A method for preparing an anode with a MnO2 / IrO2 coating

Abstract

The application relates to the field of electrodes, in particular to a preparation method of an MnO2 / IrO2-coated anode. The preparation method comprises the following steps: sequentially performing sand blasting, type correction, alkali washing, acid etching and drying on a metal anode substrate to obtain a rough metal substrate; mixing manganese salt, iridium salt, citric acid and an alcohol solvent, and standing to obtain an active metal gel; coating the active metal gel on the surface of the rough metal substrate, and then sequentially performing drying, shaping and cooling; repeating the coating-second drying-shaping-cooling process; and then performing sintering to obtain the MnO2 / IrO2-coated anode. The application takes the metal anode as a substrate material, uniformly coats the MnIr gel precursor on the metal surface through a sol-gel method, adopts drying, low-temperature shaping and high-temperature sintering to obtain the target electrode meeting the conditions of industrial application, and can be widely applied to seawater electrolysis, treatment of medical water and industrial wastewater.

Description

Technical Field

[0001] This invention relates to the field of electrodes, and more particularly to a method for preparing an anode with a MnO2 / IrO2 coating. Background Technology

[0002] Currently, electrodes are widely used, among which titanium-based electrodes have become core materials in many industrial fields due to their comprehensive performance advantages. The key breakthrough in current technological development lies in how to optimize their performance through more economical and efficient process routes. Traditional preparation of mixed metal oxide coatings often relies on complex multi-step processes and expensive precious metal raw materials, which seriously restricts the large-scale promotion and application of this technology.

[0003] Chinese patent application CN120719264A discloses a method for preparing a novel hybrid metal oxide coated titanium electrode. However, the preparation of this catalytic material requires low-temperature plasma treatment, pulsed bias magnetron sputtering, and laser-induced atomic layer deposition. The preparation process is complex, involves numerous procedures, and has high manufacturing costs. Meanwhile, Chinese patent application CN101230467A discloses a titanium-based manganese-iridium composite oxide coated anode and its preparation method, developing an economical manganese-iridium anode electrode; however, its electrode area is only 20 mm². 20mm The 1mm thickness severely limits the requirements for industrial applications; however, in industrial applications (100mm)... 100mm Achieving uniform coating loading (1 mm) presents challenges due to requirements for material surface pretreatment and stress-strain control. Therefore, developing a simple, low-cost, and uniformly stable loaded coating electrode fabrication method is both challenging and promising. Summary of the Invention

[0004] This invention provides a method for preparing an anode with a MnO2 / IrO2 coating, in order to solve the problems of excessive use of precious metals, high cost, complex preparation process and long preparation cycle in the existing electrode preparation.

[0005] To address the above problems, the present invention provides the following technical solution: This invention provides a method for preparing an anode with a MnO2 / IrO2 coating, comprising the following steps: The metal anode substrate is sequentially subjected to sandblasting, shaping, alkaline washing, acid etching, and first drying to obtain a textured metal substrate. Manganese salt, iridium salt, citric acid and alcohol solvent are mixed and allowed to stand to obtain an active metal gel; The active metal gel is coated onto the surface of the textured metal substrate, and then a second drying, shaping and cooling process is performed in sequence. The coating-second drying-shaping-cooling process is repeated, and then sintering is performed to obtain the anode of the MnO2 / IrO2 coating.

[0006] In some specific embodiments, the metal anode substrate includes titanium, ruthenium, iridium, platinum, tin, iron, copper, or nickel.

[0007] In some specific embodiments, the thickness of the MnO2 / IrO2 coating is 3~10μm.

[0008] In some specific embodiments, the sand used in the sandblasting includes corundum, and the particle size of the corundum is 15-200 mesh.

[0009] In some specific embodiments, the surface roughness Ra of the sandblasted metal anode substrate is 8~20μm.

[0010] In some specific embodiments, the alkaline washing reagent includes a sodium carbonate solution.

[0011] In some specific embodiments, the concentration of the sodium carbonate solution is 6wt% to 12wt%.

[0012] In some specific embodiments, the temperature of the alkaline washing is 50~80℃, and the time of the alkaline washing is 0.5~1h.

[0013] In some specific embodiments, the acid etching reagent includes a mixed solution of oxalic acid, hydrofluoric acid, and water.

[0014] In some specific embodiments, the concentration of oxalic acid in the mixed solution is 5wt% to 20wt%.

[0015] In some specific embodiments, the concentration of hydrofluoric acid in the mixed solution is 0.5wt% to 3wt%.

[0016] In some specific embodiments, the acid etching temperature is 80~100℃, and the acid etching time is 1~2h.

[0017] In some specific embodiments, the acid etching process further includes alternating alcohol washing and water washing of the acid-etched metal anode substrate.

[0018] In some specific embodiments, the alcohol washing reagent includes an aqueous solution of ethanol.

[0019] In some specific embodiments, the concentration of the aqueous ethanol solution is 95 wt%.

[0020] In some specific embodiments, the mixing process includes: Citric acid and alcohol solvent were mixed for the first dispersion to obtain the metal gel precursor; The manganese salt, iridium salt, and metal gel precursor were mixed for a second dispersion.

[0021] In some specific embodiments, the ratio of citric acid to alcohol solvent is (20~120) mg: 10 mL.

[0022] In some specific embodiments, the molar ratio of manganese in the manganese salt to iridium in the iridium salt is (0.2~1.2):(0.1~0.6).

[0023] In some specific embodiments, the ratio of manganese element in the manganese salt to the alcohol solvent is (0.2~1.2) mmol: 10 mL.

[0024] In some specific embodiments, the manganese salt includes manganese chloride.

[0025] In some specific embodiments, the iridium salt includes iridium chloride.

[0026] In some specific embodiments, the alcohol solvent includes ethylene glycol and / or glycerol.

[0027] In some specific embodiments, the temperature of the first dispersion is 50~70℃, and the dispersion time is 0.5~1h.

[0028] In some specific embodiments, the temperature of the second dispersion is 80~90℃, and the dispersion time is 60~120min.

[0029] In some specific embodiments, the temperature of the second drying is 120~200℃, and the drying time is 3~10min.

[0030] In some specific embodiments, the setting temperature is 200~350℃, and the setting time is 10~120min.

[0031] In some specific embodiments, the sintering temperature is 400~650℃, and the sintering time is 1~8h.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a metal anode as a substrate material and achieves uniform coating of MnIr gel precursor on the metal surface by sol-gel method. The target electrode that meets the conditions for industrial application is obtained by drying, low temperature shaping, high temperature sintering and natural cooling. It can be widely used in seawater electrolysis, medical water and industrial wastewater treatment.

[0033] (2) The method of this invention achieves one-step coating and molding on a metal substrate by optimizing the precursor formulation, eliminating the multiple sintering and intermediate processing steps in the traditional process, and significantly simplifying the production process. The use of a non-precious metal-based mixed oxide system significantly reduces material costs while ensuring electrode activity. This preparation process has low equipment requirements, is easy to operate, and has good repeatability and stability, effectively solving the long-standing problems of complex processes and high costs in the preparation of high-performance metal electrodes (especially titanium electrodes).

[0034] (3) This invention has advantages such as simple steps, low cost, scalability, and large-scale preparation, providing a solution for the preparation of low-cost metal-based electrodes. This electrode greatly reduces the amount of precious metals used, solves the problem of high cost of precious metal oxide coatings, and reduces production costs. Attached Figure Description

[0035] The above and other objects, features, and advantages of the invention will be apparent from the following description of preferred embodiments illustrating the gist of the invention and its use, and the accompanying drawings, in which: Figure 1 This is a physical image of the titanium anode with the MnO2 / IrO2 coating in Example 1.

[0036] Figure 2 The images shown are SEM images of the titanium anode with MnO2 / IrO2 coating in Example 1, where (A) is an SEM image with a scale bar of 100 μm and (B) is an SEM image with a scale bar of 50 μm.

[0037] Figure 3 The LSV curves of the titanium anodes with MnO2 / IrO2 coating in Examples 1 and 2 in simulated seawater (1M KOH + 0.5M NaCl) solution are shown.

[0038] Figure 4 LSV curves of untreated titanium anodes, titanium anodes with MnO2 / IrO2 coating in Examples 1 and 3, in simulated seawater (1M KOH + 0.5M NaCl) solution.

[0039] Figure 5 This is a comparison chart showing the performance of the titanium anode with MnO2 / IrO2 coating in Example 1 and the titanium-based materials in Comparative Examples 1-4 in simulated seawater (1M KOH + 0.5M NaCl) solution. Detailed Implementation

[0040] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.

[0041] This invention provides a method for preparing an anode with a MnO2 / IrO2 coating, comprising the following steps: The metal anode substrate is sequentially subjected to sandblasting, shaping, alkaline washing, acid etching, and first drying to obtain a textured metal substrate. Manganese salt, iridium salt, citric acid and alcohol solvent are mixed and allowed to stand to obtain an active metal gel; The active metal gel is coated onto the surface of the textured metal substrate, and then the second drying, shaping and cooling processes are performed in sequence. The coating-second drying-shaping-cooling process is repeated, and then sintering is performed to obtain the anode of the MnO2 / IrO2 coating.

[0042] In some embodiments, the metal anode substrate includes titanium, ruthenium, iridium, platinum, tin, iron, copper, or nickel. Preferably, the metal anode substrate includes titanium.

[0043] In some embodiments, the thickness of the MnO2 / IrO2 coating is 3~10 μm. As an example, the thickness of the MnO2 / IrO2 coating can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm, etc.

[0044] In this invention, by controlling the thickness of the MnO2 / IrO2 coating within the aforementioned range, it is helpful to form a robust coating while maintaining good performance. If the thickness of the MnO2 / IrO2 coating is too thick, surface cracking will occur; if the thickness of the MnO2 / IrO2 coating is too thin, oxide shedding will occur.

[0045] In some embodiments, the sand used in the sandblasting includes corundum, and the particle size of the corundum is 15 to 200 mesh.

[0046] In some embodiments, the surface roughness Ra of the sandblasted metal anode substrate is 8~20 μm. As an example, the surface roughness Ra of the sandblasted metal anode substrate can be 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 18 μm, and 20 μm, etc.

[0047] In this invention, by sandblasting the metal anode substrate, a roughness Ra of 8~20μm is created on the surface of the metal anode substrate, thereby enhancing the mechanical adhesion of the subsequent coating.

[0048] In this invention, since sandblasting may cause large areas of the metal anode substrate to deform, straightening is used to keep the metal anode substrate flat. The straightening method is not specifically limited and can be any conventional straightening method in the art. In some embodiments, the straightening method includes, but is not limited to, cold bending straightening, hot bending straightening, or hydraulic straightening.

[0049] In some embodiments, the alkaline washing reagent includes a sodium carbonate solution.

[0050] In some embodiments, the concentration of the sodium carbonate solution is 6 wt% to 12 wt%. As an example, the concentration of the sodium carbonate solution can be 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, and 12 wt%, etc.

[0051] In some embodiments, the alkaline washing temperature is 50~80°C, and the alkaline washing time is 0.5~1h. As examples, the alkaline washing temperature can be 50°C, 55°C, 65°C, 70°C, 75°C, and 80°C, etc., and the alkaline washing time can be 0.5h, 0.6h, 0.75h, and 1h, etc.

[0052] In this invention, the purpose of alkaline washing is to remove surface oil and adsorbed impurities.

[0053] In some embodiments, alkaline washing is followed by water washing.

[0054] In some embodiments, the acid etching reagent includes a mixed solution of oxalic acid, hydrofluoric acid, and water.

[0055] In some embodiments, the concentration of oxalic acid in the mixed solution is 5 wt% to 20 wt%. As an example, the concentration of oxalic acid in the mixed solution can be 5 wt%, 10 wt%, 15 wt%, and 20 wt%, etc.

[0056] In some embodiments, the concentration of hydrofluoric acid in the mixed solution is 0.5 wt% to 3 wt%. As an example, the concentration of hydrofluoric acid in the mixed solution can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, and 3 wt%.

[0057] In some embodiments, the acid etching temperature is 80~100℃, and the acid etching time is 1~2h. As an example, the acid etching temperature can be 80℃, 85℃, 90℃, 95℃, and 100℃, etc., and the acid etching time can be 1h, 1.25h, 1.5h, 1.75h, and 2h, etc.

[0058] In some embodiments, after the acid etching is completed, the method further includes: alternatingly washing the acid-etched metal anode substrate with alcohol and water.

[0059] In some embodiments, the alcohol washing reagent comprises an aqueous solution of ethanol.

[0060] In some embodiments, the concentration of the aqueous ethanol solution is 95 wt%.

[0061] In this invention, there is no particular limitation on the number of times the alcohol wash and water wash are alternately performed. In some embodiments, the number of times the alcohol wash and water wash are alternately performed can be 2 to 4.

[0062] In this invention, the temperature and time for the first drying are not specifically limited. In some embodiments, the first drying can be natural air drying at room temperature (25°C).

[0063] In some embodiments, the specific process of mixing includes: Citric acid and alcohol solvent were mixed for the first dispersion to obtain the metal gel precursor; The manganese salt, iridium salt, and metal gel precursor were mixed for a second dispersion.

[0064] In some embodiments, the ratio of citric acid to alcohol solvent is (20~120) mg:10 mL. For example, the ratio of citric acid to alcohol solvent can be 20 mg:10 mL, 40 mg:10 mL, 50 mg:10 mL, 60 mg:10 mL, 80 mg:10 mL, 100 mg:10 mL, and 120 mg:10 mL, etc.

[0065] In some embodiments, the molar ratio of manganese in the manganese salt to iridium in the iridium salt is (0.2~1.2):(0.1~0.6). As examples, the molar ratio of manganese in the manganese salt to iridium in the iridium salt can be 0.2:0.1, 0.2:0.6, 0.3:0.2, 0.3:0.3, 0.4:0.3, 0.5:0.3, 0.6:0.5, 0.8:0.5, 0.9:0.5, 1.2:0.6, 1.2:0.5, 1.2:0.4, 1.2:0.3, and 1.2:0.1, etc.

[0066] In this invention, by controlling the molar ratio of manganese in the manganese salt and iridium in the iridium salt within the aforementioned range, it is beneficial to form a stable alloy layer and achieve high catalytic performance. If the molar ratio of manganese in the manganese salt and iridium in the iridium salt is too large (i.e., the manganese content in the manganese salt is too high), it will lead to a significant decrease in activity; if the molar ratio of manganese in the manganese salt and iridium in the iridium salt is too small (i.e., the iridium content in the iridium salt is too high), it will lead to weak bonding with the metal substrate and easy detachment.

[0067] In some embodiments, the ratio of manganese element to alcohol solvent in the manganese salt is (0.2~1.2) mmol:10 mL. As examples, the ratio of manganese element to alcohol solvent in the salt can be 0.2 mmol:10 mL, 0.4 mmol:10 mL, 0.5 mmol:10 mL, 0.8 mmol:10 mL, 1 mmol:10 mL, and 1.2 mmol:10 mL, etc.

[0068] In some embodiments, the manganese salt includes, but is not limited to, manganese chloride.

[0069] In some embodiments, the iridium salt includes, but is not limited to, iridium chloride.

[0070] In some embodiments, the alcohol solvent includes, but is not limited to, ethylene glycol and / or glycerol.

[0071] In some embodiments, the temperature of the first dispersion is 50~70°C, and the dispersion time is 0.5~1h. As an example, the temperature of the first dispersion can be 50°C, 55°C, 60°C, 65°C, and 70°C, etc., and the dispersion time can be 0.5h, 0.6h, 0.75h, and 1h, etc.

[0072] In some embodiments, the rotational speed of the first dispersion can be 700~800 rpm.

[0073] In some embodiments, the temperature of the second dispersion is 80-90°C, and the dispersion time is 60-120 min. As an example, the temperature of the second dispersion can be 80°C, 82°C, 85°C, 88°C, and 90°C, etc., and the dispersion time can be 60 min, 80 min, 90 min, 100 min, and 120 min, etc.

[0074] In some embodiments, the rotational speed of the second dispersion can be 700~800 rpm.

[0075] In some embodiments, the settling time is 8 to 16 hours. As an example, the settling time can be 8 hours, 10 hours, 12 hours, 14 hours, 15 hours, and 16 hours, etc.

[0076] In this invention, a multi-component organic complexation-alcoholization-condensation reaction gradually occurs during the standing process, forming a Mn / Ir active metal gel with good fluidity and viscosity. In the above gel system, citric acid forms a stable complex structure with metal ions, while ethylene glycol and glycerol gradually promote the construction of the organic network structure during heating, which is beneficial to the uniform nucleation and co-distribution of MnO2 and IrO2 during subsequent sintering.

[0077] In this invention, the second drying specifically involves placing the textured metal substrate coated with the active metal gel on a flat heated plate. In some embodiments, the temperature of the second drying is 120~200°C, and the drying time is 3~10 min. As examples, the temperature of the second drying can be 120°C, 150°C, 160°C, 180°C, and 200°C, etc., and the drying time can be 3 min, 4 min, 5 min, 6 min, 8 min, 9 min, and 10 min, etc.

[0078] In some embodiments, the second drying process is repeated 4 to 6 times to ensure a uniform surface coating.

[0079] In this invention, the solvent in the active metal gel is evaporated through a second drying process, and the coating is cured and formed.

[0080] In some embodiments, the setting temperature is 200~350℃, and the setting time is 10~120min. As examples, the setting temperature can be 200℃, 220℃, 250℃, 280℃, 300℃, 320℃, and 350℃, etc., and the setting time can be 10min, 40min, 50min, 80min, 100min, and 120min, etc.

[0081] In this invention, the above-mentioned conditions are used to shape a precursor coating with a certain mechanical strength.

[0082] In this invention, the number of repetitions is not specifically limited, and a MnO2 / IrO2 coating with a thickness of 3~10μm can be formed in the end. In some embodiments, the number of repetitions can be 2~5 times.

[0083] In some embodiments, the sintering temperature is 400~650℃, and the sintering time is 1~8h. As examples, the sintering temperature can be 400℃, 450℃, 500℃, 550℃, 600℃, and 650℃, etc., and the sintering time can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 5h, 6h, 7h, and 8h, etc.

[0084] In some embodiments, the heating rate of sintering is 1 to 5 °C / min. As an example, the heating rate of sintering can be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, and 5 °C / min, etc.

[0085] In this invention, by sintering under the above conditions, the organic groups in the coating are fully decomposed, the metal ions undergo an oxidation reaction, and finally a temperature-controlled MnO2 / IrO2 oxide coating is formed.

[0086] In some embodiments, the cooling may be natural cooling.

[0087] The technical solution of the present invention is also applicable to the preparation of electrodes with MnO2 / IrO2 coatings from other similar metals.

[0088] The MnO2 / IrO2 coated anode prepared according to the method of the present invention can be used for seawater electrolysis, medical water and industrial wastewater treatment.

[0089] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0090] Example 1 The preparation of the MnO2 / IrO2 coated titanium anode includes the following steps: A 10mm × 20mm sample of industrial pure titanium (Ti) with a thickness of 1mm was first sandblasted with 15-30 mesh diamond abrasive to create a rough surface with an uneven structure of 10μm Ra. After sandblasting, the titanium substrate was cold-bent and shaped to maintain a flat state. Then, the titanium sheet was placed in a 10wt% sodium carbonate solution and alkaline washed at 80℃ for 0.5h. After rinsing with deionized water, the titanium substrate was immersed in a mixed solution of oxalic acid, hydrofluoric acid, and water (oxalic acid concentration of 10wt% and hydrofluoric acid concentration of 3wt%) and acid-etched at 80℃ for 1h. Finally, it was washed three times alternately with ethanol and water. Then, it was air-dried at room temperature (25℃) to obtain a gray textured metal substrate. Weigh 60 mg of citric acid and add it to 10 mL of ethylene glycol. Stir at 600 rpm for 60 min at 60 °C until it is completely dissolved to form a transparent gel precursor. Then add 0.2 mmol of anhydrous MnCl2 and 0.1 mmol of IrCl3·3H2O to the gel precursor while maintaining the temperature at 80 °C and stirring at 600 rpm for 60 min to completely dissolve the metal salt and form a homogeneous sol system. Let it stand for 12 h to obtain an active metal gel. The active metal gel was coated onto both sides of a gray matte metal substrate using a glass scraping method, with a coating thickness of 5 μm on both sides. The coated titanium substrate was then dried on a 160°C flat heating plate for 10 min to allow the solvent in the gel to evaporate and the coating to solidify. This drying process was repeated 5 times. The electrode was then placed at 300°C for 10 min to form a precursor coating with a certain mechanical strength. It was then cooled to 25°C, and the above "coating-drying-low temperature setting-cooling" process was repeated 3 times. Subsequently, the pre-shaped coated titanium sheet was placed in a muffle furnace and heated to 500°C at a rate of 5°C / min. It was then sintered at this temperature for 2 h to allow the organic groups in the coating to fully decompose and the metal ions to undergo an oxidation reaction. Finally, a stable MnO2 / IrO2 coating with a thickness of 8 μm was formed on both sides, resulting in a uniform and dense catalytic active layer.

[0091] Figure 1 This is a photograph of the titanium anode with the MnO2 / IrO2 coating prepared in Example 1.

[0092] Figure 2 The images show SEM images of the MnO2 / IrO2 coated titanium anode prepared in Example 1, where (A) is a 100 μm scale SEM image and (B) is a 50 μm scale SEM image. Figure 2 As can be seen from the scanning electron microscope, a uniform structure is formed on the surface of the material.

[0093] Example 2 The preparation of the titanium anode with MnO2 / IrO2 coating differs from that in Example 1 in that the total molar amount of MnCl2 (anhydrous) and IrCl3·3H2O remains unchanged (0.3 mmol), while the molar ratio of MnCl2 to IrCl3·3H2O is changed to 4:1, 3:1, 1:1, 1:2 and 1:3.

[0094] Everything else is the same as in Example 1.

[0095] Example 3 The preparation of the titanium anode with MnO2 / IrO2 coating differs from that in Example 1 in that the sintering time is changed to 4h, 6h and 8h respectively.

[0096] Everything else is the same as in Example 1.

[0097] Comparative Example 1 The preparation of RuO2 titanium-based material differs from that in Example 1 in that 0.2 mmol MnCl2 (anhydrous) and 0.1 mmol IrCl3·3H2O are replaced with 0.3 mmol RuCl3.

[0098] Everything else is the same as in Example 1.

[0099] Comparative Example 2 The preparation of PtO2 titanium-based materials differs from that in Example 1 in that 0.2 mmol MnCl2 (anhydrous) and 0.1 mmol IrCl3·3H2O are replaced with 0.3 mmol K2PtCl6.

[0100] Comparative Example 3 The preparation of MnO2 titanium-based materials differs from that in Example 1 in that 0.2 mmol MnCl2 (anhydrous) and 0.1 mmol IrCl3·3H2O are replaced with 0.3 mmol MnCl2.

[0101] Comparative Example 4 The preparation of IrO2 titanium-based material differs from that in Example 1 in that 0.2 mmol MnCl2 (anhydrous) and 0.1 mmol IrCl3·3H2O are replaced with 0.3 mmol IrCl3.

[0102] Performance testing The following tests were performed on the MnO2 / IrO2 coated titanium anodes prepared in the examples, the titanium-based material prepared in the comparative examples, and the untreated titanium anodes (Rare Ti): On a CHI-760E electrochemical workstation, a conventional three-electrode configuration was used. The working electrodes were the MnO2 / IrO2 coated titanium anode prepared in the examples, the titanium-based material prepared in the comparative examples, and an untreated titanium anode (RareTi). A saturated calomel electrode was used as the reference electrode, and a 4.0 mm diameter graphite rod was used as the counter electrode. The electrolyte consisted of alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl, pH = 14). LSV measurements were performed at a constant temperature of 298 K. Uncompensated LSV measurements were taken at a scan rate of 5 mV / s. -1 The OER was performed under specific conditions, with a potential range of 1.07 to 1.87 V (relative to the reversible hydrogen electrode).

[0103] Figure 3 The image shows the LSV curves of the MnO2 / IrO2 coated titanium anodes prepared in Examples 1 and 2, measured according to the above test methods, in simulated seawater (1M KOH + 0.5M NaCl) solution. Figure 3 It can be seen that the catalytic performance is optimal when the Mn / Ir molar ratio is 2:1.

[0104] Figure 4The figures shown are LSV curves of an untreated titanium anode (Rare Ti), and titanium anodes with MnO2 / IrO2 coatings prepared in Examples 1 and 3, in simulated seawater (1M KOH + 0.5M NaCl) solution, measured according to the above test method. Figure 4 It can be seen that the optimal performance is achieved when the Mn / Ir molar ratio is 2:1 and the sintering time is 2 hours.

[0105] Figure 5 The figures shown are LSV curves of the titanium anode with MnO2 / IrO2 coating in Example 1 and the titanium-based materials in Comparative Examples 1-4 in simulated seawater (1M KOH + 0.5M NaCl) solution, measured according to the above test method. Figure 5 It can be seen that, after trying various precious metals, the MnIr ratio was found to have good catalytic performance while reducing production costs.

[0106] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.

Claims

1. A method for preparing an anode with a MnO2 / IrO2 coating, characterized in that, Includes the following steps: The metal anode substrate is sequentially subjected to sandblasting, shaping, alkaline washing, acid etching, and first drying to obtain a textured metal substrate. Manganese salt, iridium salt, citric acid, and alcohol solvent are mixed and allowed to stand to obtain an active metal gel. The active metal gel is coated onto the surface of the textured metal substrate, and then the second drying, shaping and cooling are performed in sequence. The coating-second drying-shaping-cooling process is repeated, and then sintering is performed to obtain the anode of the MnO2 / IrO2 coating. The molar ratio of manganese in the manganese salt to iridium in the iridium salt is (0.2~1.2):(0.1~0.6). The setting temperature is 200~350℃, and the setting time is 10~120min; The sintering temperature is 400~650℃, and the sintering time is 1~8h.

2. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The thickness of the MnO2 / IrO2 coating is 3~10μm; The metal anode substrate includes titanium, ruthenium, iridium, platinum, tin, iron, copper, or nickel.

3. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The sand used in the sandblasting includes corundum, and the particle size of the corundum is 15~200 mesh; The surface roughness Ra of the metal anode substrate after sandblasting is 8~20μm.

4. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The alkaline washing reagent includes a sodium carbonate solution with a concentration of 6 wt% to 12 wt%. The alkaline washing temperature is 50~80℃, and the alkaline washing time is 0.5~1h.

5. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The acid etching reagents include a mixed solution of oxalic acid, hydrofluoric acid and water; The concentration of oxalic acid in the mixed solution is 5wt%~20wt%; The concentration of hydrofluoric acid in the mixed solution is 0.5wt%~3wt%; The acid etching temperature is 80~100℃, and the acid etching time is 1~2h.

6. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, After the acid etching is completed, the process also includes: alternating alcohol washing and water washing of the acid-etched metal anode substrate; The alcohol washing reagent includes an aqueous solution of ethanol with a concentration of 95 wt%.

7. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The specific process of mixing includes: Citric acid and alcohol solvent were mixed for the first dispersion to obtain the metal gel precursor; The manganese salt, iridium salt, and metal gel precursor were mixed for a second dispersion.

8. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The ratio of citric acid to alcohol solvent is (20~120) mg: 10 mL; The ratio of manganese element in the manganese salt to the alcohol solvent is (0.2~1.2) mmol: 10 mL; The manganese salt includes manganese chloride; The iridium salt includes iridium chloride; The alcohol solvents include ethylene glycol and / or glycerol.

9. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 7, characterized in that, The temperature of the first dispersion is 50~70℃, and the dispersion time is 0.5~1h; The second dispersion temperature is 80~90℃, and the second dispersion time is 60~120min.

10. The method for preparing the anode of the MnO2 / IrO2 coating according to claim 1, characterized in that, The second drying temperature is 120~200℃, and the second drying time is 3~10min.

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