Iron-based alloy oxygen evolution electrode with composite phosphide catalytic layer and preparation method and application thereof

Abstract

This application belongs to the field of water electrolysis for hydrogen production technology, and particularly relates to an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, its preparation method, and its application. In the preparation process of the iron-based alloy oxygen evolution electrode provided by this application, an iron-based alloy substrate that has undergone surface pretreatment such as polishing is immersed in a composite phosphating solution for ultrasonic-assisted phosphating. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, a composite phosphide catalyst layer can be formed in situ on the surface of the iron-based alloy oxygen evolution electrode, significantly improving the oxygen evolution reaction activity and long-term stability of the iron-based alloy oxygen evolution electrode, making it a high-performance iron-based alloy oxygen evolution electrode. Furthermore, the performance of the iron-based alloy oxygen evolution electrode is further improved by adjusting the ultrasonic time, the concentration of manganese salt, zinc salt, and chelating agents such as sodium citrate during the ultrasonic-assisted phosphating process; thus solving the technical problem of low performance of existing iron-based alloy oxygen evolution electrodes.

Description

Technical Field

[0001] This application belongs to the field of water electrolysis for hydrogen production technology, and particularly relates to an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, its preparation method, and its application. Background Technology

[0002] Among the mainstream water electrolysis hydrogen production technologies, alkaline water electrolysis hydrogen production is widely used due to its high technological maturity. Alkaline water electrolysis hydrogen production is usually carried out in an electrolyzer, with the hydrogen evolution reaction (HER) taking place at the cathode and the oxygen evolution reaction (OER) taking place at the anode. Hydrogen production equipment such as electrolyzers imposes stringent requirements on the economy and catalytic efficiency of hydrogen production.

[0003] Currently, commercially available anodes for alkaline water electrolysis to produce hydrogen mostly use nickel-based alloys, whose cost is significantly constrained by the price of nickel, making it difficult to meet the economic requirements of hydrogen production. Iron (Fe)-based alloys, due to their low raw material cost, excellent mechanical properties, and the presence of transition metals on their surface, are considered ideal materials to replace pure nickel oxygen evolution electrodes. However, when iron-based alloys are used directly for water electrolysis, they are often limited by the lack of surface active sites and the intrinsic sluggish oxygen evolution kinetics, making it difficult to directly meet the energy consumption requirements of high current density in industrial applications. By improving the electrocatalytic activity of iron-based alloys, it is hoped that the economic and catalytic efficiency requirements for alkaline water electrolysis to produce hydrogen can be met.

[0004] Surface phosphating with phosphating solution is a traditional steel corrosion protection process, and it is also an effective way to construct a metal phosphide catalytic layer. However, the elemental composition of iron-based alloys is complex. By mass percentage (wt.%), they are mainly composed of Fe (55~85), Ni (10~20), Co (5~15), Cr (2.5~3.5), Mo (0.5~1.5), and trace amounts of C ≤0.5. These elements have vastly different reactivity with phosphate ions in the phosphating solution. As a result, during the surface phosphating process, defects such as uneven metal phosphide catalytic layer, poor catalytic layer bonding, or accumulation of inactive oxides are prone to occur. It is difficult to construct an efficient and stable catalytic layer in situ on the iron-based alloy substrate material, resulting in low performance of the iron-based alloy oxygen evolution electrode. It is difficult to work in conjunction with inexpensive iron-based alloy substrates to construct an alkaline water electrolysis oxygen evolution electrode that meets the economic and catalytic efficiency requirements of alkaline water electrolysis for hydrogen production. Summary of the Invention

[0005] In view of this, this application provides an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, its preparation method, and its application, to solve the technical problem of low performance of iron-based alloy oxygen evolution electrodes in the prior art.

[0006] The first aspect of this application provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, comprising the following steps: The steps for preparing the composite phosphating solution are as follows: Manganese salt, zinc salt, chelating agent, phosphoric acid, potassium dihydrogen phosphate and water are stirred and dissolved to obtain the composite phosphating solution; The steps for pretreating the anode substrate are as follows: the iron-based alloy is subjected to surface pretreatment to obtain a pretreated iron-based alloy substrate; The surface phosphating treatment steps are as follows: The pretreated iron-based alloy substrate is immersed in the composite phosphating solution for ultrasonic-assisted phosphating to obtain an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer.

[0007] Preferably, in the step of preparing the composite phosphating solution, the manganese salt is selected from at least one of manganese chloride, manganese nitrate, manganese sulfate, manganese chloride hydrate, manganese nitrate hydrate, and manganese sulfate hydrate; The zinc salt is selected from at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc chloride hydrate, zinc nitrate hydrate, and zinc sulfate hydrate.

[0008] Preferably, in the step of preparing the composite phosphating solution, the chelating agent is selected from at least one of sodium citrate, sodium gluconate, EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid).

[0009] Preferably, in the step of preparing the composite phosphating solution, the concentration of manganese ions in the composite phosphating solution is not greater than 0.2 mol / L; The concentration of zinc ions in the composite phosphating solution is no greater than 0.3 mol / L.

[0010] Preferably, in the step of preparing the composite phosphating solution, the concentration of manganese ions in the composite phosphating solution is not greater than 0.1 mol / L; The concentration of zinc ions in the composite phosphating solution is no greater than 0.2 mol / L.

[0011] Preferably, in the step of preparing the composite phosphating solution, the molar ratio of manganese ions to zinc ions in the composite phosphating solution is 1:1 to 5.

[0012] Preferably, in the step of preparing the composite phosphating solution, the molar ratio of manganese ions to zinc ions in the composite phosphating solution is 1:2~3.

[0013] Preferably, in the step of preparing the composite phosphating solution, the concentration of the chelating ligand in the composite phosphating solution is not greater than 16.7 mmol / L.

[0014] Preferably, in the step of preparing the composite phosphating solution, the concentration of the chelating ligand in the composite phosphating solution is 3.3~5 mmol / L.

[0015] Preferably, in the step of preparing the composite phosphating solution, the volume concentration of phosphoric acid is 4-8%, and the concentration of potassium dihydrogen phosphate is 0.1-0.3 mol / L.

[0016] Preferably, in the step of preparing the composite phosphating solution, the volume concentration of phosphoric acid is 6% and the concentration of potassium dihydrogen phosphate is 0.2 mol / L.

[0017] Preferably, in the step of pretreating the anode substrate, the iron-based alloy contains elements such as Fe, Ni, Co, Cr, Mo and C, and is mainly composed of Fe (55~85), Ni (10~20), Co (5~15), Cr (2.5~3.5), Mo (0.5~1.5), and trace amounts of C ≤0.5% by mass percentage (wt.%).

[0018] Preferably, in the step of pretreating the anode substrate, the surface pretreatment process is as follows: grinding, cleaning, and drying are performed sequentially; during the pretreatment process, grinding is performed by using metallographic sandpaper of 200 to 800 mesh to grind the iron-based alloy surface step by step, cleaning is performed by placing the ground iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning in sequence, and drying is performed by wiping dry.

[0019] Preferably, in the surface phosphating step, the ultrasonic-assisted phosphating is performed by ultrasound, with the ultrasound frequency controlled at 10~100 KHz, the power controlled at 240~480 W, the reaction temperature controlled at 25~45 ℃, and the treatment time controlled at 0.5~2h.

[0020] Preferably, in the surface phosphating step, the ultrasonic-assisted phosphating is performed by ultrasound, with the ultrasound frequency controlled at 40 kHz, the power controlled at 275 W, the reaction temperature controlled at 25~45 ℃, and the treatment time controlled at 1~1.5 h.

[0021] Preferably, the surface phosphating treatment step is followed by a post-treatment, specifically: rinsing with deionized water and drying in sequence.

[0022] The second aspect of this application provides an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, which is prepared by the preparation method described in the first aspect. The composite phosphide catalyst layer grown in situ on its surface serves as a catalyst layer, which can significantly enhance the catalytic activity of the oxygen evolution reaction of the iron-based high-entropy alloy anode in water electrolysis in alkaline medium. Furthermore, since the catalyst layer is tightly bonded to the iron-based alloy substrate, the oxygen evolution electrode exhibits excellent stability during long-term electrolysis operation.

[0023] The third aspect of this application provides the application of an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, as described in the second aspect, in alkaline water electrolysis for hydrogen production.

[0024] The fourth aspect of this application provides an alkaline water electrolysis hydrogen production electrolyzer, including the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer as described in the second aspect.

[0025] Compared with the prior art, the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer provided in this application has at least the following beneficial effects: 1. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalytic layer provided in this application involves pre-treating the iron-based alloy surface, such as by grinding, and then immersing it in a composite phosphating solution prepared with manganese salt, zinc salt, chelating agent, phosphoric acid, and potassium dihydrogen phosphate solute for ultrasonic-assisted phosphating treatment. By leveraging the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided. A uniform and porous composite phosphide catalytic layer can be constructed in situ on the surface of the iron-based alloy oxygen evolution electrode, which significantly improves the oxygen evolution reaction (OER) activity and long-term stability of the iron-based alloy oxygen evolution electrode, thereby providing a high-performance iron-based alloy oxygen evolution electrode.

[0026] 2. In the preparation method of the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer provided in this application, by adjusting the ultrasonic time in the ultrasonic-assisted phosphating process, defects such as incomplete composite phosphide layer caused by too short ultrasonic time, excessive etching or destruction of composite phosphide layer structure caused by too long ultrasonic time are avoided, thereby further improving the performance of the iron-based alloy oxygen evolution electrode.

[0027] 3. In the preparation method of the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer provided in this application, by adjusting the concentration of manganese salt and zinc salt in the ultrasonic-assisted phosphating process, the two can be promoted to work together to form a composite phosphide catalyst layer with abundant defects and good conductivity, thereby further improving the performance of the iron-based alloy oxygen evolution electrode.

[0028] 4. In the preparation method of the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer provided in this application, by adjusting the concentration of chelating agents such as sodium citrate during the ultrasonic-assisted phosphating process, the defects such as difficulty in controlling the precipitation rate of manganese and zinc ions due to excessively low concentration or excessive complexation of metal ions due to excessively high concentration are avoided. This suppresses the defects such as effective deposition of the composite phosphide catalyst layer, and promotes the formation of a more uniform and controllable composite phosphide catalyst layer during the ultrasonic-assisted phosphating process, which is conducive to the formation of a denser and stronger composite phosphide catalyst layer and improves the performance of the iron-based alloy oxygen evolution electrode. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 The results of oxygen evolution reaction activity of the iron-based alloy oxygen evolution electrode provided in Test Examples 1, 2, 3, and 4 and Comparative Example 1, which were conducted for Experimental Example 1 of this application; Figure 2 The results of oxygen evolution reaction activity of the iron-based alloy oxygen evolution electrode provided in Test Example 3, Example 5 and Comparative Example 2 of this application are shown in the figure. Figure 3 The results of oxygen evolution reaction activity of the iron-based alloy oxygen evolution electrode provided in Test Examples 3, 6, and 7 and Comparative Example 3, which were conducted for Experimental Example 3 of this application; Figure 4 The oxygen evolution reaction activity results of the iron-based alloy oxygen evolution electrodes provided in Test Examples 6, 8 and 9, which were conducted for Experiment Example 4 of this application; Figure 5 X-ray diffraction patterns of the iron-based alloy oxygen evolution electrode and the pretreated iron-based alloy substrate provided in Test Example 8, which were used for Experimental Example 5 of this application; Figure 6 The images show scanning electron microscope (SEM) images and superimposed surface scanning mapping images of the pretreated iron-based alloy substrates used in Experimental Example 5 of this application. (A) is a scanning electron microscope image of the pretreated iron-based alloy substrate, and (B) is a mapping image of the pretreated iron-based alloy substrate. Figure 7 The images shown are scanning electron microscope (SEM) images and superimposed surface scan mapping images of the iron-based alloy oxygen evolution electrode used in Experimental Example 5 of this application. (A) is a scanning electron microscope image of the iron-based alloy oxygen evolution electrode, and (B) is a mapping image of the iron-based alloy oxygen evolution electrode. Figure 8 The figure shows the results of the stability test of the iron-based alloy oxygen evolution electrode in Experiment Example 6 of this application. Detailed Implementation

[0031] This application provides an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, its preparation method, and its application, which addresses the technical problem of low performance of iron-based alloy oxygen evolution electrodes in the prior art.

[0032] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Example 1

[0034] This embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment. (KH2PO4)

[0035] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0036] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0037] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. An ultrasonic device was turned on, and ultrasonic treatment was performed at 35 ℃, with an ultrasonic power of 275 W and an ultrasonic frequency of 40 kHz for 0.5 seconds. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0038] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0039] Example 2

[0040] To investigate the effect of different ultrasonic times on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0041] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0042] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0043] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and the ultrasonic treatment was performed at a temperature of 35 ℃, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0044] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0045] Example 3

[0046] To investigate the effect of different ultrasonic times on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0047] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0048] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0049] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and ultrasonic treatment was performed at 35 ℃, with an ultrasonic power of 275 W and an ultrasonic frequency of 40 kHz for 1.5 hours. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0050] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0051] Example 4

[0052] To investigate the effect of different ultrasonic times on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0053] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0054] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0055] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and the ultrasonic treatment was performed at a temperature of 35 ℃, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz for 2 hours. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0056] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0057] Comparative Example 1

[0058] To investigate the effect of different ultrasonic times on the performance of oxygen evolution electrode, this comparative example provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0059] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0060] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0061] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution and phosphated at 35°C for 2 hours to obtain an iron-based alloy oxygen evolution electrode.

[0062] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0063] Example 5

[0064] To investigate the effect of different concentrations of manganese chloride on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0065] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 6 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0066] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0067] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and ultrasonic treatment was performed at 35 ℃, with an ultrasonic power of 275 W and an ultrasonic frequency of 40 kHz for 1.5 hours. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0068] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0069] Comparative Example 2

[0070] To investigate the effect of different concentrations of manganese chloride on the performance of oxygen evolution electrode, this comparative example provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0071] The steps for preparing the composite phosphating solution include: Weigh 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 0 mmol manganese chloride (MnCl2) and 3 mmol zinc nitrate (Zn(NO3)2) and mix them to dissolve them, thus obtaining a composite phosphating solution.

[0072] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0073] The surface phosphating treatment steps include: A pretreated iron-based alloy substrate was immersed in a composite phosphating solution. An ultrasonic device was activated, and ultrasonic assisted phosphating was performed for 1.5 hours at a temperature of 35 °C, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz. This resulted in the in-situ growth of a composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate, yielding an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic assisted phosphating, zinc ions in the composite phosphating solution participated in the formation of the composite phosphide catalyst layer. The role of zinc ions was mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. Furthermore, the ultrasonic process effectively activated the surface of the iron-based alloy substrate and enhanced the mass transfer process, ensuring that the phosphating reaction proceeded uniformly on the iron-based alloy surface. This promoted the formation of a firmly bonded composite phosphide catalyst layer on the pretreated iron-based alloy substrate surface. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface were effectively avoided.

[0074] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0075] Example 6

[0076] To investigate the effect of different concentrations of zinc nitrate on the performance of oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0077] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 6 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0078] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0079] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and ultrasonic treatment was performed at 35 ℃, with an ultrasonic power of 275 W and an ultrasonic frequency of 40 kHz for 1.5 hours. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0080] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0081] Example 7

[0082] To investigate the effect of different concentrations of zinc nitrate on the performance of oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0083] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 9 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0084] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0085] The surface phosphating treatment steps include: The pretreated iron-based alloy substrate was immersed in a composite phosphating solution. The ultrasonic device was turned on, and ultrasonic treatment was performed at 35 ℃, with an ultrasonic power of 275 W and an ultrasonic frequency of 40 kHz for 1.5 hours. Ultrasonic-assisted phosphating is performed to grow a composite phosphide catalyst layer in situ on the surface of a pretreated iron-based alloy substrate, resulting in an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese and zinc ions in the composite phosphating solution participate in the formation of the composite phosphide catalyst layer. The role of manganese ions is mainly to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer, while the role of zinc ions is mainly to promote phosphate nucleation, improve the initial deposition uniformity, and form a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the iron-based alloy surface. This promotes the formation of a firmly bonded composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface are effectively avoided.

[0086] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0087] Comparative Example 3

[0088] To investigate the effect of different concentrations of zinc nitrate on the performance of oxygen evolution electrode, this comparative example provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0089] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2) and 0 mmol zinc nitrate (Zn(NO3)2) and mix them together to obtain a composite phosphating solution.

[0090] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0091] The surface phosphating treatment steps include: A pretreated iron-based alloy substrate was immersed in a composite phosphating solution. An ultrasonic device was activated, and ultrasonic assisted phosphating was performed for 1.5 hours at a temperature of 35 °C, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz. This resulted in the in-situ growth of a composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate, yielding an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic assisted phosphating, manganese ions in the composite phosphating solution participated in the formation of the composite phosphide catalyst layer. The main role of manganese ions was to participate in the formation of the manganese phosphate active phase and to regulate the defect structure and hydrophilicity of the phosphating layer. Furthermore, the ultrasonic process effectively activated the surface of the iron-based alloy substrate and enhanced the mass transfer process, ensuring uniform phosphating on the iron-based alloy surface. This promoted the formation of a firmly bonded composite phosphide catalyst layer on the pretreated iron-based alloy substrate surface. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the iron-based alloy surface were effectively avoided.

[0092] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0093] Example 8

[0094] To investigate the effect of different concentrations of sodium citrate (Na3C6H5O7) on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0095] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2), 3 mmol zinc nitrate (Zn(NO3)2), and 0.1 mmol sodium citrate (Na3C6H5O7), mix and stir to dissolve, and obtain a composite phosphating solution.

[0096] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0097] The surface phosphating treatment steps include: A pretreated iron-based alloy substrate was immersed in a composite phosphating solution. An ultrasonic device was activated, and ultrasonic-assisted phosphating was performed for 1.5 hours at a temperature of 35 °C, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz. This resulted in the in-situ growth of a composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate, yielding an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese ions, zinc ions, and the chelating agent citrate in the composite phosphating solution participated in the formation of the composite phosphide catalyst layer. Manganese ions primarily participated in the formation of the manganese phosphate active phase and regulated the defect structure and hydrophilicity of the phosphating layer. Zinc ions primarily promoted phosphate nucleation, improved initial deposition uniformity, and formed a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. The addition of citrate as a chelating agent can effectively regulate the reactivity of metal ions such as manganese and zinc in the solution and avoid the excessive precipitation of phosphate. This helps to obtain a more complete catalytic layer that is more firmly bonded to the substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the surface of the iron-based alloy. This promotes the formation of a composite phosphide catalytic layer that is firmly bonded to the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the surface of the iron-based alloy are effectively avoided.

[0098] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0099] Example 9

[0100] To investigate the effect of different concentrations of sodium citrate (Na3C6H5O7) on the performance of the oxygen evolution electrode, this embodiment provides a method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, including the steps of preparing a composite phosphating solution, pretreating the anode substrate, surface phosphating treatment, and post-treatment.

[0101] The steps for preparing the composite phosphating solution include: Weigh out 18 mL of 0.35 mol / L phosphoric acid (H3PO4), 6 mmol potassium dihydrogen phosphate (KH2PO4), 3 mmol manganese chloride (MnCl2), 3 mmol zinc nitrate (Zn(NO3)2), and 0.5 mmol sodium citrate (Na3C6H5O7), mix and stir to dissolve, and obtain a composite phosphating solution.

[0102] The steps for pretreating the anode substrate include: Prepare martensitic alloy Aermet100 (A100) as the iron-based alloy. Use metallographic sandpaper of 200 grit to 800 grit to polish the surface of the iron-based alloy step by step. Then, place the polished iron-based alloy in anhydrous ethanol and deionized water for ultrasonic cleaning. Finally, wipe it dry to obtain the pretreated iron-based alloy substrate. The pretreatment can remove oil and impurities and obtain a uniform surface state, which provides a more ideal initial surface for the subsequent formation of a uniform phosphating layer.

[0103] The surface phosphating treatment steps include: A pretreated iron-based alloy substrate was immersed in a composite phosphating solution. An ultrasonic device was activated, and ultrasonic-assisted phosphating was performed for 1.5 hours at a temperature of 35 °C, an ultrasonic power of 275 W, and an ultrasonic frequency of 40 kHz. This resulted in the in-situ growth of a composite phosphide catalyst layer on the surface of the pretreated iron-based alloy substrate, yielding an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer. During ultrasonic-assisted phosphating, manganese ions, zinc ions, and the chelating agent citrate in the composite phosphating solution participated in the formation of the composite phosphide catalyst layer. Manganese ions primarily participated in the formation of the manganese phosphate active phase and regulated the defect structure and hydrophilicity of the phosphating layer. Zinc ions primarily promoted phosphate nucleation, improved initial deposition uniformity, and formed a zinc-iron composite phosphate transition layer, thereby improving the bonding between the catalyst layer and the iron-based alloy substrate. The addition of citrate as a chelating agent can effectively regulate the reactivity of metal ions such as manganese and zinc in the solution and avoid the excessive precipitation of phosphate. This helps to obtain a more complete catalytic layer that is more firmly bonded to the substrate. On the other hand, the ultrasonic process can effectively activate the surface of the iron-based alloy substrate and enhance the mass transfer process, ensuring that the phosphating reaction is carried out uniformly on the surface of the iron-based alloy. This promotes the formation of a composite phosphide catalytic layer that is firmly bonded to the surface of the pretreated iron-based alloy substrate. Through the synergistic regulation of the physical and chemical effects of the composite phosphating solution and the ultrasonic process, the problems of difficult-to-control film formation kinetics and poor adhesion of the active layer on the surface of the iron-based alloy are effectively avoided.

[0104] Post-processing steps include: After obtaining the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, the electrode surface is thoroughly rinsed with a large amount of deionized water to remove residual phosphating solution and reaction byproducts. Thorough cleaning and drying can prevent the composite phosphide catalyst layer from being oxidized or contaminated, thus ensuring the performance of the oxygen evolution electrode.

[0105] Experimental Example 1

[0106] To investigate the effect of different ultrasonic times on the performance of oxygen evolution electrodes, this experiment tested the oxygen evolution reaction (OER) performance of the iron-based alloy oxygen evolution electrodes provided in Examples 1, 2, 3, 4, and Comparative Example 1.

[0107] The performance testing process included: using a standard three-electrode system from an electrochemical workstation, in a 1 M KOH electrolyte, the iron-based alloy oxygen evolution electrodes provided in Examples 1, 2, 3, 4, and Comparative Example 1 were used as working electrodes. The potentials of the iron-based alloy oxygen evolution electrodes at different current densities were tested. The performance test results are shown in Table 1 and... Figure 1 As shown.

[0108] As shown in Table 1, the performance test results indicate that the potential of the iron-based alloy oxygen evolution electrode decreased significantly with increasing ultrasonic time up to 1.5 h, indicating that the oxygen evolution reaction activity was improved. The performance of the iron-based alloy oxygen evolution electrode reached its optimal value at 100 mA cm⁻¹. -2 500mA cm -2 The potentials at the current densities were 1.688 V and 2.242 V, respectively. However, when the ultrasonic treatment time was extended to 2.0 h, the potential for the oxygen evolution reaction (OER) increased sharply. This indicates that an appropriate ultrasonic treatment time is beneficial for the formation of a highly active composite phosphide layer, while too short a time may result in an incomplete composite phosphide layer, and too long a time may lead to excessive etching or damage to the composite phosphide layer structure, resulting in a deterioration of the OER performance of the iron-based alloy oxygen evolution electrode. Figure 1 It also shows that in the range of 0~1000 mA cm -2 Within the current density range, under the same current, the iron-based alloy oxygen evolution electrode prepared by ultrasonication for 1.5 h only requires a lower potential drive.

[0109] Table 1: Oxygen evolution potential test results of iron-based alloy oxygen evolution electrodes prepared with different ultrasonic-assisted phosphating times at different current densities.

[0110] Experimental Example 2

[0111] To investigate the effect of different concentrations of manganese chloride (MnCl2) on the performance of oxygen evolution electrodes, this experiment tested the oxygen evolution reaction (OER) performance of the iron-based alloy oxygen evolution electrodes provided in Example 3, Example 5, and Comparative Example 2.

[0112] The performance testing process included: using a standard three-electrode system from an electrochemical workstation, and in a 1 M KOH electrolyte, the iron-based alloy oxygen evolution electrodes provided in Examples 3, 5, and Comparative Example 2 were used as working electrodes. The potentials of the iron-based alloy oxygen evolution electrodes at different current densities were tested. The performance test results are shown in Table 2 and... Figure 2 As shown.

[0113] As shown in Table 2, the performance test results indicate that without the addition of manganese chloride, the iron-based alloy oxygen evolution electrode exhibits certain oxygen evolution reaction (OER) performance due to the participation of zinc ions in the formation of the composite phosphide catalyst layer. With the concentration of manganese chloride (MnCl2) gradually increasing to 0.1 mol / L, the potential shows a significant decreasing trend, indicating that the OER activity is improved. The potential at 100 mA cm⁻¹ is [not specified in the original text]. -2 500 mA cm -2 The potentials at the current densities were 1.688 V and 2.242 V, respectively. When the concentration of manganese chloride (MnCl2) increased to 0.2 mol / L, the potential showed a slight decrease, especially at 500 mA cm⁻¹. -2 The potential at the current density was 2.280 V, indicating that an appropriate amount of manganese ions helps optimize the structure of the phosphating layer, while excessive amounts may lead to the covering of active sites in the composite phosphide catalyst layer or the formation of a non-ideal phase, which is detrimental to performance improvement. Therefore, the optimal addition concentration of manganese chloride (MnCl2) is approximately 0.1 mol / L; at the same time... Figure 2 It also shows that in the range of 0~1000 mA cm -2 Within the current density range, under the same current, the iron-based alloy oxygen evolution electrode prepared by adding 3 mmol of manganese chloride (0.1 mol / L) to 30 mL of composite phosphating solution requires only a lower potential drive.

[0114] Table 2: Oxygen evolution potential test results of iron-based alloy oxygen evolution electrodes prepared with different amounts of manganese chloride addition at different current densities.

[0115] Experimental Example 3

[0116] To investigate the effect of different concentrations of zinc nitrate (Zn(NO3)2) on the performance of oxygen evolution electrodes, this experiment tested the oxygen evolution reaction (OER) performance of the iron-based alloy oxygen evolution electrodes provided in Examples 3, 6, 7 and Comparative Example 3.

[0117] The performance testing process included: using a standard three-electrode system from an electrochemical workstation, in a 1 M KOH electrolyte, the iron-based alloy oxygen evolution electrodes provided in Examples 3, 6, 7, and Comparative Example 3 were used as working electrodes to test the potential of the iron-based alloy oxygen evolution electrodes at different current densities. The performance test results are shown in Table 3 and... Figure 3 As shown.

[0118] As shown in Table 3, the performance test results indicate that without the addition of zinc nitrate, the iron-based alloy oxygen evolution electrode exhibits certain oxygen evolution reaction (OER) performance due to the participation of manganese ions in the formation of the composite phosphide catalyst layer. With the concentration of zinc nitrate (Zn(NO3)2) gradually increasing to 0.2 mol / L, the potential shows a significant decreasing trend, indicating that the OER activity is improved, particularly at 100 mA cm⁻¹. -2 500 mA cm -2 The potentials at the current densities were 1.656 V and 2.189 V, respectively. At this point, the molar ratio of manganese salt to zinc salt was 1:2. When the concentration of zinc nitrate (Zn(NO3)2) gradually increased to 0.3 mol / L, the performance declined. This indicates that the introduction of zinc ions is crucial for the formation of a uniform and highly active manganese-zinc composite phosphide catalyst layer. An appropriate amount of zinc ions can effectively regulate the phosphating reaction and promote the formation of a defect-rich and highly conductive composite phosphide catalyst layer. However, excessive zinc ions may disrupt this synergistic effect, leading to a decrease in the oxygen evolution reaction (OER) performance of the iron-based alloy oxygen evolution electrode. Figure 3 It also shows that in the range of 0~1000 mA cm -2 Within the current density range, under the same current, the iron-based alloy oxygen evolution electrode prepared by adding 3 mmol manganese chloride (0.1 mol / L) and 6 mmol zinc nitrate (0.2 mol / L) to 30 mL of composite phosphating solution requires only a lower potential drive.

[0119] Table 3: Oxygen evolution potential test results of iron-based alloy oxygen evolution electrodes prepared with different zinc nitrate addition amounts at different current densities.

[0120] Experiment Example 4

[0121] To investigate the effect of different concentrations of sodium citrate (Na3C6H5O7) on the performance of the oxygen evolution electrode, this experiment tested the oxygen evolution reaction (OER) performance of the iron-based alloy oxygen evolution electrodes provided in Examples 6, 8, and 9.

[0122] The performance testing process included: using a standard three-electrode system from an electrochemical workstation, and in a 1 M KOH electrolyte, the iron-based alloy oxygen evolution electrodes provided in Examples 6, 8, and 9 were used as working electrodes to test the potential of the iron-based alloy oxygen evolution electrodes at different current densities. The performance test results are shown in Table 4 and... Figure 4 As shown.

[0123] As shown in Table 4, the performance test results indicate that without the addition of sodium citrate (Na3C6H5O7), the iron-based alloy oxygen evolution electrode provided in Example 6 exhibits good oxygen evolution reaction (OER) performance due to the participation of manganese and zinc ions in the formation of the composite phosphide catalyst layer. With the gradual increase of the concentration of the chelating agent sodium citrate (Na3C6H5O7) by approximately 3.3 mmol / L, the potential of the iron-based alloy oxygen evolution electrode provided in Example 8 shows a significant decreasing trend, indicating that the oxygen evolution reaction activity is improved. Its potential at 100 mA cm⁻¹ is [not specified in the original text]. -2 500 mA cm -2 The potentials at the current densities were 1.631 V and 2.132 V, respectively. When the concentration of the chelating agent sodium citrate (Na3C6H5O7) gradually increased to approximately 16.7 mmol / L, the performance declined. This indicates that sodium citrate (Na3C6H5O7), as a chelating agent, can mildly regulate the ionic activities of manganese and zinc ions in the composite phosphating solution, slowing down their precipitation rate. This makes the phosphating reaction more uniform and controllable, which is beneficial for forming a denser and more strongly bonded composite phosphide catalyst layer. However, when sodium citrate (Na3C6H5O7) is in excess, the concentration of the chelating ligand is too high, and the chelating ligand may over-complex metal ions, thus inhibiting the effective deposition of the composite phosphide catalyst layer. Simultaneously… Figure 4 It also shows that in the range of 0~1000mAcm -2 Within the current density range, under the same current, the iron-based alloy oxygen evolution electrode prepared by adding 0.1 mmol sodium citrate (3.3 mol / L) to 30 mL of composite phosphating solution requires only a lower potential drive.

[0124] Table 4: Oxygen evolution potential test results of iron-based alloy oxygen evolution electrodes prepared with different sodium citrate addition amounts at different current densities.

[0125] Experimental Example 5

[0126] To systematically characterize the effects of phosphating treatment on the surface structure, composition, and morphology of the electrode, this experimental example uses X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS) to analyze the iron-based alloy oxygen evolution electrode provided in Example 8 before and after surface phosphating treatment. The analysis results are as follows: Figure 5-7 As shown; from Figure 5 The X-ray diffraction (XRD) characterization pattern shown indicates that the iron-based alloy substrate material before surface phosphating, i.e., the pretreated material, mainly exhibits the characteristic diffraction peaks of the matrix-Fe. After ultrasonic-assisted composite phosphating, new diffraction peaks appear in the sample, indicating that in-situ chemical transformation and the formation of new crystalline phase products occurred on the electrode material surface. Combined with phase analysis, it can be seen that the new products are mainly Zn2Fe(PO4)2·4H2O and H2Mn5(PO4)4(H2O)4, indicating that under the action of the ultrasonic field, the iron element on the electrode material surface undergoes a synergistic reaction with the zinc, manganese, chelated ligands, and phosphate components in the composite phosphating solution, forming a composite phosphide catalyst layer in situ on the substrate surface. The characteristic diffraction peaks of the iron-based alloy substrate still exist after phosphating, indicating that the formed composite phosphide catalyst layer is formed in situ on the iron-based alloy surface without destroying the main structure of the substrate. This demonstrates that a stable composite phosphide catalyst layer can be constructed on the surface of the iron-based alloy electrode material, providing a basis for improving the catalytic activity and long-term operational stability of oxygen evolution at the anode in alkaline water electrolysis.

[0127] At the same time, from Figure 6 , Figure 7 The scanning electron microscope combined with energy dispersive spectroscopy (SEM-EDS) characterization image shown is as follows. Figure 6 , Figure 7 As shown in Figure (A), the morphology indicates that the iron-based alloy substrate material before surface phosphating, i.e., the pretreated material, is relatively smooth after pretreatment processes such as grinding, with only visible mechanical grinding marks. After surface phosphating, a porous and rough composite phosphide catalyst layer is formed on the surface of the iron-based alloy oxygen evolution electrode, exhibiting a uniformly distributed granular or plate-like structure, significantly increasing the electrochemical active area of ​​the electrode. Figure 6 , Figure 7 As shown in Figure (B), the mapping analysis reveals that the signals of elements such as phosphorus, zinc, and manganese are significantly enhanced on the surface of the phosphating electrode, and their distribution is highly consistent with the morphological characteristics. This indicates that the iron-based alloy oxygen evolution electrode has successfully formed a composite phosphide catalyst layer in situ and achieved uniform distribution. At the same time, the signals of substrate elements such as Fe and Cr are weakened in the phosphating layer coverage area, further confirming the in-situ uniform growth and coverage of the composite phosphide catalyst layer on the substrate surface.

[0128] Experimental Example 6

[0129] To investigate the oxygen evolution catalytic stability of the composite phosphide catalyst layer constructed in situ on the surface of the iron-based alloy oxygen evolution electrode, this experimental example tests the iron-based alloy oxygen evolution electrode provided in Example 8.

[0130] The iron-based alloy oxygen evolution electrode provided in Example 8 was tested using an electrochemical workstation.

[0131] The time-voltage curve obtained for stability over 300 hours is shown below. Figure 8 As shown; from Figure 8 As can be seen, during the test process of regularly replacing the fresh concentration of 1M KOH solution, the potential only fluctuated slightly by about 30 mV and remained stable. The good stability was ensured by the in-situ constructed composite phosphide catalyst layer, which provides key technical support for its replacement of traditional nickel-based oxygen evolution anodes and its application in industrial-grade water electrolysis hydrogen production scenarios.

[0132] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for the preparation of an iron-based alloy oxygen evolution electrode with a composite phosphide catalytic layer, characterized in that, Includes the following steps: The steps for preparing the composite phosphating solution are as follows: Manganese salt, zinc salt, chelating agent, phosphoric acid, potassium dihydrogen phosphate and water are stirred and dissolved to obtain the composite phosphating solution; The steps for pretreating the anode substrate are as follows: the iron-based alloy is subjected to surface pretreatment to obtain a pretreated iron-based alloy substrate; The surface phosphating treatment steps are as follows: The pretreated iron-based alloy substrate is immersed in the composite phosphating solution for ultrasonic-assisted phosphating to obtain an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer.

2. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The manganese salt is selected from at least one of manganese chloride, manganese nitrate, manganese sulfate, manganese chloride hydrate, manganese nitrate hydrate, and manganese sulfate hydrate; The zinc salt is selected from at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc chloride hydrate, zinc nitrate hydrate, and zinc sulfate hydrate.

3. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The chelating agent is selected from at least one of sodium citrate, sodium gluconate, EDTA, and DTPA.

4. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The concentration of manganese ions in the composite phosphating solution is no greater than 0.2 mol / L, and the concentration of zinc ions is no greater than 0.3 mol / L.

5. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The molar ratio of manganese ions to zinc ions in the composite phosphating solution is 1:1~5.

6. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The concentration of the chelating ligand in the composite phosphating solution is no greater than 16.7 mmol / L.

7. The method for preparing an iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer according to claim 1, characterized in that, The ultrasonic-assisted phosphating is performed by ultrasound, with the frequency controlled at 10~100 kHz, the power controlled at 240~480 W, the reaction temperature controlled at 25~45 ℃, and the treatment time controlled at 0.5~2 h.

8. An iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer as described in claim 8 in alkaline water electrolysis for hydrogen production.

10. An alkaline water electrolysis electrolyzer for hydrogen production, characterized in that, The iron-based alloy oxygen evolution electrode with a composite phosphide catalyst layer as described in claim 8.

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