2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium-titanium mixed oxide / polymer temperature response type electrocatalytic oxidation electrode and preparation method thereof

Abstract

The invention discloses a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium-titanium mixed oxide / polymer temperature response type electrocatalytic oxidation electrode and a preparation method, and belongs to the technical field of electrocatalytic oxidation electrode preparation. Amorphous antimony-doped tin dioxide is loaded on molecular sieve particles in a hydrolytic polycondensation reaction and annealing mode; coating a thermal expansion layer formed by polyurethane on the surface to obtain auxiliary electrode particles; bonding a ruthenium-titanium mixed oxide layer on the porous titanium substrate, and then spraying a polymer layer formed by an N-isopropylacrylamide-acrylic acid copolymer to obtain a main electrode; suspending the auxiliary electrode particles on the main electrode, then standing, reducing the diameter of a surface pore channel, close to the auxiliary electrode particles, of the main electrode, heating and expanding a thermal expansion layer, close to one end of the main electrode, of the auxiliary electrode particles, and finally locking the thermal expansion layer in the pore channel of the main electrode to obtain the temperature response type electrocatalytic oxidation electrode. The main electrode and the particle auxiliary electrode are fully and stably combined, the electrode composition structure is endowed with the dynamic self-adaptive adjustment capability, the traditional electrode composition / structure adjustment limitation is overcome, and the in-situ adjustable performance and the in-situ material recovery characteristic are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic oxidation electrode preparation, and specifically relates to a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode and a preparation method thereof. Background Art

[0002] Water resources are an indispensable and precious resource on the earth and are vital to the sustainable development of human society. People are currently facing a serious water shortage problem, especially in arid areas and industrial concentrated areas. With the acceleration of the industrialization process, the discharge of wastewater has also continued to increase, resulting in increasingly serious water pollution, further exacerbating the above-mentioned water shortage problem. Therefore, it is particularly necessary to efficiently treat all types of wastewater. Among the many types of wastewater, organic wastewater, especially high-concentration, highly toxic and difficult-to-degrade organic wastewater, poses a serious threat to the environment and people's health. However, the classic physical-biochemical-chemical water treatment process has limitations in treating this type of organic wastewater. As a new type of wastewater treatment technology, electrocatalytic oxidation has the advantages of being green, efficient, simple and controllable, and is particularly suitable for treating the above-mentioned organic wastewater.

[0003] Electrocatalytic oxidation technology has shown significant advantages in the treatment of difficult-to-degrade pollutants due to its unique dual-pathway degradation mechanism - direct electron transfer at the anode (DET, i.e., direct oxidation pathway) and in situ generation of highly reactive oxygen species such as OH (i.e., indirect oxidation pathway). Its high efficiency, simplicity, controllability, anti-interference and environmental friendliness provide a reliable solution for engineering applications. The anode material is the core of electrocatalytic oxidation technology. The choice of anode material has a great influence on the reaction mechanism and reaction efficiency of electrocatalytic degradation of organic wastewater. The current anode systems mainly revolve around lead dioxide (PbO2), doped tin dioxide (SnO2), titanium oxide (Ti4O7) and boron-doped diamond (BDD). However, the inherent defects of these electrodes limit their practical application, such as metal leaching toxicity, low stability and high manufacturing cost.

[0004] In terms of electrode structure, traditional two-dimensional (2D) electrode systems suffer from limited electrochemically active surface area (ECSA) and boundary layer effects in mass transfer. Although three-dimensional (3D) electrode systems significantly increase ECSA through particle packing, they also face new challenges, such as difficulty in material recycling and renewal, and increased operating costs. More critically, traditional 2D / 3D electrode systems, limited by their inherent structural consistency and monotonous composition, are generally unsuitable for treating complex and variable wastewater compositions. The bottleneck lies in the difficulty of fixed electrode composition / structure to adapt to dynamic changes in pollutant concentration and composition in real time, resulting in a decrease in both mass transfer efficiency and reaction activity. To address these issues, Shao Dan et al. developed a novel magnetically assembled electrode (MAE) in 2015. This MAE dynamically arranges micro-nano magnetic particles (secondary electrodes) on the surface of a 2D primary electrode using a magnetic field, forming a hierarchical structure intermediate between 2D and 3D electrodes. This structure combines the directional electron transfer capability of a 2D electrode with the high specific surface area of ​​a 3D electrode, hence the name 2.5-dimensional electrode (2.5D electrode). The 2.5D electrode can regulate the electrode porosity and topology in real time through a magnetic field, which largely solves the problem that the fixed electrode composition / structure of traditional 3D electrodes is difficult to match the dynamic changes of pollutant concentration and composition in real time, and the problem that particles are difficult to recycle and update.

[0005] However, the current 2.5-dimensional electrocatalytic oxidation electrodes still have some problems: ① The binding force between the main and secondary electrodes strongly depends on magnetic force, requiring a continuous and high-intensity external magnetic field to maintain the electrode structure, and the magnetic binding method is difficult to scale up in practical applications; ② The material is not flexible enough, and the contact area between the magnetic particle secondary electrodes and even between the particle secondary electrodes and the main electrode is insufficient, resulting in large interface resistance, making it difficult to fully exert the catalytic ability of the particle secondary electrodes; ③ Relying solely on magnetic field regulation, it is impossible to achieve flexible loading and unloading through temperature changes. Summary of the Invention

[0006] The purpose of the present invention is to provide a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode and a preparation method to solve the problem that the binding force between the main and auxiliary electrodes strongly depends on magnetic force, the catalytic ability of the granular auxiliary electrode is difficult to fully exert and only relies on magnetic field regulation. The obtained Ti / RuO2-TiO2 / NIPAM-co-AAc (main electrode) + MS / Sb-SnO2 / SMP (auxiliary electrode) 2.5-dimensional electrode system regulates the binding state of the auxiliary electrode by temperature, so that the main electrode and the granular auxiliary electrode are fully and stably combined, and the electrode composition structure is given the ability of dynamic adaptive adjustment, overcoming the limitations of traditional electrode composition / structure regulation, and having both in-situ adjustable performance and in-situ material recovery characteristics.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for preparing a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode comprises the following steps:

[0009] S1, loading amorphous antimony-doped tin dioxide on molecular sieve particles by hydrolysis-polycondensation reaction and annealing, and then coating the surface with a thermal expansion layer formed by polyurethane to obtain secondary electrode particles;

[0010] S2, bonding a ruthenium-titanium mixed oxide layer on a porous titanium substrate, and then spraying a polymer layer formed of N-isopropylacrylamide-acrylic acid copolymer to obtain a main electrode;

[0011] S3, suspending the secondary electrode particles on the main electrode, and then letting it stand, the diameter of the surface pores of the main electrode near the secondary electrode particles shrinks, the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat, and finally locked in the pores of the main electrode, obtaining a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode.

[0012] A further improvement of the present invention is:

[0013] The molecular sieve particles described in S1 and the porous titanium matrix described in S2 are respectively obtained by the following processes:

[0014] The initial molecular sieve particles are immersed in ammonia water and ethanol, first stirred in a water bath at a constant temperature of 55-65°C for 5-7 hours, then centrifuged, the supernatant is discarded, and the residual ammonia water is removed with ethanol, and finally vacuum dried to obtain the molecular sieve particles;

[0015] The surface of the sheet-like porous titanium substrate was polished smooth with coarse sandpaper to reveal the metallic luster, then placed in a NaOH solution to remove surface oil stains, then placed in an oxalic acid aqueous solution to etch the surface to remove the passivation oxide layer on the surface, and finally rinsed with deionized water to obtain the porous titanium substrate.

[0016] S1 dissolves tin tetrachloride, antimony trichloride and citric acid in deionized water at 35-45°C, and then adjusts the pH of the resulting mixed solution to 1.5-2.5 to obtain a first mixed solution, and subjecting the molecular sieve particles and the first mixed solution to a hydrolysis-condensation reaction at 75-85°C. Thereafter, the reaction is annealed at 280-320°C in an oxygen-free environment to obtain a molecular sieve-based amorphous antimony-doped tin dioxide, and finally, a thermal expansion layer formed by polyurethane is coated on the surface of the molecular sieve-based amorphous antimony-doped tin dioxide to obtain secondary electrode particles.

[0017] In the mixed solution, the molar ratio of tin tetrachloride to antimony trichloride is 10:1. 4+The concentration of antimony is 0.15-0.25M, the molecular sieve particles and the first mixed solution are hydrolyzed and condensed at 75-85°C for 5-50 minutes, and then annealed at 280-320°C for 45-75 minutes in an oxygen-free environment to obtain molecular sieve-based amorphous antimony-doped tin dioxide.

[0018] S1: dissolving thermoplastic polyurethane in N,N-dimethylformamide, adding 1% to 2.25% of expanded graphite by mass of the thermoplastic polyurethane and dispersing it evenly to obtain a second mixed solution, immersing molecular sieve-based amorphous antimony-doped tin dioxide in the second mixed solution for solidification to obtain secondary electrode particles.

[0019] The curing is carried out as follows:

[0020] First, pre-curing is carried out at 75-85°C for 20-30 minutes, then placing in liquid nitrogen for 9-11 seconds, and finally freeze-drying at -55--45°C for 11-13 hours under the condition of 10-15 Pa.

[0021] S2 dissolves ruthenium trichloride trihydrate into a mixture consisting of 20% tetrabutyl titanate, 55% isopropyl alcohol, 23% anhydrous ethanol, 0.5% acetylacetone and 1.5% concentrated hydrochloric acid by volume, with a molar ratio of Ru to Ti of 3:5, to obtain a third mixed solution, immerses the porous titanium substrate in the third mixed solution, and after uniform absorption, takes out and sequentially dries, sinters and cools, repeating 2 to 12 times to obtain a porous titanium-based ruthenium titanium mixed oxide, and then sprays a polymer layer formed by N-isopropylacrylamide-acrylic acid copolymer on the surface of the porous titanium-based ruthenium titanium mixed oxide to obtain a main electrode.

[0022] S2: N-isopropylacrylamide and acrylic acid are uniformly mixed in a mass ratio of (1 to 5): (1 to 7), and then 0.01% to 1% of the total mass of N-isopropylacrylamide and acrylic acid is added to C3N4, and the resulting mixture is dissolved in a mixed solvent consisting of ethanol and acetic acid, and the mixture is reacted at 30 to 60°C for 30 minutes to obtain a fourth mixed liquid, and the fourth mixed liquid is uniformly sprayed onto the surface of the porous titanium-based ruthenium titanium mixed oxide, and then irradiated under ultraviolet light for 1 to 60 minutes, and heated at 50 to 100°C for 1 to 60 minutes to obtain a main electrode.

[0023] S3 heats deionized water to 40-90°C, and then evenly suspends the secondary electrode particles on the main electrode by ultrasound assistance. The process is then allowed to stand for 1-10 minutes. The diameter of the surface pores of the main electrode near the secondary electrode particles shrinks, and the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat and is locked in the pores of the main electrode, thereby obtaining a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode.

[0024] A 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode obtained by the preparation method of any one of the above-mentioned 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrodes.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention discloses a method for preparing a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium-titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode. The method comprises the following steps: loading amorphous antimony-doped tin dioxide on molecular sieve particles and coating the surface with polyurethane to form a thermal expansion layer for use as secondary electrode particles; bonding the ruthenium-titanium mixed oxide layer to a porous titanium substrate, and then spraying a polymer layer formed by N-isopropylacrylamide-acrylic acid copolymer to use as a main electrode; the secondary electrode particles are suspended on the main electrode and then allowed to stand, the diameter of the surface pores of the main electrode near the secondary electrode particles shrinks, the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat, and finally is locked in the pores of the main electrode; the binding state of the secondary electrode particles on the main electrode of the prepared novel temperature-responsive flexible self-assembled 2.5-dimensional electrode can be flexibly adjusted with temperature changes, giving the electrode unique in-situ performance adjustability and in-situ material recyclability. The electrocatalytic oxidation electrode obtained by the present invention can realize the intelligent retention and controllable release of the particle secondary electrode in the main electrode channel through precise temperature response matching and interface. It is suitable for electrochemical reaction systems that require timely replacement of catalysts, such as the electrocatalytic oxidation treatment of wastewater with complex and changeable components. In addition, compared with the limitations of traditional 2D electrodes, 3D electrodes and other typical 2.5D electrodes that are difficult to flexibly adjust the composition / structure, the temperature-responsive flexible self-assembled 2.5D electrode prepared by the present invention has stronger catalytic ability, higher organic matter degradation conversion efficiency and catalytic stability. The temperature response mechanism is used to flexibly assemble an appropriate amount of micron- or nanometer-scale particle secondary electrodes (molecular sieve-based antimony-doped tin dioxide / shape memory polyurethane, referred to as MS / Sb-SnO2 / SMP) on a two-dimensional main electrode (porous titanium-based ruthenium titanium mixed oxide / N-isopropylacrylamide-acrylic acid copolymer composite electrode, referred to as Ti / RuO2-TiO2 / NIPAM-co-AAc) to form a new 2.5-dimensional electrode. By regulating the binding state of the secondary electrode through temperature, the main electrode and the particle secondary electrode are fully and stably combined, and the electrode composition structure is given the ability to dynamically and adaptively adjust. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the MS / Sb-SnO2 / SMP particle sub-electrode prepared in the present invention;

[0028] Figure 2aThis is a super-depth scanning image of the Ti / RuO2-TiO2 / NIPAM-co-AAc main electrode prepared by the present invention with a magnification of 20;

[0029] Figure 2b This is a super-depth scanning image of the Ti / RuO2-TiO2 / NIPAM-co-AAc main electrode prepared by the present invention with a magnification of 200;

[0030] Figure 3 Schematic diagram of the structure of the 2.5-dimensional anode in the present invention;

[0031] Figure 4a A comparison of the degradation rate of the simulated pollutant Acid Red G by electrocatalytic oxidation degradation over time for the 2.5-dimensional electrode (2.5D electrode) prepared in Example 1 of the present invention, the 2D electrode, the traditional 2.5D electrode, and the 3D electrode;

[0032] Figure 4b A comparison of the degradation rate of the simulated pollutant bisphenol A by electrocatalytic oxidation degradation over time using the 2.5-dimensional electrode (2.5D electrode) prepared in Example 1 of the present invention, a 2D electrode, a traditional 2.5D electrode, and a 3D electrode;

[0033] Figure 4c A comparison of the degradation rate of the simulated pollutant tetracycline by electrocatalytic oxidation degradation over time of the 2.5-dimensional electrode (2.5D electrode) prepared in Example 1 of the present invention, a 2D electrode, a traditional 2.5D electrode, and a 3D electrode;

[0034] Figure 4d A comparison of the degradation rate of the simulated pollutant ciprofloxacin by electrocatalytic oxidation degradation over time of the 2.5-dimensional electrode (2.5D electrode) prepared in Example 1 of the present invention, the 2D electrode, the traditional 2.5D electrode, and the 3D electrode;

[0035] Figure 5 A bar graph comparing the COD removal rates of two actual wastewaters electrocatalytically oxidized by a 2.5-dimensional electrode (2.5D electrode) prepared in Example 2 of the present invention, a 2D electrode, a traditional 2.5D electrode, and a 3D electrode;

[0036] Figure 6 A bar graph comparing the COD removal rates of two industrial wastewaters electrocatalytically oxidized by a 2.5-dimensional electrode (2.5D electrode) prepared in Example 3 of the present invention, a 2D electrode, a traditional 2.5D electrode, and a 3D electrode;

[0037] Figure 7 This is a diagram showing the long-term electrocatalytic oxidation treatment results of tanning wastewater by the 2.5-dimensional electrode (2.5D electrode) prepared in Example 3 of the present invention, the 2D electrode, the traditional 2.5D electrode and the 3D electrode. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to specific embodiments and drawings, which are intended to explain rather than limit the present invention.

[0039] For the convenience of writing, the porous Ti / RuO2-TiO2 / NIPAM-co-AAc electrode loaded with MS / Sb-SnO2 / SMP particles is recorded as MS-Ti / RuO2-TiO2, and 2D-Ti / RuO2-TiO2, traditional 2.5-dimensional electrodes (magnetic assembly electrode, the main electrode is Ti / RuO2-TiO2, and the particle secondary electrode is Fe3O4 / Sb-SnO2) and 3D-Ti / RuO2-TiO2 (filling particles are MS / Sb-SnO2 particles) are prepared for comparison.

[0040] The specific preparation process of 3D-Ti / RuO2-TiO2 (filler particles are MS / Sb-SnO2 particles) and 2.5-dimensional electrodes (magnetic assembly electrode, the main electrode is Ti / RuO2-TiO2, and the particle secondary electrode is Fe3O4 / Sb-SnO2) is as follows:

[0041] 3D-Ti / RuO2-TiO2 means that particles are filled between the anode and cathode. The anode is 2D-Ti / RuO2-TiO2, the cathode is Ti, and the particles are MS / Sb-SnO2.

[0042] The preparation method of the particle sub-electrode Fe3O4 / Sb-SnO2 in the 2.5-dimensional electrode is as follows: Fe3O4 magnetic particles and mixed solution I are transferred to a beaker and mixed in a ratio of 1g:2mL. After stirring evenly, the mixture is placed in an oven and baked at 75℃ for 4h, and then placed in a muffle furnace and calcined at 450℃ for 15min to form a Sb-SnO2 layer on the surface of the Fe3O4 particles. This step is repeated 7 times; wherein, the Fe3O4 magnetic particles and Sb-SnO2 are bonded by chemical bonds (mainly Fe-O-Sn / Sb bonds) formed by high-temperature calcination.

[0043] The 2.5-dimensional mentioned in the present invention refers to a new electrode structure that combines planes and particles, which is between the 2-dimensional (planar electrode system) and 3-dimensional (particle electrode system) structures. The binding state of the secondary electrode particles on the main electrode can be flexibly adjusted with temperature changes, giving the electrode unique performance in situ adjustability and in situ recyclability of materials (replaced with new secondary electrode particles), stronger catalytic ability, higher organic matter degradation conversion efficiency and catalytic stability.

[0044] The present invention discloses a method for preparing a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode. The method comprises the following steps: loading amorphous antimony-doped tin dioxide on molecular sieve particles through a hydrolysis-polycondensation reaction and annealing; coating the surface with a thermal expansion layer formed by polyurethane to obtain secondary electrode particles; bonding the ruthenium titanium mixed oxide layer to a porous titanium substrate; and spraying a polymer layer formed by N-isopropylacrylamide-acrylic acid copolymer to obtain a main electrode. The secondary electrode particles are suspended on the main electrode and then allowed to stand. The diameter of the surface pores of the main electrode near the secondary electrode particles decreases, and the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat. Finally, the secondary electrode particles are locked in the pores of the main electrode to obtain the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode. The electrocatalytic oxidation electrode has in-situ performance adjustable capability and can be flexibly self-assembled. The method specifically comprises the following steps:

[0045] (1) Pre-treating micro-nano sized molecular sieve particles (such as ZSM-5) and porous titanium substrates respectively;

[0046] Immerse the molecular sieve particles in ammonia and ethanol with a mass percentage concentration of 26%. Stir in a 60°C water bath for 6 hours, then centrifuge for 5 minutes and discard the supernatant. Rinse with ethanol three times to remove residual ammonia, and finally vacuum dry at 80°C for 24 hours before use. This treatment process is mainly to remove the residual organic template and residual ammonia during the molecular sieve synthesis process, ultimately achieving the effect of cleaning the molecular sieve pores and improving its adsorption capacity.

[0047] Using a porous titanium sheet as the substrate, polish the surface with 200-grit coarse sandpaper to remove the surface oxide layer and reveal a metallic luster. The substrate is then placed in a 10% NaOH solution and heated and boiled for 10 minutes to remove surface oil. The surface is then acid-etched in a 10% oxalic acid solution and heated and boiled for 2 hours to remove the passive oxide layer. The substrate is then rinsed with deionized water and set aside.

[0048] (2) Tin tetrachloride (SnCl4) and antimony trichloride (SbCl3) were mixed at a molar ratio of Sn:Sb of 10:1, 0.5 mol of citric acid was added as a complexing agent, and then dissolved in 1 L of deionized water. The pH was adjusted to 2 with concentrated hydrochloric acid, and stirred for 90 min until the solution was clear to obtain a mixed solution I, in which Sn 4+ The concentration was 0.2M and the solution temperature was controlled at 40°C to avoid Sn 4+ and Sb 3+ Hydrolyze to obtain mixed solution Ⅰ;

[0049] Dissolve thermoplastic polyurethane (TPU) in N,N-dimethylformamide (DMF) at a ratio of 1 to 15 wt % by mass, add 1 to 15 wt % (1 to 15% by mass of DMF) of expanded graphite as a thermal expansion filler, and stir for 1 to 6 hours (temperature 30 to 90° C.) until completely dispersed to obtain a mixed solution II (thermal expansion layer coating mixed solution II);

[0050] 17.8 g of ruthenium trichloride trihydrate (RuCl3·3H2O) was added to a solution of 20% by volume of tetrabutyl titanate, 55% of isopropyl alcohol, 23% of anhydrous ethanol, 0.5% of acetylacetone, and 1.5% of concentrated hydrochloric acid, and stirred for 10 minutes until the solution was uniform, to obtain mixed solution III, in which the molar ratio of Ru to Ti was 3:5;

[0051] N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) are uniformly mixed in a mass ratio of (1-5):(1-7), and then 0.01-1 wt% (based on the total mass of NIPAM and AAc) of C3N4 as an initiator is added. The mixture is slowly stirred and uniformly dissolved in a mixed solvent consisting of ethanol and acetic acid in a mass ratio of (1-5):(1-7) at a mass percentage of 5-15 wt%, and reacted at 30-60° C. for 30 min to obtain a temperature-responsive adhesive IV.

[0052] The specific reactions are:

[0053]

[0054]

[0055] Where R· is the active free radical generated on the C3N4 surface, and NIPAM-co-AAc represents the copolymer of N-isopropylacrylamide (NIPAM) and acrylic acid (AAc), with the following structural formula:

[0056]

[0057] R·Production chain initiation:

[0058]

[0059] Chain Growth:

[0060]

[0061] Where X is:

[0062] -C(O)NHCH(CH3)2(NIPAM)

[0063] Y is:

[0064] -COOH(AAc)

[0065] a:b is determined by the feed ratio

[0066] (3) The molecular sieve particles obtained in step (1) and the mixed solution I obtained in step (2) are transferred to a beaker and mixed at a ratio of 2 g:5 mL. The mixture is stirred in a constant temperature water bath at 80°C for 5 to 50 minutes to undergo a hydrolysis and polycondensation reaction to obtain a solid phase product (molecular sieve particles loaded with amorphous antimony-doped tin dioxide (Sb-SnO2) precursor). The solid phase product is then annealed at 300°C for 1 hour under nitrogen protection to obtain MS / Sb-SnO2 particles. The molecular sieve particles and Sb-SnO2 are bonded by covalent bonds formed by high temperature calcination.

[0067] (4) Immersing the MS / Sb-SnO2 particles obtained in step (3) in the mixed solution II obtained in step (2) at a ratio of 2 g:3 mL, and obtaining a MS / Sb-SnO2 / SMP (shape memory polyurethane) particle secondary electrode after gradient curing, wherein the shape memory polyurethane (SMP, i.e., thermoplastic polyurethane TPU) is coated on the surface of the MS / Sb-SnO2 as a thermal expansion layer;

[0068] The specific process of gradient curing is as follows: First, pre-curing at 80°C in an oven for 20-30 minutes. 80°C is above the TPU glass transition temperature (Tg), enabling molecular chain mobility. Simultaneously, the DMF solvent begins to evaporate, increasing the solution concentration. Second, quenching with liquid nitrogen (-196°C for 10 seconds) causes the system to instantly cross the glass transition region, instantly freezing the motion of the TPU molecular chains and expanded graphite sheets. The solvent, DMF (freezing point approximately -61°C), is also instantly frozen solid, its spatial distribution "locked," creating uniform channels for subsequent sublimation and forming the basis of the future porous structure. Third, freeze-drying (-50°C, 10Pa, 12h) occurs at -50°C, well below the TPU glass transition temperature (Tg), under high vacuum (10Pa). The frozen DMF (solid) sublimes directly (from solid to gas) and is removed. At this temperature, molecular chain motion is still suppressed, preserving the fine structure formed during the quenching phase. After the solvent is completely removed, the physical interactions (hydrogen bonds, crystallization, entanglement) between the TPU molecular chains are finally fixed to form a permanent network with shape memory effect.

[0069] (5) Immerse the porous titanium substrate pretreated in step (1) in the mixed solution III of step (2), take out the porous titanium substrate after evenly absorbing the solution, dry it, sinter it (temperature 450°C, time 10min), and cool it. Repeat the absorption-drying-sintering-cooling steps 2-12 times to obtain a porous Ti / RuO2-TiO2 electrode. Compared with a single treatment, repeating this step can increase the coating thickness and uniformity and improve the electrochemical active area. The porous titanium and ruthenium titanium mixed oxide are bonded by the Ti-O-Ru / porous Ti chemical bond formed by high-temperature calcination, i.e., the above-mentioned 2D-Ti / RuO2-TiO2.

[0070] (6) Use a spray gun to evenly spray a certain amount of the mixed solution IV obtained in step (2) onto the surface of the porous Ti / RuO2-TiO2 electrode obtained in step (5). Specifically, aim the spray gun at the electrode surface (at a distance of 5 to 20 cm), spray evenly, and repeat the spraying 3 to 20 times until the coating thickness reaches 1 to 100 μm. Then, perform curing under certain conditions (turn on an ultraviolet lamp with a wavelength of 365 nm for 1 to 60 minutes) and post-processing (place it in a 50 to 100°C oven for 1 to 60 minutes). The curing is mainly to make the coating firmly adhere to the porous Ti / RuO2-TiO2 electrode substrate to prevent it from falling off during subsequent operations or use. The heating is mainly to completely remove the residual solvent, make the coating denser, and reduce defects, so that a porous Ti / RuO2-TiO2 / NIPAM-co-AAc main electrode can be obtained;

[0071] (7) Electrode assembly: The assembly principle is temperature-triggered deformation to achieve precise loading / unloading of molecular sieve particles in the electrode pores.

[0072] Loading steps: First, heat deionized water to 40-90°C (higher than the lowest co-solubility temperature of polyNIPAM 32°C and the polyurethane expansion threshold 35°C), then put the main electrode and sub-electrode particles into a water bath, turn on ultrasonic assistance (100W, 40kHz) for 1-10 minutes to ensure that the particles are evenly suspended on the main electrode. Then turn off the ultrasound and let it stand for 1-10 minutes. During this period, the following synergistic changes occur: the polyNIPAM-co-AAc layer on the main electrode side dehydrates and shrinks, pulling the channel diameter to shrink by about 15%; the polyurethane layer on the sub-electrode side of the particle expands due to heat, and the diameter expands. The expanded particles are mechanically locked in the contracted porous main electrode channel, such as Figure 3 As shown, a new 2.5-dimensional electrode is formed.

[0073] Unloading step: Place the assembly in a 0°C ice-water bath for 1-20 minutes. The poly-NIPAM-co-AAc layer absorbs water and expands (restoring its original volume), while the polyurethane layer shrinks (returning to its initial volume). The assembly is then rapidly vibrated to completely release the binding force between the particle secondary electrode and the primary electrode.

[0074] Example 1

[0075] (1) ZSM-5 molecular sieve (SiO2 / Al2O3=50, where the molar ratio of SiO2 to Al2O3 in the molecular sieve is 50) was immersed in ammonia water and ethanol, where the ammonia water accounted for 10% of the total volume of the ammonia water and ethanol. The mixture was stirred in a 60°C water bath for 6 hours, then centrifuged for 5 minutes, and the supernatant was discarded. The mixture was then rinsed with ethanol three times to remove residual ammonia water, and finally vacuum dried at 80°C for 24 hours before use.

[0076] A 3mm thick, 5cm x 5cm porous titanium substrate was used as the substrate. The surface was polished smooth with 200-grit coarse sandpaper to remove the surface oxide layer and reveal the metallic luster. The substrate was placed in a 10% NaOH solution and heated and boiled for 10 minutes to remove surface oil. The surface was then acid-etched in a 10% oxalic acid solution and heated and boiled for 2 hours. The substrate was rinsed with deionized water and set aside for use.

[0077] (2) Tin tetrachloride (SnCl4) and antimony trichloride (SbCl3) were mixed at a molar ratio of Sn:Sb of 10:1, 0.5 mol of citric acid was added as a complexing agent, and the mixture was dissolved in 1 L of deionized water. The pH was adjusted to 2 with concentrated hydrochloric acid, and the mixture was stirred for 90 min until the solution was clear to obtain a mixed solution I. 4+ The concentration was 0.2M and the solution temperature was controlled at 40°C to avoid Sn 4+ and Sb 3+ hydrolysis.

[0078] The molecular sieve particles obtained in step (1) and the mixed solution I were transferred to a beaker in an amount of 20 g and 50 mL, respectively, and mixed. The mixture was stirred in a constant temperature water bath at 80°C for 10 min to undergo a hydrolysis and polycondensation reaction to obtain a solid phase product (molecular sieve particles loaded with amorphous antimony-doped tin dioxide (Sb-SnO2) precursor). The solid phase product was annealed at 300°C for 1 h under nitrogen protection to obtain MS / Sb-SnO2 particles. The molecular sieve particles and Sb-SnO2 are bonded by covalent bonds formed by high-temperature calcination.

[0079] (3) 3 wt% of thermoplastic polyurethane (TPU) was dissolved in N,N-dimethylformamide (DMF), 2 wt% of expanded graphite was added as a thermal expansion filler, and stirred for 2 h (temperature 40°C) until completely dispersed to obtain a thermal expansion layer coating mixed solution II.

[0080] Next, immerse the MS / Sb-SnO2 particles obtained in step (2) in mixed solution II in an amount of 20 g and 30 mL, and pre-cured in an oven at 80°C for 20 min. Pour the pre-cured particles while still hot (>60°C) into a stainless steel colander, immerse the colander in liquid nitrogen to completely submerge it, and time for 10 seconds. Finally, quickly transfer the liquid nitrogen-treated particles to a pre-cooled aluminum tray and place them in a freeze dryer at a pressure of 10 Pa and a cold trap temperature of -50°C for 12 hours to obtain MS / Sb-SnO2 / SMP particles.

[0081] like Figure 1 As shown, these granular secondary electrodes have an approximately spherical shape and a particle size between 400 μm and 800 μm.

[0082] (4) 17.8 g of ruthenium trichloride trihydrate (RuCl3·3H2O) was added to a solution of 20% by volume of tetrabutyl titanate, 55% of isopropyl alcohol, 23% of anhydrous ethanol, 0.5% of acetylacetone, and 1.5% of concentrated hydrochloric acid (the mass fraction is generally 36% to 38%), and stirred for 10 minutes until the solution was uniform and the ruthenium trichloride trihydrate was completely dissolved to obtain a mixed solution III; furthermore, the molar ratio of Ru to Ti was 3:5.

[0083] The porous titanium substrate pretreated in step (1) is immersed in the mixed solution III. After uniformly absorbing the solution, the porous titanium substrate is taken out and dried - sintered (temperature 450°C, time 10min) - cooled. After repeating the absorption - drying - sintering - cooling steps twice, a porous Ti / RuO2-TiO2 electrode is obtained. Compared with a single treatment, repeating this step can increase the coating thickness and uniformity and improve the electrochemical active area. Among them, the porous titanium and ruthenium titanium mixed oxide are bonded by the Ti-O-Ru / Ti chemical bond formed by high-temperature calcination;

[0084] (5) N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) were uniformly mixed in a mass ratio of 1:2, and then 0.2 wt% of C3N4 (initiator) was added. The above mixture was slowly stirred and uniformly dissolved in a mixed solvent of ethanol / acetic acid with a mass ratio of 1:3 at a ratio of 5 wt%, and reacted at 40 ° C for 30 min to obtain a temperature-responsive adhesive IV;

[0085] Use a small spray gun to evenly spray the mixed solution IV onto the surface of the porous Ti / RuO2-TiO2 electrode prepared in step (4) (at a distance of 15 cm), spraying a thin layer each time (thickness of 3 μm), and repeat the spraying 5 times until the total thickness reaches 15 μm. Then turn on the ultraviolet lamp (wavelength 365 nm) to irradiate the electrode for 10 minutes, and then place it in a 60°C oven for 10 minutes to obtain a porous Ti / RuO2-TiO2 / NIPAM-co-AAc electrode.

[0086] like Figure 2a and Figure 2b As shown, at low magnification, it can be seen that the electrode has a dense surface structure and a relatively uniform pore distribution. At high magnification, it can be seen that the electrode pore sizes vary, ranging from 10μm to 100μm.

[0087] (6) Loading step: Deionized water is heated to 60°C (higher than the lowest co-solubility temperature of poly NIPAM at 32°C and the polyurethane expansion threshold at 35°C). Then, the MS / Sb-SnO2 / SMP particles prepared in step (3) and the porous Ti / RuO2-TiO2 / NIPAM-co-AAc prepared in step (5) are placed in a water bath. Ultrasonic assistance (100W, 40kHz) is turned on for 3 minutes to ensure that the particles are evenly suspended on the main electrode. Then, the ultrasound is turned off and the mixture is allowed to stand for 3 minutes. During this period, the following synergistic changes occur: the poly NIPAM-co-AAc layer on the electrode side dehydrates and shrinks, pulling the pore diameter to shrink by about 15%. The polyurethane layer on the particle side expands due to heat and expands in diameter. The expanded particles are mechanically locked in the shrinking electrode pores, and the anode assembly is completed.

[0088] Unloading step: Place the assembly in a 0°C ice-water bath for 3 minutes. The poly-NIPAM-co-AAc layer absorbs water and expands (restoring its original volume), while the polyurethane layer shrinks (returning to its initial volume). The assembly is then rapidly vibrated to completely release the binding force between the particle secondary electrode and the primary electrode.

[0089] (7) Degradation experiment: The 2.5D electrode assembled in step (6) and the conventional 2D, 2.5D and 3D anodes were used to degrade four simulated pollutants [acid red G (ARG, 0.1 g L -1 ), bisphenol A (BPA, 0.1 g·L -1 ), tetracycline (TC, 0.1 g·L -1 ), ciprofloxacin (CIP, 0.1 g·L -1 )] carried out degradation experiments (such as Figure 4a 、 Figure 4b 、 Figure 4c and Figure 4d As shown), experimental conditions: [Na2SO4] = 10g·L -1 , solution volume = 0.1 L, current density = 20 mA cm -2), the results showed that at 60 min, the degradation rates of the four pollutants by the 2D-Ti / RuO2-TiO2 anode were all lower than 76%, while the removal rates of ARG and TC by the 3D-Ti / RuO2-TiO2 anode and the traditional 2.5D-Ti / RuO2-TiO2 anode were not much different from those of the MS-Ti / RuO2-TiO2 anode. However, for the two pollutants BPA and CIP, the MS-Ti / RuO2-TiO2 anode showed a higher degradation rate, and the final degradation rates were all above 97%, achieving efficient removal of the four pollutants ARG, BPA, TC and CIP.

[0090] (8) The specific method for in-situ recycling and renewal of the particle secondary electrode after the degradation of the simulated wastewater is as follows: during the wastewater treatment process, ice cubes are added to the water near the anode to reduce the temperature near the electrode to 0°C, causing the particle secondary electrode to fall off from the pores of the main electrode and be recycled. Then, the new secondary electrode particles are directed to the main electrode through water pulses, and the ice cubes are removed. The temperature of the electrode surface can be gradually increased by the Joule heating effect, so that the updated particle secondary electrode expands due to heat and the diameter increases, while the pore size of the porous main electrode decreases, completing the renewal process of the 2.5-dimensional electrode.

[0091] Example 2

[0092] (1) Immerse ZSM-5 molecular sieve (SiO2 / Al2O3=50) in ammonia / ethanol solution, with ammonia accounting for 10% of the total volume of ammonia and ethanol. Stir in a 60°C water bath for 6 h, then centrifuge for 5 min and discard the supernatant. Rinse with ethanol three times to remove residual ammonia, and finally vacuum dry at 80°C for 24 h before use.

[0093] A 3mm thick, 6cm x 6cm porous titanium substrate was used as the substrate. The surface was polished smooth with 200-grit coarse sandpaper to remove the surface oxide layer and reveal the metallic luster. The substrate was placed in a 10% NaOH solution and heated and boiled for 10 minutes to remove surface oil. The surface was then acid-etched in a 10% oxalic acid solution and heated and boiled for 2 hours. The substrate was rinsed with deionized water and set aside for use.

[0094] (2) Tin tetrachloride (SnCl4) and antimony trichloride (SbCl3) were mixed at a molar ratio of Sn:Sb of 10:1, 0.5 mol of citric acid was added as a complexing agent, and the mixture was dissolved in 1 L of deionized water. The pH was adjusted to 2 with concentrated hydrochloric acid, and the mixture was stirred for 90 min until the solution was clear to obtain a mixed solution I. 4+ The concentration is 0.2M and the bath temperature is controlled at 40°C to avoid Sn 4+ and Sb 3+ hydrolysis.

[0095] The molecular sieve particles obtained in step (1) and the mixed solution I were transferred to a beaker in an amount of 20 g and 50 mL, respectively, and mixed. The mixture was stirred in a constant temperature water bath at 80°C for 25 min to undergo a hydrolysis and polycondensation reaction to obtain a solid phase product (molecular sieve particles loaded with amorphous antimony-doped tin dioxide (Sb-SnO2) precursor). The solid phase product was annealed at 300°C for 1 h under nitrogen protection to obtain MS / Sb-SnO2 particles. The molecular sieve particles and Sb-SnO2 are bonded by covalent bonds formed by high-temperature calcination.

[0096] (3) Thermoplastic polyurethane (TPU) was dissolved in N,N-dimethylformamide (DMF) at 6 wt%, and 5 wt% of expanded graphite was added as a thermal expansion filler. The mixture was stirred for 4 h (temperature 60°C) until it was completely dispersed to obtain a thermal expansion layer coating mixed solution II.

[0097] Next, immerse the MS / Sb-SnO2 particles obtained in step (2) in mixed solution II at a dosage of 20 g and 30 mL, and pre-cure in an oven at 80°C for 25 min. Pour the pre-cured particles while still hot (>60°C) into a stainless steel colander, immerse the colander in liquid nitrogen to completely submerge it, and time for 10 seconds. Finally, quickly transfer the liquid nitrogen-treated particles to a pre-cooled aluminum tray and place them in a freeze dryer at a pressure of 10 Pa and a cold trap temperature of -50°C for 12 hours to obtain MS / Sb-SnO2 / SMP particles.

[0098] (4) 17.8 g of ruthenium trichloride trihydrate (RuCl3·3H2O) was added to a solution of 20% by volume of tetrabutyl titanate, 55% of isopropyl alcohol, 23% of anhydrous ethanol, 0.5% of acetylacetone, and 1.5% of concentrated hydrochloric acid, and stirred for 10 minutes until the solution was uniform, to obtain a mixed solution III; furthermore, the molar ratio of Ru to Ti was 3:5.

[0099] The porous titanium substrate pretreated in step (1) is immersed in the mixed solution III. After uniformly absorbing the solution, the porous titanium substrate is taken out and dried - sintered (temperature 450°C, time 10min) - cooled. After repeating the absorption - drying - sintering - cooling steps 11 times, a porous Ti / RuO2-TiO2 electrode is obtained. Compared with a single treatment, repeating this step can increase the coating thickness and uniformity and improve the electrochemical active area. Among them, the porous titanium and ruthenium titanium mixed oxide are bonded by the Ti-O-Ru / Ti chemical bond formed by high-temperature calcination;

[0100] (5) N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) were uniformly mixed in a mass ratio of 5:7, and then 0.4 wt% of C3N4 (initiator) was added. The above mixture was slowly stirred and uniformly dissolved in a mixed solvent of ethanol / acetic acid with a mass ratio of 1:4 at a ratio of 8 wt%, and reacted at 50 ° C for 30 min to obtain a temperature-responsive adhesive IV;

[0101] Use a small spray gun to evenly spray the mixed solution IV onto the surface of the porous Ti / RuO2-TiO2 electrode prepared in step (4) (at a distance of 15 cm), spraying a thin layer each time (thickness of 3 μm), and repeat the spraying 10 times until the total thickness reaches 30 μm. Then turn on the ultraviolet lamp (wavelength 365 nm) to irradiate the electrode for 30 minutes, and then place it in an 80°C oven for 30 minutes to obtain a porous Ti / RuO2-TiO2 / NIPAM-co-AAc electrode.

[0102] (6) Loading step: Deionized water is heated to 70°C (higher than the lowest co-solubility temperature of poly NIPAM at 32°C and the polyurethane expansion threshold at 35°C). Then, the MS / Sb-SnO2 / SMP particles prepared in step (3) and the porous Ti / RuO2-TiO2 / NIPAM-co-AAc prepared in step (5) are placed in a water bath. Ultrasonic assistance (100W, 40kHz) is turned on for 5 minutes to ensure that the particles are evenly suspended on the main electrode. Then, the ultrasound is turned off and the mixture is allowed to stand for 5 minutes. During this period, the following synergistic changes occur: the poly NIPAM-co-AAc layer on the electrode side dehydrates and shrinks, pulling the pore diameter to shrink by about 15%. The polyurethane layer on the particle side expands due to heat and expands in diameter. The expanded particles are mechanically locked in the shrinking electrode pores, and the anode assembly is completed.

[0103] Unloading step: Place the assembly in a 0°C ice-water bath for 10 minutes. The poly-NIPAM-co-AAc layer absorbs water and expands (restoring its original volume), while the polyurethane layer shrinks (returning to its initial volume). The assembly is then rapidly vibrated to completely release the binding force between the particle secondary electrode and the primary electrode.

[0104] (7) Actual wastewater degradation experiments: Degradation experiments were conducted on two types of actual wastewater (high-concentration laboratory wastewater and low-concentration medical wastewater) using the 2.5D electrode assembled in step (6) and conventional 2D, 2.5D, and 3D anodes. Experimental conditions: solution volume = 0.25 L, current density = 20 mA cm -2 like Figure 5As shown in the figure, COD tests were carried out on the initial samples and the samples after 60 minutes of degradation. The results showed that the COD removal rates of the 2D-Ti / RuO2-TiO2 anode for both actual wastewaters were less than 56%, while the COD removal rates of the 3D-Ti / RuO2-TiO2 anode and the traditional 2.5D-Ti / RuO2-TiO2 anode for laboratory wastewater were higher (89.74% and 82.56%, respectively), but lower for medical wastewater (<75%). The COD removal rates of the MS-Ti / RuO2-TiO2 anode for both teams of actual wastewaters were above 88%, which was significantly better than the traditional 2D, 2.5D and 3D structured Ti / RuO2-TiO2 anodes. This advantage stems from its optimized electrode structure: on the one hand, while retaining the high reaction area of ​​the 3D electrode, the anode improves the mass transfer path through pore distribution or surface morphology design, solving the problem of low pollutant diffusion efficiency in low-concentration wastewater; on the other hand, its structural design is more adaptable to complex wastewater systems, which can not only efficiently treat high-concentration organic loads, but also overcome the defect of insufficient reaction kinetics in low-concentration wastewater.

[0105] (8) The specific method for in-situ recycling and updating of the particle secondary electrode after the actual wastewater is degraded is as follows: during the wastewater treatment process, ice cubes are added to the water near the anode to reduce the temperature near the electrode to 0°C, causing the particle secondary electrode to fall off from the pores of the main electrode and be recovered. Then, the new secondary electrode particles are directed to the main electrode through water pulses, and the ice cubes are removed. The temperature of the electrode surface can be gradually increased by the Joule heating effect, so that the updated particle secondary electrode expands due to heat and the diameter increases, while the pore size of the porous main electrode decreases, completing the 2.5-dimensional electrode update process.

[0106] Example 3

[0107] (1) Immerse ZSM-5 molecular sieve (SiO2 / Al2O3=50) in ammonia / ethanol solution, with ammonia accounting for 10% of the total volume of ammonia and ethanol. Stir in a 60°C water bath for 6 h, then centrifuge for 5 min and discard the supernatant. Rinse with ethanol three times to remove residual ammonia, and finally vacuum dry at 80°C for 24 h before use.

[0108] A 3mm thick, 10cm x 10cm porous titanium substrate was used as the substrate. The surface was polished smooth with 200-grit coarse sandpaper to remove the surface oxide layer and reveal the metallic luster. The substrate was then placed in a 10% NaOH solution and heated and boiled for 10 minutes to remove surface oil. The surface was then acid-etched in a 10% oxalic acid solution and heated and boiled for 2 hours. The substrate was then rinsed with deionized water and set aside.

[0109] (2) Tin tetrachloride (SnCl4) and antimony trichloride (SbCl3) were mixed at a molar ratio of Sn:Sb of 10:1, 0.5 mol of citric acid was added as a complexing agent, and the mixture was dissolved in 1 L of deionized water. The pH was adjusted to 2 with concentrated hydrochloric acid, and the mixture was stirred for 90 min until the solution was clear to obtain a mixed solution I. 4+ The concentration was 0.2M and the solution temperature was controlled at 40°C to avoid Sn 4+ and Sb 3+ hydrolysis.

[0110] The molecular sieve particles obtained in step (1) and the mixed solution I were transferred to a beaker in an amount of 20 g and 50 mL, respectively, and mixed. The mixture was stirred in a constant temperature water bath at 80°C for 50 min to undergo a hydrolysis and polycondensation reaction to obtain a solid phase product (molecular sieve particles loaded with amorphous antimony-doped tin dioxide (Sb-SnO2) precursor). The solid phase product was annealed at 300°C for 1 h under nitrogen protection to obtain MS / Sb-SnO2 particles. The molecular sieve particles and Sb-SnO2 are bonded by covalent bonds formed by high-temperature calcination.

[0111] (3) Thermoplastic polyurethane (TPU) was dissolved in N,N-dimethylformamide (DMF) at 6 wt%, and 15 wt% of expanded graphite was added as a thermal expansion filler. The mixture was stirred for 6 h (temperature 90°C) until it was completely dispersed to obtain a thermal expansion layer coating mixed solution II.

[0112] Next, immerse the MS / Sb-SnO2 particles obtained in step (2) in mixed solution II in an amount of 20 g and 30 mL, and pre-curing in an oven at 80°C for 30 min. Then, pour the pre-cured particles while still hot (>60°C) into a stainless steel colander, immerse the colander in liquid nitrogen to completely submerge it, and time for 10 seconds. Finally, quickly transfer the liquid nitrogen-treated particles to a pre-cooled aluminum tray and place it in a freeze dryer at a pressure of 10 Pa and a cold trap temperature of -50°C for 12 hours to obtain MS / Sb-SnO2 / SMP particles.

[0113] (4) 17.8 g of ruthenium trichloride trihydrate (RuCl3·3H2O) was added to a solution of 20% by volume of tetrabutyl titanate, 55% of isopropyl alcohol, 23% of anhydrous ethanol, 0.5% of acetylacetone, and 1.5% of concentrated hydrochloric acid, and stirred for 10 minutes until the solution was uniform, to obtain a mixed solution III; furthermore, the molar ratio of Ru to Ti was 3:5.

[0114] The porous titanium substrate pretreated in step (1) is immersed in the mixed solution III. After uniformly absorbing the solution, the porous titanium substrate is taken out and dried - sintered (temperature 450°C, time 10min) - cooled. After repeating the absorption - drying - sintering - cooling steps 6 times, a porous Ti / RuO2-TiO2 electrode is obtained. Compared with a single treatment, repeating this step can increase the coating thickness and uniformity and improve the electrochemical active area. Among them, the porous titanium and ruthenium titanium mixed oxide are bonded by the Ti-O-Ru / Ti chemical bond formed by high-temperature calcination;

[0115] (5) N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) were uniformly mixed in a mass ratio of 5:1, and then 1 wt% of C3N4 (initiator) was added. The above mixture was slowly stirred and uniformly dissolved in a mixed solvent of ethanol / acetic acid with a mass ratio of 1:5 at a ratio of 15 wt%, and reacted at 60 ° C for 30 min to obtain a temperature-responsive adhesive IV;

[0116] Use a small spray gun to evenly spray the mixed solution IV onto the surface of the porous Ti / RuO2-TiO2 electrode prepared in step (4) (at a distance of about 15 cm), spraying a thin layer each time (thickness ≈ 3 μm), and repeat the spraying 15 times until the total thickness reaches about 45 μm. Then turn on the ultraviolet lamp (wavelength 365 nm) to irradiate the electrode for 60 minutes, and then place it in a 100°C oven for 60 minutes to obtain a porous Ti / RuO2-TiO2 / NIPAM-co-AAc electrode.

[0117] (6) Loading step: Deionized water is heated to 90°C (higher than the lowest co-solubility temperature of poly NIPAM at 32°C and the polyurethane expansion threshold at 35°C). Then, the MS / Sb-SnO2 / SMP particles prepared in step (3) and the porous Ti / RuO2-TiO2 / NIPAM-co-AAc prepared in step (5) are placed in a water bath. Ultrasonic assistance (100W, 40kHz) is turned on for 10 minutes to ensure that the particles are evenly suspended on the main electrode. Then, the ultrasound is turned off and the mixture is allowed to stand for 10 minutes. During this period, the following synergistic changes occur: the poly NIPAM-co-AAc layer on the electrode side dehydrates and shrinks, pulling the pore diameter down by about 15%. The polyurethane layer on the particle side expands due to heat, and the diameter expands. The expanded particles are mechanically locked in the contracted electrode pores, and the anode assembly is completed.

[0118] Unloading step: Place the assembly in a 0°C ice-water bath for 20 minutes. The poly-NIPAM-co-AAc layer absorbs water and expands (restoring its original volume), while the polyurethane layer shrinks (returning to its initial volume). The assembly is then rapidly vibrated to completely release the binding force between the particle secondary electrode and the primary electrode.

[0119] (7) Industrial wastewater degradation treatment: Two types of industrial wastewater (>1000ppm petrochemical wastewater, volume 0.5L, main components include petroleum compounds, sulfides and heavy metals; >2000ppm tanning wastewater, volume 0.5L, main components include high concentration of organic matter, sulfides, chromium salts and ammonia nitrogen, etc.) were degraded using the 2.5D electrode assembled in step (6) and traditional 2D, 2.5D and 3D anodes. Figure 6 As shown, experimental conditions: solution volume = 0.5 L, degradation time 60 min, current density = 20 mA cm -2 The results showed that the degradation rates of the 2D-Ti / RuO2-TiO2 anode for all four pollutants were less than 40%, while the 3D-Ti / RuO2-TiO2 anode achieved a COD removal rate of 96.19% for tannery wastewater, but only 60.9% for petrochemical wastewater. The conventional 2.5D-Ti / RuO2-TiO2 anode achieved a maximum COD removal rate of only 81.32% and 74.34% for the two wastewaters, while the MS-Ti / RuO2-TiO2 anode achieved a COD removal rate of around 93% for both industrial wastewaters. The results showed that the MS-Ti / RuO2-TiO2 anode exhibited stable and efficient degradation capabilities (COD removal rates of 93%) for both high-concentration and complex industrial wastewaters (petrochemical wastewater and tannery wastewater), once again demonstrating its universal advantages.

[0120] (8) Long-term wastewater treatment test: Tannery wastewater with a concentration of >2000 ppm (mainly composed of high concentrations of organic matter, sulfide, chromium salts, and ammonia nitrogen) was degraded using the 2.5D electrode assembled in step (6) and conventional 2D, 2.5D, and 3D anodes. Experimental conditions: Current density = 20 mA cm -2 ,like Figure 7 As shown in the figure, after 100 hours of continuous operation, the COD removal efficiency of the 2D-Ti / RuO2-TiO2 anode for tanning wastewater dropped to below 20%, the COD removal efficiency of the 3D-Ti / RuO2-TiO2 anode for tanning wastewater decreased to 50%, and the COD removal efficiency of the 2.5D-Ti / RuO2-TiO2 anode for tanning wastewater decreased to 60%. In contrast, the COD removal efficiency of the MS-Ti / RuO2-TiO2 anode for tanning wastewater remained close to 93%, showing good sustained stability, which is attributed to the unique in-situ recyclability of the electrode material.

[0121] The specific method for in-situ recycling and renewal of the granular secondary electrode is as follows: during the wastewater treatment process, ice cubes are added to the water near the anode to reduce the temperature near the electrode to 0°C, causing the granular secondary electrode to fall off from the pores of the main electrode and be recovered. Then, new secondary electrode particles are directed to the main electrode through water pulses, and the ice cubes are removed. The temperature of the electrode surface can be gradually increased through the Joule heating effect, so that the updated granular secondary electrode expands due to heat and its diameter increases, while the pore size of the porous main electrode decreases, completing the renewal process of the 2.5-dimensional electrode.

Claims

1. A method for preparing a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode, characterized in that: The following steps are involved: S1, loading amorphous antimony-doped tin dioxide on molecular sieve particles by hydrolysis-polycondensation reaction and annealing, and then coating the surface with a thermal expansion layer formed by polyurethane to obtain secondary electrode particles; S2, bonding a ruthenium-titanium mixed oxide layer on a porous titanium substrate, and then spraying a polymer layer formed of N-isopropylacrylamide-acrylic acid copolymer to obtain a main electrode; S3, suspending the secondary electrode particles on the main electrode, and then letting it stand, the diameter of the surface pores of the main electrode near the secondary electrode particles shrinks, the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat, and finally locked in the pores of the main electrode, obtaining a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode.

2. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 1, characterized in that: The molecular sieve particles described in S1 and the porous titanium matrix described in S2 are respectively obtained by the following processes: The initial molecular sieve particles are immersed in ammonia water and ethanol, first stirred in a water bath at a constant temperature of 55-65°C for 5-7 hours, then centrifuged, the supernatant is discarded, and the residual ammonia water is removed with ethanol, and finally vacuum dried to obtain the molecular sieve particles; The surface of the sheet-like porous titanium substrate was polished smooth with coarse sandpaper to reveal the metallic luster, then placed in a NaOH solution to remove surface oil stains, then placed in an oxalic acid aqueous solution to etch the surface to remove the passivation oxide layer on the surface, and finally rinsed with deionized water to obtain the porous titanium substrate.

3. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 1, characterized in that: S1 dissolves tin tetrachloride, antimony trichloride and citric acid in deionized water at 35-45°C, and then adjusts the pH of the resulting mixed solution to 1.5-2.5 to obtain a first mixed solution, and subjecting the molecular sieve particles and the first mixed solution to a hydrolysis-condensation reaction at 75-85°C. Thereafter, the reaction is annealed at 280-320°C in an oxygen-free environment to obtain a molecular sieve-based amorphous antimony-doped tin dioxide, and finally, a thermal expansion layer formed by polyurethane is coated on the surface of the molecular sieve-based amorphous antimony-doped tin dioxide to obtain secondary electrode particles.

4. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 3, characterized in that: In the mixed solution, the molar ratio of tin tetrachloride to antimony trichloride is 10:

1. 4+ The concentration of antimony is 0.15-0.25M, the molecular sieve particles and the first mixed solution are hydrolyzed and condensed at 75-85°C for 5-50 minutes, and then annealed at 280-320°C for 45-75 minutes in an oxygen-free environment to obtain molecular sieve-based amorphous antimony-doped tin dioxide.

5. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 4, characterized in that: S1: dissolving thermoplastic polyurethane in N,N-dimethylformamide, adding 1% to 2.25% of expanded graphite by mass of the thermoplastic polyurethane and dispersing it evenly to obtain a second mixed solution, immersing molecular sieve-based amorphous antimony-doped tin dioxide in the second mixed solution for solidification to obtain secondary electrode particles.

6. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 5, characterized in that: The curing is carried out as follows: First, pre-curing is carried out at 75-85°C for 20-30 minutes, then placing in liquid nitrogen for 9-11 seconds, and finally freeze-drying at -55--45°C for 11-13 hours under the condition of 10-15 Pa.

7. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 1, characterized in that: S2 dissolves ruthenium trichloride trihydrate into a mixture consisting of 20% tetrabutyl titanate, 55% isopropyl alcohol, 23% anhydrous ethanol, 0.5% acetylacetone and 1.5% concentrated hydrochloric acid by volume, with a molar ratio of Ru to Ti of 3:5, to obtain a third mixed solution, immerses the porous titanium substrate in the third mixed solution, and after uniform absorption, takes out and sequentially dries, sinters and cools, repeating 2 to 12 times to obtain a porous titanium-based ruthenium titanium mixed oxide, and then sprays a polymer layer formed by N-isopropylacrylamide-acrylic acid copolymer on the surface of the porous titanium-based ruthenium titanium mixed oxide to obtain a main electrode.

8. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 7, characterized in that: S2: N-isopropylacrylamide and acrylic acid are uniformly mixed in a mass ratio of (1 to 5): (1 to 7), and then 0.01% to 1% of the total mass of N-isopropylacrylamide and acrylic acid is added to C3N4, and the resulting mixture is dissolved in a mixed solvent consisting of ethanol and acetic acid, and the mixture is reacted at 30 to 60°C for 30 minutes to obtain a fourth mixed liquid, and the fourth mixed liquid is uniformly sprayed onto the surface of the porous titanium-based ruthenium titanium mixed oxide, and then irradiated under ultraviolet light for 1 to 60 minutes, and heated at 50 to 100°C for 1 to 60 minutes to obtain a main electrode.

9. The method for preparing the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to claim 1, characterized in that: S3 heats deionized water to 40-90°C, and then evenly suspends the secondary electrode particles on the main electrode by ultrasound assistance. The process is then allowed to stand for 1-10 minutes. The diameter of the surface pores of the main electrode near the secondary electrode particles shrinks, and the thermal expansion layer of the secondary electrode particles near one end of the main electrode expands due to heat and is locked in the pores of the main electrode, thereby obtaining a 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode.

10. A 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode obtained by the preparation method of the 2.5-dimensional antimony-doped tin dioxide / polyurethane-ruthenium titanium mixed oxide / polymer temperature-responsive electrocatalytic oxidation electrode according to any one of claims 1 to 9.

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