steel mesh electrocatalyst material in Comparative Example 1 exhibits a current density of 300 mA cm⁻¹ under 1 M KOH conditions. -2 The oxygen evolution overpotential was 399 mV, significantly higher than that of the five examples prepared above, indicating poor oxygen evolution catalytic performance. Furthermore, the Tafel slope was 123.5 mV dec. -1 The impedance increases significantly, and the double-layer capacitance is only 0.2 mF cm⁻¹. -2 This indicates that it has relatively small oxygen evolution reaction kinetics and a low specific surface area.

[0101] Comparative Example 2

[0102] A commercial electrocatalyst material is purchased directly from an electrode company.

[0103] The scanning electron microscope image of this comparative example is as follows: Figure 4As shown, the catalyst is unevenly distributed and detaches significantly, which is detrimental to maintaining its activity.

[0104] Figure 6 The LSV plot of electrode 2 in this comparative example is shown; Figure 8 The Tafel slope plot of electrode 2 in this comparative example is shown; Figure 10 The impedance diagram of electrode 2 in this comparative example is shown; Figure 12 The double-layer capacitance diagram of the electrode in Comparative Example 2 is shown. As can be seen from the figure, the commercial electrocatalyst material in Comparative Example 2 requires an overpotential of 284 mV to achieve 300 mAcm under 1 M KOH conditions. -2 The low current density indicates reduced oxygen evolution catalytic activity. Its low Tafel slope and high charge transfer impedance suggest slow reaction kinetics. The double-layer capacitance is 1.1 mF / cm². 2 The number is far less than 5 examples.

[0105] Compared with Comparative Examples 1 and 2, the electrode obtained in this application exhibits higher electrocatalytic activity and stability. Furthermore, the process of this invention is controllable. Through stepwise electrodeposition, calcination, and corrosion treatment, a porous structure with high specific surface area and good mass transfer is effectively constructed. The resulting integrated electrode can be directly used as the anode for alkaline water electrolysis oxygen evolution reaction (OER), with ideal application results.

Claims

1. A method for preparing a porous nickel-iron alloy integrated electrode, characterized in that, The method includes the following steps: (1) Clean the stainless steel mesh with anhydrous ethanol, alkaline solution, acidic solution and deionized water for 5-10 minutes respectively. (2) The stainless steel mesh obtained in step (1) is electrodeposited in a mixed solution containing iron salt, nickel salt and ammonium chloride. The electrodeposition method is constant current method, and the current density is 1-10 mA cm⁻¹. -2 The reaction time is 1-5 hours; after the reaction is completed, the nickel-iron alloy electrocatalyst material grown on a stainless steel mesh is obtained after soaking, washing and drying. (3) The electrocatalyst material obtained in step (2) is electrodeposited in a solution containing zinc salt. The electrodeposition method is a constant current method with a current density of 1-100 mA cm⁻¹. -2 The reaction time is 1-5 hours. After the reaction is completed, the electrocatalyst material is soaked, washed and dried, and then calcined at high temperature to obtain nickel-iron-zinc alloy electrocatalyst material grown on stainless steel mesh. (4) The electrocatalyst material obtained in step (3) is etched in an alkaline solution. After soaking, washing and drying, a porous nickel-iron alloy integrated electrode is obtained.

2. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The alkaline solution mentioned in step (1) is potassium hydroxide solution and the acidic solution is hydrochloric acid solution.

3. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The iron salt mentioned in step (2) is FeSO4·7H2O, and the nickel salt is NiCl2·6H2O and NiSO4·6H2O, which are added at the same time.

4. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The soaking and washing described in step (2) involves washing with deionized water and anhydrous ethanol 3-8 times in sequence.

5. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The zinc salt mentioned in step (3) is a mixed solution of ZnSO4·7H2O and Na2SO4.

6. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The soaking and washing in step (3) involves washing with deionized water and anhydrous ethanol 3-8 times in sequence; the calcination temperature is 300-800℃ and the time is 1-4 h.

7. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The alkaline solution mentioned in step (4) is potassium hydroxide, with a corrosion temperature of 20-60 ℃ and a corrosion time of 2-10 h.

8. The method for preparing the porous nickel-iron alloy integrated electrode according to claim 1, characterized in that, The soaking and washing described in step (4) involves washing with deionized water and anhydrous ethanol 3-8 times in sequence.

9. A porous nickel-iron alloy integrated electrode, characterized in that, The electrode material is prepared by the preparation method according to any one of claims 1-8, and the microstructure of the electrode material is a porous structure.

10. The application of the porous nickel-iron alloy integrated electrode of claim 9 as an oxygen evolution anode in alkaline water electrolysis.

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