Surface-modified stainless steel water oxidation electrode and preparation method thereof
By hydrothermal treatment of the stainless steel mesh, a modified water oxidation electrode is formed, which solves the problem of slow kinetic process in the oxygen evolution reaction of the existing electrodes, and achieves efficient and stable water oxidation performance and reduces costs.
Patent Information
- Application Number
- CN202411473792.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-03-11
AI Technical Summary
The kinetic process of existing water oxidation electrode materials in oxygen evolution reactions is slow, requiring large potential driving, and precious metal catalysts are expensive, limiting large-scale applications.
By using the stainless steel mesh as a substrate, a mixed aqueous solution of potassium hydroxide and sodium sulfate is used to perform hydrothermal reaction, and the surface of the stainless steel is modified to form an electrode with high efficiency water oxidation performance.
The surface-modified stainless steel water oxidation electrode prepared has an overpotential of only 300mV at a current density of 10mA cm-2 and a Tafel slope of 43.69mV dec-1, which has excellent stability and efficient water oxidation properties.
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Figure CN119592983A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrocatalysts, and in particular relates to a surface-modified stainless steel water oxidation electrode and a preparation method thereof. Background Art
[0002] Hydrogen energy refers to the technology of using hydrogen as a fuel to generate energy. At present, hydrogen energy is regarded as a highly potential renewable clean energy source, which is expected to replace fossil fuels as the main energy source. People are constantly exploring efficient, convenient and economical methods of hydrogen production, and the use of renewable energy to electrolyze water to produce hydrogen is also the process with the lowest carbon emissions among the many hydrogen production methods currently available. The water electrolysis process includes two half reactions, namely the hydrogen evolution reaction at the cathode and the oxygen evolution reaction at the anode. Among them, the oxygen evolution reaction is a four-electron, four-proton transfer process. Compared with the hydrogen evolution reaction, it is a slow kinetic process and requires a larger potential drive. Therefore, how to improve the electrocatalytic performance of the oxygen evolution reaction is the key to hydrogen production by electrolysis of water.
[0003] In modern scientific research, water oxidation reactions often rely on precious metals as catalysts. Precious metals (such as platinum, palladium, etc.) usually have efficient OER catalytic performance and excellent stability. However, due to their high cost and limited earth reserves, their large-scale application in the field of water splitting is limited. Electrocatalysts of non-precious metals and their alloys have the advantages of low cost and good chemical stability. Iron and nickel are commonly used elements in the field of non-precious metals. Studies have found that nickel-iron composite metals exhibit excellent water oxidation activity. Nickel-iron alloys have gradually attracted the attention of researchers due to their high electrical conductivity, excellent deformation resistance and excellent corrosion resistance.
[0004] Stainless steel (SS) is a cheap alloy composed of Ni and Fe, which has the advantages of low cost, high mechanical strength, good hardness and chemical stability. However, SS itself has no obvious OER activity. The reason is that the passivation film Cr on the surface of stainless steel is used to protect stainless steel from pollution and corrosion, thus restricting its oxygen evolution performance. Summary of the invention
[0005] The purpose of the present invention is to solve the shortcomings of the above-mentioned existing water oxidation electrode materials and provide a method for preparing a surface-modified stainless steel water oxidation electrode. The method is simple to operate, low in cost, and has a wide source of raw materials. The prepared water oxidation electrode has good OER water oxidation performance.
[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a surface-modified stainless steel water oxidation electrode comprises the following steps:
[0008] (1) cutting the stainless steel mesh into electrode sheets, ultrasonically cleaning them with a hydrochloric acid solution, and then ultrasonically cleaning them with deionized water, anhydrous ethanol, and acetone in sequence, and then vacuum drying them to obtain a stainless steel mesh substrate;
[0009] (2) placing the stainless steel mesh substrate obtained in step (1) in a reaction kettle, adding a mixed aqueous solution of sodium sulfate and potassium hydroxide into the reaction kettle, then sealing the reaction kettle, placing it in an oven, and performing a hydrothermal reaction at 120 to 180° C. for 4 to 12 hours. After the reaction is completed, cooling to room temperature, taking out and rinsing, and finally drying to obtain a surface-modified stainless steel water oxidation electrode.
[0010] Furthermore, in step (1), the concentration of the hydrochloric acid solution is 1 mol / L, and the ultrasonic treatment time is 15 min.
[0011] Furthermore, in step (1), the vacuum drying temperature is 50-60°C.
[0012] Furthermore, in step (2), in the mixed aqueous solution of sodium sulfate and potassium hydroxide, the concentration of potassium hydroxide is 1 mol / L, and the concentration of sodium sulfate is 0.01-0.1 mol / L.
[0013] Furthermore, in step (2), the temperature of the hydrothermal reaction is 180° C. and the time is 8 hours.
[0014] The stainless steel water oxidation electrode is prepared by the above method.
[0015] Beneficial effects of the present invention: The present invention uses potassium hydroxide and sodium sulfate as the corrosive liquid stock solution and a stainless steel mesh as the substrate to prepare a surface-modified stainless steel water oxidation electrode. The method has low cost, a wide source of raw materials, and is easy to operate. The prepared stainless steel water oxidation electrode has high efficiency, high conductivity, fast mass transfer rate, and abundant active sites. It has excellent water oxidation performance. When the current density is 10 mA cm -2 When the overpotential is 300mV, the Tafel slope is 43.69mV dec. -1 At the same time, it was found from long-term chronoamperometric tests that its overpotential can remain stable, and it also has good stability in the segmented constant current electrolysis mode, and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The SEM images of the stainless steel water oxidation electrodes prepared in Example 1 and Comparative Examples 1-2;
[0017] Figure 2 LSV curves of the water oxidation electrodes prepared in Examples 1-4;
[0018] Figure 3LSV curves of the water oxidation electrodes prepared in Example 1 and Comparative Example 1;
[0019] Figure 4 LSV curves of the water oxidation electrodes prepared in Example 1 and Comparative Example 2;
[0020] Figure 5 The stability test results of the water oxidation electrode prepared in Example 1;
[0021] Figure 6 CV curves and ECSA diagrams of the water oxidation electrodes prepared in Example 1 and Example 2 at different scan rates. DETAILED DESCRIPTION
[0022] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments.
[0023] In the following examples and comparative examples, the stainless steel mesh used is 304 stainless steel mesh (200 meshes), and its main components and contents are: 12.0% Ni, 17.0% Cr, and 67.0% Fe, but it is not limited thereto.
[0024] Example 1
[0025] A method for preparing a surface-modified stainless steel water oxidation electrode comprises the following steps:
[0026] (1) Cut the stainless steel mesh into electrode sheets with a size of 10 mm × 5 mm × 1 mm, use 1 mol / L hydrochloric acid solution for ultrasonic cleaning for 15 min, then use deionized water, anhydrous ethanol and acetone for ultrasonic cleaning for 5 min each, and then vacuum dry at 50° C. for 3 h to obtain a stainless steel mesh substrate;
[0027] (2) The stainless steel mesh substrate obtained in step (1) is placed in a reaction kettle, and 7 mL of a mixed aqueous solution of sodium sulfate and potassium hydroxide is added to the reaction kettle, wherein the concentration of potassium hydroxide in the mixed aqueous solution is 1 mol / L and the concentration of sodium sulfate is 0.05 mol / L. The reaction kettle is sealed and placed in an oven for hydrothermal reaction at 180° C. for 8 h. After the reaction is completed, the reaction kettle is cooled to room temperature, taken out and rinsed with deionized water, anhydrous ethanol, and acetone in sequence, and finally dried to obtain a surface-modified stainless steel water oxidation electrode.
[0028] Example 2
[0029] In step (2), the hydrothermal reaction temperature is 120° C., and the rest is the same as in Example 1.
[0030] Example 3
[0031] In step (2), the hydrothermal reaction temperature is 140° C., and the rest is the same as in Example 1.
[0032] Example 4
[0033] In step (2), the hydrothermal reaction temperature is 160° C., and the rest is the same as in Example 1.
[0034] Comparative Example 1
[0035] A method for preparing a surface-modified stainless steel water oxidation electrode comprises the following steps:
[0036] (1) Cut the stainless steel mesh into electrode sheets with a size of 10 mm × 5 mm × 1 mm, use 1 mol / L hydrochloric acid solution for ultrasonic cleaning for 15 min, then use deionized water, anhydrous ethanol and acetone for ultrasonic cleaning for 5 min each, and then vacuum dry at 50° C. for 3 h to obtain a stainless steel mesh substrate;
[0037] (2) The stainless steel mesh substrate obtained in step (1) is placed in a reaction kettle, and 7 mL of a mixed aqueous solution of sodium sulfite and potassium hydroxide is added to the reaction kettle, wherein the concentration of potassium hydroxide in the mixed aqueous solution is 1 mol / L and the concentration of sodium sulfite is 0.05 mol / L. The reaction kettle is sealed and placed in an oven for hydrothermal reaction at 180° C. for 8 h. After the reaction is completed, the reaction kettle is cooled to room temperature, taken out and rinsed with deionized water, anhydrous ethanol, and acetone in sequence, and finally dried to obtain a surface-modified stainless steel water oxidation electrode.
[0038] Comparative Example 2
[0039] A method for preparing a stainless steel water oxidation electrode: a stainless steel mesh is cut into electrode sheets with a size of 10 mm×5 mm×1 mm, and ultrasonically cleaned with a 1 mol / L hydrochloric acid solution for 15 min, and then ultrasonically cleaned with deionized water, anhydrous ethanol and acetone for 5 min each, and then vacuum dried at 50° C. for 3 h to obtain a stainless steel water oxidation electrode, which is recorded as SSM.
[0040] Figure 1 The SEM images of the stainless steel water oxidation electrodes prepared in Example 1 and Comparative Examples 1-2 are shown in FIG. Figure 1 (a) is a SEM image of the stainless steel water oxidation electrode prepared in Comparative Example 2, Figure 1 (b) is a SEM image of the stainless steel water oxidation electrode prepared in Example 1. Figure 1 (c) is a SEM image of the stainless steel water oxidation electrode prepared in Comparative Example 2. It can be seen from the figure that the surface of the untreated stainless steel mesh (Comparative Example 2) is smooth. Under the combined action of KOH and sodium sulfate (Example 1), a large number of nanoparticles grow on the electrode surface, which has a larger specific surface area and more active sites, which is conducive to the oxygen evolution reaction. In contrast, the sodium sulfite treatment (Comparative Example 1) only corrodes the electrode.
[0041] Performance Test:
[0042] 1. After the stainless steel water oxidation electrodes prepared in Examples 1-4 and Comparative Examples 1-2 were activated, a linear sweep voltammetry (LSV) test was then performed under the condition that the resistance compensation reached 90%.
[0043] Figure 2 The LSV curves of the water oxidation electrodes prepared in Examples 1-4 show that, under the same sodium sulfate concentration and the same hydrothermal reaction time, when the reaction temperature is 180°C (Example 1), the electrochemical performance of the water oxidation electrode material is the best compared with other examples. -2 At a current density of , the overpotential is the lowest, only 300mV.
[0044] Figure 3 The LSV curves of the water oxidation electrodes prepared in Example 1 and Comparative Example 1 are shown in FIG. Figure 3 It can be seen that compared with Comparative Example 1 (with 0.05M Na 2 SO 3 The water oxidation electrode prepared in Example 1 (with 0.05MNa 2 SO 4 The water oxidation performance of the corrosive solution is significantly better at an overpotential of 10 mA cm -2 At the current density, its value is only 300 mV, which indicates that the water oxidation electrode prepared in Example 1 of the present invention has better OER performance, lower overpotential and better reaction rate.
[0045] Figure 4 The LSV curves of the water oxidation electrodes prepared in Example 1 and Comparative Example 2 are shown in FIG. Figure 4 (a) is the LSV curve, Figure 4 (b) is the corresponding Tafel slope diagram. It can be seen from the figure that the electrode performance is significantly improved after being treated with sodium sulfate etchant. -2 The overpotential under current density is only 300 and 350 mV, which is much better than the stainless steel mesh substrate. In addition, the Tafel slope of the water oxidation electrode prepared in Example 1 is only 46.6 mV dec. -1 , reflecting its rapid kinetic process.
[0046] 2. The water oxidation electrode prepared in Example 1 was subjected to a stability test.
[0047] Test method: The water oxidation electrode prepared in Example 1 was subjected to an electrolytic reaction in 1.0 mol / L KOH solution at a current density of 1 mA cm -2 Multi-step increase to 100mA cm -2The segmented constant current electrolysis test was carried out, and the electrolysis was performed for half an hour under each current density condition to observe the change of its overpotential. Then, the controlled current electrolysis was carried out in a 1.0 mol / L KOH aqueous solution, and the controlled current density was 10 mA cm -2 , record the overpotential for 24 hours and observe its change over time, then use origin software to draw a graph and observe the change in the size of the overpotential.
[0048] Figure 5 The stability test results of the water oxidation electrode prepared in Example 1 are as follows: Figure 5 (a) is the test result of segmented constant current electrolysis. Figure 5 (b) is the result of long-term chronopotentiometry test. It can be seen from the results of segmented constant current electrolysis test that the current density increases from 1 mA cm -2 Multi-step increase to 100mA cm -2 , and their overpotentials can remain stable, which indicates that KOH / Na 2 SO 4 -SSM has good stability at all current densities; Figure 5 (b) It can be seen that the water oxidation electrode prepared in Example 1 can be -2 It can work stably and continuously for 24 hours at a current density of , and there is no obvious fluctuation in the overpotential, which proves its excellent stability.
[0049] 3. Cyclic voltammetry (CV) tests were performed on the water oxidation electrodes prepared in Example 1 and Comparative Example 2 in 1 M potassium hydroxide, with the scan rate ranging from 10 to 100 mV s -1 The CV curves at the time of dl ) to evaluate the ECSA of the material.
[0050] Figure 6 The CV curves and ECSA diagrams of the water oxidation electrodes prepared in Example 1 and Comparative Example 2 at different scan rates are shown, wherein: Figure 6 (a) is the CV curve of the water oxidation electrode prepared in Example 1 at different scanning rates, Figure 6 (b) is the CV curve of the water oxidation electrode prepared in Comparative Example 1 at different scanning rates, Figure 6 (c) is an ECSA graph made according to the CV curve. It can be seen that compared with the water oxidation electrode prepared in Comparative Example 1, the CV coverage area of the water oxidation electrode prepared in Example 1 is larger. On this basis, the CV curves of the two are processed using origin to obtain C dl , the C of the water oxidation electrode prepared in Example 1 can be obtained dl The value is 1.82mF·cm -2 , while the C of Comparative Example 2 (untreated SSM)dl The value is only 1.19mF·cm -2 , it can be obtained that the electrochemical surface area of the water oxidation electrode prepared in Example 1 is 1.53 times that of the untreated SSM (Comparative Example 2), indicating that the water oxidation electrode prepared in Example 1 has more OER catalytic active sites and thus has better water oxidation activity.
Claims
1. A method for preparing a surface-modified stainless steel water oxidation electrode, characterized in that: The steps include: (1) cutting the stainless steel mesh into electrode sheets, ultrasonically cleaning them with a hydrochloric acid solution, and then ultrasonically cleaning them with deionized water, anhydrous ethanol, and acetone in sequence, and then vacuum drying them to obtain a stainless steel mesh substrate; (2) placing the stainless steel mesh substrate obtained in step (1) in a reaction kettle, adding a mixed aqueous solution of sodium sulfate and potassium hydroxide into the reaction kettle, then sealing the reaction kettle, placing it in an oven, and performing a hydrothermal reaction at 120-180° C. for 8 h. After the reaction is completed, cooling it to room temperature, taking it out and rinsing it, and finally drying it to obtain a surface-modified stainless steel water oxidation electrode.
2. The method for preparing the surface-modified stainless steel water oxidation electrode according to claim 1, characterized in that: In step (1), the concentration of the hydrochloric acid solution is 1 mol / L, and the ultrasonic treatment time is 15 min.
3. The method for preparing the surface-modified stainless steel water oxidation electrode according to claim 1, characterized in that: In step (1), the vacuum drying temperature is 50-60°C.
4. The method for preparing the surface-modified stainless steel water oxidation electrode according to claim 1, characterized in that: In step (2), in the mixed aqueous solution of sodium sulfate and potassium hydroxide, the concentration of potassium hydroxide is 1 mol / L, and the concentration of sodium sulfate is 0.01-0.1 mol / L.
5. The method for preparing the surface-modified stainless steel water oxidation electrode according to any one of claims 1 to 4, characterized in that: In step (2), the temperature of the hydrothermal reaction is 180° C. and the time is 8 hours.
6. A stainless steel water oxidation electrode prepared by the method according to any one of claims 1 to 5.