Modification method of ferric oxide based on current regulation and control and anode material

Abstract

The invention provides a modification method of ferric oxide based on current regulation and control and a ferric oxide anode material, and relates to the technical field of electrochemical materials. The method comprises the following steps: pretreating the surface of foamed nickel to obtain a foamed nickel substrate; calcining the ferric hydroxide powder to obtain a ferric oxide material; adding an iron oxide material into the mixed dispersion liquid, and uniformly dispersing the iron oxide material in the mixed dispersion liquid to obtain a mixed solution; transferring the mixed solution to the surface of a foamed nickel substrate, removing the solvent in the mixed solution, and after the iron oxide material is loaded on the surface of the foamed nickel substrate, obtaining an iron oxide-loaded foamed nickel material; a strong alkaline solution is adopted as an electrolyte, the foamed nickel material loaded with the iron oxide is adopted as an anode, alternating current with preset parameters is applied to the foamed nickel material loaded with the iron oxide through a programmable power supply, and the iron oxide anode material modified through current regulation and control is obtained. The overpotential of the iron oxide anode material prepared by the method is remarkably reduced, and the electrochemical activity is relatively high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical materials, in particular to a modification method of iron oxide based on current regulation and an anode material. BACKGROUND

[0002] With the rapid development of fluctuating renewable energy such as wind power and photovoltaic power, water electrolysis hydrogen production technology has become a key path for green electricity consumption and cross-season energy storage. Under this background, the oxygen evolution reaction as the main source of electrolytic cell energy consumption, its catalytic efficiency and dynamic response performance directly determine the efficiency, operation stability and hydrogen production cost of the hydrogen production system when coupled with wind / photovoltaic power fluctuations. However, the current non-noble metal oxygen evolution catalysts (such as nickel, iron-based compounds, etc.) designed for fluctuating power sources still face three major challenges in industrial application: first, the dynamic reaction kinetics is lagging, it is difficult to achieve rapid response at low overpotential when the wind / photovoltaic power changes rapidly, resulting in increased energy loss; second, the structure stability is insufficient under intermittent operation conditions, and the active layer is prone to peeling or crystal structure degradation due to repeated oxidation and reduction during frequent start-stop and high-low load switching; third, the catalytic activity and mass transfer efficiency are insufficient under high fluctuating current density, which restricts the efficient and stable oxygen evolution capacity in a wide power range, limiting the performance improvement of electrolysis systems directly coupled with renewable energy. SUMMARY

[0003] The purpose of the present application is to provide a modification method of iron oxide based on current regulation and an iron oxide anode material, which can improve the electrochemical performance of the iron oxide anode material, realize dynamic in-situ regulation of the oxidation-reduction state of the iron oxide material surface, effectively adapt to the change of reaction environment under fluctuating conditions; simple operation, low equipment requirement, good potential for large-scale application, conducive to reducing the preparation cost and improving the process compatibility.

[0004] In order to achieve the above purpose, in the first aspect, the present application provides a modification method of iron oxide based on current regulation, comprising: providing a foamed nickel, pretreating the surface of the foamed nickel to obtain a foamed nickel substrate; preparing a ferric hydroxide powder, calcining the ferric hydroxide powder to obtain an iron oxide material; preparing a mixed dispersion liquid, adding the iron oxide material into the mixed dispersion liquid, and uniformly dispersing the iron oxide material in the mixed dispersion liquid to obtain a mixed solution; transferring the mixed solution to the surface of the foamed nickel substrate, removing the solvent in the mixed solution, and loading the iron oxide material on the surface of the foamed nickel substrate to obtain a foamed nickel material loaded with iron oxide; The method comprises the following steps: using a strong alkaline solution as an electrolyte, taking a foam nickel material loaded with iron oxide as an anode, applying alternating current with predetermined parameters to the foam nickel material loaded with iron oxide through a programmable power supply, and obtaining an iron oxide anode material modified by current regulation.

[0005] The method comprises the following steps: pretreating a surface of a foam nickel to obtain a foam nickel substrate, and the method comprises the following steps: The foam nickel is immersed in acetone for ultrasonic treatment for a first time length. The foam nickel is taken out of the acetone, and the foam nickel is placed in hydrochloric acid for ultrasonic treatment for a second time length. The foam nickel is taken out of the hydrochloric acid, washed with deionized water, and dried in an oven after being washed clean, so as to obtain the foam nickel substrate. The method comprises the following steps: preparing iron hydroxide powder, and the method comprises the following steps: Iron nitrate, urea and ammonium fluoride are sequentially added into a container, ultrapure water is added into the container, the solution after being uniformly stirred is transferred into a reaction kettle, and the reaction kettle is sealed. The reaction kettle is placed in an oven, heated to a first temperature, and kept for a third time length. After the reaction is completed, the reaction kettle is naturally cooled to room temperature, the reaction kettle is opened, and the materials in the reaction kettle are transferred into a centrifugal tube for centrifugal operation, so as to separate the iron hydroxide precipitate from the solution, the iron hydroxide precipitate is repeatedly washed with deionized water after being separated, the washed iron hydroxide precipitate is placed in an oven for vacuum drying, and iron hydroxide powder is obtained. The method comprises the following steps: calcining the iron hydroxide powder to obtain iron oxide material, and the method comprises the following steps: The iron hydroxide powder is placed in a crucible, and the crucible is placed in a muffle furnace. The muffle furnace is heated at a preset heating rate, so that the temperature in the muffle furnace gradually increases from room temperature; when the temperature reaches a second temperature, the second temperature is kept for a fourth time length for calcination; After the calcination is completed, the power supply of the muffle furnace is turned off, the crucible is naturally cooled to room temperature with the muffle furnace, the crucible is taken out, and iron oxide material is obtained. The method comprises the following steps: preparing a mixed dispersion liquid, adding the iron oxide material into the mixed dispersion liquid, and uniformly dispersing the iron oxide material in the mixed dispersion liquid to obtain a mixed solution, and the method comprises the following steps: Isopropyl alcohol, ultrapure water and Nafion solution are added into the same container and uniformly stirred to prepare the mixed dispersion liquid; the iron oxide material is added into the mixed dispersion liquid, and ultrasonic treatment is performed, so that the iron oxide material is uniformly dispersed in the mixed dispersion liquid to obtain the mixed solution. According to the modified method for regulating iron oxide based on current provided by the application, the mixed solution is transferred to the surface of the foamed nickel substrate, the solvent in the mixed solution is removed, the iron oxide material is loaded on the surface of the foamed nickel substrate, and the foamed nickel material loaded with iron oxide is obtained. Using a micropipette, a preset volume of mixed solution is sucked each time and dropped on the surface of the foamed nickel substrate; the foamed nickel material loaded with iron oxide is obtained by placing it in a room temperature environment and naturally air-drying to volatilize the solvent in the mixed solution, so that the iron oxide material is firmly loaded on the surface of the foamed nickel substrate. According to the modified method for regulating iron oxide based on current provided by the application, the strong alkaline solution includes a potassium hydroxide solution or a sodium hydroxide solution. According to the modified method for regulating iron oxide based on current provided by the application, the predetermined parameters include the waveform of alternating current, the electrification time and the current size.

[0006] According to the modified method for regulating iron oxide based on current provided by the application, the waveform of alternating current is a square wave, the electrification time is 1 min-60 min; the positive cycle time of the square wave is 5s-15s, the positive cycle current is 5mA-15mA, the negative cycle time is 25s-35s, and the negative cycle current is 15mA-25mA.

[0007] In the second aspect, the application provides an iron oxide anode material prepared by the method of the first aspect.

[0008] Compared with the existing modification technology for iron oxide material, the application has the following advantages: 1. Strong dynamic in-situ regulation capability. Breakthrough the limitation of traditional static material regulation, use asymmetric alternating square wave to periodically polarize the iron oxide anode material, realize dynamic in-situ regulation of the oxidation and reduction state of the surface of the iron oxide material through the alternation of the positive and negative cycles designed accurately, and effectively adapt to the change of the reaction environment under fluctuating conditions.

[0009] 2. Performance improvement is precisely controllable. By accurately setting the parameters of alternating current (for example, the waveform is a square wave; the electrification time is 10 minutes; the positive cycle current of the square wave is 10mA, the positive cycle time is 10s, the negative cycle current is 20mA, and the negative cycle time is 30s), different degrees of oxidation and reduction reactions are alternately induced on the surface of the iron oxide material, the formation of active sites and interface charge transport are effectively promoted, the electrochemical activity is significantly improved, and the whole process has good controllability and repeatability.

[0010] 3. Simple process flow, easy to integrate. Without relying on complex material synthesis or post-modification process, performance optimization can be achieved by applying alternating current with a specific waveform, which is simple to operate and has low equipment requirements, has good potential for large-scale application, is conducive to reducing the preparation cost and improving the process compatibility.

[0011] 4. Breakthrough the limitations of traditional technology. In the process of improving the reaction kinetics of iron oxide, the electrode polarization and structural damage problems caused by traditional alternating current regulation are effectively avoided, and balance is achieved between promoting material activation and maintaining structural stability through asymmetric cycle design, providing a new path for efficient and flexible modification of electrochemical materials. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0013] In the drawings: Figure 1 XRD pattern of 10 min alternating current iron oxide anode material for a specific embodiment of the present application; Figure 2 Linear sweep voltammetry curve of iron oxide material control group, 10 min alternating current iron oxide anode material and RuO2 electrode material for a specific embodiment of the present application; Figure 3 Overpotential comparison chart of iron oxide material control group, 10 min alternating current iron oxide anode material and RuO2 electrode material at a current density of 10 mA cm -2 for a specific embodiment of the present application; Figure 4 Electrochemical impedance spectrum of iron oxide material control group, 10 min alternating current iron oxide anode material and RuO2 electrode material for a specific embodiment of the present application; Figure 5 Tafel slope chart of iron oxide material control group, 10 min alternating current iron oxide anode material and RuO2 electrode material for a specific embodiment of the present application; Figure 6 8-hour stability image of 10 min alternating current iron oxide anode material and RuO2 electrode material at a current density of 10 mA cm -2 for a specific embodiment of the present application; Figure 7 Flow chart of the modification method of iron oxide based on current regulation of the present application. DETAILED DESCRIPTION

[0014] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0015] Some embodiments of the present application will be described in detail below in combination with the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0016] Iron oxide, as a transition metal oxide with wide sources, low cost and good environmental compatibility, exhibits unique advantages in the electrolysis of water for hydrogen production to adapt to fluctuating wind and solar power. By improving its oxygen evolution catalytic performance, the response capability and structural stability of the electrolytic cell under dynamic conditions such as severe current density fluctuations and frequent start-stop can be significantly enhanced, the energy loss caused by power fluctuations can be effectively reduced, and the overall energy efficiency of the system under intermittent operation mode can be improved. This progress will directly promote the development of low-cost and high-adaptability electrolytic cell technology coupled with renewable energy efficiently, and has important practical value for building a large-scale green hydrogen production system based on wind and solar power.

[0017] Based on this, the present application provides a dynamic modification strategy based on alternating current regulation, which effectively makes up for the shortcomings of traditional methods by in-situ electrochemical treatment of iron oxide with asymmetric alternating current. This method exhibits unique advantages in the following aspects: In terms of dynamic response, alternating current treatment can induce dynamic restructuring of the surface layer of iron oxide, forming an active phase structure rich in vacancies and lattice distortion. This structural evolution significantly accelerates the transmission efficiency of interface charges. When the current density fluctuates rapidly, the iron oxide electrode modified by alternating current can maintain a low overpotential growth rate, showing excellent electrochemical stability, thereby effectively suppressing energy loss under dynamic conditions.

[0018] Secondly, for the structural stability problem, the periodic polarization of alternating current Depolarization can promote the release of internal stress of iron oxide and inhibit the structural fatigue of the active layer during cyclic voltammetry scanning or current mutation. Studies have shown that iron oxide treated with specific parameters (such as asymmetric waveform and alternating period) exhibits better mechanical integrity and phase structure retention capability in simulated wind and light fluctuation tests.

[0019] In addition, in terms of mass transfer and catalytic efficiency under high fluctuating current density, alternating current treatment not only optimizes the electronic structure of iron oxide, but also can The electrolyte interface forms a dynamically updated microenvironment, promoting bubble detachment and ion transport, thereby maintaining high apparent activity and durability over a wide current density range.

[0020] Therefore, the alternating current regulation of the present application as a new external field assisted modification method can realize multi-dimensional dynamic optimization of the iron oxide surface interface structure and electronic properties without introducing external components, thereby providing a new technical path for improving the comprehensive performance of iron oxide (as a non-noble metal oxygen evolution catalyst) in fluctuating green electricity scenarios.

[0021] Please refer to Figure 7 The present application provides a modification method for iron oxide based on current regulation, comprising the following steps: Step 1, providing a foamed nickel, pretreating the surface of the foamed nickel to obtain a foamed nickel substrate; In some embodiments, the surface of the foamed nickel is pretreated to obtain a foamed nickel substrate, comprising: The foamed nickel is immersed in acetone for ultrasonic treatment for a first duration; The foamed nickel is taken out of the acetone and placed in hydrochloric acid for ultrasonic treatment for a second duration; The foamed nickel is taken out of the hydrochloric acid, rinsed with deionized water, and after rinsing, the foamed nickel is placed in an oven for drying to obtain a foamed nickel substrate.

[0022] Step 2, preparing iron hydroxide powder, calcining the iron hydroxide powder to obtain an iron oxide material; In some embodiments, the iron hydroxide powder is prepared, comprising: Iron nitrate, urea and ammonium fluoride are sequentially added to a container, ultrapure water is added to the container, and the solution after stirring and mixing is transferred to a reaction kettle, and the reaction kettle is sealed; The reaction kettle is placed in an oven and heated to a first temperature for a third duration; After the reaction is completed, the reaction kettle is naturally cooled to room temperature, the reaction kettle is opened, and the material inside the reaction kettle is transferred to a centrifuge tube for centrifugation to separate the iron hydroxide precipitate from the solution. After separation, the iron hydroxide precipitate is repeatedly washed with deionized water, and the washed iron hydroxide precipitate is placed in an oven for vacuum drying to obtain iron hydroxide powder.

[0023] The iron hydroxide powder is calcined to obtain an iron oxide material, comprising: The iron hydroxide powder is placed in a crucible, and the crucible is placed in a muffle furnace; The muffle furnace is heated at a predetermined heating rate to gradually increase the temperature in the muffle furnace from room temperature; when the temperature reaches a second temperature, the second temperature is maintained for a fourth duration of calcination; After calcination, turn off the power to the muffle furnace and allow the crucible to cool naturally to room temperature along with the muffle furnace; remove the crucible to obtain iron oxide material.

[0024] Step 3: Prepare a mixed dispersion by adding iron oxide material to the mixed dispersion and ensuring that the iron oxide material is evenly dispersed in the mixed dispersion to obtain a mixed solution. In some embodiments, step 3 specifically includes: adding isopropanol, ultrapure water, and Nafion solution (a perfluorosulfonic acid polymer; in the electrocatalysis process, the problem of electrocatalyst falling off the electrode surface is often encountered. Since Nafion itself is a polymer with a certain viscosity and excellent conductivity, this property can be used for the catalytic process) into the same container, stirring evenly to prepare a mixed dispersion; adding iron oxide material to the mixed dispersion, and then performing ultrasonic treatment to make the iron oxide material uniformly dispersed in the mixed dispersion to obtain a mixed solution.

[0025] Step 4: Transfer the mixed solution to the surface of the nickel foam substrate, remove the solvent from the mixed solution, and load the iron oxide material onto the surface of the nickel foam substrate to obtain the nickel foam material loaded with iron oxide. In some embodiments, step 4 specifically includes: using a micropipette to aspirate a preset volume of mixed solution each time and drop it onto the surface of the nickel foam substrate; placing it at room temperature to air dry naturally, allowing the solvent in the mixed solution to evaporate, thereby firmly loading the iron oxide material onto the surface of the nickel foam substrate, and obtaining the nickel foam material loaded with iron oxide.

[0026] Step 5: Using a strongly alkaline solution as the electrolyte, the nickel foam material loaded with iron oxide is used as the anode, and any material with cathode properties is used as the cathode. An alternating current with predetermined parameters is applied to the nickel foam material loaded with iron oxide through a programmable power supply to obtain the iron oxide anode material modified by current regulation.

[0027] In some embodiments, the strongly alkaline solution includes a potassium hydroxide solution or a sodium hydroxide solution, and the predetermined parameters include the waveform of the alternating current, the energizing time, and the magnitude of the current.

[0028] Specifically, the waveform of the alternating current is a square wave, and the energizing time is 1 min to 60 min; among which, the positive period of the square wave is 5 s to 15 s, the positive period current is 5 mA to 15 mA, the negative period is 25 s to 35 s, and the negative period current is 15 mA to 25 mA.

[0029] Based on the same inventive concept, another embodiment of the present invention provides an iron oxide anode material, which is prepared by the method of the aforementioned embodiment.

[0030] The following is a specific embodiment of the current-controlled iron oxide modification method of the present invention.

[0031] Step 1, to realize the function of nickel foam as an electrochemical material loading substrate, it needs to be systematically pretreated. Measure 20 mL of acetone, immerse the nickel foam completely, and perform ultrasonic treatment for 10 minutes. This step mainly utilizes the solubility of acetone for organic matter, effectively removing oil stains and other organic impurities attached to the surface of the nickel foam.

[0032] Pour out the acetone, measure 20 mL of 1 mol / L hydrochloric acid solution, and place the acetone-treated nickel foam into the hydrochloric acid for ultrasonic treatment for 20 minutes. The acid treatment process aims to completely remove the oxide layer and metal residues on the surface of the nickel foam.

[0033] Take out the nickel foam and rinse it repeatedly with deionized water to remove the residual hydrochloric acid on the surface; after rinsing, place the nickel foam in an oven at 80°C to dry, obtaining a clean, dry, and surface-active nickel foam substrate for use.

[0034] Step 2, preparation of iron hydroxide precursor. A hydrothermal method is used to prepare iron hydroxide using iron nitrate, urea, and ammonium fluoride as raw materials in a reaction kettle, with the following steps: Accurately weigh 0.450 mmol of iron nitrate, 1.875 mmol of urea, and 1.500 mmol of ammonium fluoride, and add the three reagents to the container in sequence. Add 50 mL of ultrapure water to the container, start the magnetic stirrer, and fully stir the mixture to completely dissolve the reagents, forming a transparent and uniformly mixed solution.

[0035] Transfer the uniformly mixed solution to a 100 mL polytetrafluoroethylene-lined stainless steel reaction kettle, seal the reaction kettle; then place the reaction kettle in an oven and heat to 120°C for 10 hours to generate the iron hydroxide precursor.

[0036] After the reaction is complete, allow the reaction kettle to cool naturally to room temperature, open the reaction kettle, and transfer the internal material to a centrifuge tube; perform centrifugation (set the speed to 10,000 rpm and the time to 5 minutes) to separate the iron hydroxide precipitate from the solution; after separation, wash the iron hydroxide precipitate repeatedly with deionized water for 3-5 times to completely remove soluble impurities; finally, dry the washed iron hydroxide precipitate in an 80°C oven to obtain the final required dry iron hydroxide powder.

[0037] Step 3, preparation of iron oxide material. The prepared iron hydroxide powder is calcined to convert it into an iron oxide material, with the following operation: Take the dry iron hydroxide powder and evenly spread it in a crucible, and place the crucible in a muffle furnace.

[0038] The temperature rising program of the muffle furnace is set as follows: the muffle furnace is heated at a temperature rising rate of 5 ℃ / min, so that the temperature in the furnace gradually rises from room temperature; when the temperature reaches 500 ℃, the temperature is kept for calcination for 2 hours, so that the iron hydroxide is fully decomposed and converted into iron oxide.

[0039] After the calcination is completed, the power of the muffle furnace is turned off, and the crucible is naturally cooled to room temperature along with the muffle furnace; the crucible is taken out, and the final required iron oxide material is obtained.

[0040] Step 4, preparing the iron oxide-loaded nickel foam material. The iron oxide material is mixed with isopropanol, ultrapure water and Nafion solution to prepare a mixed solution and loaded on a nickel foam substrate to prepare the iron oxide-loaded nickel foam material, and the specific steps are as follows: 800 μL of isopropanol, 170 μL of ultrapure water and 30 μL of Nafion solution are measured and added into the same container, and stirred uniformly to prepare a mixed dispersion. 5 mg of the prepared iron oxide material is added into the dispersion, and an ultrasonic device is turned on to ultrasonically treat the mixed system, so that the iron oxide material is uniformly dispersed in the solution.

[0041] A microsyringe is used to suck 10 μL of the prepared mixed solution each time, and drop it onto the surface of the pretreated 1 cm×1 cm nickel foam substrate; the nickel foam substrate with the dropped mixed solution is placed in a room temperature environment for natural air drying, so that the solvent in the mixed solution is volatilized, and thus the iron oxide material is firmly loaded on the surface of the nickel foam substrate, to obtain the iron oxide-loaded nickel foam material.

[0042] Step 5, using KOH solution as the electrolyte, taking two iron oxide-loaded nickel foam materials as the cathode and the anode respectively, and applying alternating current with predetermined parameters through a programmable power supply. The iron oxide material of the cathode has poor performance improvement effect under alternating current, and cannot meet the requirements of the electrochemical material modification. Therefore, the iron oxide-loaded nickel foam material as the anode is the object of the alternating current modification in the present application, and the iron oxide anode material with excellent electrochemical performance can be prepared.

[0043] In order to verify the electrochemical performance of the iron oxide anode material prepared in the present application, a three-electrode system is used for testing, a platinum sheet sandwich electrode is used to clamp the iron oxide-loaded nickel foam material obtained in step 4 of the present embodiment to prepare a working electrode; a mercury / mercury oxide electrode is selected as a reference electrode, and a graphite rod electrode is selected as a counter electrode; 1 mol / L KOH solution is prepared as an electrolyte, and the working electrode, the reference electrode and the counter electrode are all immersed in the electrolyte to ensure good contact between the electrodes and the electrolyte.

[0044] Two working electrodes were set up. One working electrode was subjected to a square wave alternating current through a programmable power supply. The power-on time was 10 min, the positive cycle current was 10 mA, the positive cycle time was 10 s, the negative cycle current was 20 mA, and the negative cycle time was 30 s. This caused the working electrode to undergo an electrochemical reaction under the alternating current environment (that is, to perform the treatment in step 5 to obtain the iron oxide anode material prepared in this embodiment). The electrochemical activity of the iron oxide material was enhanced by alternating redox reactions of different degrees on the anode, which served as the experimental group. The other working electrode was not subjected to alternating current, which served as the control group.

[0045] Using an electrochemical workstation, linear sweep voltammetry (LSV) tests were performed on the working electrodes with and without AC current applied. The LSV curves were analyzed to assess the difference in potential between the AC-current-applied working electrode and the control sample without AC current when the same current is applied, thus evaluating the effect of AC current on improving the performance of the electrochemical material. Electrochemical impedance spectroscopy (EIS), Tafel slope, X-ray diffraction (XRD), and stability tests were then performed on the AC-modified iron oxide anode material.

[0046] It should be noted that in this embodiment, the potential is converted relative to the reversible hydrogen electrode ( vs. RHE The electrode potential of the reversible hydrogen electrode (using...) The calculation formula for (represented by):

[0047] Where E1 is the measured potential of the electrochemical workstation, and E2 is the reference electrode potential. In this embodiment, a 1 mol / L KOH solution is used as the electrolyte, with a pH of 14; a mercury / mercury oxide electrode is selected as the reference electrode, and the reference electrode potential E2 is set to 0.0977.

[0048] XRD tests were performed on the iron oxide material after alternating current modification, and the test results are as follows: Figure 1 As shown, 25°, 33°, 36°, and 44° are characteristic peaks of this iron oxide material.

[0049] like Figure 2 As shown, for the iron oxide material at the anode, the LSV curve of the experimental group subjected to alternating current for 10 min shifted to the left compared to the control group without alternating current, indicating a decrease in overpotential at the same current density. This demonstrates that the electrochemical performance of the iron oxide material undergoing alternating redox reactions of varying degrees is significantly improved. Specifically, at a current density of 10 mA cm⁻¹... -2 When AC current is applied for 10 minutes, its overpotential is reduced from 372mV to 328mV, and the result is as follows. Figure 3As shown. Linear sweep voltammetry verification confirmed that, under the above parameters, the iron oxide anode material achieves the same current density (10 mA cm⁻¹). -2 The absolute value of the potential decreased by 44 mV, the reaction overpotential decreased significantly, and the electrochemical activity was significantly improved.

[0050] The above results demonstrate that this invention improves the performance of iron oxide electrochemical materials by applying alternating current with predetermined parameters. The core idea is to optimize material performance by controlling the dynamic process of the electrochemical reaction. After applying alternating current with certain parameters, the potential of the iron oxide anode material decreases at the same current, resulting in a smaller overpotential and higher electrochemical activity. Therefore, this invention provides a method for improving the performance of iron oxide electrochemical materials by applying alternating current.

[0051] Next, other performance tests were conducted on the iron oxide anode material subjected to AC current for 10 minutes. Figure 4 The EIS image of the iron oxide anode material subjected to AC current for 10 minutes was fitted, and the solution resistance used for testing was found to be approximately 1.6 Ω. Figure 5 The Tafel image of the iron oxide anode material subjected to AC current for 10 minutes was obtained, and its Tafel slope was measured to be 83.7 mV dec. -1 . Figure 6 The image shows the stability of the iron oxide anode material under a 10mA current for 10 minutes of alternating current, indicating that the iron oxide material modified by current has good stability.

[0052] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. It should be understood that the invention is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for modifying iron oxide based on current regulation, characterized in that, include: Provide nickel foam, pretreat the surface of the nickel foam to obtain a nickel foam substrate; Iron hydroxide powder is prepared, and the iron hydroxide powder is calcined to obtain iron oxide material; To prepare a mixed dispersion, the iron oxide material is added to the mixed dispersion and uniformly dispersed in the mixed dispersion to obtain a mixed solution. The mixed solution is transferred to the surface of a nickel foam substrate, the solvent in the mixed solution is removed, and the iron oxide material is loaded on the surface of the nickel foam substrate to obtain a nickel foam material loaded with iron oxide. A strongly alkaline solution is used as the electrolyte, and the nickel foam material loaded with iron oxide is used as the anode. An alternating current with predetermined parameters is applied to the nickel foam material loaded with iron oxide through a programmable power supply to obtain an iron oxide anode material modified by current regulation.

2. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The pretreatment of the nickel foam surface to obtain the nickel foam substrate includes: The nickel foam was immersed in acetone and ultrasonically treated for a first duration. Remove the nickel foam from the acetone and place it in hydrochloric acid for ultrasonic treatment for a second duration. Remove the nickel foam from the hydrochloric acid, rinse with deionized water, and after rinsing, dry the nickel foam in an oven to obtain a nickel foam substrate.

3. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The preparation of ferric hydroxide powder includes: Add ferric nitrate, urea, and ammonium fluoride to the container in sequence, add ultrapure water to the container, transfer the well-mixed solution to the reaction vessel, and seal the reaction vessel. The reactor was placed in an oven and heated to the first temperature for a third duration. After the reaction is complete, allow the reactor to cool naturally to room temperature. Open the reactor and transfer the contents of the reactor to a centrifuge tube for centrifugation to separate the ferric hydroxide precipitate from the solution. After separation, wash the ferric hydroxide precipitate repeatedly with deionized water. Place the washed ferric hydroxide precipitate in an oven for vacuum drying to obtain ferric hydroxide powder.

4. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The step of calcining the iron hydroxide powder to obtain iron oxide material includes: The iron hydroxide powder is placed in a crucible, and the crucible is placed in a muffle furnace; The muffle furnace is heated at a preset heating rate, so that the temperature inside the muffle furnace gradually increases from room temperature; when the temperature reaches the second temperature, the second temperature is maintained for a fourth time. After calcination, turn off the power to the muffle furnace and allow the crucible to cool naturally to room temperature along with the muffle furnace; remove the crucible to obtain iron oxide material.

5. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The preparation of the mixed dispersion involves adding the iron oxide material to the mixed dispersion and uniformly dispersing the iron oxide material in the mixed dispersion to obtain a mixed solution, comprising: Isopropanol, ultrapure water, and Nafion solution were added to the same container and stirred until homogeneous to prepare a mixed dispersion. The iron oxide material was then added to the mixed dispersion and subjected to ultrasonic treatment to ensure that the iron oxide material was uniformly dispersed in the mixed dispersion, thus obtaining a mixed solution.

6. The method for modifying iron oxide based on current regulation according to claim 5, characterized in that, The process of transferring the mixed solution to the surface of a nickel foam substrate, removing the solvent from the mixed solution, and loading the iron oxide material onto the surface of the nickel foam substrate to obtain an iron oxide-loaded nickel foam material includes: Using a micropipette, a predetermined volume of the mixed solution is aspirated and dropped onto the surface of the nickel foam substrate. The solution is then left to air dry at room temperature to allow the solvent in the mixed solution to evaporate, thereby firmly loading the iron oxide material onto the surface of the nickel foam substrate, resulting in nickel foam material loaded with iron oxide.

7. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The strongly alkaline solution includes potassium hydroxide solution or sodium hydroxide solution.

8. The method for modifying iron oxide based on current regulation according to claim 1, characterized in that, The predetermined parameters include the waveform of the alternating current, the energizing time, and the magnitude of the current.

9. The method for modifying iron oxide based on current regulation according to claim 8, characterized in that, The waveform of the alternating current is a square wave, and the energizing time is 1 min to 60 min; the positive period of the square wave is 5 s to 15 s, the positive period current is 5 mA to 15 mA, the negative period is 25 s to 35 s, and the negative period current is 15 mA to 25 mA.

10. An iron oxide anode material, characterized in that, It is prepared by the method described in any one of claims 1-9.

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