A novel high-stability, anti-fouling coated titanium anode, its preparation method and application

Abstract

This invention belongs to the field of electrochemical electrode materials technology, specifically relating to a novel high-stability, anti-fouling coated titanium anode and its preparation method, comprising: (1) pretreating a TA2 pure titanium substrate; (2) anolyzing the pretreated substrate in an ethylene glycol aqueous solution containing ammonium fluoride to grow a TiO2 nanotube array on the substrate surface, followed by thermal reduction to generate a sub-titanium oxide nanotube conductive intermediate layer; (3) immersing the substrate with the sub-titanium oxide nanotube conductive intermediate layer into a coating solution, performing a coating-drying-thermal decomposition operation to generate an iridium-tantalum composite oxide active layer; (4) immersing the substrate in a cerium nitrate ethanol solution to generate an iridium-tantalum-cerium composite oxide active layer enriched with cerium islands on the surface, thus obtaining a novel high-stability, anti-fouling coated titanium anode. This coated titanium anode is used in the production of electrolytic copper foil or the recovery of copper from acidic etching waste liquid. This invention enables the anode to maintain low tank pressure and high stability during long-term operation in the production of electrolytic copper foil and the recovery of copper from acidic etching waste liquid.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical electrode materials technology, specifically relating to a novel high-stability, anti-fouling coated titanium anode, its preparation method, and its application. Background Technology

[0002] Coated titanium anodes are a type of insoluble anode with a pure titanium or titanium alloy matrix coated with a noble metal oxide or ceramic coating. They combine the corrosion resistance of titanium metal with the high electrocatalytic activity of the coating material, and are widely used in chlor-alkali industries, electrolytic metallurgy, electrochemical synthesis, and metal surface treatment. In the production of electrolytic copper foil, coated titanium anodes serve as oxygen-evolving anodes, and their performance directly determines the uniformity of copper foil thickness, surface smoothness, and power consumption. In the copper recovery process of acidic etching waste liquid, coated titanium anodes perform the anodic oxygen evolution function of copper ion electrodeposition, and are a key component for maintaining the recycling of waste liquid.

[0003] The electrolyte used in the production of electrolytic copper foil is typically a copper sulfate-sulfuric acid system, with the copper ion concentration maintained at 70-90 g / L, the sulfuric acid concentration at 90-120 g / L, and the anolyte current density as high as 8000-10000 A / m. 2 Under these conditions of high acidity, high copper content, and high current density, a violent oxygen evolution reaction occurs on the anode surface. Numerous oxygen bubbles erode the coating surface at high speed, causing continuous cavitation wear. More significantly, the electrolytic copper raw materials inevitably contain trace amounts of lead impurities. Lead ions in the electrolyte typically have a concentration of 1-5 mg / L, which are oxidized at the high potential of the anode and combine with sulfate ions to form lead sulfate deposits. Lead sulfate has a solubility of only about 7 ppm in a 10% sulfuric acid solution at 25°C, making it almost insoluble. Therefore, it continuously accumulates on the anode surface, forming a dense insulating scale layer. This scale layer reduces the effective anode area, causes uneven current distribution, and results in longitudinal streaks or even pinholes on the copper foil. In severe cases, it forces production to stop for cleaning or replacement of the anode. The cost of replacing the anode in a single electrolytic cell can reach hundreds of thousands of yuan, and the shutdown also results in lost production capacity.

[0004] Existing technologies address these issues primarily from three directions. First, electrolyte purification involves removing lead ions through ion exchange resins or chemical precipitation to reduce lead ion concentration in the electrolyte and decrease scale formation sources. However, purification equipment requires significant investment and has high operating costs. Furthermore, excessive purification may alter the balance between copper ions and sulfuric acid in the electrolyte, affecting copper foil deposition quality and potentially introducing new impurity ions. Second, anode maintenance involves periodic acid washing, high-pressure water rinsing, or mechanical scraping to remove scale. However, this requires shutdown operations, reducing equipment utilization, and frequent cleaning itself accelerates coating wear and shortens anode lifespan. Third, coating material improvement addresses the issue. While traditional IrO2-Ta2O5 binary composite oxide coatings exhibit good oxygen evolution catalytic activity and corrosion resistance, their relatively smooth and dense surface, coupled with strong adhesion between PbSO4 crystal nuclei and the coating, makes it difficult for scale to be naturally carried away by electrolyte flow. Additionally, the coating's hardness is limited, typically ranging from 300-500 HV, making it prone to fatigue cracking and peeling under cavitation. If local defects appear in the coating, the electrolyte will penetrate into the titanium substrate, and a non-conductive titanium dioxide passivation layer will be formed on the substrate surface, leading to a continuous increase in cell voltage and energy consumption, and eventually anode failure.

[0005] The aforementioned existing technologies, when addressing either scaling or wear as a single problem, often overlook the mutually reinforcing effects of the two. Scale buildup leads to uneven current distribution, with increased local current density accelerating wear; conversely, the freshly exposed surface exposed by wear is more prone to adsorbing lead ions and forming scale, creating a positive feedback loop. Furthermore, existing coatings are mostly physically attached to the titanium substrate or simply chemically bonded. During frequent start-ups and shutdowns of the electrolytic cell, the internal stress generated by the difference in thermal expansion coefficients between the coating and the substrate easily causes the coating to crack and peel off. Therefore, there is a need to design a novel, highly stable, anti-scaling coated titanium anode, along with its preparation method and applications. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this paper provides a novel coated titanium anode with high stability and anti-fouling properties, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a novel, highly stable, anti-fouling coated titanium anode, comprising the following steps: (1) Pretreatment of TA2 pure titanium matrix; (2) The pretreated substrate is placed in an aqueous solution of ammonium fluoride in ethylene glycol for anodic oxidation, so that TiO2 nanotube arrays are grown on the substrate surface. After being rinsed with deionized water and dried at 80-100℃, the substrate with TiO2 nanotube arrays is thermally reduced in a mixed atmosphere of hydrogen and nitrogen to generate a sub-titanium oxide nanotube conductive intermediate layer. Step (3) involves dissolving chloroiridium acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone to prepare a coating solution. The volume ratio of n-butanol to acetylacetone is 8:1 to 10:1. n-Butanol has a high boiling point and slowly evaporates during infrared drying, allowing the metal salt to be uniformly deposited on the substrate surface. The substrate with a conductive intermediate layer of sub-titanium oxide nanotubes is immersed in the coating solution and coated using an dip-coating method. After drying under an infrared lamp, it is placed in a muffle furnace and held at 480-520℃ for 10-12 minutes to crystallize the iridium-tantalum oxide. This process is repeated 8-12 times to ensure the active layer is densely deposited layer by layer. During the layer-by-layer coating process, each layer of coating solution penetrates into the micropores and cracks of the previous layer, acting as a filler and repair agent. Ultimately, the active layer becomes dense and complete, with reduced porosity. Finally, annealing is performed at 520-550℃ for 1-1.5 hours to allow sufficient interfacial diffusion between layers, forming a gradient transition layer and further improving the overall integrity and bonding strength of the coating.

[0008] Step (4) involves immersing the substrate with the iridium-tantalum composite oxide active layer in a cerium nitrate ethanol solution. The cavitation and acoustic flow effects generated by ultrasonic impregnation cause cerium ions to adsorb onto the surface of the active layer and penetrate into the surface micropores and rough depressions. After drying, the substrate is thermally decomposed at 350-400℃ for 10-15 minutes. This temperature is lower than the recrystallization temperature of the iridium-tantalum oxide, which will not damage the main crystalline structure of the active layer, and is sufficient to decompose cerium nitrate into cerium oxide. Due to the short thermal decomposition time and low temperature, cerium oxide only nucleates and grows on the outermost layer of the active layer, forming discrete nanoislands with a particle size of 20-50 nm, an island spacing of 60-120 nm, and a coverage of 15%-30%.

[0009] Cerium oxide has a lower surface energy than iridium tantalum oxide, and under the thermodynamic drive of the surface, it is stably anchored on the surface of the active layer without diffusing into the coating.

[0010] In step (1), the specific pretreatment process is as follows: first, the TA2 pure titanium substrate is roughened by sandblasting with 60-80 mesh brown corundum sand, then it is degreased by alkaline washing at 60-80℃ for 20-40 minutes in a sodium hydroxide solution with a mass fraction of 8%-12%, and then etched at 85-95℃ for 1-2 hours in an oxalic acid solution with a mass fraction of 10%-15%.

[0011] When coated titanium anodes are used in the long-term operation of electrolytic copper foil production and copper recovery from acid etching waste liquid, the difference in thermal expansion coefficients between the titanium substrate and the surface active layer causes cyclic internal stress due to temperature fluctuations caused by frequent start-ups and shutdowns of the electrolytic cell, making the coating prone to cracking and peeling. Existing technologies mostly use physical adhesion or simple chemical bonding methods to directly coat the active layer onto the surface of the titanium substrate, resulting in limited interfacial bonding strength and difficulty in withstanding thermal cycling stress under high current density.

[0012] Step (1) of this application involves pretreatment of the TA2 pure titanium substrate by sandblasting roughening, alkaline washing for degreasing, and acid etching. Sandblasting roughening creates a micron-level uneven structure on the substrate surface, increasing the physical anchoring area for subsequent coatings. Alkaline washing removes grease contaminants from the substrate surface, preventing contaminants from blocking direct contact between the coating and the substrate. Oxalic acid etching forms chemically active sites on the titanium surface, making subsequent anodizing reactions easier to initiate. These three pretreatment steps provide a clean, rough, and chemically active surface foundation for subsequent in-situ nanotube growth.

[0013] In step (2), the specific process of anodizing is as follows: the pretreated substrate is placed in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution is prepared by mixing ethylene glycol and deionized water in a mass ratio of 85:15 to 95:5. The amount of ammonium fluoride is 0.3%-0.8% of the total mass of the ethylene glycol aqueous solution. The substrate is used as the anode and the platinum sheet is used as the cathode. A DC voltage of 35-45V is applied at room temperature, and anodizing is performed for 1-2 hours to grow a TiO2 nanotube array on the surface of the substrate.

[0014] In step (2), the specific steps of thermal reduction are as follows: the substrate with TiO2 nanotube array is placed in a tube furnace, the vacuum is evacuated to below 5 Pa, a mixed gas of H2 and N2 is introduced, the gas flow rate is 100-150 mL / min, the temperature is increased to 840-880℃ at 3-5℃ / min, the temperature is reduced at a constant temperature for 30-50 min, and after natural cooling, a sub-titanium oxide nanotube conductive intermediate layer is obtained.

[0015] The volume ratio of H2 to N2 in the mixed gas is 1:50 to 1:80; the diameter of the TiO2 nanotube array is 50-100 nm, the wall thickness is 10-15 nm, the depth is 2-5 μm, and the thickness of the conductive intermediate layer of the titanium suboxide nanotube is 2-5 μm.

[0016] Step two involves growing a titanium oxide nanotube array on the pretreated substrate surface using an anodic oxidation process. Using ammonium fluoride as the electrolyte and ethylene glycol as the solvent, electrochemical oxidation occurs on the titanium substrate surface under a DC voltage of 35-45V. Titanium atoms lose electrons and combine with oxygen in the solution to form titanium oxide. Due to the selective etching effect of fluoride ions on the titanium oxide, nanoscale pits are formed on the titanium oxide surface. These pits grow directionally perpendicular to the surface under the influence of an electric field, ultimately forming a hollow nanotube array structure. The nanotubes have a diameter of 50-100 nm, a wall thickness of 10-15 nm, and a depth of 2-5 μm. This high aspect ratio structure increases the contact area between the intermediate layer and the subsequent active layer by 5-10 times compared to a planar structure, creating a three-dimensional mechanical interlocking effect.

[0017] After anodizing, the titanium dioxide nanotube array is rinsed with deionized water to remove residual electrolyte, and then thermally reduced in a mixed atmosphere of hydrogen and nitrogen. At high temperature, hydrogen reacts with titanium dioxide, removing some oxygen atoms from the titanium dioxide lattice to form oxygen vacancies, transforming titanium dioxide into sub-titanium dioxide. Sub-titanium dioxide has a rutile crystal structure, with oxygen vacancies forming continuous electron transport channels in the lattice, resulting in a room temperature conductivity exceeding 1000 S / cm, far surpassing the insulating properties of titanium dioxide. The lattice distortion of the nanotube walls further increases the electron transport paths, enabling the intermediate layer to construct a highly efficient three-dimensional conductive network between the active layer and the substrate. Simultaneously, the Vickers hardness of sub-titanium dioxide is approximately 600-800 HV, higher than the 200-300 HV of pure titanium matrix, providing some resistance to mechanical damage caused by bubble erosion. The coefficient of thermal expansion of sub-titanium dioxide falls between that of the titanium matrix and iridium-tantalum oxide, acting as a thermal stress buffer during temperature fluctuations and reducing interfacial shear stress.

[0018] The raw materials for electrolytic copper contain trace amounts of lead impurities. The concentration of lead ions in the electrolyte is typically 1-5 mg / L, which are oxidized to Pb at the high potential of the anode. 2+ It combines with sulfate ions to form lead sulfate deposits. Lead sulfate has extremely low solubility in acidic environments and will continuously accumulate on the anode surface to form a dense insulating scale layer, resulting in uneven current distribution and longitudinal streaks on the copper foil. The traditional iridium-tantalum binary composite oxide coating in existing technology has a smooth and dense surface, and the adhesion between the lead sulfate crystal nuclei and the coating is strong, making it difficult for the scale to be naturally carried away by the electrolyte flow after it forms.

[0019] In step (3), the mass ratio of chloroiridic acid to butyl tantalate is 55-65:40; the mixed solvent of n-butanol and acetylacetone provides an anhydrous environment to prevent butyl tantalate from hydrolyzing upon contact with water, while acetylacetone and butyl tantalate form a coordination complex to improve the stability of the coating solution.

[0020] In step (3) of this application, the substrate with a conductive intermediate layer of titanium suboxide nanotubes is immersed in a coating solution and coated using an dip-coating method. After drying under an infrared lamp, it is placed in a muffle furnace and held at 480-520℃ for 10-12 minutes to crystallize the iridium-tantalum oxide. This process is repeated 8-12 times to ensure the active layer is densely deposited layer by layer. During the layer-by-layer coating process, each layer of coating solution penetrates into the micropores and cracks of the previous layer, playing a filling and repairing role. Ultimately, the active layer is dense and complete, and the porosity is reduced. Finally, it is annealed at 520-550℃ for 1-1.5 hours to allow sufficient interfacial diffusion between layers, forming a gradient transition layer, which further improves the overall integrity and bonding strength of the coating.

[0021] In step (4), the concentration of the cerium nitrate ethanol solution is 0.05-0.15 mol / L, the ultrasonic impregnation power is 200-400W, the time is 10-20 min, and the temperature is 25-35℃.

[0022] In step (4) of this application, the substrate with the iridium-tantalum composite oxide active layer is immersed in a cerium nitrate ethanol solution. The cavitation and acoustic flow effects generated by ultrasonic impregnation cause cerium ions to be adsorbed on the surface of the active layer and penetrate into the surface micropores and rough depressions. After drying, it is thermally decomposed at 350-400℃ for 10-15 minutes. This temperature is lower than the recrystallization temperature of iridium-tantalum oxide, which will not destroy the main crystallization structure of the active layer, and is sufficient to decompose cerium nitrate into cerium oxide. Due to the short thermal decomposition time and low temperature, cerium oxide only nucleates and grows on the outermost layer of the active layer, forming discrete nano-islands with a particle size of 20-50 nm, an island spacing of 60-120 nm, and a coverage of 15%-30%. The surface energy of cerium oxide is lower than that of iridium-tantalum oxide, and it is stably anchored on the surface of the active layer under the thermodynamic drive of the surface, without diffusing into the coating interior.

[0023] The cerium oxide nanoislands have a particle size of 20-50 nm, an island spacing of 60-120 nm, and an island coverage of 15%-30%.

[0024] In step (4), the specific steps of impregnation-drying-thermal decomposition are as follows: the substrate with the iridium-tantalum composite oxide active layer is immersed in cerium nitrate ethanol solution, ultrasonic impregnation is performed so that cerium ions are adsorbed on the surface of the active layer and penetrate into the surface micropores, and after drying, it is placed in a muffle furnace for thermal decomposition at 350-400℃ for 10-15 minutes, so that the cerium salt is decomposed to form cerium oxide nano islands and anchored on the surface of the active layer.

[0025] The presence of these cerium oxide nanoislands optimizes the performance of the active layer in three ways. First, in terms of morphology, the nanoislands increase the surface roughness Ra of the active layer from 0.2-0.5 μm in smooth coatings to 0.6-1.2 μm. This reduces the actual contact area between the lead sulfate crystal nuclei and the coating surface. According to adhesion theory, solid-solid interface adhesion is proportional to the contact area; a smaller contact area results in lower adhesion. The scale layer becomes a loose, island-like structure rather than a continuous, dense film, making it easier to detach under electrolyte flow and bubble shearing. Second, in terms of electrocatalysis, cerium oxide possesses Ce... 4+ / Ce 3+ The redox pair, with a standard electrode potential of approximately 1.61V, can undergo oxidation at the anodic working potential. This reaction competes with the oxygen evolution reaction, altering the electron distribution on the anodic surface and resulting in a more uniform distribution of active sites for the oxygen evolution reaction. This prevents localized overpotentials that could lead to rapid localized oxidation and deposition of lead ions. Thirdly, regarding structural stability, the introduction of cerium oxide refines the IrO2 grain size. Grain refinement improves the coating's hardness and strength, enhancing its resistance to bubble erosion.

[0026] This application presents a novel, highly stable, anti-fouling coated titanium anode design that combines a conductive intermediate layer of sub-titanium oxide nanotubes with an active layer of iridium-tantalum-cerium composite oxide enriched on the surface islands. The three-dimensional conductive network of the intermediate layer prevents substrate passivation, while the nanotube structure provides mechanical anchoring and buffers thermal stress. The discrete cerium oxide nanoislands in the active layer reduce lead sulfate adhesion and optimize electrocatalytic activity. Multiple thermal decomposition and low-temperature anchoring processes ensure dense crystallization of the coating and effective formation of cerium oxide nanoislands. When trace amounts of lead ions in the electrolyte are anolyzed, the loose scale layer is easily carried away by the fluid, preventing a reduction in effective area and an increase in local current density, thereby reducing cavitation wear. Simultaneously, the dense crystalline structure of the active layer resists bubble erosion, preventing coating peeling and exposure of fresh surfaces, breaking the positive feedback chain of mutually reinforcing scaling and wear, and enabling the anode to maintain long-term stable operation in electrolytic copper foil production and copper recovery from acidic etching wastewater.

[0027] The coated titanium anode was prepared by the method described above.

[0028] The coated titanium anode is used for the production of electrolytic copper foil or the recovery of copper from acid etching waste liquid, and the electrolyte is a copper sulfate-sulfuric acid system.

[0029] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This application employs a pretreated TA2 pure titanium substrate to generate a sub-titanium oxide nanotube conductive intermediate layer in situ on the surface. This intermediate layer is derived from the thermal reduction of a titanium oxide nanotube array through a mixed atmosphere of hydrogen and nitrogen, forming an integral structure with the titanium substrate rather than a simple physical attachment. The nanotube structure extends throughout the thickness of the intermediate layer, constructing a three-dimensional conductive channel between the active layer and the substrate. This prevents passivation of the substrate surface caused by electrolyte penetration, ensuring that the anode maintains a low interfacial resistance in the copper sulfate-sulfuric acid system over a long period.

[0030] 2. After coating the iridium-tantalum composite oxide active layer, this application uses ultrasonic impregnation with cerium nitrate ethanol solution to adsorb cerium ions onto the surface of the active layer and penetrate into the surface micropores. Then, low-temperature thermal decomposition at 350-400℃ decomposes the cerium salt into cerium oxide nano-islands on the outermost layer of the active layer. These nano-islands are directly anchored to the surface of the active layer, exhibiting a discrete distribution, increasing surface roughness, reducing the actual contact area between lead sulfate crystal nuclei and the coating surface, decreasing adhesion, and resulting in a loose, island-like scale layer rather than a continuous, dense film. This scale layer is easily detached under the flow of electrolyte and the shearing action of bubbles, thereby inhibiting the continuous accumulation of lead sulfate.

[0031] 3. This application uses chloroiridium acid and butyl tantalate as precursors. Through impregnation-coating and multiple thermal decomposition processes, a dense iridium-tantalum composite oxide active layer is formed on the surface of the conductive intermediate layer of titanium suboxide nanotubes. Then, cerium oxide nano-islands are anchored on the surface of the active layer through post-treatment to construct the iridium-tantalum-cerium composite oxide active layer. The process sequence of high-temperature crystallization followed by low-temperature post-treatment avoids abnormal grain growth and coating cracking caused by the simultaneous decomposition of cerium salt and iridium-tantalum precursors, ensuring a dense and intact active layer. The presence of cerium oxide nano-islands optimizes the electronic structure of the active layer surface, promotes the adsorption and desorption of oxygen evolution reaction intermediates, and maintains stable oxygen evolution catalytic activity of the anode in the copper sulfate-sulfuric acid system.

[0032] 4. The novel high-stability, anti-fouling coated titanium anode of this application combines the high conductivity of the sub-titanium nanotube conductive intermediate layer with the anti-fouling properties of the iridium-tantalum-cerium composite oxide active layer enriched with cerium islands on the surface. The intermediate layer prevents substrate passivation and improves mechanical anchoring, while the active layer reduces lead sulfate adhesion and maintains catalytic activity. The two are structurally and functionally matched. When trace amounts of lead ions in the electrolyte are anolyzed, the loose scale layer is easily carried away by the fluid, avoiding a reduction in effective area and an increase in local current density, thereby reducing cavitation wear. At the same time, the dense crystalline structure of the active layer resists bubble erosion, preventing the coating from peeling off and exposing a fresh surface, breaking the positive feedback chain of mutually reinforcing scaling and wear, and enabling the anode to maintain long-term stable operation in the production of electrolytic copper foil and the recovery of copper from acidic etching waste liquid. Attached Figure Description

[0033] Figure 1 This is a schematic diagram comparing the cell pressure of the coated titanium anodes prepared in the embodiments of the present invention and the comparative examples.

[0034] Figure 2 This is a schematic diagram comparing the lead sulfate deposition amount of the coated titanium anodes prepared in the embodiments of the present invention and the comparative examples.

[0035] Figure 3 This is a schematic diagram comparing the failure time of the coated titanium anodes prepared in the embodiments of the present invention and the comparative examples. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the specific embodiments of this application, the sources of the main raw materials are briefly described as follows: TA2 pure titanium substrate: purchased from Baoji Titanium Industry Co., Ltd., CAS number 7440-32-6, model TA2 pure titanium plate.

[0038] Brown fused alumina sand: purchased from Zhengzhou Haixu Abrasives Co., Ltd., CAS number 1344-28-1, model 60-80 mesh sandblasting grade brown fused alumina.

[0039] Oxalic acid: purchased from Tianjin Damao Chemical Reagent Factory, CAS number 144-62-7.

[0040] Ammonium fluoride: purchased from Aladdin Biochemical Technology Co., Ltd., CAS No. 12125-01-8.

[0041] Platinum flakes: Purchased from Guizhou Platinum Industry Co., Ltd., CAS No. 7440-06-4, model is high purity platinum flakes.

[0042] Cerium nitrate: purchased from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 10294-41-4, grade cerium nitrate hexahydrate, analytical grade.

[0043] Chloroiridic acid: purchased from Heraeus Precious Metals Technology (China) Co., Ltd., CAS No. 110802-84-1.

[0044] Butyl tantalate: purchased from Nanjing Jinyuan Chemical Co., Ltd., CAS No. 5593-70-4.

[0045] The technical solution of this application is as follows: A method for preparing a novel, highly stable, anti-fouling coated titanium anode, comprising the following steps: (1) Pretreatment of TA2 pure titanium matrix; (2) The pretreated substrate is placed in an aqueous solution of ammonium fluoride in ethylene glycol for anodic oxidation, so that TiO2 nanotube arrays are grown on the substrate surface. After being rinsed with deionized water and dried at 80-100℃, the substrate with TiO2 nanotube arrays is thermally reduced in a mixed atmosphere of hydrogen and nitrogen to generate a sub-titanium oxide nanotube conductive intermediate layer. (3) Dissolve chloroiridium acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone to prepare a coating solution, wherein the volume ratio of n-butanol to acetylacetone is 8:1 to 10:1. Immerse the substrate with the conductive intermediate layer of titanium suboxide nanotubes into the coating solution and perform coating-drying-thermal decomposition operation 8-12 times. Each thermal decomposition is held at 480-520℃ for 10-12 min to crystallize the iridium-tantalum oxide. Finally, anneal at 520-550℃ for 1-1.5 h to generate an iridium-tantalum composite oxide active layer. (4) The substrate with the iridium-tantalum composite oxide active layer is immersed in cerium nitrate ethanol solution and ultrasonically impregnated to allow cerium ions to be adsorbed on the surface of the active layer and penetrate into the surface micropores. After drying, it is thermally decomposed at 350-400℃ for 10-15 minutes to decompose the cerium salt to form cerium oxide nano islands and anchor them on the surface of the active layer, thus generating an iridium-tantalum-cerium composite oxide active layer with cerium enriched on the surface island, thereby obtaining a novel high-stability anti-scaling coated titanium anode.

[0046] In step (1), the specific pretreatment process is as follows: first, the TA2 pure titanium substrate is roughened by sandblasting with 60-80 mesh brown corundum sand, then it is degreased by alkaline washing at 60-80℃ for 20-40 minutes in a sodium hydroxide solution with a mass fraction of 8%-12%, and then etched at 85-95℃ for 1-2 hours in an oxalic acid solution with a mass fraction of 10%-15%.

[0047] In step (2), the specific process of anodizing is as follows: the pretreated substrate is placed in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution is prepared by mixing ethylene glycol and deionized water in a mass ratio of 85:15 to 95:5. The amount of ammonium fluoride is 0.3%-0.8% of the total mass of the ethylene glycol aqueous solution. The substrate is used as the anode and the platinum sheet is used as the cathode. A DC voltage of 35-45V is applied at room temperature, and anodizing is performed for 1-2 hours to grow a TiO2 nanotube array on the surface of the substrate.

[0048] In step (2), the specific steps of thermal reduction are as follows: the substrate with TiO2 nanotube array is placed in a tube furnace, the vacuum is evacuated to below 5 Pa, a mixed gas of H2 and N2 is introduced, the gas flow rate is 100-150 mL / min, the temperature is increased to 840-880℃ at 3-5℃ / min, the temperature is reduced at a constant temperature for 30-50 min, and after natural cooling, a sub-titanium oxide nanotube conductive intermediate layer is obtained.

[0049] The volume ratio of H2 to N2 in the mixed gas is 1:50 to 1:80; the diameter of the TiO2 nanotube array is 50-100 nm, the wall thickness is 10-15 nm, the depth is 2-5 μm, and the thickness of the conductive intermediate layer of the titanium suboxide nanotube is 2-5 μm.

[0050] In step (3), the mass ratio of chloroiridic acid to butyl tantalate is 55-65:40.

[0051] In step (4), the concentration of the cerium nitrate ethanol solution is 0.05-0.15 mol / L, the ultrasonic impregnation power is 200-400W, the time is 10-20 min, and the temperature is 25-35℃; the particle size of the cerium oxide nanoislands is 20-50 nm, the island spacing is 60-120 nm, and the island coverage is 15%-30%.

[0052] The specific steps of coating-drying-thermal decomposition are as follows: the substrate with the conductive intermediate layer of titanium suboxide nanotubes is immersed in the coating solution, coated by dip-coating method, dried under infrared lamp and placed in muffle furnace, and kept at 480-520℃ for 10-12 min to crystallize iridium tantalum oxide. The operation is repeated until the total number of times is 8-12, and finally annealed at 520-550℃ for 1-1.5 h.

[0053] The coated titanium anode was prepared by the method described above.

[0054] The coated titanium anode is used for the production of electrolytic copper foil or the recovery of copper from acid etching waste liquid, and the electrolyte is a copper sulfate-sulfuric acid system.

[0055] This invention utilizes a design of a conductive intermediate layer of titanium suboxide nanotubes and an active layer of iridium-tantalum-cerium composite oxide enriched with cerium islands on the surface. First, a dense iridium-tantalum composite oxide active layer is formed through multiple coating and thermal decomposition processes. Then, ultrasonic impregnation and low-temperature thermal decomposition are used to directly anchor the cerium oxide nano-islands onto the surface of the active layer. This reduces the adhesion of lead sulfate and breaks the positive feedback chain of scaling and wear. At the same time, the three-dimensional conductive network of the intermediate layer prevents the substrate from becoming passivated, enabling the anode to maintain low tank pressure and high stability in the long term during the production of electrolytic copper foil and the recovery of copper from acidic etching waste liquid.

[0056] The present invention will be described in detail below through examples and comparative examples, but the scope of protection of the present invention is not limited to these examples. Unless otherwise specified, the chemical reagents and raw materials used in the following examples and comparative examples are all conventional commercially available products.

[0057] Example 1 The TA2 pure titanium substrate was pretreated by first roughening it with 80-mesh brown corundum sand, then washing it with 10% sodium hydroxide solution at 70°C for 30 min to remove oil, and finally etching it with 12% oxalic acid solution at 90°C for 1.5 h. The pretreated substrate was anodized in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution was prepared by mixing ethylene glycol and deionized water at a mass ratio of 95:5. The amount of ammonium fluoride was 0.55% of the total mass of the ethylene glycol aqueous solution. The substrate was used as the anode and a platinum sheet as the cathode. A DC voltage of 35V was applied at room temperature and anodized for 2 hours to grow a TiO2 nanotube array on the substrate surface. After rinsing with deionized water and drying at 90°C, the substrate with the TiO2 nanotube array was placed in a tube furnace and evacuated to below 5Pa. A mixed gas of H2 and N2 was introduced at a flow rate of 125mL / min. The temperature was increased to 880°C at a rate of 3°C / min and reduced at a constant temperature for 40 minutes. After natural cooling, a sub-titanium oxide nanotube conductive intermediate layer was obtained. The volume ratio of H2 to N2 in the mixed gas was 1:50, and the thickness of the sub-titanium oxide nanotube conductive intermediate layer was 5μm.

[0058] A coating solution was prepared by dissolving chloroiridic acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone, with a volume ratio of n-butanol to acetylacetone of 9:1 and a mass ratio of chloroiridic acid to butyl tantalate of 55:40. The substrate with a conductive intermediate layer of titanium suboxide nanotubes was immersed in the coating solution and coated using an dip-coating method. After drying under an infrared lamp, the substrate was placed in a muffle furnace for coating-drying-thermal decomposition 12 times. Each time, the substrate was held at 500℃ for 10 min to crystallize the iridium-tantalum oxide. Finally, the substrate was annealed at 520℃ for 1.2 h to generate an active layer of iridium-tantalum composite oxide. The substrate with an iridium-tantalum composite oxide active layer is immersed in a cerium nitrate ethanol solution with a concentration of 0.10 mol / L. Ultrasonic impregnation causes cerium ions to be adsorbed onto the surface of the active layer and penetrate into the surface micropores. The ultrasonic impregnation power is 200 W, the time is 20 min, and the temperature is 30 °C. After drying, the substrate is placed in a muffle furnace and thermally decomposed at 400 °C for 13 min, causing the cerium salt to decompose and form cerium oxide nano-islands that are anchored on the surface of the active layer, thus generating an iridium-tantalum-cerium composite oxide active layer with cerium-enriched islands on the surface. This yields a novel high-stability, anti-scaling coated titanium anode.

[0059] The coated titanium anode was used in the production of electrolytic copper foil. The electrolyte was a copper sulfate-sulfuric acid system, with 1000 parts by mass of deionized water, 90 parts by mass of copper sulfate, 90 parts by mass of sulfuric acid, and 0.003 parts by mass of lead ions. The anode current density was 10000 A / m. 2 The electrolyte temperature is 45℃ and the pH value is 0.75.

[0060] Example 2 In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows: The TA2 pure titanium substrate was pretreated by first roughening it with 60-mesh brown corundum sand, then washing it with 10% sodium hydroxide solution at 70°C for 30 min to remove oil, and finally etching it with 12% oxalic acid solution at 90°C for 1.5 h. The pretreated substrate was anodized in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution was prepared by mixing ethylene glycol and deionized water at a mass ratio of 85:15. The amount of ammonium fluoride was 0.8% of the total mass of the ethylene glycol aqueous solution. The substrate was used as the anode and a platinum sheet as the cathode. A DC voltage of 40V was applied at room temperature and anodized for 1 hour to grow a TiO2 nanotube array on the substrate surface. After rinsing with deionized water and drying at 90°C, the substrate with the TiO2 nanotube array was placed in a tube furnace and evacuated to below 5Pa. A mixed gas of H2 and N2 was introduced at a flow rate of 150mL / min. The temperature was increased to 840°C at a rate of 4°C / min and reduced at a constant temperature for 50 minutes. After natural cooling, a sub-titanium oxide nanotube conductive intermediate layer was obtained. The volume ratio of H2 to N2 in the mixed gas was 1:65, and the thickness of the sub-titanium oxide nanotube conductive intermediate layer was 2μm.

[0061] A coating solution was prepared by dissolving chloroiridic acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone, with a volume ratio of n-butanol to acetylacetone of 8:1 and a mass ratio of chloroiridic acid to butyl tantalate of 65:40. The substrate with a conductive intermediate layer of titanium suboxide nanotubes was immersed in the coating solution and coated using an dip-coating method. After drying under an infrared lamp, the substrate was placed in a muffle furnace for coating-drying-thermal decomposition 10 times. Each time, the substrate was held at 480℃ for 12 min to crystallize the iridium-tantalum oxide. Finally, the substrate was annealed at 535℃ for 1.5 h to generate an active layer of iridium-tantalum composite oxide. The substrate with an iridium-tantalum composite oxide active layer is immersed in a cerium nitrate ethanol solution with a concentration of 0.05 mol / L. Ultrasonic impregnation causes cerium ions to be adsorbed onto the surface of the active layer and penetrate into the surface micropores. The ultrasonic impregnation power is 400 W, the time is 10 min, and the temperature is 35 °C. After drying, the substrate is placed in a muffle furnace and thermally decomposed at 375 °C for 10 min, causing the cerium salt to decompose and form cerium oxide nano-islands that are anchored on the surface of the active layer. This generates an iridium-tantalum-cerium composite oxide active layer with cerium-enriched islands on the surface, thus obtaining a novel high-stability, anti-scaling coated titanium anode.

[0062] The coated titanium anode was used for copper recovery from acid etching waste liquid. The electrolyte was a copper sulfate-sulfuric acid system, with 1000 parts by mass of deionized water, 80 parts by mass of copper sulfate, 105 parts by mass of sulfuric acid, and 0.001 parts by mass of lead ions. The anode current density was 9000 A / m. 2 The electrolyte temperature was 47℃ and the pH value was 1.0.

[0063] Example 3 In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows: The TA2 pure titanium substrate was pretreated by first roughening it with 70-mesh brown corundum sand, then washing it with 10% sodium hydroxide solution at 70°C for 30 min to remove oil, and finally etching it with 12% oxalic acid solution at 90°C for 1.5 h. The pretreated substrate was anodized in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution was prepared by mixing ethylene glycol and deionized water at a mass ratio of 90:10. The amount of ammonium fluoride was 0.3% of the total mass of the ethylene glycol aqueous solution. The substrate was used as the anode and a platinum sheet as the cathode. A DC voltage of 45V was applied at room temperature and anodized for 1.5 hours to grow a TiO2 nanotube array on the substrate surface. After rinsing with deionized water and drying at 90°C, the substrate with the TiO2 nanotube array was placed in a tube furnace and evacuated to below 5Pa. A mixed gas of H2 and N2 was introduced at a flow rate of 100mL / min. The temperature was increased to 860°C at a rate of 5°C / min and reduced at a constant temperature for 30 minutes. After natural cooling, a sub-titanium oxide nanotube conductive intermediate layer was obtained. The volume ratio of H2 to N2 in the mixed gas was 1:80, and the thickness of the sub-titanium oxide nanotube conductive intermediate layer was 3μm.

[0064] A coating solution was prepared by dissolving chloroiridic acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone, with a volume ratio of n-butanol to acetylacetone of 10:1 and a mass ratio of chloroiridic acid to butyl tantalate of 55:40. The substrate with a conductive intermediate layer of titanium suboxide nanotubes was immersed in the coating solution and coated using an dip-coating method. After drying under an infrared lamp, the substrate was placed in a muffle furnace for coating-drying-thermal decomposition 12 times. Each time, the substrate was held at 500℃ for 10 min to crystallize the iridium-tantalum oxide. Finally, the substrate was annealed at 520℃ for 1.2 h to generate an active layer of iridium-tantalum composite oxide. The substrate with an iridium-tantalum composite oxide active layer is immersed in a cerium nitrate ethanol solution with a concentration of 0.10 mol / L. Ultrasonic impregnation causes cerium ions to be adsorbed onto the surface of the active layer and penetrate into the surface micropores. The ultrasonic impregnation power is 200 W, the time is 15 min, and the temperature is 25 °C. After drying, the substrate is placed in a muffle furnace and thermally decomposed at 400 °C for 12 min, causing the cerium salt to decompose and form cerium oxide nano-islands that are anchored on the surface of the active layer. This generates an iridium-tantalum-cerium composite oxide active layer with cerium-enriched islands on the surface, thus obtaining a novel high-stability, anti-scaling coated titanium anode.

[0065] The coated titanium anode was used in the production of electrolytic copper foil. The electrolyte was a copper sulfate-sulfuric acid system, with 1000 parts by mass of deionized water, 90 parts by mass of copper sulfate, 90 parts by mass of sulfuric acid, and 0.005 parts by mass of lead ions. The anode current density was 10000 A / m2, the electrolyte temperature was 47℃, and the pH value was 0.5.

[0066] Example 4 In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows: The TA2 pure titanium substrate was pretreated by first roughening it with 70-mesh brown corundum sand, then washing it with 10% sodium hydroxide solution at 70°C for 30 min to remove oil, and finally etching it with 12% oxalic acid solution at 90°C for 1.5 h. The pretreated substrate was anodized in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution was prepared by mixing ethylene glycol and deionized water at a mass ratio of 90:10. The amount of ammonium fluoride was 0.5% of the total mass of the ethylene glycol aqueous solution. The substrate was used as the anode and a platinum sheet as the cathode. A DC voltage of 40V was applied at room temperature and anodized for 1.5 hours to grow a TiO2 nanotube array on the substrate surface. After rinsing with deionized water and drying at 90°C, the substrate with the TiO2 nanotube array was placed in a tube furnace and evacuated to below 5Pa. A mixed gas of H2 and N2 was introduced at a flow rate of 125mL / min. The temperature was increased to 860°C at a rate of 4°C / min and reduced at a constant temperature for 40 minutes. After natural cooling, a sub-titanium oxide nanotube conductive intermediate layer was obtained. The volume ratio of H2 to N2 in the mixed gas was 1:65, and the thickness of the sub-titanium oxide nanotube conductive intermediate layer was 4μm.

[0067] A coating solution was prepared by dissolving chloroiridic acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone, with a volume ratio of n-butanol to acetylacetone of 9:1 and a mass ratio of chloroiridic acid to butyl tantalate of 60:40. The substrate with a conductive intermediate layer of titanium suboxide nanotubes was immersed in the coating solution and coated using an dip-coating method. After drying under an infrared lamp, the substrate was placed in a muffle furnace for coating-drying-thermal decomposition 10 times. Each time, the substrate was held at 500℃ for 11 min to crystallize the iridium-tantalum oxide. Finally, the substrate was annealed at 535℃ for 1.2 h to generate an active layer of iridium-tantalum composite oxide. The substrate with an iridium-tantalum composite oxide active layer is immersed in a cerium nitrate ethanol solution with a concentration of 0.10 mol / L. Ultrasonic impregnation causes cerium ions to be adsorbed onto the surface of the active layer and penetrate into the surface micropores. The ultrasonic impregnation power is 300 W, the time is 15 min, and the temperature is 30 °C. After drying, the substrate is placed in a muffle furnace and thermally decomposed at 375 °C for 12 min, causing the cerium salt to decompose and form cerium oxide nano-islands that are anchored on the surface of the active layer, thus generating an iridium-tantalum-cerium composite oxide active layer with cerium-enriched islands on the surface. This yields a novel coated titanium anode with high stability and anti-scaling properties.

[0068] The coated titanium anode was used in the production of electrolytic copper foil. The electrolyte was a copper sulfate-sulfuric acid system, with 1000 parts by weight of deionized water, 80 parts by weight of copper sulfate, 105 parts by weight of sulfuric acid, and 0.003 parts by weight of lead ions. The anode current density was 9000 A / m.2 The electrolyte temperature was 47℃ and the pH value was 0.75.

[0069] Comparative Example 1 The preparation methods of Comparative Example 1 and Example 1 are basically the same, except that step (4) is omitted, the ultrasonic impregnation of cerium nitrate ethanol solution and thermal decomposition at 350-400℃ are not performed, and the process is completed directly after annealing of the iridium-tantalum composite oxide active layer, resulting in no cerium oxide nano-islands.

[0070] Comparative Example 2 The preparation methods of Comparative Example 2 and Example 2 are basically the same, except that thermal reduction is not performed in step (2). After anodic oxidation, the sample is rinsed with deionized water and dried before proceeding directly to step (3). Titanium oxide nanotubes are used as the intermediate layer instead of sub-titanium oxide nanotube conductive intermediate layer.

[0071] Comparative Example 3 The preparation methods of Comparative Example 3 and Example 3 are basically the same, except that cerium nitrate, chloroiridic acid, and butyl tantalate are dissolved together in the coating solution and decomposed simultaneously during 8-12 coating-thermal decomposition processes. Cerium oxide is uniformly dispersed inside the coating rather than distributed in island-like patterns on the surface.

[0072] Comparative Example 4 The preparation methods of Comparative Example 4 and Example 4 are basically the same, except that the traditional preparation method is used, without anodic oxidation of nanotubes, thermal reduction, or cerium doping. The iridium-tantalum binary composite oxide coating is directly coated on the pretreated titanium substrate, with a thermal decomposition temperature of 500°C, and the process is repeated 10 times.

[0073] Performance Test Results and Analysis Coated titanium anode samples were prepared according to the parameters of the examples and comparative examples, respectively. Performance tests were performed on these samples, and the results are shown in Table 1 and [Table data missing]. Figure 1 As shown.

[0074] The study employed scanning electron microscopy to observe the distribution morphology of cerium oxide nanoislands on the anode surface and the deposition state of lead sulfate scale. An electrochemical workstation was used to test the polarization curve of the anode in a copper sulfate-sulfuric acid system, recording the initial tank pressure and the change in tank pressure after 100 hours of operation. A two-probe method was used to measure the resistance of the coating / substrate composite system, connecting wires to the back of the substrate and the surface of the coating, measuring the total resistance, and then converting it to apparent interfacial resistance based on the coating area. Continuous electrolysis was performed in a lead-ion-containing electrolyte, with samples taken and weighed every 24 hours to record the amount of lead sulfate deposited per unit area. The failure time of the anode was recorded when the tank pressure increased to 1.2 times the initial value.

[0075] Table 1 shows the coating structure parameters and interface resistance. As can be seen from Table 1, all four examples (Examples 1-4) formed a conductive intermediate layer of titanium suboxide nanotubes, with an interface resistance of 8-15 mΩ·cm. 2 Example 2, due to its lower reduction temperature, longer reduction time but moderate heating rate, and an intermediate layer thickness of only 2 μm, exhibits a relatively higher interface resistance of 15 mΩ·cm. 2 However, it was still significantly lower than that of the comparative examples. Comparative Example 2 used titanium oxide nanotubes as an intermediate layer. Titanium oxide is intrinsically insulating, which hinders electron transport, and the interface resistance exceeded the range, indicating that the thermal reduction step is indispensable for constructing conductive channels. Comparative Example 4 had no intermediate layer, and the iridium-tantalum coating was in direct contact with the titanium substrate. Due to the large difference in thermal expansion coefficients and the limited bonding area, the interface resistance was 45 mΩ·cm. 2 The resistance of Comparative Example 1 is higher than that of Examples 1 to 4, indicating that the three-dimensional conductive network of the sub-titanium oxide nanotube intermediate layer effectively reduces the interfacial transport resistance. The interfacial resistance of Comparative Example 1 is close to that of Example 1, indicating that the cerium oxide nanoislands are located on the surface of the active layer and do not change the interfacial conductive structure between the coating and the substrate.

[0076] Table 1 Coating structure parameters and interface resistance Example 1 Titanium suboxide nanotubes 35 75 22 12 Example 2 Titanium suboxide nanotubes 28 60 18 15 Example 3 Titanium suboxide nanotubes 42 85 19 10 Example 4 Titanium suboxide nanotubes 38 80 18 8 Comparative Example 1 Titanium suboxide nanotubes — — — 13 Comparative Example 2 Titanium oxide nanotubes 32 64 19 — Comparative Example 3 Titanium suboxide nanotubes — — — 16 Comparative Example 4 — — — — 45 The distribution of cerium oxide nanoislands directly affects anti-fouling performance. In Examples 1 to 4, the cerium oxide nanoislands had a particle size of 28-42 nm, an inter-island spacing of 60-85 nm, and a coverage of 17%-20%, exhibiting a discrete island distribution. Comparative Example 1, without cerium doping, had no cerium oxide nanoislands on its surface. Scanning electron microscopy revealed smooth, continuous iridium-tantalum oxide grains on its surface, allowing lead sulfate to easily form a continuous, dense film. Compared to Example 3, Comparative Example 3, because cerium nitrate was dissolved together with chloroiridic acid and butyl tantalate in the coating solution, decomposed simultaneously during the coating-thermal decomposition process. The cerium oxide was uniformly dispersed within the coating rather than anchored to the surface, resulting in the absence of discrete nanoisland structures and a significantly reduced anti-fouling effect.

[0077] like Figure 1-3 As shown, the initial tank pressure in Examples 1 to 4 was 4.15-4.30V, and after 100 hours of operation, the tank pressure increased by 0.08-0.15V, with lead sulfate deposition rates of 0.4-1.0 mg / cm³. 2 The failure time was 780-1050 h. In Example 4, all parameters were taken at their optimal values. The cerium oxide nanoislands were uniformly distributed with a moderate intermediate layer thickness. The initial cell voltage was the lowest at 4.15V, and after 100 h of operation, it only increased to 4.22V. The lead sulfate deposition was the lowest at 0.4 mg / cm³. 2The longest failure time was 1050 hours, resulting in the best overall performance. In Example 2, due to the shorter anodizing time, thinner intermediate layer, and lower cerium impregnation concentration and time, the cerium oxide nano-island coverage was relatively low, and the lead sulfate deposition amount was 1.0 mg / cm³. 2 The failure time was 780 hours, which was the lowest among the four embodiments, but still better than all comparative examples.

[0078] Comparative Example 1 was identical to Example 1 except for the absence of cerium oxide nanoislands. Its initial tank pressure was 4.40V, higher than the 4.25V of Example 1. After 100 hours of operation, the tank pressure increased to 4.85V, an increase of 0.45V, and the lead sulfate deposition rate was 2.5 mg / cm³. 2 The failure time was only 520 hours. This indicates that without cerium oxide nanoislands, lead sulfate forms a continuous and dense scale layer on the smooth iridium-tantalum surface, deteriorating the current distribution and accelerating coating degradation due to increased local overpotential. Compared with Example 3, Comparative Example 3, because cerium nitrate and the iridium-tantalum precursor were co-incorporated into the coating solution, they decomposed simultaneously during the coating-thermal decomposition process. Cerium oxide was uniformly dispersed inside the coating rather than anchored on the surface, and there was no discrete nanoisland structure on the surface, resulting in a significant reduction in anti-scaling effect. In Comparative Example 3, cerium oxide was uniformly dispersed inside the coating, and there was no nanoisland structure on the surface; therefore, particle size, island spacing, and coverage are represented by "---".

[0079] Comparative Example 4 used a traditional iridium-tantalum binary coating without an intermediate layer or cerium doping. The initial tank voltage was 4.45V, which increased to 5.30V after 100 hours of operation, resulting in a lead sulfate deposition rate as high as 3.2 mg / cm³. 2 The failure time was only 220 hours. The continuous increase in tank voltage stemmed from two factors: firstly, the lack of a conductive interlayer of titanium suboxide nanotubes led to gradual passivation of the substrate; secondly, the absence of cerium oxide nano-islands resulted in the continuous accumulation of lead sulfate. In contrast, Comparative Example 2, with its insulating titanium oxide interlayer, had an initial tank voltage as high as 4.80V, rising to 5.60V after 100 hours of operation, with a failure time of only 280 hours. Although the slightly higher surface roughness resulted in a lead sulfate deposition of 1.2 mg / cm³, the actual failure was minimal. 2 It is lower than Comparative Example 1 and Comparative Example 4, but the lack of conductivity leads to excessive energy consumption, making it unsuitable for practical application.

[0080] Test results show that Examples 1 to 4, through the interaction of the sub-titanium oxide nanotube conductive interlayer and the iridium-tantalum-cerium composite oxide active layer enriched with cerium islands on the surface, outperform the comparative examples in terms of conductivity, scale resistance, and durability. The sub-titanium oxide nanotube interlayer provides a three-dimensional conductive channel and enhances mechanical anchoring, while the cerium oxide nanoislands reduce lead sulfate adhesion and optimize the surface electronic structure. The process sequence of high-temperature crystallization followed by low-temperature anchoring ensures the effective formation of nanoislands. The coupling of these three elements breaks the positive feedback chain of mutually aggravating scaling and wear, enabling the anode to maintain long-term stable operation in the production of electrolytic copper foil and the recovery of copper from acidic etching waste liquid.

[0081] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a novel, highly stable, anti-scaling coated titanium anode, characterized in that, The method includes the following steps: (1) Pretreatment of TA2 pure titanium matrix; (2) The pretreated substrate was placed in an aqueous solution of ammonium fluoride in ethylene glycol for anodic oxidation, so that TiO2 nanotube arrays were grown on the substrate surface. After being rinsed with deionized water, it was dried at 80-100℃. Then the substrate with TiO2 nanotube arrays was thermally reduced in a mixed atmosphere of hydrogen and nitrogen to generate a sub-titanium oxide nanotube conductive intermediate layer. (3) Dissolve chloroiridic acid and butyl tantalate in a mixed solvent of n-butanol and acetylacetone to prepare a coating solution. The volume ratio of n-butanol to acetylacetone is 8:1 to 10:

1. Immerse the substrate with the conductive intermediate layer of titanium suboxide nanotubes into the coating solution and perform coating-drying-thermal decomposition operation 8-12 times. Each thermal decomposition is held at 480-520℃ for 10-12 min to crystallize the iridium-tantalum oxide. Finally, anneal at 520-550℃ for 1-1.5 h to generate the iridium-tantalum composite oxide active layer. (4) The substrate with the iridium-tantalum composite oxide active layer is immersed in cerium nitrate ethanol solution and ultrasonically impregnated to allow cerium ions to be adsorbed on the surface of the active layer and penetrate into the surface micropores. After drying, it is thermally decomposed at 350-400℃ for 10-15 minutes to decompose the cerium salt to form cerium oxide nano islands and anchor them on the surface of the active layer, thus generating an iridium-tantalum-cerium composite oxide active layer with cerium enriched on the surface island, thereby obtaining a novel high-stability anti-scaling coated titanium anode.

2. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (1), the specific pretreatment process is as follows: first, the TA2 pure titanium substrate is roughened by sandblasting with 60-80 mesh brown corundum sand, then it is degreased by alkaline washing at 60-80℃ for 20-40 minutes in a sodium hydroxide solution with a mass fraction of 8%-12%, and then etched at 85-95℃ for 1-2 hours in an oxalic acid solution with a mass fraction of 10%-15%.

3. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (2), the specific process of anodizing is as follows: the pretreated substrate is placed in an ethylene glycol aqueous solution containing ammonium fluoride. The ethylene glycol aqueous solution is prepared by mixing ethylene glycol and deionized water in a mass ratio of 85:15 to 95:

5. The amount of ammonium fluoride is 0.3%-0.8% of the total mass of the ethylene glycol aqueous solution. The substrate is used as the anode and the platinum sheet is used as the cathode. A DC voltage of 35-45V is applied at room temperature, and anodizing is performed for 1-2 hours to grow a TiO2 nanotube array on the surface of the substrate.

4. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (2), the specific steps of thermal reduction are as follows: the substrate with TiO2 nanotube array is placed in a tube furnace, the vacuum is evacuated to below 5 Pa, a mixed gas of H2 and N2 is introduced, the gas flow rate is 100-150 mL / min, the temperature is increased to 840-880℃ at 3-5℃ / min, the temperature is reduced at a constant temperature for 30-50 min, and after natural cooling, a sub-titanium oxide nanotube conductive intermediate layer is obtained.

5. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 4, characterized in that, The volume ratio of H2 to N2 in the mixed gas is 1:50 to 1:80; the diameter of the TiO2 nanotube array is 50-100 nm, the wall thickness is 10-15 nm, the depth is 2-5 μm, and the thickness of the conductive intermediate layer of the titanium suboxide nanotube is 2-5 μm.

6. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (4), the concentration of the cerium nitrate ethanol solution is 0.05-0.15 mol / L, the ultrasonic impregnation power is 200-400W, the time is 10-20 min, and the temperature is 25-35℃; the particle size of the cerium oxide nanoislands is 20-50 nm, the island spacing is 60-120 nm, and the island coverage is 15%-30%.

7. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (3), the mass ratio of chloroiridic acid to butyl tantalate is 55-65:

40.

8. The method for preparing a novel high-stability, anti-scaling coated titanium anode according to claim 1, characterized in that, In step (3), the specific steps of coating-drying-thermal decomposition are as follows: the substrate with the conductive intermediate layer of titanium suboxide nanotubes is immersed in the coating liquid, coated by dip-coating method, dried under infrared lamp and placed in muffle furnace, and kept at 480-520℃ for 10-12 min to crystallize iridium tantalum oxide. The operation is repeated until the total number of times is 8-12, and finally annealed at 520-550℃ for 1-1.5 h.

9. A novel high-stability, anti-scaling coated titanium anode, characterized in that, The coated titanium anode is prepared by the method described in any one of claims 1 to 8.

10. The application of a novel high-stability, anti-scaling coated titanium anode as described in claim 9, characterized in that, The coated titanium anode is used in the production of electrolytic copper foil or the recovery of copper from acid etching waste liquid, with the electrolyte being a copper sulfate-sulfuric acid system.

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