An electrolyzed water oxygen evolution catalytic electrode and its preparation process

Abstract

The present invention discloses an electrolytic water oxygen evolution catalytic electrode and a preparation process thereof, relating to the field of electrode materials. When preparing the electrolytic water oxygen evolution catalytic electrode of the present invention, nickel foam is etched with oxalic acid and then surface-modified with sodium oxalate to obtain a modified substrate; then the modified substrate, a nickel mesh anode and an electrodeposition solution are subjected to electrodeposition to prepare the electrolytic water oxygen evolution catalytic electrode. The electrolytic water oxygen evolution catalytic electrode prepared by the present invention has excellent stability, catalytic uniformity and process repeatability.

Description

Technical Field

[0001] The present invention relates to the field of electrode materials, and specifically to an electrolytic water oxygen evolution catalytic electrode and a preparation process thereof. Background Art

[0002] As the most ideal energy carrier, hydrogen energy is becoming the focus of people's attention, and the green production of hydrogen energy has also become the key to the future research and development of hydrogen energy technology. Hydrogen production by electrolyzing water, combined with renewable energy power generation systems represented by photovoltaic and wind power, can provide an ideal technical means for future sustainable hydrogen energy supply. The anion exchange membrane electrolytic water hydrogen production (AEM) technology, as a clean and sustainable hydrogen production and renewable energy conversion method, has attracted much attention. As an important component of the AEM system technology, the core components of the electrolytic cell are the anode electrode plate and the cathode electrode plate, whose functions are to catalyze oxygen production and hydrogen production respectively, and the oxygen evolution process is the key reaction determining the efficiency of electrolytic water.

[0003] With the continuous increase in the market demand for hydrogen energy, the market's requirement for the hydrogen production efficiency of the electrode plate is getting higher and higher. Common methods for making electrode plates mainly include surface coating method, bonding method, etc. Among them, the surface catalytic performance of the electrode plates prepared by methods such as surface coating method and bonding method is uneven, the process repeatability is poor, and the stability during the long-term electrolytic water hydrogen production process is also poor. Therefore, the present invention prepares an electrolytic water oxygen evolution catalytic electrode with good stability, uniform catalytic performance distribution and high process repeatability. Summary of the Invention

[0004] The purpose of the present invention is to provide an electrolytic water oxygen evolution catalytic electrode and a preparation process thereof to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] An electrolytic water oxygen evolution catalytic electrode, which is prepared by electrodeposition of a modified substrate, a nickel mesh anode and an electrodeposition solution.

[0007] As an optimization, the modified substrate is obtained by etching nickel foam with oxalic acid and then performing surface modification with sodium oxalate.

[0008] A preparation process of an electrolytic water oxygen evolution catalytic electrode includes the following preparation steps:

[0009] (1) Take out nickel foam after ultrasonic treatment in deionized water at 20 - 30 °C for 3 - 10 min, immerse it in an oxalic acid solution with a concentration of 0.1 - 5 mol / L for etching for 23 - 25 h, spray and wash it with deionized water atomization for 3 - 10 min, then immerse it again in a sodium oxalate solution with a concentration of 0.1 - 1 mol / L, keep it warm at 40 - 60 °C for 3 - 6 h, take it out and spray and wash it with deionized water atomization for 4 - 6 min to obtain a modified substrate;

[0010] (2) Mix ferric nitrate, nickel nitrate, oxalic acid and deionized water to obtain an electrodeposition solution; place the modified substrate and the nickel mesh anode in parallel in an electroplating box, add the electrodeposition solution, and carry out electrodeposition at 10 - 100 mA / cm 2 for 60 - 300 s, and spray and wash with deionized water atomization for 5 - 10 min to obtain an electrolytic water oxygen evolution catalytic electrode.

[0011] As an optimization, the concentration of Fe 3+ in the electrodeposition solution described in step (2) is 0.06 mol / L.

[0012] As an optimization, the concentration of Ni 2+ in the electrodeposition solution described in step (2) is 0.24 mol / L.

[0013] As an optimization, the concentration of oxalic acid in the electrodeposition solution described in step (2) is 0.0075 mol / L.

[0014] As an optimization, the vertical distance between the modified substrate and the nickel mesh anode in the electroplating box is 3 - 10 cm.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0016] When preparing the electrolytic water oxygen evolution catalytic electrode of the present invention, the nickel foam is etched with oxalic acid and then surface - modified with sodium oxalate to obtain a modified substrate; then the modified substrate, the nickel mesh anode and the electrodeposition solution are used for electrodeposition to prepare the electrolytic water oxygen evolution catalytic electrode.

[0017] First, the nickel foam is etched with oxalic acid and then surface - modified with sodium oxalate to obtain a modified substrate; through the surface etching and modification process, the nickel foam forms a micro - rough surface, which improves the specific surface area of the nickel foam. At the same time, oxalate ions are introduced to form complexes with metal ions on the surface of the nickel foam, promoting the adsorption of Ni 2+ and Fe 3+ ions on the surface of the nickel foam to form an amorphous, micro - porous and composition - uniform high - performance NiFeOOH in an amorphous state, improving the catalytic uniformity and stability of the electrolytic water oxygen evolution catalytic electrode.

[0018] Second, the modified substrate, the nickel mesh anode and the electrodeposition solution are used for electrodeposition to prepare the electrolytic water oxygen evolution catalytic electrode; the slightly acidic environment formed by oxalic acid in the electrodeposition process can remove the catalysts with poor binding force on the surface of the modified substrate. At the same time, during the cathode deposition and reduction process, the surface of the catalyst is regulated to expose more active sites, thereby increasing the electrochemical performance; compared with the preparation methods of physical adsorption such as the traditional coating method and the bonding method, the catalytic layer prepared by the electrodeposition method has stronger adsorption stability, mature technology, wide applicability and low cost. Description of the Drawings

[0019] Figure 1 This is the process diagram of the electrode sheet of the oxygen evolution catalytic electrode for electrolyzed water according to the present invention.

[0020] Figure 2 This is the scanning electron microscope image of amorphous a-NiFeOOH on the oxygen evolution catalytic electrode for electrolyzed water according to the present invention.

[0021] Figure 3 This is the transmission electron microscope image of amorphous a-NiFeOOH on the oxygen evolution catalytic electrode for electrolyzed water according to the present invention.

[0022] Figure 4 This is the oxygen evolution performance test chart of different oxygen evolution electrodes of the oxygen evolution catalytic electrode for electrolyzed water according to the present invention under a three-electrode system.

[0023] Figure 5 This is the stability test chart of the oxygen evolution catalytic electrode for electrolyzed water according to the present invention in a self-developed AEM electrolytic cell.

[0024] Figure 6 This is the test chart of the uniformity of the electrode sheet of the oxygen evolution catalytic electrode for electrolyzed water according to the present invention.

[0025] Figure 7 This is the test chart of the process repeatability of the oxygen evolution catalytic electrode for electrolyzed water according to the present invention. Detailed Embodiments

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] The following nickel foam comes from Kunshan Jiayisheng Electronics Co., Ltd.; the nickel mesh anode comes from Hebei Kangwei Metal Products Co., Ltd.; Embodiment

[0028] A preparation process of an oxygen evolution catalytic electrode for electrolyzed water, the preparation process of the oxygen evolution catalytic electrode for electrolyzed water includes the following preparation steps:

[0029] (1) Take out a 50 cm × 50 cm nickel foam after ultrasonic cleaning in deionized water at 25°C for 5 minutes, immerse it in a 2 mol / L oxalic acid solution for etching for 24 hours, spray and wash it with deionized water atomization for 5 minutes, then immerse it again in a 0.5 mol / L sodium oxalate solution, keep it at 50°C for 4.5 hours, take it out and spray and wash it with deionized water atomization for 5 minutes to obtain a modified substrate;

[0030] (2) Mix ferric chloride, nickel nitrate, oxalic acid and deionized water to obtain an electrodeposition solution; place the modified substrate and the nickel mesh anode parallel in the electroplating box, add the electrodeposition solution, and deposit at 30 mA / cm 2 for 100 s, and spray and wash with deionized water atomization for 7 min to obtain an electrolytic water oxygen evolution catalytic electrode.

[0031] In the above-mentioned electrodeposition solution, the concentration of Fe 3+ is 0.06 mol / L, the concentration of Ni 2+ is 0.24 mol / L, and the concentration of oxalic acid is 0.0075 mol / L.

[0032] Test Example 1: Surface Morphology

[0033] Test method: Perform scanning electron microscopy test (refer to Figure 2 ) and transmission electron microscopy test (refer to Figure 3 ) on the electrolytic water oxygen evolution catalytic electrode obtained in the example.

[0034] It can be seen from Figure 2 that the etching modification process makes the nickel foam form a microscopically rough surface, increasing the specific surface area. The introduced oxalate ions form complexes with the metal ions on the surface of the nickel foam. During the electrodeposition process, Ni 2+ and Fe 3+ ions adsorb on the surface of the nickel foam to form a microscopically porous and compositionally uniform amorphous high-performance NiFeOOH in an amorphous state; it can be seen from Figure 3 that in the electrolytic water oxygen evolution catalytic electrode obtained in the example, the elemental compositions of Ni, Fe, and O are uniformly distributed, and no diffraction spots or diffraction rings are found in the diffraction test, indicating that the catalyst is amorphous.

[0035] Test Example 2: Oxygen Evolution Performance

[0036] Test method: Take 1 cm * 1 cm test samples of the electrolytic water oxygen evolution catalytic electrode obtained in the example, the commercially available NiFe-LDH catalyst, the nickel foam substrate, and the Raney nickel electrode respectively, and perform oxygen evolution performance tests in a three-electrode system (the counter electrode is a platinum sheet, the reference electrode is Hg / HgO, and the electrolyte is 1 mol / L potassium hydroxide solution) (refer to Figure 4 ).

[0037] It can be seen from Figure 4 that the amorphous a-NiFeOOH has a low internal resistance, a high oxygen production efficiency, and a catalytic performance higher than that of the NiFe-LDH catalyst prepared by traditional electrodeposition, and also higher than that of the nickel foam substrate and the Raney nickel electrode commonly used in traditional ALK cells.

[0038] Test Example 3: Stability

[0039] Test method: Cut the electrolytic water oxygen evolution catalytic electrode obtained in the example into test samples with a size of 5 cm * 5 cm, and use a self-made AEM electrolytic water hydrogen production electrolytic cell (effective reaction area: 5 cm * 5 cm). Under the conditions of 1 A / cm², 60 °C, and 1 mol / L potassium hydroxide solution, test the decay of the cell voltage (refer to Figure 5 ).

[0040] It can be seen from Figure 5 that the single cell voltage of the electrolytic water oxygen evolution catalytic electrode obtained in the example can reach 1.92 V, and no obvious decay of the cell voltage is found after 320 h of testing, indicating good stability.

[0041] Test Example 4: Catalytic performance uniformity

[0042] Test method: Cut 10 test samples with a size of 1 cm * 1 cm from the electrolytic water oxygen evolution catalytic electrode obtained in the example at different positions. In a three-electrode system (the counter electrode is a platinum sheet, the reference electrode is Hg / HgO, and the electrolyte is 1 mol / L potassium hydroxide solution), test the catalytic performance of the test samples, and calculate the difference value from the average catalytic performance = (sample catalytic performance - average catalytic performance) / average catalytic performance * 100% (refer to Figure 6 ).

[0043] It can be seen from Figure 6 that for the electrolytic water oxygen evolution catalytic electrode obtained in the example, the difference between the oxygen evolution performance at different positions and the average value is within + / - 5%. Compared with the traditional coating method and bonding method, the process of combining surface etching modification and electrodeposition makes the distribution of the catalytic layer on the electrode sheet more uniform.

[0044] Test Example 5: Process repeatability

[0045] Test method: Cut test samples with a size of 1 cm * 1 cm from the electrolytic water oxygen evolution catalytic electrodes of different batches obtained in the example at the same position. In a three-electrode system (the counter electrode is a platinum sheet, the reference electrode is Hg / HgO, and the electrolyte is 1 mol / L potassium hydroxide solution), test the catalytic performance of the samples, and calculate the difference value from the average value = (sample catalytic performance - average catalytic performance) / average catalytic performance * 100% (refer to Figure 7 ).

[0046] It can be seen from Figure 7 that for the electrolytic water oxygen evolution catalytic electrodes of different batches obtained in the example, the difference between the oxygen evolution performance at the same position and the average value is within + / - 5%. Compared with the traditional coating method and bonding method, the process of combining surface etching modification and electrodeposition has high process repeatability and small batch-to-batch performance differences of the catalytic electrode sheets.

[0047] From Figures 2 - 7Comparing the experimental data therein, it can be found that the electrolytic water oxygen evolution catalytic electrode prepared by the present invention has good stability, catalytic uniformity and process repeatability.

[0048] The specific embodiments described above further elaborate on the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation process of an electrolytic water oxygen evolution catalytic electrode, characterized in that, It includes the following preparation steps: (1) Take out the nickel foam after ultrasonic treatment in deionized water at 20~30°C for 3~10 min, immerse it in an oxalic acid solution with a concentration of 0.1~5 mol / L for etching for 23~25 h, spray and wash it with deionized water atomization for 3~10 min, immerse it again in a sodium oxalate solution with a concentration of 0.1~1 mol / L, keep it warm at 40~60°C for 3~6 h, take it out and spray and wash it with deionized water atomization for 4~6 min to obtain a modified substrate; (2)Mix ferric chloride, nickel nitrate, oxalic acid and deionized water to obtain an electrodeposition solution; place the modified substrate and the nickel mesh anode parallel in the electroplating box, add the electrodeposition solution, and perform electrodeposition at 10~100 mA / cm 2 for 60~300 s, and then clean it by atomizing and spraying with deionized water for 5~10 min to obtain an electrolytic water oxygen evolution catalytic electrode.

2. The preparation process of an electrolytic water oxygen evolution catalytic electrode according to claim 1, characterized in that, The Fe in the electrodeposition solution described in step (2) 3+ has a concentration of 0.06 mol / L.

3. The preparation process of an electrolytic water oxygen evolution catalytic electrode according to claim 1, characterized in that, The Ni in the electrodeposition solution described in step (2) 2+ has a concentration of 0.24 mol / L.

4. The preparation process of an electrolytic water oxygen evolution catalytic electrode according to claim 1, characterized in that, In step (2), the oxalic acid concentration in the electrodeposition solution is 0.0075 mol / L.

5. The preparation process of an electrolytic water oxygen evolution catalytic electrode according to claim 1, characterized in that, In step (2), the vertical distance between the modified substrate and the nickel mesh anode in the electroplating box is 7 cm.

6. The preparation process of an electrolytic water oxygen evolution catalytic electrode according to claim 1, characterized in that, In step (2), the size of the nickel mesh anode is the same as that of the modified substrate.

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