Preparation method and application of IrO2-FTO coated composite anode plate

Abstract

The invention belongs to the technical field of electrolytic metallurgy and functional electrode materials, is applied to corrosion prevention and mud control on the surface of a lead alloy anode in a strong acid electrolysis environment, and particularly relates to a preparation method and application of an IrO2-FTO coated composite anode plate. The method comprises the following steps: step 1, pre-treating a lead alloy substrate; step 2, preparing an IrO2-SnO2: F (IrO2-FTO) composite functional layer by a double-target magnetron co-sputtering one-step method; step 3, constructing a surface structure by laser micro-nano; and step 4, forming a conductive sulfonic acid polymer layer in situ through electrochemistry. According to the method, an integrated composite functional layer without a clear interface can be constructed on the surface of a lead matrix, nanoscale compounding of anti-corrosion and conductive components is achieved, a composite functional surface which is lower in overpotential, better in conductivity and more durable in protection effect is obtained, emission of electrolytic particulate matter generated by bubble blasting is remarkably reduced, and the service life of the lead matrix is prolonged. And the efficiency, economical efficiency and environmental friendliness of the electrolysis process are comprehensively improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrolytic metallurgy and functional electrode materials, and is applied to the corrosion prevention and slime control of lead alloy anode surface in a strong acid electrolysis environment, and particularly relates to a preparation method and application of an IrO2-FTO coated composite anode plate. BACKGROUND

[0002] Lead-based anodes (such as Pb-Ag, Pb-Ca, Pb-Sr alloys, etc.) are widely used in the wet electrolytic smelting and electrodeposition processes of non-ferrous metals such as copper, zinc, manganese, cobalt, and nickel due to their low cost, good electrical conductivity, and excellent mechanical processing performance. However, in harsh electrolytic environments with strong acidity (such as 150-200 g / L H2SO4) and high oxidation potential (>1.6 V vs. SHE), traditional lead alloy anodes undergo severe electrochemical corrosion. The PbO2 film layer generated on the surface is often loose and porous, leading to continuous dissolution of the lead substrate, which not only causes consumption of the anode material and shortens its service life, but also produces a large amount of anode slime (mainly composed of α-PbO2, β-PbO2, and unreacted lead particles). These anode slimes settle at the bottom of the electrolytic cell, polluting the cathode product, reducing the quality of metal deposition and current efficiency, and increasing the subsequent refining cost.

[0003] More seriously, during the electrolysis process, oxygen gas bubbles are continuously generated on the anode surface. The generation, growth, coalescence, and final explosion of gas bubbles at the electrolyte interface form an aerosol with electrolyte and solid particles (including corrosion products, undissolved salts, etc.), which is dispersed into the workshop air in the form of PM 2.5 , PM 10 , etc. This not only leads to the loss of valuable metals, but also poses a serious threat to the health of operating personnel and causes environmental pollution. In the prior art, in order to improve the corrosion resistance of lead anodes, specific alloy elements (such as Ag, Ca, Sr, Sn, etc.) are usually added or surface modification treatment is performed, such as pre-generating a conductive oxide film layer. However, these methods still face problems such as insufficient stability of the film layer, weak adhesion to the substrate, and inability to effectively control the behavior of gas bubbles in long-term operation. SUMMARY

[0004] The application provides a preparation method and application of an IrO2-FTO coated composite anode plate, aiming to overcome the shortcomings of existing lead alloy anode technology and solve the following key problems: 1、Solve the interface failure risk problem of multi-layer film structure. In the prior art, multi-functionalization is realized by sequentially depositing film layers with different functions on the surface of a lead anode. However, when such a multi-layer film structure is in a harsh electrolysis environment for a long time, the clear interface between different film layers due to the mismatch of physical and chemical properties (such as thermal expansion coefficient and lattice constant) is prone to become a weak point in performance, leading to decreased interlayer adhesion, interface corrosion and early peeling of the film layer, affecting the long-term stability of the anode. The present application needs to provide a method that can directly build an integrated composite functional layer with uniform composition and no clear interface on the surface of a lead substrate, thereby fundamentally eliminating the interface failure risk.

[0005] 2、Solve the complexity and uniformity problem of the step-by-step deposition process. The step-by-step deposition process has a long process flow, high equipment requirements and complex parameter control, and may introduce contamination or damage during the switching process between different processes, affecting the density and uniformity of the final film layer. The present application needs to provide a preparation method with high process integration and simple and controllable steps, which can realize the nanoscale compounding of corrosion-resistant and conductive components through a single continuous process, ensure the high quality and performance consistency of the film layer, and be easy to scale up.

[0006] 3、Realize the optimal synergy of corrosion-resistant and conductive components at the nanoscale. Simple functional superposition (such as IrO2 layer responsible for corrosion and FTO layer responsible for conductivity) may not be able to fully exert the synergistic effect between materials. The present application needs to realize the in-situ compounding of IrO2 and SnO2:F (FTO) during the deposition process, so that the high electrocatalytic activity of IrO2 and the high conductivity and stability of SnO2:F (FTO) are combined at the atomic / molecular level, forming a "1+1>2" synergistic effect, thereby obtaining a composite functional surface with lower overpotential, better conductivity and more durable protection effect.

[0007] 4、On the basis of realizing the above high-performance composite functional layer, further solve the problem of uncontrollable bubble behavior on the surface of the anode. By constructing a stable gas-repellent micro-nano structure on the composite layer, the nucleation, growth, coalescence and detachment behavior of the anode oxygen evolution bubbles is effectively controlled, the bubbles are promoted to release quickly in small size, and the formation and violent explosion of large bubbles are inhibited, thereby significantly reducing the emission of electrolytic particulate matter (acid mist) caused by bubble explosion.

[0008] 5、Integrate high-performance corrosion-resistant and conductive substrate with high-efficiency emission reduction function, provide a composite functional anode plate with simple and controllable process, high integration degree of film layer and durable performance, to comprehensively improve the efficiency, economy and environmental friendliness of the electrolysis process.

[0009] To solve the above technical problems, the technical scheme of the present application is as follows: The application discloses a preparation method of an IrO2-FTO coated composite anode plate, and belongs to the technical field of anode plate preparation. Step 1: pretreatment of a lead alloy substrate Step 2: preparation of an IrO2-SnO2:F (IrO2-FTO) composite functional layer by a double-target magnetron co-sputtering one-step method Step 3: laser micro-nano construction of a surface structure Step 4: in-situ formation of a conductive sulfonic acid polymer layer by electrochemistry Preferably, in step 1, the lead alloy substrate is subjected to mechanical polishing, oil removal and acid pickling activation to obtain a clean and activated surface.

[0010] Preferably, step 2 comprises the following specific steps: the pretreated lead alloy substrate is used as a substrate and is loaded into a cavity of a high-vacuum magnetron sputtering system, two independent sputtering targets are installed in the system in parallel, the first target is an iridium target with a purity of greater than or equal to 99.95% and is used as a source of IrO2, and the second target is a fluorine-doped tin dioxide ceramic target, which is a sintered body of SnO2 and SnF2 and is used as a source of SnO2:F (FTO); first, the cavity is vacuumed to a pressure of less than or equal to 5.0 × 10 -4 Pa, then, argon and oxygen are introduced as working gases, the gas flow is controlled through a mass flow meter, the cavity working pressure is stabilized at 0.4-0.7 Pa through an adjusting baffle valve, the substrate table water cooling system is turned on to ensure that the substrate temperature is lower than 160°C during the deposition process to prevent the lead substrate from softening and deforming, then, the radio frequency power sources of the first target and the second target are started at the same time, the atomic ratio of Ir to Sn in the composite film is adjusted by independently controlling the sputtering power of the two targets, metallic Ir is formed into IrO2 by reactive sputtering, and the material stream sputtered from the FTO target contributes to the required Sn, O and F elements, the two are transported to the substrate surface in a plasma atmosphere and are co-deposited to form a composite layer with uniform composition and no clear interface; after the deposition is completed, in-situ post-annealing treatment is performed to form a solid solution structure mainly in the rutile phase, oxygen vacancies are repaired, and the conductivity, stability and adhesion of the film layer are significantly enhanced.

[0011] The main functions of the IrO2-SnO2:F (IrO2-FTO) composite functional layer are: 1. synergistic corrosion prevention and energy-saving efficiency improvement: the excellent electrocatalytic activity and chemical stability of IrO2 are combined with the high conductivity and physical barrier capability of SnO2:F (FTO) to form a double barrier with "physical shielding" and "electrochemical protection". This layer can effectively inhibit the corrosion of the lead matrix and the formation of unstable PbO2 layer, fundamentally reducing the source of anode mud, while its low resistance characteristics provide an efficient electron channel for oxygen evolution reaction, reducing the anode overpotential and achieving energy saving and emission reduction. 2. ideal functional substrate: the composite layer surface is simultaneously rich in IrO2 electrocatalytic active sites and SnO2:F (FTO) oxygen vacancies / hydroxyl groups, providing a more uniform and stable active interface for subsequent laser micro-nano construction and polymer modification, which is conducive to the firm construction of functional surface.

[0012] It should be noted that the present application composites IrO2 and SnO2:F at the nanoscale through a dual-target magnetron sputtering process, rather than simply physically stacking. This composite produces a "1+1>2" synergistic effect: it forms a one-piece composite functional layer with a component gradient transition and no clear interface. This structure not only completely avoids the early failure risk caused by interface problems in multi-layer films, greatly improving the bonding strength and long-term stability of the film layer; more importantly, it optimizes the electronic structure of the material at the atomic scale, enabling the deep integration of high-catalytic-activity sites of IrO2 and high-conductivity network of FTO, and jointly constructing a working surface with lower overpotential, better conductivity, and more comprehensive protection.

[0013] Preferably, step 3 comprises the following specific steps: using a laser micro-processing system to etch micron-scale groove structures on the IrO2-FTO composite surface obtained in step 2. The function of this microstructure is to guide the directional merging and release of bubbles, providing a predetermined path and position for the merging and detachment of bubbles, enabling the bubbles to detach from the surface in a more orderly and smaller size, thereby accurately controlling the final detachment particle size of the bubbles. This microstructure cooperates with the polar substance modification layer to construct a stable gas-repellent surface, enhancing the durability of the gas-repellent effect. In addition, the microstructure increases the specific surface area, which can reduce the true current density to some extent, which is beneficial to the oxygen evolution reaction.

[0014] Preferably, step 4 comprises the following specific steps: forming a conductive sulfonic acid-based gas-repellent layer on the IrO2-FTO micro-groove composite surface obtained in step 3 by in-situ electrochemical polymerization, i.e. using electrochemical anodic oxidation polymerization to electro-polymerize sulfonate-modified conductive monomers on the laser micro-nano structured IrO2-FTO substrate, forming a dense polymer film layer with conductivity and gas repellency. This method does not require additional initiators or metal catalysts, is simple to operate, and the obtained film layer has excellent stability and adhesion in strong acid medium.

[0015] The main function of the modification layer is to endow the surface with super gas properties, to regulate the adhesion work and growth kinetics of the bubbles on the surface, to make it easy to detach with small particle size, and to control the number and particle size of the particulate matter generated when the bubbles burst on the liquid surface. In addition, the conductive polymer skeleton is rich in conjugated pi electron system, which can conduct electrons without being rapidly oxidized and decomposed in the anodic oxidation environment; the sulfonic acid group is stable under acidic conditions and does not hydrolyze or fall off. In addition, the film forms a dense ion-conducting film, effectively blocking the direct erosion of acid radicals on IrO2, significantly reducing the corrosion current, and prolonging the anode life. The presence of sulfonic acid groups endows the film layer with the characteristics of proton exchange membranes, which can promote the migration of H + and H2O molecules in strong acid, making the local interface pH more stable, thereby improving the local reaction kinetics and making the bubble generation more controllable.

[0016] The method for testing and evaluating the performance of the lead alloy anode plate prepared by the above method is as follows: Chemical performance test: the standard three-electrode system is used to determine the corrosion current density.

[0017] Anode mud production test: under the simulated industrial electrolysis conditions, the generated anode mud is collected and weighed.

[0018] Bubble behavior and particulate matter monitoring: a high-speed camera is used to record the generation, growth and detachment dynamics of oxygen bubbles on the anode surface.

[0019] Long-term stability test: after continuous or intermittent electrolysis for 300 hours, the surface morphology, gas permeability and electrochemical performance of the plate are checked.

[0020] The application also discloses an application of the IrO2-FTO coated composite anode plate preparation method, which is a lead alloy anode plate prepared by the IrO2-FTO coated composite anode plate preparation method and is applied to the wet electrolytic smelting and electrodeposition process of non-ferrous metals.

[0021] Compared with the prior art, the IrO2-FTO coated composite anode plate preparation method and application have the following beneficial effects: The composite anode plate of the application exhibits excellent comprehensive benefits in economy and environment. In the economic aspect, the service life of the anode plate is significantly prolonged by the strong corrosion resistance of the IrO2-FTO composite film, reducing the replacement and maintenance cost; energy saving and consumption reduction are realized by reducing the oxygen evolution overpotential and enhancing the conductivity of the plate, and the electrolysis energy consumption is reduced by more than 5% compared with the traditional lead anode; at the same time, the pollution of anode mud to the cathode product is effectively reduced, the quality of metal deposition and current efficiency are improved, the cost problem caused by the addition of manganese element in the traditional process is avoided, and the production process is simplified. In the environmental aspect, the generation of anode mud is greatly inhibited by the synergistic effect of the surface gas regulation and the dense protective layer, reducing the pressure of solid waste treatment; and by promoting the rapid desorption of small-sized bubbles, the emission of PM 2.5 , PM 10 and other particulate matters caused by bubble burst is significantly reduced, the air quality in the workshop is improved, and green and clean production of the electrolysis process is realized.

[0022] Specifically, the beneficial effects of the application are as follows: 1. Significant energy saving effect: IrO2 and FTO layer have high electrocatalytic activity and excellent electronic conductivity, which can significantly reduce the overpotential of oxygen evolution reaction, thereby reducing the energy consumption of electrolysis process. The electrolysis energy consumption of the modified anode is reduced from 3188.21 kW·h / t of the traditional plate to 2954.1-3005.21 kW·h / t, with energy saving of more than 5%, improving the economy of electrolytic smelting.

[0023] 2. Excellent corrosion resistance: IrO2 and SnO2:F are compounded on a nanoscale by a double-target magnetron sputtering process, not simply physically superimposed. This compounding produces a "1+1>2" synergistic effect: it forms a one-piece composite barrier with physical shielding and electrochemical protection functions, with a composition gradient transition and no clear interface. This structure not only completely avoids the early failure risk of multi-layer films due to interface problems, greatly improving the bonding strength and long-term stability of the film layer, and the film layer is firmly combined with the lead matrix (adhesion up to 4B level), effectively preventing the corrosion of strong acid electrolyte, inhibiting the continuous dissolution of the lead matrix and the generation of unstable PbO2 layer. Electrochemical tests show that the corrosion current density is reduced by more than 50% compared with the untreated lead anode, greatly improving the service life and stability of the anode in a strong acid and high potential environment.

[0024] 3. Effective particulate matter emission reduction capability: A stable gas-repellent interface was constructed by laser micro-nano structuring surface groove structure and in-situ electrochemical formation of conductive sulfonic acid polymer layer. The structure regulates the bubble nucleation, growth and detachment behavior, reduces the average bubble detachment diameter from 1.1 mm of the traditional anode to 0.1-0.3 mm, reduces the bubble coalescence and violent explosion, and significantly reduces the emission of PM 2.5 particles during the electrolysis process. Particle monitoring results show that the particle concentration is reduced by more than 40%, which effectively guarantees the health of the operating personnel and the workshop environment.

[0025] 4. Effective control of anode slime generation: The IrO2-FTO composite film fundamentally inhibits the corrosion and side reactions of the lead matrix, reducing the sources of α-PbO2, β-PbO2 and lead particles, etc. anode slime. Under simulated industrial electrolysis conditions, the amount of anode slime is reduced by more than 40%, which not only reduces the consumption of anode material and the cost of waste residue treatment, but also reduces the pollution of anode slime to cathode products, improving the purity of metal deposition and current efficiency.

[0026] 5. Enhanced film integration and reliability: The IrO2-FTO composite functional layer formed by one-step co-sputtering fundamentally eliminates the physical interface between the IrO2 film and the FTO film in the step-by-step deposition. This interface-free structure avoids the risk of interface corrosion and interlayer peeling caused by the difference in thermal expansion coefficient of the materials and electrolyte penetration, further improving the bonding strength, density and long-term running stability of the film layer.

[0027] 6. Long-term stability and process feasibility: After continuous or intermittent operation for 300 hours, the film layer has no significant shedding, the gas-repellent property and electrochemical performance are good, and the decay rate is low. The preparation process steps are clear and controllable, and easy to realize large-scale production, providing reliable technical support for energy saving, emission reduction and quality improvement of wet electrolytic smelting.

[0028] In summary, the present application successfully realizes the integration of corrosion prevention, energy saving, emission reduction and mud control through the multi-level integration of IrO2-FTO composite film, micro-nano structure and gas-repellent modification layer, effectively solves the technical bottleneck of traditional lead anode in strong acid electrolysis environment, and has important industrial application value and popularization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 : Comparison chart of average bubble particle size of traditional lead anode and modified lead anode of the present application in the electrolysis process.

[0030] Figure 2 : Comparison chart of bubble particle production of traditional lead anode and modified lead anode of the present application in the electrolysis process.

[0031] Figure 3 : Comparison chart of anode slime generation in the electrolysis process between traditional lead anode and modified lead anode of the present application.

[0032] Figure 4 : Comparison chart of electrolysis energy consumption between traditional lead anode and modified lead anode. DETAILED DESCRIPTION

[0033] The following detailed description is provided in a progressive manner to the embodiments of the present application, which is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0034] The present application is a preparation method of IrO2-FTO coated composite anode plate, comprising the following steps: Step 1: Pre-treatment of the plate; Selection and preparation of the substrate: Commercial grade Pb-Ag-Ca alloy plate is selected as the substrate, and the typical chemical composition is: Pb content is the balance, Ag content is 1 wt%, and Ca content is 0.05 wt%. The alloy plate is cut into the required size (such as 100 mm × 50 mm × 3 mm).

[0035] 800 mesh, 1200 mesh, 1500 mesh, and 2000 mesh metallographic sandpaper are used to polish the surface of the plate step by step until the surface presents a uniform metal luster, so as to completely remove the surface oxidation layer, oil stains and mechanical damage layer, so as to obtain a moderate surface roughness, thereby enhancing the mechanical interlocking effect. The polished plate is sequentially placed in analytical pure acetone, anhydrous ethanol and deionized water, and ultrasonic cleaning is performed for 10-15 minutes, respectively, so as to remove the residual abrasive particles and organic pollutants on the surface. The cleaned plate is immersed in a dilute nitric acid solution with a concentration of 5 wt%, and soaked for 2 minutes, so as to remove the extremely thin passivation film, activate the surface, and increase the surface reaction active sites. Then, the plate is immediately rinsed with a large amount of deionized water, dried with nitrogen or placed in a 70℃ oven for drying for standby.

[0036] Step 2: Magnetron sputtering deposition of IrO2 film; The pretreated lead alloy substrate was loaded into the chamber of a high vacuum magnetron sputtering system. Two independent sputtering targets were installed in the system in parallel, with the center line symmetrically clamped at a specific angle of ± 30° with the substrate normal to optimize the uniformity of the deposited film: the first target was a high-purity (≥99.95%) metal iridium target as the source of IrO2; the second target was a fluorine-doped tin dioxide ceramic target, which was a dense ceramic body sintered by hot pressing from SnO2 and 0.5-1.0 wt% SnF2, with the proportion of fluorine atoms controlled in the range of 3-5 at.% by precursor ratio, as the functional source of SnO2:F (FTO).

[0037] First, the chamber background vacuum was pumped to ≤5.0 × 10 -4 Pa by a molecular pump group, which was a key prerequisite to ensure film purity and avoid impurity gas pollution. Then, high-purity (≥99.999%) argon and oxygen were introduced as working gases. The gas flow was accurately controlled by mass flow meters: argon as the main ionizing gas, with a stable flow of 30-45 sccm; oxygen as the reaction gas, with a flow of 6-12 sccm. This range of oxygen partial pressure was to ensure that metal Ir was fully oxidized to stoichiometric IrO2, while avoiding the balance point of excessive oxidation of the FTO target surface, which would cause the sputtering rate to drop and fluorine to be lost. By precisely adjusting the baffle valve, the chamber working pressure was stabilized at 0.4-0.7 Pa, which was beneficial to maintaining a stable glow plasma and ensuring that the deposited particles had sufficient kinetic energy, thereby forming a dense film.

[0038] The water-cooled circulation system of the substrate table was turned on to ensure that the substrate temperature was always below 160°C during the entire deposition process, which aimed to prevent the lead alloy substrate from softening, deforming or grain growth due to overheating. Then, the radio frequency power sources (frequency 13.56 MHz) of the first and second targets were started simultaneously. Independent control of the sputtering power of the two targets was the core means to accurately regulate the Ir to Sn atomic ratio in the composite film (Ir:Sn could be flexibly adjusted in the range of 1:9 to 4:6). The specific parameters were: the power density of the metal Ir target was controlled at 2-4 W / cm 2 , and the power density of the fluorine-doped tin dioxide ceramic target was controlled at 3-6 W / cm 2In this optimized parameter, the metal Ir target is reacted sputtered to generate IrO2 by combining with active oxygen atoms in the plasma; meanwhile, the FTO target is sputtered to provide the required Sn, O and F element components. The two streams of matter are activated and ionized in the plasma atmosphere and are co-transported to the substrate surface for co-deposition. Since the atoms / ions reaching the substrate have sufficient diffusion energy, they are not simply physically mixed, but form an Ir-Sn-O-F composite layer with uniform composition and no clear interface through surface migration and reaction, realizing material compounding on a nanoscale.

[0039] The deposition time is accurately controlled according to the required film thickness, usually 80-150 minutes, to obtain a composite film layer with a thickness of about 400-600 nm. After deposition, in-situ post annealing is immediately performed: in a pure oxygen atmosphere of 0.5-1.0 Pa, the sample is heated to 220-260°C at a heating rate of 5-10°C / min and kept for 30-45 minutes, and then cooled with the furnace. This annealing process has three key roles: 1. Promote crystallization: further crystallize the amorphous or microcrystalline composite oxide to form a thermodynamically stable rutile phase solid solution structure, and this coherent structure is the basis for obtaining high conductivity.

[0040] 2. Repair defects: use annealing energy to repair point defects such as oxygen vacancies generated during the deposition process, optimize the stoichiometric ratio of the film layer, and significantly improve its chemical stability.

[0041] 3. Release stress: eliminate the internal stress of the film layer, enhance the bonding force between it and the lead substrate, and ultimately obtain a composite functional layer with excellent adhesion, excellent conductivity and long-term stability.

[0042] Step 3: Infrared picosecond laser microstructure processing; An infrared picosecond laser processing system is used, mainly including: a picosecond laser (central wavelength 1030 nm, pulse width 10 ps), a beam scanning system (such as a galvanometer scanner), and a precision three-dimensional moving platform (positioning accuracy ±1 μm).

[0043] Parameter setting and pattern design: laser power density 0.3-0.6 J / cm 2 , scanning speed 100-300 mm / s, spot spacing 10-20 μm, and scanning pattern is a groove structure.

[0044] The processed electrode plate is fixed on the machining platform, and the laser beam is scanned on the working surface of the electrode plate according to the preset pattern under the control of the computer. The laser ablation acts on the surface of the IrO2-FTO composite film to accurately manufacture a micron-level groove structure. At the same time, due to the interaction between laser and material (such as melting, vaporization, and redeposition), nanoscale protrusions, particles, or wrinkles are formed inside and around the microstructure, thereby constructing a micro-nano composite rough structure. Laser micro-nano structuring provides roughness and high surface area, forming a large number of active sites (hydroxyl groups, oxygen vacancies, etc.), which helps the nucleation and mechanical locking of the subsequent polymer film. This structure also provides a support skeleton for the subsequent interpenetration of the polymer.

[0045] Step 4: In-situ electrochemical formation of a conductive sulfonic acid polymer layer; A sulfonate-modified conductive monomer is electro-polymerized on the laser micro-nano structured IrO2-FTO substrate using an electrochemical anodic oxidation polymerization method to form a dense polymer film layer with conductivity and gas resistance. Due to the micropores and grooves produced by the laser structure, the polymer can grow on the surface and inside, forming an "interpenetrating network" type covering layer, and forming a chemical bond + physical embedding dual combination with the IrO2-FTO layer.

[0046] First, the laser micro-structured IrO2-FTO electrode sample is used as the working electrode. To ensure good electrical contact and avoid edge discharge, the back of the sample is connected with silver paste, and the edge is insulated with epoxy resin. Electrochemical polymerization is carried out in a three-electrode system, where the reference electrode is Ag / AgCl (saturated KCl), the counter electrode is a high-purity platinum sheet (with an area of about 3-5 times that of the working electrode), and the electrolytic cell is made of glass. The system is placed in a constant temperature water bath to maintain 25±2 °C.

[0047] The electro-polymerization solution is prepared from the sulfonate-modified monomer 3,4-ethylenedioxythiophene-sodium sulfonate (EDOT-SO3Na), with a monomer concentration of 20 mM, deionized water as the solvent, and 0.1-0.3 M sulfuric acid (H2SO4) as the supporting electrolyte. This acidic medium not only ensures the dissociation of the monomer, but also simulates the actual electrolytic conditions. If the solubility of the monomer is insufficient, a mixture of water and ethanol with a volume ratio of 9:1 can be used to improve solubility. The solution is purged with high-purity nitrogen for 10 minutes to remove dissolved oxygen and prevent spontaneous oxidation polymerization.

[0048] Before polymerization, the working electrode was pretreated with a voltammetry scan to stabilize the interface and remove reducible impurities: 5 cycles were scanned in the range of -0.2~+1.2 V (vs Ag / AgCl) at 50 mV / s. Subsequently, the electro-polymerization reaction was carried out in the constant potential mode, with the potential controlled at +0.9 V (vs Ag / AgCl), and the polymerization time was 100-300 s. The current-time curve was recorded during the reaction, and the initial current rapidly decreased to a stable value, indicating that the film layer was uniform and dense.

[0049] To further improve the local polymerization rate and film density, laser-assisted irradiation was applied during the constant potential electro-polymerization. A near-infrared picosecond laser (wavelength 1030 nm, pulse width 10 ps, power density 0.3 J / cm 2 ), with a scanning speed of 200 mm / s, was used to synchronously scan the electrode surface. The local thermal effect of the laser and the photo-induced electron excitation can promote the oxidation reaction rate of the monomer, achieve regional selectivity, or enhance the film formation effect. After the polymerization was completed, the current was immediately stopped, the sample was taken out and rinsed with deionized water for 3 times to remove the unreacted monomer and solution residues, and then dried in a vacuum oven at 60 °C for 30 min. The surface color of the obtained sample changed from gray-white to deep blue or black, indicating that a polymer film had been formed. The film thickness was 100-200 nm.

[0050] Step 5: Performance test and evaluation; Electrochemical performance test: A standard three-electrode system (working electrode: test plate; reference electrode: saturated calomel electrode SCE; counter electrode: platinum plate) was used to perform potentiodynamic polarization (Tafel curve) and electrochemical impedance spectroscopy (EIS) tests in a sulfuric acid solution simulating the actual electrolysis conditions (such as 150 g / L H2SO4). The results showed that, compared with the untreated lead alloy anode, the corrosion potential of the plate of the application shifted positively, and the corrosion current density decreased by more than 50%.

[0051] Anode mud production test: A 200-hour accelerated life test was carried out under simulated industrial electrolysis conditions (such as zinc deposition: Cu 2+ 40 g / L, H2SO4 160 g / L, temperature 60℃, current density 320 A / m 2 ). The generated anode mud was collected and weighed. The results showed that, compared with the untreated lead alloy anode, the weight of the anode mud generated by the plate of the application was reduced by more than 40%.

[0052] Bubble behavior and particulate matter monitoring: A high-speed camera was used to record the generation, growth, and detachment dynamics of oxygen bubbles on the anode surface. Image analysis showed that the average detachment diameter of the bubbles was reduced from 1.1 mm for the traditional anode to 0.1 mm. A particulate matter counter was used to monitor the PM2.5 The results show that the concentration of particulate matter is reduced by more than 40%.

[0053] Long-term stability test: After 300 hours of continuous or intermittent electrolysis operation, the surface morphology and electrochemical performance of the electrode plate are checked, confirming that the film layer has no significant peeling off, the bubble performance is well maintained, and the performance decay rate is low.

[0054] Example 1: Substrate: Pb-1%Ag-0.05%Ca alloy plate (100 mm × 50 mm × 3 mm).

[0055] Pre-treatment: mechanical polishing to 2000 mesh according to step 1, ultrasonic cleaning with acetone, ethanol, and deionized water for 10 min each, 5 wt% HNO3 activation for 2 min, deionized water rinse, and nitrogen blowing dry.

[0056] Double-target magnetron co-sputtering one-step preparation of IrO2-SnO2:F (IrO2-FTO) composite functional layer: the pretreated lead alloy plate is used as the substrate and is loaded into a high vacuum magnetron sputtering system. The first target is a high-purity (≥99.95%) iridium metal target, and the second target is a fluorine-doped tin dioxide ceramic target (a sintered body of SnO2 and 0.8 wt% SnF2). The base vacuum is pumped to ≤5.0 × 10 -4 Pa, the working gas is argon (flow rate 40 sccm) and oxygen (flow rate 10 sccm), and the working pressure is stabilized at 0.6 Pa. The substrate temperature is controlled below 150°C. The double-target radio frequency power supply is started simultaneously, the Ir target power density is 3 W / cm 2 , the FTO target power density is 5 W / cm 2 , and the deposition time is 150 minutes to obtain a composite film with a thickness of about 600 nm. After deposition, in-situ annealing is performed: pure oxygen atmosphere, 240°C, holding for 40 minutes.

[0057] Laser micro-nano construction: an infrared picosecond laser micro-processing system is used, the laser power density is 0.6 J / cm 2 , the scanning speed is 200 mm / s, the spot spacing is 20 μm, and parallel micro-groove arrays with a width of 30 μm, a depth of 20 μm, and a spacing of 100 μm are etched on the gas-lean surface.

[0058] Electrochemical in-situ formation of conductive sulfonic acid polymer layer: First, laser micro-nano structured IrO2-FTO samples cleaned by ultrasonic washing (deionized water and ethanol for 5 min each) and dried at 120 °C were used as working electrodes, and the back was connected with silver paste and insulated with epoxy resin. The electrochemical polymerization process was carried out in a three-electrode system, with Ag / AgCl (saturated KCl) as the reference electrode and high-purity platinum sheet as the counter electrode. The electrolytic cell was made of glass and kept at a constant temperature of 25±2 °C. When preparing the polymerization solution, 3,4-ethylenedioxythiophene-sodium sulfonate (EDOT-SO3Na) was dissolved in 0.1 M sulfuric acid (H2SO4) aqueous solution, and the monomer concentration was controlled at 20 mM. If the solubility is insufficient, a mixed solvent of deionized water and ethanol with a volume ratio of 9:1 can be used. To prevent spontaneous oxidation, the solution was purged with high-purity nitrogen for 10 min to remove dissolved oxygen before polymerization. Then the sample was immersed in the electrolyte, and first scanned 5 cycles at-0.2~+1.2 V (vs Ag / AgCl) with a scan rate of 50 mV / s to activate the interface, and then switched to constant potential mode, and the anodic electropolymerization reaction was carried out at +0.9 V (vs Ag / AgCl) for 120 s. The current-time curve was recorded during the reaction, and the current rapidly decayed and stabilized, indicating that the film layer was formed dense and uniform. To further improve the local polymerization rate and film uniformity, laser irradiation was applied simultaneously during polymerization. A picosecond laser with a wavelength of 1030 nm, a pulse width of 10 ps, a power density of 0.3 J / cm 2 , and a scanning speed of 200 mm / s was used to scan the surface of the working electrode synchronously to enhance the electrochemical reaction activity. After the polymerization was completed, the power was turned off, the sample was taken out and washed with deionized water three times to remove residual monomers and electrolyte, and then dried in a vacuum oven at 60 °C for 30 min. The obtained film layer was blue-black, and the thickness was about 100 nm.

[0059] Performance test: In 150 g / L H2SO4, the corrosion current density was reduced by 63% compared with the untreated lead anode. Simulated zinc deposition for 200 h, the amount of anode mud was reduced by 47%. High-speed photography showed that the average bubble detachment diameter was reduced from 1.1 mm to 0.1 mm. The PM 2.5 concentration above the electrolytic cell was reduced by 49%. The electrolytic energy consumption was 2954.10 kW·h / t, which was about 6% lower than the traditional plate electrolytic energy consumption.

[0060] Example 2: Substrate: Pb-1%Ag-0.05%Ca alloy plate (100 mm × 50 mm × 3 mm).

[0061] Pre-treatment: mechanical polishing to 2000 mesh, ultrasonic cleaning in acetone, anhydrous ethanol, deionized water for 10 minutes, respectively, then activated in 5 wt% HNO3 solution for 2 minutes, washed with deionized water and dried by nitrogen.

[0062] The pre-treated lead alloy plate was loaded into a high vacuum magnetron sputtering system. The first target was a high-purity (≥99.95%) iridium metal target, and the second target was a fluorine-doped tin dioxide ceramic target (sintered body of SnO2 and 0.5 wt% SnF2). The background vacuum was pumped to ≤5.0 × 10 -4 Pa, the working gas was argon (flow rate 40 sccm) and oxygen (flow rate 10 sccm), and the working pressure was stabilized at 0.6 Pa. The substrate temperature was controlled below 150°C. The double-target radio frequency power supply was started simultaneously, the Ir target power density was 3 W / cm 2 , the FTO target power density was 5 W / cm 2 , the deposition time was 100 minutes, and a composite film with a thickness of about 500 nm was obtained. After deposition, in-situ post-annealing was performed: pure oxygen atmosphere, 240°C, holding for 40 minutes.

[0063] Laser micro-nano construction: an infrared picosecond laser processing system was used, the laser power density was 0.6 J / cm 2 , the scanning speed was 200 mm / s, the spot spacing was 20 μm, and parallel micro-groove arrays with a width of 30 μm, a depth of 20 μm, and a spacing of 100 μm were etched on the air-lean surface.

[0064] Electrochemical in-situ formation of conductive sulfonic acid polymer layer: First, the laser micro-nano structured IrO2-FTO sample cleaned by ultrasonic washing (deionized water and ethanol for 5 min each) and dried at 110 °C was used as the working electrode, the back was connected with silver paste and insulated with epoxy resin. The electrochemical polymerization process was carried out in a three-electrode system, the reference electrode was Ag / AgCl (saturated KCl), the counter electrode was a high-purity platinum sheet, and the electrolytic cell was made of glass and kept at a constant temperature of 25±2 °C. When preparing the polymerization solution, 3,4-ethylenedioxythiophene-sodium sulfonate (EDOT-SO3Na) was dissolved in 0.2 M sulfuric acid (H2SO4) aqueous solution, and the monomer concentration was controlled at 20 mM. If the solubility is insufficient, a mixed solvent of deionized water and ethanol with a volume ratio of 9:1 can be used. To prevent spontaneous oxidation, the solution was purged with high-purity nitrogen for 10 min to remove dissolved oxygen before polymerization. Then the sample was immersed in the electrolyte, first scanned 5 cycles at-0.2~+1.2 V (vs Ag / AgCl) with a scan rate of 50 mV / s to activate the interface, then switched to constant potential mode and carried out anodic electropolymerization at +0.9 V (vs Ag / AgCl) for 200 s. The current-time curve was recorded during the reaction, and the current rapidly decayed and stabilized, indicating that the film layer was formed dense and uniform. To further improve the local polymerization rate and film uniformity, laser irradiation was applied during polymerization. A picosecond laser with a wavelength of 1030 nm, a pulse width of 10 ps, a power density of 0.3 J / cm 2 , and a scanning speed of 200 mm / s was used to scan the surface of the working electrode synchronously to enhance the electrochemical reaction activity. After the polymerization was completed, the power was turned off, the sample was taken out and washed with deionized water three times to remove residual monomers and electrolyte, and then dried in a vacuum oven at 60 °C for 30 min. The obtained film layer was blue-black in color and about 120 nm thick.

[0065] Performance test: Electrochemical test in 150 g / L H2SO4 solution showed that the corrosion current density was reduced by 58% compared with untreated lead anode. Under the condition of simulated copper electrowinning, the anode mud production was reduced by 42% after 200 hours of test. High-speed camera analysis showed that the average bubble detachment diameter was reduced from 1.1 mm to 0.3 mm, and the PM 2.5 concentration above the electrolytic cell was reduced by 41%. The electrolysis energy consumption was 3005.21 kW·h / t, which was about 5% lower than that of traditional electrode plate.

[0066] Comparative Example 1 (traditional lead alloy anode): The Pb-Ag-Ca alloy plate with the same components and pretreatment as in Example 1 is not subjected to IrO2-SnO2:F (IrO2-FTO) composite functional layer preparation, laser microstructure construction and electrochemical in-situ conductive sulfonic acid polymer layer formation.

[0067] Performance test: under the same test conditions, the corrosion current density is high, the electrolytic energy consumption is the highest (3188.21 kW·h / t), the amount of anode sludge generated is large, the average diameter of the bubbles is 1.1 mm, the PM 2.5 The emission concentration is high.

[0068] Comparative Example 2 (only IrO2 film, gas-averse microstructure): The IrO2-SnO2:F (IrO2-FTO) composite functional layer is prepared according to the method of Example 1, but the laser microstructure construction and the electrochemical in-situ conductive sulfonic acid polymer layer formation are not performed.

[0069] Performance test: the corrosion prevention effect is better, and the electrolytic energy consumption is lower (3045.19 kW·h / t), but the electrolytic emission reduction effect is poor, the bubble behavior is similar to that of the traditional anode, the bubbles are large, the desorption is slow, and the PM 2.5 The emission reduction effect is not obvious.

[0070] The above examples and comparative examples fully illustrate the synergistic advantages and necessity of the composite structure (IrO2-FTO composite film + gas-averse microstructure) of the present application in realizing the integration of corrosion prevention and emission reduction.

Claims

1. A method for preparing an IrO2-FTO coated composite anode plate, characterized in that, The method comprises the following steps: Step 1, lead alloy substrate pretreatment: Step 2, double-target magnetron co-sputtering one-step method for preparing IrO2-SnO2:F composite functional layer: Step 3, laser micro-nano structuring surface structure: Step 4, in-situ electrochemical formation of conductive sulfonic acid polymer layer.

2. The method for preparing IrO2-FTO coated composite anode plate according to claim 1, characterized in that, In step 1, the lead alloy substrate is mechanically polished, degreased, and activated by pickling to obtain a clean and activated surface.

3. The method for preparing IrO2-FTO coated composite anode plate according to claim 2, characterized in that, The step 2 comprises the following specific steps: taking the pretreated lead alloy substrate as a substrate, loading it into a cavity of a high-vacuum magnetron sputtering system, and installing two independent sputtering targets in the system in parallel: a first target is an iridium target with a purity of ≥99.95%, serving as a source of IrO2; a second target is a fluorine-doped tin dioxide ceramic target, which is a sintered body of SnO2 and SnF2, serving as a source of SnO2:F; first, the cavity background is vacuum-extracted to ≤5.0 × 10 -4 Pa, then, argon and oxygen are introduced as working gases, the gas flow is controlled through a mass flow meter, the cavity working pressure is stabilized at 0.4-0.7 Pa through an adjusting baffle valve; the substrate table water-cooling system is turned on to ensure that the substrate temperature is lower than 160°C during the deposition process, so as to prevent the lead substrate from softening and deforming; then, the radio frequency power sources of the first target and the second target are started simultaneously; the atomic ratio of Ir and Sn in the composite film is regulated by independently controlling the sputtering power of the two targets; the metallic Ir is formed into IrO2 by reactive sputtering, and the material stream sputtered from the FTO target contributes to the required Sn, O and F elements, both of which are transported to the substrate surface in the plasma atmosphere to perform co-deposition, forming a composite layer with uniform composition and no clear interface. After deposition, in-situ post-annealing is performed to form a solid solution structure mainly in the rutile phase and repair oxygen vacancies.

4. The method for preparing IrO2-FTO coated composite anode plate according to claim 3, characterized in that, Step 3 includes the following specific steps: using a laser micro-processing system, etching micron-scale groove structures on the IrO2-FTO composite surface obtained in step 2.

5. The method for preparing an IrO2-FTO coated composite anode plate as described in claim 4, characterized in that, Step 4 includes the following specific steps: on the IrO2-FTO micro-groove composite surface obtained in step 3, an in-situ conductive sulfonic acid gas-repellent layer is formed by electrochemical polymerization, that is, a sulfonate-modified conductive monomer is electrochemically polymerized on the laser micro-nano structured IrO2-FTO substrate by using an electrochemical anodic oxidation polymerization method, forming a dense polymer film layer with both conductivity and gas repellency.

6. The application of the preparation method of IrO2-FTO coated composite anode plate, characterized in that, The lead alloy anode plate prepared by the method of any one of claims 1-5 is applied to the wet electrolytic smelting and electrodeposition process of non-ferrous metals.

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