Composite anode with gradient pore channels and self-repairing function and preparation method of composite anode

Abstract

The invention discloses a composite anode plate with gradient pore channels and a self-repairing function and a preparation method of the composite anode plate. The anode plate comprises a titanium mesh substrate, the surface of the titanium mesh substrate is provided with three-stage gradient pore channels with micropores of 30-100 microns, mesopores of 3-10 microns and nanopores of 150-300 nm, the pore channels are asymmetrically distributed in a staggered mode, and the included angle between the pore channels and the horizontal plane is 30-60 degrees; a Ta2O5-IrO2 gradient intermediate layer, a WO3 nanorod array and a PbO2 active layer of a Na2WO4 microcapsule are sequentially covered on the titanium mesh substrate; the content of Ir in the Ta2O5-IrO2 gradient intermediate layer is 15-18 wt%, the thickness of the Ta2O5-IrO2 gradient intermediate layer is 50-80 nm, the rod diameter of the WO3 nanorod array is 50-80 nm, the length of the WO3 nanorod array is 200-300 nm, and the microcapsules release WO4 < 2-> at 80 DEG C to achieve The preparation method comprises the steps of titanium mesh pretreatment, femtosecond laser grading punching, gradient middle layer coating sintering, WO3 nanorod pulse electrodeposition and PbO2 composite electrodeposition. The anode plate has the advantages of blockage resistance, corrosion resistance and high catalytic activity, can reduce the maintenance cost, and is suitable for complex oil field water treatment.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical water treatment technology, specifically a composite anode with gradient channels and self-healing function and its preparation method. Background Technology

[0002] In the oil extraction industry, the treatment of produced water is crucial. With the continuous expansion of global oil extraction, the production of produced water is constantly increasing. This produced water contains large amounts of pollutants such as salt, organic matter, suspended solids, and bacteria. Direct discharge without effective treatment will cause serious environmental pollution and also fail to meet increasingly stringent environmental regulations. To achieve water resource recycling and reduce production costs, efficient produced water treatment technology has become a key requirement for the industry's development. Currently, electrochemical treatment technology is widely used in the field of produced water treatment due to its advantages such as high treatment efficiency and ease of operation. The anode material, as the core component of electrochemical treatment, directly affects the treatment effect and cost.

[0003] Some anode materials used for oilfield produced water treatment have numerous problems. In terms of materials, traditional anode materials such as SnO2-Sb2O3 anodes have issues in high Cl... - In environments with Cl⁻ > 50 g / L, the corrosion rate is too rapid (> 1 μm / 100 h⁻¹), resulting in a short anode lifespan. Frequent anode replacements not only increase costs but also affect production efficiency. While BDD (boron-doped diamond) anodes offer better performance, their high cost makes large-scale industrial application difficult. Structurally, nanotube array anodes are easily clogged by suspended solids in water, affecting mass transfer efficiency. Planar electrodes also exhibit low mass transfer efficiency, with current efficiency typically < 65%, failing to fully leverage the advantages of electrochemical treatment. Furthermore, existing anodes generally lack scale repair capabilities; calcium and magnesium deposition can lead to electrode deactivation, requiring shutdown for acid washing. This not only results in production losses but also increases maintenance costs and operational complexity.

[0004] A patent application with application number CN202020788118.6 discloses a titanium anode assembly for oilfield wastewater treatment. This prior art consists of several titanium electrode bodies arranged in a spaced configuration, with RuO4, IrO2, SnO2, and Sb2O3 coatings sequentially applied to the titanium electrode substrate. Although this anode assembly has a high oxygen evolution overpotential, can almost completely degrade COD in wastewater, and boasts low power consumption, fast electrolysis speed, high corrosion resistance, low pollution, and long service life, it still has some shortcomings. When treating complex oilfield produced water with high salinity and high organic matter content, its structure is not specifically designed to prevent suspended solids from clogging, which may affect the treatment effect and mass transfer efficiency due to the accumulation of suspended solids. Furthermore, this anode assembly does not mention a self-healing function; when calcium and magnesium deposits or other scaling occur on the electrode surface, it cannot self-repair, potentially requiring shutdown for manual treatment. This leads to reduced production capacity and increased maintenance costs, making it difficult to meet the long-term stable operation requirements under complex conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a composite anode with gradient channels and self-healing function, and a method for preparing the same, to solve the following technical problems raised in the background art: Traditional anode materials have poor corrosion resistance and short lifespan in high-salt environments; existing anodes lack self-repairing scaling function, and calcium and magnesium deposition can easily lead to electrode deactivation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A composite anode plate with gradient channels and self-healing function includes a titanium mesh substrate, the surface of which is provided with three-level gradient channels; the three-level gradient channels include a microporous layer, a mesoporous layer, and nanopores; wherein... Microporous layer: pore size 30-100μm; Mesoporous layer: pore size 3-10μm; Nanopores: pore size 150-300 nm; The channels are asymmetrically and staggered, with the channel axis making an angle of 30-60° with the horizontal plane. The titanium mesh substrate is covered with a Ta2O5-IrO2 gradient intermediate layer, in which the Ir content is 15-18wt% and the thickness is 50-80nm; WO3 nanorod arrays with diameters of 50-80 nm and lengths of 200-300 nm are grown on the gradient intermediate layer. The surface of the WO3 nanorod array is composited with a PbO2 active layer, in which Na2WO4 microcapsules are uniformly dispersed; the microcapsule shell is made of polystyrene to trigger the release of WO4 at 80℃. 2- .

[0007] Furthermore, the titanium mesh substrate has a thickness of 0.8mm-2.5mm and a porosity of 30-40%.

[0008] Furthermore, the Na2WO4 microcapsules have a particle size of 1-5 μm and are added to the PbO2 active layer at a rate of 0.3-1.0 g / L.

[0009] Furthermore, the material ratio of the WO3 nanorod array to the PbO2 active layer is 1:4.

[0010] Furthermore, the surface of the composite anode plate is a superoleophobic surface with a contact angle >150°.

[0011] A method for preparing a composite anode plate with gradient channels and self-healing function, comprising the following steps: A. The titanium mesh is sequentially subjected to alkaline washing, acid etching, and deionized water rinsing. B, using femtosecond laser graded drilling: Microporous layer: A single laser scan with a power of 25W forms pores with a diameter of 30-100μm; Mesoporous layer: Laser power 15W scan 3 times to form pores with a diameter of 3-10μm; Nanoporous layer: 8W laser power scan 10 times to form pores with a diameter of 150-300nm; C. A mixture of H2IrCl6 and TaCl5 precursors was coated onto the surface of a titanium mesh, sintered at 450℃ and repeated three times to form a Ta2O5-IrO2 layer. D. Using 0.1 mol / L Na₂WO₄ solution as electrolyte, WO₃ nanorod arrays were generated by pulse electrodeposition; (5 ms on / 10 ms off, current density 20 A / dm², time 10 min). E, in a plating bath containing 0.3-1.0 g / L Na₂WO₄ microcapsules, at a current density of 20 A / dm² 2 PbO2 was electrodeposited at 40℃ to embed the microcapsules into the active layer.

[0012] Furthermore, in step A, the alkaline washing uses a 10% NaOH solution at a temperature of 80°C; the ratio of oxalic acid to HF in the acid etching solution is 3:1.

[0013] Furthermore, in step B, the scanning speed of the femtosecond laser is 80-200 mm / s.

[0014] Furthermore, in step C, the mixing ratio of H2IrCl6 and TaCl5 is adjusted according to the Ir content of 15-18wt% in the final Ta2O5-IrO2 gradient intermediate layer.

[0015] Furthermore, in step E, the plating solution is continuously stirred during the electrodeposition of PbO2 to ensure that the Na2WO4 microcapsules are uniformly dispersed and embedded in the active layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the three-level gradient channels combined with an asymmetric staggered distribution can reduce the risk of suspended solids clogging. At the same time, the multi-level channel structure optimizes the electrolyte flow path, improves mass transfer efficiency, and avoids the mass transfer bottleneck caused by the simple structure of traditional electrodes.

[0017] Ta2O 5- The IrO2 gradient interlayer effectively blocks the corrosion of the titanium mesh substrate by the electrolyte, balancing conductivity and chemical stability. This solves the problem of rapid corrosion rate in traditional anodes under high-salt environments, extending electrode lifespan. The WO3 nanorod array provides numerous active sites, synergistically enhancing oxidation performance with the PbO2 active layer. It can efficiently catalyze the degradation of pollutants in water, making it suitable for treating oilfield wastewater with high organic content.

[0018] Na2WO4 microcapsules uniformly dispersed in the PbO2 active layer trigger the release of WO4 at 80℃. 2- By replenishing the worn active layer through electrodeposition reaction, downtime repairs caused by scaling or wear can be avoided, thus reducing production capacity loss.

[0019] The various structural levels are mutually compatible, which not only ensures the mechanical strength and stability of the electrodes, but also improves the electrochemical performance through ultra-microstructure optimization, making it suitable for long-term operation in complex oilfield water environments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the overall structure of the anode plate of the present invention; Figure 3 This is a schematic diagram of the three-stage gradient channel of the present invention.

[0022] Figure reference numerals: 1-Titanium mesh substrate, 2-Microporous layer, 3-Mesoporous layer, 4-Nanopore. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example: A composite anode plate with gradient channels and self-healing function includes a titanium mesh substrate 1, the surface of which is provided with three-level gradient channels. The titanium mesh substrate 1 serves as the supporting skeleton of the anode plate. Titanium material has good conductivity, corrosion resistance and mechanical strength, which can provide a stable adhesion substrate for each functional layer. At the same time, compared with traditional titanium plates, the mesh structure of titanium mesh can increase the contact area with electrolyte and improve mass transfer efficiency.

[0025] The three-level gradient pore system comprises a microporous layer 2, a mesoporous layer 3, and nanopores 4; among which... Microporous layer 2: pore size 30-100μm; its main function is to reduce the risk of blockage by suspended solids. The larger pore size allows most suspended solids in the water to pass through smoothly, avoiding accumulation on the electrode surface and ensuring the flowability of the electrolyte.

[0026] Mesoporous layer 3: pore size 3-10μm; located between microporous layer 2 and nanoporous layer 4, it plays a transitional role, further optimizing the mass transfer path, making the electrolyte flow more uniform inside the electrode, and at the same time, it can intercept some smaller suspended matter, reducing the blockage of nanoporous layer 4.

[0027] Nanopore 4: Pore size 150-300nm; Nanoscale pore size can significantly increase the specific surface area of ​​the electrode, increase the number of active sites for electrochemical reactions, and thus enhance electrolysis efficiency; In addition, the nanopore 4 structure can also promote the migration and diffusion of ions in the electrolyte and improve the reaction rate.

[0028] The channels are asymmetrically and staggered, with the channel axis making an angle of 30-60° with the horizontal plane. This distribution can change the flow direction and path of the electrolyte in the channels, avoid local wear caused by direct vertical impact of water flow, and increase the residence time of the electrolyte inside the electrode, thereby improving mass transfer efficiency and reaction sufficiency and reducing dead volume.

[0029] The titanium mesh substrate 1 is covered with a Ta2O5-IrO2 gradient intermediate layer, wherein the Ir content is 15-18wt% and the thickness is 50-80nm. This intermediate layer has good conductivity and chemical stability, which can effectively block the electrolyte from corroding the titanium mesh substrate 1, protect the substrate from damage, and extend the service life of the anode plate.

[0030] An array of WO3 nanorods, with diameters of 50-80 nm and lengths of 200-300 nm, is grown on a gradient intermediate layer. The WO3 nanorod array possesses a large specific surface area and excellent catalytic activity, enhancing the oxidation performance of the anode and promoting the oxidative decomposition of pollutants in water. The nanorod diameter and length design ensures uniform growth on the gradient intermediate layer, forming a regular array structure that provides a good adhesion surface for the PbO2 active layer without affecting electrolyte penetration and ion migration. The WO3 and subsequent PbO2 form a composite active system, which increases the oxygen evolution potential of the anode, reduces oxygen evolution, and allows more electrical energy to be used for the oxidative decomposition of pollutants in the water, thus improving current efficiency.

[0031] The surface of the WO3 nanorod array is composited with a PbO2 active layer, in which Na2WO4 microcapsules are uniformly dispersed; the microcapsule shell is made of polystyrene to trigger the release of WO4 at 80℃. 2- The PbO2 active layer is the main reaction layer of the anode plate, possessing excellent electrochemical catalytic activity and corrosion resistance. It can efficiently catalyze the oxidation of organic matter in water, kill bacteria, and remove pollutants such as oil, making it the core functional layer for purifying oilfield produced water. The core function of the Na2WO4 microcapsules is to enable the anode plate to self-repair. When the PbO2 active layer is worn or corroded due to the electrolytic reaction, under triggering conditions of 80℃, if the local temperature rises during electrolysis, the polystyrene shell ruptures, releasing WO4²⁻.

[0032] Released WO4 2- It will react with Pb in the electrolyte 2+ (A small amount of PbO2 dissolved) reacts to form WO4. 2- +Pb 2+ +2H₂O→PbWO₄+4H + The generated PbWO4 precipitate is deposited on the surface of the active layer under the action of an electric field, replenishing the worn parts, restoring the activity of the anode, and reducing the production capacity loss caused by downtime maintenance.

[0033] The microcapsules are uniformly dispersed in the PbO2 active layer, which can ensure the uniform release of the repair substances and the comprehensiveness of the repair. The particle size of 1-5μm allows them to be well embedded in the active layer without affecting the overall structure and catalytic performance of the active layer.

[0034] This composite anode plate solves the problems of short lifespan, simple structural design, and need for shutdown and repair after scaling by the synergistic effect of its components. It is suitable for the treatment of produced water from oil and gas fields with high salt and high organic matter content. It can efficiently remove pollutants such as oil, COD, hardness and bacteria, and has good prospects for industrial application.

[0035] In a preferred embodiment, the titanium mesh substrate 1 has a thickness of 0.8 mm to 2.5 mm and a porosity of 30 to 40%.

[0036] Specifically, a thickness of 0.8mm or more ensures that the titanium mesh is not easily deformed during laser processing of gradient channels and coating preparation. It also withstands external forces such as electrolyte flow impact and installation fixation, guaranteeing the overall stability of the anode plate structure. A thickness not exceeding 2.5mm avoids material waste and weight increase due to excessive thickness, while reducing electrode resistance and balancing mechanical properties and conductivity. Furthermore, the three-level gradient channels require a certain substrate thickness as a processing carrier. A thickness of 0.8mm-2.5mm meets the requirements for continuous processing of asymmetric staggered channels, ensuring that the channels extend from the surface of the titanium mesh to the interior, forming continuous mass transfer channels and preventing incomplete channel penetration or structural integrity damage due to insufficient thickness.

[0037] A porosity of 30-40% means that the titanium mesh substrate 1 retains sufficient open space, which can significantly improve the flow of electrolyte inside the electrode. On the one hand, it allows more contaminants to come into contact with the active coating of the inner layer through the pores, avoiding mass transfer bottlenecks caused by excessively low porosity. On the other hand, it reduces the flow resistance of the electrolyte, allowing reaction products to be discharged quickly and avoiding accumulation on the electrode surface.

[0038] When the porosity is below 30%, the titanium mesh is too dense, which reduces the contact area with the coating and lowers the adhesion stability of the active layer. When the porosity exceeds 40%, the skeletal structure of the titanium mesh becomes too sparse, which may lead to a decrease in mechanical strength and make it prone to breakage during processing or use. A porosity of 30-40% strikes a good balance between the coating adhesion area and the load-bearing capacity of the substrate.

[0039] A porosity of 30-40% provides a basis for the layered processing of three-level gradient channels. The microporous layer 2, mesoporous layer 3 and nanoporous layer 4 can be further expanded based on the original pore structure of the titanium mesh to form a multi-level mass transfer network from macroporous to micro-gradient channels, maximizing the contact efficiency between the electrode and the electrolyte.

[0040] In a preferred embodiment, the Na2WO4 microcapsules have a particle size of 1-5 μm and are added to the PbO2 active layer at an amount of 0.3-1.0 g / L.

[0041] Specifically, the thickness of the PbO2 active layer is typically in the micrometer range, and a particle size of 1-5 μm ensures that the microcapsules are uniformly embedded within the active layer, rather than being exposed on the surface or submerged in the bottom layer. If the particle size exceeds 5 μm, it can easily lead to local protrusions or structural discontinuities in the active layer, affecting the surface smoothness of the electrode and the uniformity of current distribution; if the particle size is less than 1 μm, the microcapsule shell is prone to rupture during electrodeposition, prematurely releasing WO4. 2-It loses its sustained-release repair function. A particle size of 1-5 μm can accommodate a sufficient amount of Na₂WO₄ core, ensuring the release of WO₄ in a single burst. 2- It can meet the needs of local remediation. At the same time, this particle size will not excessively occupy the active layer space, avoiding a reduction in PbO2 catalytic sites due to excessive microcapsule proportion, ensuring that the oxidation efficiency of the active layer for pollutants is not significantly affected. The thermal responsiveness of the polystyrene shell is related to the particle size. Microcapsules of 1-5μm can rupture rapidly and synchronously at 80℃, while excessively large particle sizes will cause uneven heating of the shell, resulting in premature or delayed rupture in some areas; excessively small particle sizes may be mistakenly triggered by slight temperature fluctuations in environments below 80℃, reducing the utilization rate of the remediation material.

[0042] An addition of 0.3 g / L is the minimum effective dosage, ensuring sufficient microcapsules to provide repair material when the anode plate experiences minor wear during initial operation; while the upper limit of 1.0 g / L avoids over-repair due to excessive microcapsules. Excessive WO4 caused by over-repair... 2- Release will generate excess PbWO4 precipitate, which will block the pores of the active layer or cover the catalytic sites, reducing the electrolysis efficiency.

[0043] The core function of the PbO2 active layer is the catalytic oxidation of pollutants, and its electrochemical performance depends on its continuous crystal structure. When the addition amount exceeds 1.0 g / L, a large number of microcapsules will disrupt the continuous phase of PbO2, leading to increased electrode resistance and decreased oxygen evolution potential. When the addition amount is below 0.3 g / L, the remediation material is insufficient to form effective remediation, and the anode plate will still rapidly deactivate due to wear. An addition amount of 0.3-1.0 g / L can achieve a balance between remediation function and catalytic performance.

[0044] During the PbO2 electrodeposition process, the microcapsules need to be uniformly suspended in the plating solution and move with the Pb. 2+ Co-deposition. A concentration of 0.3-1.0 g / L ensures appropriate solution viscosity, preventing microcapsule aggregation or sedimentation, and ensuring uniform distribution of microcapsules embedded in the active layer for comprehensive repair.

[0045] In a preferred embodiment, the material ratio of the WO3 nanorod array to the PbO2 active layer is 1:4.

[0046] WO3, as a transition metal oxide, possesses excellent semiconductor properties and photocatalytic activity. In an electrochemical environment, it can participate in oxidation reactions through lattice oxygen, significantly promoting the bond-breaking process of recalcitrant organic matter in water. Its nanorod array structure provides a large number of surface active sites, enhancing its adsorption and activation capabilities for pollutants.

[0047] WO3, which accounts for 1 / 5 of the total, can precisely match the oxidation pathway of PbO2: WO3 first adsorbs pollutants and performs preliminary oxidation through surface hydroxyl groups (-OH), and then transfers intermediate products to PbO2 for deep mineralization, thereby increasing the COD removal rate to over 91%.

[0048] PbO2 has an extremely high oxygen evolution potential, making it more likely to generate highly oxidizing hydroxyl radicals (·OH) in electrochemical reactions. These hydroxyl radicals are the core component for achieving complete mineralization of pollutants. A PbO2 composition of 4 / 5 ensures sufficient ·OH generation, meeting the requirements for advanced treatment of high-concentration organic wastewater, while suppressing side reactions and maintaining current efficiency above 85%.

[0049] If the proportion of PbO2 is less than 4 / 5, the formation of •OH will be insufficient, and the mineralization of pollutants will be incomplete; if the proportion is too high, the catalytic assistance of WO3 will be weakened, and the accumulation of intermediate products will lead to a decrease in reaction efficiency.

[0050] WO3 is an n-type semiconductor with a conductivity of approximately 10 at room temperature. -5 S / cm, while PbO2 is a good conductor with a conductivity of approximately 10. 2 A 1:4 ratio (S / cm) allows the continuous phase of PbO2 to form a conductive network, with WO3 nanorod arrays embedded within it as a framework. This avoids the increase in electrode resistance caused by excessive WO3, keeping the resistance below 5Ω, while also leveraging the efficient electron transport capability of PbO2 to rapidly deliver electrons from the external circuit to the active sites on the WO3 surface, ensuring the continuous progress of the oxidation reaction.

[0051] The WO3 nanorod array is chemically bonded to the Ta2O5-IrO2 gradient interlayer, while the PbO2 active layer is electrodeposited using the WO3 nanorods as anchors, forming a three-dimensional intercalated structure. The 1:4 ratio allows PbO2 to fully fill the gaps between the WO3 nanorods, enhancing the mechanical interlocking force between the two layers and preventing delamination under high-flow-rate electrolyte scouring. Experimental data show that the coating adhesion at this ratio can reach over 30 MPa, which is 1.5 times that of a single PbO2 coating.

[0052] When the PbO2 active layer wears down, WO4 is released from the microcapsules. 2- With Pb 2+ The reaction generates PbWO4, and the 1:4 basic ratio ensures that the ratio of WO3 to PbO in the repair product is consistent with that of the original coating, avoiding a decrease in catalytic performance due to compositional deviations in the repair layer. Simultaneously, the WO3 nanorods serve as a structural template, guiding the directional deposition of the repair product and maintaining the original porous structure and catalytic site distribution of the repaired active layer.

[0053] In a preferred embodiment, the surface of the composite anode plate is a superoleophobic surface with a contact angle >150°.

[0054] Specifically, crude oil in produced water from oil fields exists in the form of emulsified oil, dispersed oil, etc. If it adheres to the electrode surface, it will form an oil film that blocks the contact between the electrolyte and the active sites of the electrode. At the same time, it may block the gradient channels, resulting in a decrease in mass transfer efficiency and a reduction in current efficiency.

[0055] Superoleophobic surfaces, with their extremely low surface energy, prevent oil droplets from spreading, causing them to roll in a spherical shape, thus reducing oil adhesion by more than 95%. Experimental data shows that after 100 hours of operation, the surface oil coverage of traditional electrodes reaches 30-40%, while that of superoleophobic surfaces is only 1-2%. This self-cleaning effect maintains the flowability of the gradient channels, ensuring that the suspended matter throughput remains above 80%, avoiding downtime for cleaning due to oil clogging.

[0056] The superoleophobic surface ensures continuous exposure of the catalytic sites of the PbO2 active layer and WO3 nanorod array by reducing oil film formation. On the one hand, the ·OH generation efficiency of PbO2 remains unaffected, enabling efficient oxidation of organic matter; on the other hand, the semiconductor properties of WO3 nanorods provide stability, allowing them to continuously participate in electron transfer and pollutant activation.

[0057] Superoleophobic surfaces reduce oil adhesion and prevent the formation of corrosion microcells: the potential difference between the oil film-covered area and the exposed area can cause local current concentration, while the uniformity of the superoleophobic surface can make the current distribution more stable, reducing selective corrosion caused by potential unevenness.

[0058] A method for preparing a composite anode plate with gradient channels and self-healing function, comprising the following steps: A. The titanium mesh is sequentially subjected to alkaline washing, acid etching, and deionized water rinsing.

[0059] Alkaline washing typically involves treating the titanium mesh surface with a 10% NaOH solution at 80°C. The purpose is to remove oil, rolling oil, and organic impurities. The strong alkaline environment causes saponification of organic matter, forming water-soluble substances, thus preventing impurities from affecting the adhesion of subsequent coatings.

[0060] Acid etching uses a solution of oxalic acid and HF mixed in a 3:1 ratio. On the one hand, it removes the oxide layer on the surface of the titanium mesh, exposing the fresh metal surface to enhance conductivity. On the other hand, the acid corrosion forms micro-pits on the surface of the titanium mesh, increasing the contact area with the subsequent Ta2O5-IrO2 coating and improving the adhesion of the coating.

[0061] Rinsing with deionized water is used to thoroughly remove residual acid and alkali solutions and corrosion products, preventing residual ions from causing coating defects during subsequent high-temperature sintering or electrodeposition.

[0062] B, using femtosecond laser graded drilling: Microporous layer 2: A single laser scan with a power of 25W forms pores with a diameter of 30-100μm; Mesoporous layer 3: Laser power 15W scan 3 times to form pores with a diameter of 3-10μm; Four layers of nanopores: 8W laser power scanned 10 times to form pores with a diameter of 150-300nm; C. A mixture of H2IrCl6 and TaCl5 precursors was coated onto the surface of a titanium mesh, sintered at 450℃, and repeated three times to form a Ta2O5-IrO2 layer.

[0063] Specifically, H₂IrCl₆ and TaCl₅ are mixed in a specific ratio and dissolved in ethanol or isopropanol to form a homogeneous solution, ensuring uniform composition during coating. A temperature of 450℃ allows for complete decomposition of the precursor while preventing excessive oxidation of the titanium mesh substrate 1. During sintering, IrO₂ and Ta₂O₅ form a solid solution, enhancing the chemical stability of the coating. Three coating and sintering cycles are repeated, each forming a coating of approximately 15-25 nm, resulting in a total thickness of 50-80 nm after three cycles. This ensures effective protection of the titanium mesh without increasing interfacial resistance due to excessive thickness. The gradient design matches the electron conduction requirements from the titanium mesh to the active layer, reducing energy loss.

[0064] D. Using 0.1 mol / L Na2WO4 solution as electrolyte, WO3 nanorod arrays were generated by pulse electrodeposition; the current was applied for 5 ms and de-energized for 10 ms, the current density was 20 A / dm², and the time was 10 min.

[0065] Specifically, a 0.1 mol / L Na₂WO₄ solution provides WO₄. 2- Too high an ion concentration will cause nanorods to aggregate, while too low a concentration will result in slow growth. (WO4 during the electrification stage) 2- Under the influence of an electric field, the ions migrate to the surface of the titanium mesh and are reduced to WO3 crystal nuclei. During the power-off phase, ions are allowed to re-diffuse, avoiding irregular growth caused by excessively high local concentrations, ultimately forming a uniform array with a diameter of 50-80 nm and a length of 200-300 nm; current density 20 A / dm². 2 The growth rate of nanorods can be controlled by a time of 10 min, ensuring that the length matches the pore size of the mesoporous layer 3 and avoiding overgrowth that can clog the pores. At the same time, this current density can promote the growth of WO3 along the crystal orientation and enhance its semiconductor catalytic activity.

[0066] E, in a plating bath containing 0.3-1.0 g / L Na₂WO₄ microcapsules, at a current density of 20 A / dm² 2 PbO2 was electrodeposited at 40℃ to embed the microcapsules into the active layer.

[0067] Specifically, the microcapsules are uniformly suspended in the plating solution, along with Pb 2+Co-deposited embedded PbO2 layers ensure uniform distribution of the repair material; current density 20 A / dm 2 It can promote Pb 2+ The WO3 nanorods are oxidized to PbO2 on their surface, forming a dense and strongly adherent active layer; a temperature of 40°C is used to prevent the microcapsule shell from softening and rupturing prematurely due to high temperatures, while simultaneously accelerating the oxidation of Pb. 2+ Diffusion enhances deposition uniformity. Microcapsules embed themselves into the PbO2 layer through physical encapsulation, without affecting catalytic activity; WO4 release is triggered only at 80℃. 2- This enables in-situ repair.

[0068] The pretreatment process provides a clean, roughened surface for subsequent processing; laser-guided graded drilling constructs gradient mass transfer channels; the intermediate layer combines protection and conductivity; WO3 nanorods enhance catalysis and provide structural support; and a PbO2 active layer supports microcapsules to achieve functional integration. Through precise parameter control, a composite functional anode plate is ultimately formed, adaptable to the stringent requirements of complex water treatment in oil fields.

[0069] In a preferred embodiment, in step A, the alkaline washing uses a 10% NaOH solution at a temperature of 80°C; the ratio of oxalic acid to HF in the acid etching solution is 3:1.

[0070] Specifically, a 10% NaOH solution creates a strongly alkaline environment that can dissolve organic oil stains through saponification, while also softening the loose oxide layer on the titanium mesh surface. The saponification reaction takes 1-2 hours at room temperature, but this time can be shortened to 30-40 minutes at 80℃, ensuring thorough dissolution of deep-seated oil stains and achieving a surface oil removal rate of over 99%. If the NaOH concentration is too low, the cleaning power will be insufficient; if the concentration is too high, it will lead to excessive corrosion of the titanium mesh surface, damaging the integrity of the substrate. High-temperature alkaline washing can cause localized dissolution and reconstruction of the natural oxide layer on the titanium mesh surface, forming an active surface that is more readily reacted with subsequent acid etching, laying the foundation for uniform roughening during acid etching.

[0071] Oxalic acid, as an organic acid, can adjust the pH of a solution and also release H+ slowly. + Oxalic acid, in combination with HF, forms a synergistic corrosion effect. Adsorbed on the titanium surface, oxalic acid guides HF to preferentially dissolve the oxide layer rather than the titanium substrate, reducing excessive corrosion of the metal substrate. A 3:1 ratio balances dissolution efficiency and substrate protection. Excessive HF content can lead to titanium mesh corrosion and even porosity; excessive oxalic acid content results in incomplete oxide layer removal, affecting subsequent coating adhesion. Titanium is prone to hydrogen embrittlement in strongly acidic environments, and oxalic acid, as a corrosion inhibitor, can reduce the hydrogen evolution rate. At a 3:1 ratio, the risk of hydrogen embrittlement is reduced, ensuring that the titanium mesh substrate 1 maintains good mechanical strength during subsequent laser processing, high-temperature sintering, and other processes.

[0072] In a preferred embodiment, in step B, the scanning speed of the femtosecond laser is 80-200 mm / s.

[0073] Specifically, for the microporous layer 2, a larger pore size is required, typically paired with 25W high power and a single scan, with the scanning speed controlled at 80-120mm / s. The slower speed allows the high-power laser sufficient time to penetrate the titanium mesh, ensuring the channels are connected and the pore size meets the requirements, while avoiding excessive ablation due to excessively slow speed.

[0074] For the third intermediate layer, a medium power of 15W and three scans are used, with the scanning speed controlled at 120-160mm / s. The medium speed balances the energy input of a single scan, and the three superpositions achieve precise hole reduction, avoiding discontinuities in the channel caused by excessive speed.

[0075] For the four nanopore layers, a low power of 8W and 10 scans were used, with the scanning speed controlled at 160-200 mm / s. High-speed scanning reduces the energy input per action, and nanoscale ablation is achieved through 10 low-energy superpositions, avoiding the aggregation of nanopores caused by excessively slow speeds.

[0076] Furthermore, at low speeds of 80-120 mm / s, the laser head deflects 30°, and high power ensures the continuity of the tilted micropores; at high speeds of 160-200 mm / s, the laser head deflects 60°, and multiple low-energy scans prevent channel displacement of the tilted nanopores 4. This matching of speed and angle ensures the turbulence effect of the asymmetric channels and enhances mass transfer efficiency.

[0077] In a preferred embodiment, in step C, the mixing ratio of H2IrCl6 and TaCl5 is adjusted according to the Ir content of 15-18 wt% in the final Ta2O5-IrO2 gradient intermediate layer.

[0078] IrO2, as a noble metal oxide, possesses excellent conductivity and electrochemical stability, making it the primary material for electron transport in the interlayer. Ta2O5 exhibits extremely high chemical stability, effectively preventing corrosion of the titanium mesh substrate 1 by the electrolyte; however, its conductivity is relatively poor, and excessive amounts can increase interfacial resistance. By adjusting the ratio of H2IrCl6 to TaCl5, the Ir content in the final interlayer is controlled at 15-18 wt%, achieving synergistic functionality between the two. 15 wt% represents the minimum effective Ir content, at which point IrO2 forms a continuous conductive network, maintaining electron transport efficiency above 90% and avoiding bottlenecks caused by insufficient Ir. 18 wt% represents the upper limit of Ir, ensuring conductivity while enhancing corrosion resistance through a high proportion of Ta2O5, allowing the interlayer to withstand corrosion at 58000 mg / L Cl₂. - The corrosion rate in the solution was controlled to be below 0.1 μm / 100h.

[0079] When the Ir content is 15-18 wt%, IrO2 can be uniformly doped into the Ta2O5 lattice to form a solid solution. This structure can reduce grain boundary defects, enhance the compactness of the coating, and effectively block Cl. - Corrosive ions penetrate into the titanium mesh matrix 1; If the Ir content is less than 15wt%, IrO2 cannot form a continuous conductive network, and the resistance of the intermediate layer will increase sharply to more than 5Ω, resulting in a decrease in electron transfer efficiency.

[0080] If the Ir content is higher than 18wt%, the excess IrO2 will accumulate at the grain boundaries, forming stress concentration points. During high-temperature sintering or long-term electrolysis, microcracks are easily generated, reducing the protective ability of the titanium mesh.

[0081] By adjusting the ratio of H2IrCl6 to TaCl5 in stages, for example, with an Ir content of 15wt% in the first coating, 16.5wt% in the second, and 18wt% in the third, and combining this with a three-coating and sintering process, a gradient distribution of Ir content can be achieved. The low Ir, high Ta region near the titanium mesh side prioritizes corrosion resistance and blocks Cl. - Erosion of the substrate; The high Ir, low Ta region near the active layer prioritizes conductivity, accelerating electron transfer to the WO3 nanorods. This gradient design ensures that the intermediate layer does not become a resistive barrier while fully utilizing the protective effect of Ta2O5, thus balancing electrode lifetime and energy efficiency.

[0082] It should also be noted that this ratio needs to be precisely calculated in conjunction with the decomposition efficiency of the precursor. For example, if the target Ir content is 16wt%, the mass ratio of H2IrCl6 to TaCl5 should be calculated to be approximately 1:5.2 based on the atomic weights of Ir and Ta and the molecular weights of their oxides.

[0083] In a preferred embodiment, during step E, the plating solution is continuously stirred during the PbO2 electrodeposition process to ensure that the Na2WO4 microcapsules are uniformly dispersed and embedded in the active layer.

[0084] Among them, Na2WO4 microcapsules are solid particles encapsulated in a polystyrene shell. If left to stand or not stirred sufficiently, they will settle due to gravity or agglomerate into large particles due to van der Waals forces.

[0085] The turbulence generated by mechanical stirring breaks down the agglomeration forces between microcapsules, allowing them to remain monodisperse in the plating solution. The uniformly suspended microcapsules can then move with the Pb... 2+ Ions migrate together to the electrode surface and eventually embed themselves uniformly into the PbO2 active layer. If microcapsules aggregate or settle, it will lead to an excess or absence of microcapsules in some parts of the active layer, which will seriously affect the uniformity of the self-repair function.

[0086] The process of electrodeposition of PbO2 is Pb 2+ Under the influence of an electric field, the particles migrate toward the anode and are oxidized into PbO2 crystals, while the microcapsules need to be simultaneously embedded into the interstitial spaces of the crystals through physical encapsulation.

[0087] Continuous stirring can reduce the amount of Pb in the plating solution. 2+ Maintaining a uniform concentration ensures a stable PbO2 crystal growth rate, providing a uniform lattice gap for microcapsule embedding; insufficient stirring can lead to Pb concentration issues near the electrode surface. 2+ Rapid consumption can lead to uneven crystal growth, causing microcapsules to be repelled on the surface of the active layer and detached during subsequent use due to electrolyte rinsing. With continuous stirring, microcapsules and PbO2 crystals can form an embedded structure with an embedding depth of 60-70% of the active layer thickness, reducing the detachment rate to below 5% and ensuring the long-term retention of the self-healing substance.

[0088] During electrodeposition, local pH changes occur on the electrode surface due to reaction consumption. If the plating bath remains stagnant, an acidic boundary layer will form, leading to abnormal PbO2 crystal growth and potentially causing premature aging of the microcapsule shell in a locally high-acid environment. Continuous stirring can accelerate plating bath convection and promptly remove H+ from the electrode surface. + This ensures that the overall pH of the plating solution remains stable, guaranteeing that PbO2 grows according to the expected tetragonal phase structure. At the same time, the uniform plating solution environment can prevent microcapsules from prematurely rupturing due to local temperature or pH fluctuations, ensuring that the repair material is released only when needed.

[0089] It should also be noted that the stirring rate must be matched with the electrodeposition parameters. Too low a stirring speed will not suppress sedimentation and agglomeration; too high a stirring speed will cause excessive turbulence in the plating solution, which will interfere with Pb deposition. 2+ The directional migration of these molecules reduces the density of the active layer. In actual operation, a stirring rate of 200-300 r / min and a stirring rate of 20 A / dm³ are suitable. 2 The synergistic effect of high current density and 40°C temperature ultimately enables the PbO2 active layer to maintain high catalytic activity while achieving long-term self-repair through uniformly distributed microcapsules, perfectly meeting the complex water treatment needs of oilfields.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite anode plate with gradient channels and self-healing function, characterized in that: It includes a titanium mesh substrate (1), the surface of which is provided with a three-level gradient channel; the three-level gradient channel includes a microporous layer (2), a mesoporous layer (3), and nanopores (4); wherein, Microporous layer (2): pore size 30-100μm; Mesoporous layer (3): pore size 3-10 μm; Nanopores (4): pore size 150-300 nm; The channels are asymmetrically and staggered, with the channel axis making an angle of 30-60° with the horizontal plane. A Ta2O5-IrO2 gradient intermediate layer is covered on the titanium mesh substrate (1), wherein the Ir content is 15-18wt% and the thickness is 50-80nm; WO3 nanorod arrays with diameters of 50-80 nm and lengths of 200-300 nm are grown on the gradient intermediate layer. The surface of the WO3 nanorod array is composited with a PbO2 active layer, in which Na2WO4 microcapsules are uniformly dispersed; the microcapsule shell is made of polystyrene to trigger the release of WO4 at 80℃. 2- .

2. The composite anode plate with gradient channels and self-healing function according to claim 1, characterized in that: The titanium mesh substrate (1) has a thickness of 0.8mm-2.5mm and a porosity of 30-40%.

3. The composite anode plate with gradient channels and self-healing function according to claim 1, characterized in that: The Na2WO4 microcapsules have a particle size of 1-5 μm and are added to the PbO2 active layer at a rate of 0.3-1.0 g / L.

4. The composite anode plate with gradient channels and self-healing function according to claim 1, characterized in that: The material ratio of the WO3 nanorod array to the PbO2 active layer is 1:

4.

5. A composite anode plate with gradient channels and self-healing function according to claim 1, characterized in that: The surface of the composite anode plate is superoleophobic, with a contact angle >150°.

6. A method for preparing a composite anode plate with gradient channels and self-healing function, used to prepare the composite anode plate with gradient channels and self-healing function as described in any one of claims 1-5, characterized in that: Includes the following steps: A. The titanium mesh is sequentially subjected to alkaline washing, acid etching, and deionized water rinsing. B, using femtosecond laser graded drilling: Microporous layer (2): A single laser scan with a power of 25W forms pores with a diameter of 30-100μm; Mesoporous layer (3): Laser power 15W scan 3 times to form pores with a diameter of 3-10μm; Nanopore (4) layer: Laser power 8W scan 10 times to form pores with a diameter of 150-300nm; C. A mixture of H2IrCl6 and TaCl5 precursors was coated onto the surface of a titanium mesh, sintered at 450℃ and repeated three times to form a Ta2O5-IrO2 layer. D. Using 0.1 mol / L Na2WO4 solution as electrolyte, WO3 nanorod arrays were generated by pulse electrodeposition. E, in a plating bath containing 0.3-1.0 g / L Na₂WO₄ microcapsules, at a current density of 20 A / dm² 2 PbO2 was electrodeposited at 40℃ to embed the microcapsules into the active layer.

7. The method for preparing a composite anode plate with gradient channels and self-healing function according to claim 6, characterized in that: In step A, the alkaline washing uses a 10% NaOH solution at a temperature of 80°C; the ratio of oxalic acid to HF in the acid etching solution is 3:

1.

8. The method for preparing a composite anode plate with gradient channels and self-healing function according to claim 6, characterized in that: In step B, the scanning speed of the femtosecond laser is 80-200 mm / s.

9. The method for preparing a composite anode plate with gradient channels and self-healing function according to claim 6, characterized in that: In step C, the mixing ratio of H2IrCl6 and TaCl5 is adjusted according to the Ir content of 15-18wt% in the final Ta2O5-IrO2 gradient intermediate layer.

10. The method for preparing a composite anode plate with gradient channels and self-healing function according to claim 6, characterized in that: In step E, the plating solution is continuously stirred during the electrodeposition of PbO2.

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