Microporous SnO2-Sb / Ti@C composite anode and preparation method and application thereof

Abstract

The application discloses a microporous SnO2-Sb / Ti@C composite anode and a preparation method and application thereof, and belongs to the technical field of electrochemical treatment of wastewater. The microporous SnO2-Sb / Ti@C composite electrode is composed of flower-shaped structure SnO2-Sb in-situ grown on a microporous Ti@C film base. The flower-shaped structure SnO2-Sb has a large specific surface area, and active sites are fully exposed, thereby exhibiting high catalytic activity. The flower-shaped structure SnO2-Sb is in-situ grown on the microporous Ti@C film base, is combined with good stability, is more uniformly dispersed, and the entire microporous SnO2-Sb / Ti@C composite electrode has stable catalytic activity on organic dyes and the like in a high-salt environment, and has a long service life, and can be widely applied to electrocatalytic degradation of high-salt organic wastewater.

Description

Technical Field

[0001] This invention relates to an electrocatalytic anode, particularly a microporous SnO2-Sb / Ti@C composite anode, and also to its preparation method and application in the electrocatalytic degradation of high-salt organic wastewater, belonging to the field of electrochemical wastewater treatment. Background Technology

[0002] Several technologies can be applied to reduce the organic matter content in different types of wastewater. While traditional physical, chemical, and biological treatment technologies each have their advantages in wastewater treatment, they also have limitations. This is especially true in wastewater treatment from industries such as petrochemicals, pharmaceuticals, and textiles, where the wastewater contains large amounts of toxic, harmful, and recalcitrant organic pollutants, and the diversity and complexity of their composition makes it difficult for traditional water treatment technologies to achieve satisfactory results.

[0003] Electrochemical oxidation, an environmentally friendly technology, involves electrodes generating oxidizing ·OH or other active groups under an applied electric field. These groups react with pollutants in water to produce harmless CO2 and H2O. This green technology has been widely applied in treating wastewater with high chemical oxygen demand (COD), such as dyeing and printing wastewater, pharmaceutical wastewater, and chemical wastewater. Therefore, it is one of the most promising technologies for wastewater treatment. Electrode materials are the core of the electrocatalytic oxidation reaction, and finding highly active, stable, and reusable electrode materials is crucial for electrocatalytic oxidation technology. Among these, antimony-doped SnO2 (Sb-SnO2) electrodes are considered one of the most effective catalysts for treating dye wastewater due to their lack of heavy metal leakage and high oxygen evolution potential (OEP).

[0004] Existing Ti / SnO2-Sb electrodes suffer from drawbacks such as poor adhesion between the active layer and the substrate, easy detachment, short lifespan, and low degradation efficiency, hindering their application in large-scale industrial production. Current research focuses on improving electrode materials, such as adding intermediate layers. These layers can enhance electrode bonding, block the diffusion and penetration of reactive oxygen species into the Ti matrix, reduce the formation rate of the TiO2 film, and delay the passivation of the Ti matrix. However, during degradation, it has been found that while the addition of certain intermediate layers improves the stability of the SnO2 electrode, the electrocatalytic activity of the electrode does not increase significantly and may even decrease. Doping the catalyst layer with exogenous materials can alter its morphology and structure to improve electrode stability; rare earth elements, for example, can also improve stability. However, their high cost limits their industrial application. Furthermore, modifying the Ti substrate to alter its surface morphology and spatial properties increases the specific surface area and catalyst loading of the electrode. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a microporous SnO2-Sb / Ti@C composite anode, which has advantages such as high catalytic activity, good salt tolerance, and high stability, and can be widely used in the electrocatalytic oxidation degradation of high-salt organic wastewater.

[0006] The second objective of this invention is to provide a method for preparing a microporous SnO2-Sb / Ti@C composite anode, which is simple, low-cost, controllable in operation, and easy for industrial mass production.

[0007] The third objective of this invention is to provide an application of a microporous SnO2-Sb / Ti@C composite anode in the electrocatalytic degradation of high-salt organic wastewater. Based on the fact that the SnO2-Sb / Ti@C composite anode has a large number of active sites and stable activity in a high-salt environment, it has the characteristics of high degradation efficiency and fast rate for organic dyes in high-salt wastewater, and has a long service life. It can be widely used in the electrocatalytic oxidation degradation of high-salt organic wastewater.

[0008] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing a microporous SnO2-Sb / Ti@C composite anode, the method comprising the following steps:

[0009] 1) A slurry is formed by mixing metallic titanium powder, titanium hydride powder and an organic binder solution. The slurry is then cast, dried and sintered to obtain a microporous Ti@C membrane.

[0010] 2) After the microporous Ti@C film is etched, it is placed in a reaction vessel, and a mixed solution containing tin source, antimony source and complexing agent is added to carry out a solvothermal reaction to obtain the microporous SnO2-Sb / Ti@C precursor;

[0011] 3) The microporous SnO2-Sb / Ti@C precursor is heat-treated to obtain the final product.

[0012] This invention prepares a microporous Ti@C membrane substrate material using powder metallurgy during the fabrication of a microporous SnO2-Sb / Ti@C composite anode. The key lies in the casting and sintering of metallic titanium powder and titanium hydride powder with an organic binder. The organic binder not only effectively bonds the metallic titanium powder and titanium hydride powder but also acts as a pore-forming agent during vacuum sintering. During high-temperature sintering, pyrolysis generates small molecule volatilization, creating pores. Simultaneously, the carbon residue from the pyrolysis of the organic binder acts as carbon doping, improving the material's conductivity. This results in a microporous Ti@C membrane substrate material with a three-dimensional porous microstructure. Compared to traditional flat titanium, this substrate material exhibits high porosity and a large specific surface area, allowing the SnO2-Sb active layer to adhere more uniformly and densely to its surface. This prevents the active layer from detaching, resulting in more uniform dispersion, significantly improving the electrode's catalytic performance and extending its lifespan. Furthermore, controlling the carbon distribution at a certain concentration on its surface effectively enhances the conductivity of the substrate material. Furthermore, an active layer of SnO2-Sb was grown in situ on the substrate using a solvothermal method. This resulted in a tighter bond between SnO2-Sb and the microporous Ti@C membrane substrate, making it less prone to detachment and significantly improving electrode stability. Simultaneously, the SnO2-Sb generated via the solvothermal method possesses a unique nanoflower-like structure with a large specific surface area, fully exposing active sites and greatly enhancing catalytic activity. Therefore, compared to composite electrodes prepared from ordinary titanium mesh or titanium plates, the SnO2-Sb / Ti@C composite electrode exhibits a significantly increased number of active sites and maintains stable activity in high-salt environments, thereby improving the overall electrocatalytic degradation performance of high-salt organic wastewater.

[0013] As a preferred embodiment, the mass percentage composition of the metallic titanium powder and titanium hydride powder is 70-95% : 5-30%. Since vacuum alone cannot successfully sinter the compacted titanium powder into a dense composition during the sintering process, the surface of the titanium particles in the passivated titanium dioxide layer must be effectively removed before the sintering process. This is achieved by using an appropriate proportion of titanium hydride TiH2, which decomposes at 288°C into very high H... + This forms very fine Ti, effectively promoting the sintering process of the Ti component. In-situ formed H... + The titanium hydride reacts with the passivation layer of titanium dioxide, decomposing into Ti metal and water vapor, which is then removed using a vacuum. If too much titanium hydride is used, H2 will be rapidly generated during heating. As H2 diffuses rapidly from the interior to the exterior of the microporous titanium, the generation rate may exceed its diffusion rate, leading to internal accumulation and localized disruption of the structural continuity, potentially damaging the microporous titanium's own structure and microstructure. If too little titanium hydride is used, the purpose of removing the titanium dioxide passivation layer from the titanium powder surface will not be achieved.

[0014] As a preferred embodiment, the mass ratio of the organic binder solution to the titanium powder is 1:0.5 to 1:2. With increasing proportions of organic binder, agglomeration occurs during mixing, especially with a larger amount of organic binder, resulting in more pronounced agglomeration and leaving larger pores after removal. Furthermore, the significant density difference between titanium powder and organic binder leads to the aggregation of similar materials during mixing, particularly with increasing organic binder content, resulting in macropores. Conversely, insufficient organic binder content hinders the formation of microporous structures, leading to a denser state.

[0015] As a preferred embodiment, the solid content of the organic binder solution is 5% to 35%.

[0016] As a preferred embodiment, the average particle size of the titanium hydride powder is 36 μm.

[0017] As a preferred embodiment, the titanium powder has an average particle size of 36–74 μm and a purity of ≥99.8%.

[0018] As a preferred embodiment, the solute in the organic binder solution is at least one selected from polyvinyl butyral, phenolic resin, sodium carboxymethyl cellulose, polyvinylpyrrolidone, and polyacrylonitrile, and the solvent is at least one selected from ethanol, butanone, and terpineol. The preferred organic binder can be pyrolyzed and released at a relatively low temperature, with its decomposition product being CO2, which is emitted in gaseous form. This ensures both complete release of the pore-forming agent and prevents contamination of the porous titanium material.

[0019] As a preferred embodiment, the sintering process employs a continuous gradient heating vacuum sintering method, with a vacuum level below 10. - 3The maximum temperature for vacuum sintering is 1200℃, with a heating rate of 5–15℃ / min. Three to five holding periods are performed within the range of 300–1100℃, with each holding period lasting 1–5 hours. After sintering, the furnace is cooled to below 200℃. The first stage is mainly the thermal decomposition stage of the organic binder, starting from room temperature and holding for one period within the range of 300℃–450℃ to ensure complete thermal decomposition of the organic binder. The second stage is the dehydrogenation stage of the TiH2 powder, mainly involving one to three holding periods within the temperature range of 450℃ to 800℃, allowing the TiH2 powder to release hydrogen gas to reduce the titanium dioxide on the surface of the titanium powder. The third stage is the pre-sintering stage of elemental titanium particles. Within the temperature range of 800℃ to 1100℃, the green film composed of powder has a high free surface energy. During vacuum sintering, the powder will reduce its surface energy through particle aggregation, transitioning from a high-energy state to a low-energy state. Through atomic diffusion, the powder particles will approach each other and metallurgically bond to form a sintered phase. However, complete sintering requires a higher temperature, thus requiring further heating to temperatures above 1100℃ to complete sintering. Therefore, in the continuous gradient heating vacuum sintering process, the temperature is first held at 300℃ to 450℃ for 1 to 5 hours, then heated to 450℃ to 800℃ for 1 to 3 holding periods, each for 1 to 5 hours, then heated to 800℃ to 1100℃ for 1 to 5 hours, and finally heated to above 1100℃ for sintering, with the highest sintering temperature being 1200℃.

[0020] As a preferred embodiment, the etching process includes alkaline treatment, acid etching, and cleaning. Alkaline treatment primarily removes oil contaminants; acid etching primarily removes the dense TiO2 oxide film from the microporous Ti@C surface. The titanium substrate lacking this protective layer readily absorbs hydrogen in acids such as oxalic acid, forming TiH hydrides. 1.5 Polarization corrosion occurs. As hydrogen accumulates, it enters the interstitial spaces of the crystal lattice and diffuses inward, resulting in a dense, pitted corrosion morphology on the surface. Acid etching exposes a fresh, clean titanium layer, significantly increasing the actual surface area and improving the mechanical adhesion between the titanium substrate and the coating.

[0021] As a preferred embodiment, the alkali treatment is performed by immersion in an alkaline solution at a temperature of 50–90°C for a time of 0.5–1.5 h.

[0022] As a preferred embodiment, the acid etching is performed by immersion in an acidic solution at a temperature of 30–90°C for 0.5–2 hours.

[0023] As a preferred embodiment, the cleaning process employs solvent rinsing until the pH value reaches 5.5–7.5.

[0024] As a preferred embodiment, the alkaline solution is at least one of NaOH solution, Na2CO3 solution, and NaHCO3 solution with a mass concentration of 10% to 40%.

[0025] As a preferred embodiment, the acidic solution is at least one of the following: H2SO4 solution, H3PO4 solution, HCl solution, and H2C2O4 solution with a mass concentration of 10% to 30%.

[0026] As a preferred embodiment, the solvent is water and acetone.

[0027] As a preferred embodiment, the molar ratio of the tin source to the complexing agent is (3-7):10. Sodium citrate, thiourea, and other complexing agents, as chelating ligands with strong coordination ability, can react with tin ions (Sn). 2+ Coordination forms a stable hierarchical structure. The formation of complexes greatly reduces the availability of free tin ions in aqueous solution, resulting in a slower reaction rate, which plays a crucial role in the formation of well-dispersed nanoflowers.

[0028] As a preferred embodiment, the molar ratio of the tin source to the antimony source is 10:(1-5).

[0029] As a preferred embodiment, the tin source includes at least one of potassium stannate trihydrate, stannic acid dichloride hydrate, stannous sulfate, stannic nitrate, and stannous oxalate.

[0030] As a preferred embodiment, the complexing agent includes at least one of sodium citrate and thiourea.

[0031] As a preferred embodiment, the antimony source comprises antimony trichloride.

[0032] As a preferred embodiment, the solvothermal reaction conditions are: temperature 120–300℃, duration 6–20 h. By carrying out the solvothermal reaction under appropriate conditions, SnO2-Sb with a nanoflower-like structure can be generated. This structure consists of ultrathin nanosheets that aggregate in a certain regular pattern, such that one corner of a single nanosheet is connected to its side, thus forming an almost triangular shape. Furthermore, the entire diagonal of the nanosheet has a smooth and clean surface.

[0033] As a preferred embodiment, a surfactant is also added during the solvothermal reaction; the surfactant includes at least one of hexamethylenetetramine, sodium dodecyl sulfonate, and hexadecyltrimethylammonium bromide. The solvent used in the solvothermal method is ethanol and deionized water in a volume ratio of 1:(1-1.5).

[0034] As a preferred embodiment, the heat treatment conditions are: in an air atmosphere, a heat treatment temperature of 300–600 °C, a holding time of 1–3 h, and a heating rate of 2–5 °C / min. The solvothermal method successfully grew nanoflower-like SnO2-Sb on a microporous Ti@C substrate, but the crystallinity was poor, and the spaces between the nanosheets were not open. However, after annealing at an appropriate temperature, well-crystallized SnO2-Sb nanoflowers could be observed on the surface of the synthesized electrode. These nanoflowers were self-assembled from nanosheets and had a smooth, glossy surface.

[0035] The present invention also provides a microporous SnO2-Sb / Ti@C composite anode, which is obtained by the preparation method described above.

[0036] The microporous SnO2-Sb / Ti@C composite electrode provided by this invention is composed of flower-like SnO2-Sb grown in situ on a microporous Ti@C membrane substrate. The flower-like SnO2-Sb has a large specific surface area and fully exposed active sites, exhibiting high catalytic activity. Furthermore, the in-situ growth of the flower-like SnO2-Sb on the microporous Ti@C membrane substrate results in good binding stability and more uniform dispersion. The entire microporous SnO2-Sb / Ti@C composite electrode exhibits stable catalytic activity against organic dyes and other pollutants in high-salt environments and has a long service life, making it widely applicable to the electrocatalytic degradation of high-salt organic wastewater.

[0037] This invention also provides an application of a microporous SnO2-Sb / Ti@C composite anode, which is used for the electrocatalytic oxidation degradation of high-salt organic wastewater. The high-salt organic wastewater contains organic pollutants, such as organic dyes like methylene blue, methyl orange, malachite green, and crystal violet, etc. The concentration of total organic pollutants in the wastewater is 10–1000 mg / L, and the content of inorganic salts is not higher than 20000 mg / L.

[0038] The specific preparation method of the microporous SnO2-Sb / Ti@C composite anode of the present invention is as follows:

[0039] Step (1): Prepare a microporous Ti@C membrane substrate by mixing Ti powder with an organic binder solution to obtain a slurry; control the coating of the slurry on a quartz plate separated by a thin layer of zinc stearate to prevent film adhesion, with a thickness of 100-300 μm, place it in a vacuum drying oven at 50-80℃ overnight, flatten it, and obtain a microporous Ti@C membrane preform. The Ti powder is composed of titanium hydride and metallic titanium powder. The average particle size of titanium hydride is 36 μm, and the average particle size of metallic titanium powder is 36–74 μm. The purity is ≥99.8%, and the mass ratio is 5–30 wt%. The organic binder uses one of the following as the solute: polyvinyl butyral, phenolic resin, sodium carboxymethyl cellulose, polyvinylpyrrolidone, or polyacrylonitrile. The solvent used is one of the following: ethanol, butanone, or terpineol. The mass concentration of the solute is 5%–35%. The organic binder and Ti powder are mixed at a mass ratio of 1:0.5–1:2. After thorough stirring, the mixture is sealed and allowed to stand to form a film-forming slurry with uniformly dispersed powder particles and no air bubbles.

[0040] Step (2): A microporous Ti@C membrane substrate is obtained by high-temperature vacuum calcination. The dried microporous Ti@C membrane preform is laid flat on a porous high-temperature resistant plate coated with a thin layer of zinc stearate for isolation. The porous high-temperature resistant plate can be either an alumina plate or a zirconia plate, with a pore size of 2-5 mm. Continuous gradient heating vacuum sintering is then performed, with a vacuum degree lower than 10. -3 Pa, the maximum temperature of vacuum sintering is 1200℃, the heating rate is 5~15℃ / min, and 3 to 5 stages of holding are carried out in the range of 300~1100℃, with the holding time controlled in the range of 1~5h; after the sintering process is completed, the furnace is cooled to below 200℃ to obtain microporous Ti@C film material substrate.

[0041] Step (3): Pre-treat the microporous Ti@C film substrate, which has a carbon content of 0.5wt%–10.0wt%, a porosity of 25%–45%, and an average pore size of 1μm–15μm. Perform a surface alkaline treatment—acid etching—cleaning pre-treatment on the Ti@C film substrate. Store the pre-treated microporous Ti@C film substrate in anhydrous ethanol for later use. The alkaline treatment solution can be one or two of NaOH, Na2CO3, and NaHCO3; the acid etching solution can be one or more of H2SO4, H3PO4, HCl, H2C2O4, and HNO3. The mass fraction of the solute in the alkaline treatment solution is 10%–40%, the temperature is 50–90℃, and the treatment time is 0.5–1.5h; the mass fraction of the solute in the acid etching solution is 10%–30%, the temperature is 30–90℃, and the etching time is 0.5–2h. Finally, the substrate was washed with deionized water and acetone until the pH value reached 5.5–7.5, and then vacuum dried to obtain the microporous Ti@C membrane substrate.

[0042] Step (4): On the pretreated Ti@C film substrate, a nanoflower-structured SnO2-Sb active layer was grown in situ using a solvothermal method, followed by heat treatment. The solvothermal reaction solution consisted of one of the following as tin salts: potassium stannate trihydrate, tin dichloride hydrate, stannous sulfate, tin nitrate, and stannous oxalate; one of the following as ligands: sodium citrate and thiourea; one of the following as surfactants: hexamethylenetetramine, sodium dodecyl sulfonate, and hexadecyltrimethylammonium bromide; and antimony trichloride as the antimony source. The molar ratio of tin salt to ligand was (3–7):10, and the molar ratio of tin salt to antimony source was 10:(1–5). The solvent was ethanol and deionized water in a volume ratio of 1:(1–1.5). The solvothermal reaction temperature was 120–300℃, and the reaction time was 6–20 h. The heat treatment temperature was 300–600℃, the holding time was 1–3 h, and the heating rate was 2–5℃ / min.

[0043] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0044] The microporous SnO2-Sb / Ti@C composite electrode provided by this invention is composed of flower-like SnO2-Sb grown in situ on a microporous Ti@C membrane substrate. The flower-like SnO2-Sb has a large specific surface area and fully exposed active sites, exhibiting high catalytic activity. Furthermore, the in-situ growth of the flower-like SnO2-Sb on the microporous Ti@C membrane substrate results in good bonding stability, more uniform dispersion, and denser growth. The entire microporous SnO2-Sb / Ti@C composite electrode exhibits stable catalytic activity against organic dyes and other pollutants in high-salt environments and has a long service life, making it widely applicable to the electrocatalytic degradation of high-salt organic wastewater.

[0045] The present invention provides a method for preparing a microporous SnO2-Sb / Ti@C composite anode. First, a microporous Ti@C membrane substrate material is prepared by powder metallurgy. The resulting substrate material has a three-dimensional porous microstructure with high porosity, large specific surface area, and good conductivity, which can better bind SnO2-Sb. Then, an active layer of SnO2-Sb is grown in situ on the substrate by a solvothermal method, making the SnO2-Sb bond with the microporous Ti@C membrane substrate even tighter, the SnO2-Sb dispersion more uniform, and less prone to detachment, which greatly improves the stability of the electrode. In particular, the SnO2-Sb generated by the solvothermal method has a special nanoflower-like structure with a large specific surface area, which can fully expose the active sites and greatly improve the catalytic activity.

[0046] The preparation method of the microporous SnO2-Sb / Ti@C composite anode provided by this invention is simple to operate, low in cost, and conducive to large-scale production.

[0047] The microporous SnO2-Sb / Ti@C anode material provided by this invention is used to treat high-salt wastewater containing methylene blue. After 150 min of electrocatalytic oxidation, its COD degradation rate reaches 95%, demonstrating strong ability and high efficiency in removing methylene blue. Attached Figure Description

[0048] Figure 1 The image shows a SEM image of the microporous Ti@C membrane substrate obtained in Example 1; it can be seen from the image that the microporous Ti@C membrane substrate has a rich pore structure.

[0049] Figure 2 The image shows a SEM image of the microporous SnO2-Sb / Ti@C anode material obtained in Example 1. It can be seen from the image that antimony-doped tin oxide nanoflowers with a diameter of 3-6 μm were successfully synthesized and uniformly covered on the microporous Ti@C. It can also be seen that there are no typical cracks on the active layer, and the nanoflowers are self-assembled from individual nanosheets.

[0050] Figure 3 The image shows the XRD pattern of the microporous SnO2-Sb / Ti@C anode material obtained in Example 1. The image shows that the diffraction peaks of the prepared microporous SnO2-Sb / Ti@C anode material at 2θ = 27.1°, 34.5°, 38.6°, 40.7°, 52.3°, 55.3°, 63.5°, 71.4°, and 76.8° correspond to the tetragonal rutile of tin oxide. The diffraction peaks of Sb are not determined, possibly because Sb enters the tin oxide lattice and forms a uniform distribution.

[0051] Figure 4 The graph shows the bilayer capacitance and electrochemically active surface area of ​​the anode materials prepared on different substrates in Example 1; it can be seen from the graph that the microporous SnO2-Sb / Ti@C electrode has the highest bilayer capacitance (C DL ) and the largest specific electrochemical active surface area (ECSA).

[0052] Figure 5 The figures show the degradation effect of methylene blue by different substrates of the anode materials prepared in Example 1. It can be seen from the figures that the microporous SnO2-Sb / Ti@C anode is significantly better at removing methylene blue wastewater than the SnO2-Sb electrode with titanium plate or titanium mesh as substrate.

[0053] Figure 6 The figures show the COD removal effect of different substrate-based anode materials in Example 1 on the degradation of methylene blue. It can be seen from the figures that the microporous SnO2-Sb / Ti@C anode is significantly better at removing methylene blue wastewater than the SnO2-Sb electrode with titanium plate or titanium mesh as substrate. Detailed Implementation

[0054] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0055] Comparative Example 1

[0056] The only difference compared to Example 1 is the vacuum sintering conditions: the vacuum level is lower than 10. -3 Pa controls the heating rate and holding platform, holding at 350℃ for 30 min, and holding at 500℃, 800℃, and 950℃ for 60 min, 30 min, and 30 min respectively. The maximum temperature for vacuum sintering is 1000℃, held for 30 min, and after the program ends, the furnace is cooled to below 200℃.

[0057] To verify the catalytic performance of the microporous SnO2-Sb / Ti@C electrode, a methylene blue degradation experiment was conducted: the simulated wastewater volume was 200 mL, the target pollutant was methylene blue with a concentration of 25 mg / L, the Na2SO4 concentration was 10 g / L, and the current density was 40 mA / cm². 2 The efficiency of degrading methylene blue was only 45% after 150 minutes.

[0058] Comparative Example 2

[0059] Compared with Example 1, the only difference is the heat treatment conditions: the material is placed in a ceramic boat and placed in a muffle furnace. The heating rate is 5℃ / min, and the temperature is held at 700℃ for 1 hour. After cooling to room temperature, the microporous SnO2-Sb / Ti@C electrode can be obtained.

[0060] To verify the catalytic performance of the microporous SnO2-Sb / Ti@C electrode, a methylene blue degradation experiment was conducted: the simulated wastewater volume was 200 mL, the target pollutant was methylene blue with a concentration of 25 mg / L, the Na2SO4 concentration was 10 g / L, and the current density was 30 mA / cm². 2 The efficiency of degrading methylene blue was only 42% after 150 minutes.

[0061] Example 1

[0062] At 40℃, 3g of polyvinyl butyral ester was dissolved in 35mL of anhydrous ethanol using ultrasonication to obtain a polyvinyl butyral solution. 10g of 36μm titanium powder, 3g of 36μm titanium hydride powder, and 15g of the polyvinyl butyral solution were magnetically stirred until a uniform slurry was formed. The slurry was then sealed and allowed to stand for 2 hours until no bubbles appeared. A thin layer of zinc stearate was used to isolate a smooth, scratch-free quartz surface. 4g of the slurry was used to coat a 20cm² area. 2 The material is placed in a vacuum drying oven at 60°C for 8 hours; the resulting preform is then removed from the quartz plate surface and laid flat on a porous alumina plate coated with a thin layer of zinc stearate for isolation, and then placed in a vacuum sintering furnace for sintering. The vacuum level is below 10. -3The heating rate (10℃ / min) and holding plateau were controlled. The substrate was held at 400℃ for 90 min, then at 700℃, 900℃, and 1000℃ for 120 min, 180 min, and 90 min respectively. The maximum vacuum sintering temperature was 1200℃, held for 70 min. After the program, the substrate was cooled to below 200℃ in the furnace to obtain a microporous Ti@C membrane substrate. A 2×3 cm microporous Ti@C membrane substrate was placed in a 40% NaOH solution and treated with alkali at 80℃ for 1 h. After removal, it was sonicated in deionized water for 10 min. The alkali-treated microporous Ti@C was then placed in a 10% oxalic acid solution and acid-etched at 85℃ for 1 h. After removal, it was sonicated in deionized water for 10 min. Finally, the microporous Ti@C substrate was washed with deionized water and acetone until the pH reached 5.5. Weigh 4.7056 g of sodium citrate (C6H5Na3O7), 0.1824 g of antimony trichloride (SbCl3), and 1.8052 g of tin dichloride hydrate (SnCl2·2H2O), and place them in a mixture of 30 mL of ethanol and 30 mL of deionized water. Stir to dissolve, and place the mixture in a polytetrafluoroethylene autoclave. Place the microporous Ti@C membrane substrate in the autoclave and heat it at 180 °C for 12 h. After natural cooling, remove the material, rinse it with ethanol and deionized water, and dry it at 60 °C for 2 h. Finally, place the material in a porcelain boat and place it in a muffle furnace. Heat the material at 500 °C for 2 h at a rate of 5 °C / min. After cooling to room temperature, the microporous SnO2-Sb / Ti@C electrode is obtained.

[0063] To verify the excellent catalytic performance of the microporous SnO2-Sb / Ti@C electrode, a methylene blue degradation experiment was conducted: the simulated wastewater volume was 200 mL, the target pollutant was methylene blue with a concentration of 25 mg / L, the Na2SO4 concentration was 10 g / L, and the immersion area of ​​the microporous SnO2-Sb / Ti@C electrode prepared in Example 1 was 6 cm². 2 A copper plate is used as the anode and a copper plate as the cathode. The distance between them is controlled at 2 cm, and the current density is 30 mA / cm². 2 Compared with SnO2-Sb prepared on titanium mesh or titanium plate as a substrate (with titanium mesh or titanium plate replacing the microporous Ti@C membrane substrate), the microporous SnO2-Sb / Ti@C electrode showed the best ability to degrade methylene blue, with a removal rate of 99%, which is much higher than the SnO2-Sb electrode prepared on titanium mesh and titanium plate as a substrate.

[0064] Example 2

[0065] At 40℃, 5g of phenolic resin was ultrasonically dissolved in 45mL of terpineol to obtain a phenolic resin solution. 10g of 36μm titanium powder, 1.5g of 36μm titanium hydride powder, and 20g of the phenolic resin solution were magnetically stirred until a uniform slurry was formed. The mixture was then sealed and allowed to stand for 2 hours until no bubbles appeared. A thin layer of zinc stearate was used to isolate a smooth, scratch-free quartz surface. 4g of the slurry was used to coat a 20cm² area. 2 The material is placed in a vacuum drying oven at 70°C for 8 hours; the resulting preform is then removed from the quartz plate surface and laid flat on a porous alumina plate coated with a thin layer of zinc stearate for isolation, and then placed in a vacuum sintering furnace for sintering. The vacuum level is below 10. -3 The heating rate (10℃ / min) and holding plateau were controlled. The temperature was maintained at 300℃ for 60 min, then at 800℃, 1000℃, and 1100℃ for 120 min, 180 min, and 60 min respectively. The maximum vacuum sintering temperature was 1200℃, held for 60 min. After the program ended, the temperature was cooled to below 200℃ in the furnace to obtain a microporous Ti@C membrane. A 2×3 cm² microporous Ti@C material was placed in a 40% NaOH solution and treated with alkali at 80℃ for 0.5 h. After removal, it was sonicated in deionized water for 10 min. The alkali-treated microporous Ti@C membrane substrate was placed in a 10% oxalic acid solution and acid-etched at 80℃ for 1 h. After removal, it was sonicated in deionized water for 10 min. Finally, the microporous Ti@C membrane substrate was washed with deionized water and acetone until pH 5.5. Weigh out 0.7612g thiourea (CH4N2S), 0.2281g antimony trichloride (SbCl3), 0.9026g tin dichloride hydrate (SnCl2·2H2O), and 0.1447g sodium dodecyl sulfonate (C 12 H 25 SO4Na) was dissolved in a mixture of 30 mL ethanol and 30 mL deionized water. The solution was stirred until dissolved and then placed in a polytetrafluoroethylene autoclave. The microporous Ti@C membrane substrate was placed in the autoclave and hydrothermally heated at 160 °C for 6 hours. After natural cooling, the material was removed, rinsed with ethanol and deionized water, and dried at 60 °C for 2 hours. Finally, the material was placed in a ceramic boat and placed in a muffle furnace at a heating rate of 5 °C / min, held at 600 °C for 2 hours, and cooled to room temperature to obtain the microporous SnO2-Sb / Ti@C electrode.

[0066] To verify the excellent catalytic performance of the microporous SnO2-Sb / Ti@C electrode, a methyl orange degradation experiment was conducted: the simulated wastewater volume was 200 mL, the target pollutant was methyl orange with a concentration of 100 mg / L, the NaCl concentration was 10 g / L, and the immersion area of ​​the microporous SnO2-Sb / Ti@C electrode prepared in Example 2 was 8 cm². 2 A copper plate is used as the anode and a copper plate as the cathode. The distance between them is controlled at 2 cm, and the current density is 30 mA / cm².2 Compared with SnO2-Sb prepared on titanium mesh and titanium plate substrates, the microporous SnO2-Sb / Ti@C electrode showed the best ability to degrade methyl orange, with a removal rate of 96%, which is much higher than that of SnO2-Sb electrodes prepared on titanium mesh and titanium plate substrates.

[0067] Example 3

[0068] At 40℃, 5g of polyvinylpyrrolidone was ultrasonically dissolved in 45mL of terpineol to obtain a polyvinylpyrrolidone solution. 12g of titanium dioxide powder (74μm), 2g of titanium hydride powder (36μm), and 20g of the polyvinylpyrrolidone solution were magnetically stirred until a uniform slurry was formed. The mixture was then sealed and allowed to stand for 2 hours until no air bubbles were observed. A thin layer of zinc stearate was used to isolate a smooth, scratch-free quartz surface. 7g of the slurry was used to coat a 25cm² area. 2 The material is placed in a vacuum drying oven at 70°C for 8 hours; the resulting preform is then removed from the quartz plate surface and laid flat on a porous alumina plate coated with a thin layer of zinc stearate for isolation, and then placed in a vacuum sintering furnace for sintering. The vacuum level is below 10. - 3 The heating rate (10℃ / min) and holding plateau were controlled. The temperature was maintained at 450℃ for 80 min, then at 800℃, 1000℃, and 1100℃ for 100 min, 90 min, and 60 min respectively. The maximum vacuum sintering temperature was 1200℃, held for 90 min. After the program, the temperature was cooled to below 200℃ in the furnace to obtain a microporous Ti@C membrane. A 3×3 cm microporous Ti@C material was placed in a 30% NaOH solution and treated with alkali at 80℃ for 1 h. After removal, it was sonicated in deionized water for 10 min. The alkali-treated microporous Ti@C membrane substrate was placed in a 10% phosphoric acid solution and acid-etched at 80℃ for 0.5 h. After removal, it was sonicated in deionized water for 10 min. Finally, the microporous Ti@C membrane substrate was washed with deionized water and acetone until pH 5.5. Weigh out 1.5685g sodium citrate (C6H5Na3O7), 0.1217g antimony trichloride (SbCl3), 0.6017g tin dichloride hydrate (SnCl2·2H2O), and 0.1402g hexamethylenetetramine (C6H5Na3O7). 12 N4) was placed in a mixture of 20 mL ethanol and 15 mL deionized water. The mixture was stirred until dissolved and then placed in a polytetrafluoroethylene autoclave. The microporous Ti@C membrane substrate was placed in the autoclave and hydrothermally heated at 200 °C for 8 hours. After natural cooling, the material was removed, rinsed with ethanol and deionized water, and dried at 60 °C for 2 hours. Finally, the material was placed in a ceramic boat and placed in a muffle furnace at a heating rate of 5 °C / min, held at 500 °C for 3 hours, and cooled to room temperature to obtain the microporous SnO2-Sb / Ti@C electrode.

[0069] To verify the excellent catalytic performance of the microporous SnO2-Sb / Ti@C electrode, a crystal violet degradation experiment was conducted: the simulated wastewater volume was 500 mL, the target pollutant was crystal violet with a concentration of 500 mg / L, the NaCl concentration was 10 g / L, and the immersion area of ​​the microporous SnO2-Sb / Ti@C electrode prepared in Example 3 was 9 cm². 2 A copper plate is used as the anode and the cathode. The distance between them is controlled at 3 cm, and the current density is 50 mA / cm². 2 Compared with SnO2-Sb prepared on titanium mesh and titanium plate substrates, the microporous SnO2-Sb / Ti@C electrode showed the best ability to degrade methylene blue, with a removal rate of 96%, which is much higher than that of SnO2-Sb electrodes prepared on titanium mesh and titanium plate substrates.

Claims

1. A method for preparing a microporous SnO2-Sb / Ti@C composite anode, characterized by comprising the following steps: The method comprises the following steps: ​ 1) mixing metal titanium powder and titanium hydride powder and an organic binder solution to form a slurry, which is cast into a film, dried and sintered to obtain a microporous Ti@C film; 2) after etching treatment, the microporous Ti@C film is placed in a reaction kettle and a mixed solution containing a tin source, an antimony source and a complexing agent is added for solvothermal reaction to obtain a microporous SnO2-Sb / Ti@C precursor; 3) the microporous SnO2-Sb / Ti@C precursor is subjected to heat treatment.

2. The method according to claim 1, characterized in that: the mass percentage composition of the metal titanium powder and the titanium hydride powder is 70-95%:5-30%; the mass ratio of the organic binder solution to the metal titanium powder is 1:0.5-1:2; the solid content of the organic binder solution is 5%-35%.

3. The method according to claim 1 or 2, characterized in that: the average particle size of the titanium hydride powder is 36 μm; the average particle size of the metal titanium powder is 36-74 μm, and the purity is ≥99.8%; the solute in the organic binder solution is at least one of polyvinyl butyral, phenolic resin, carboxymethyl cellulose, polyvinylpyrrolidone and polyacrylonitrile, and the solvent is at least one of ethanol, butanone and terpineol.

5. The method according to claim 1, characterized in that: the etching treatment comprises alkaline treatment, acid etching and cleaning processes; the alkaline treatment adopts an alkaline solution immersion method, the treatment temperature is 50-90 ℃, and the treatment time is 0.5-1.5 h; the acid etching adopts an acid solution immersion method, the treatment temperature is 30-90 ℃, and the treatment time is 0.5-2 h; 4. The method according to claim 1, wherein the method is characterized by: The sintering adopts a continuous gradient temperature rising vacuum sintering mode, the vacuum degree is less than 10 -3 Pa, the highest temperature of vacuum sintering is 1200℃, the temperature rising rate is 5-15℃ / min, 3-5 stage temperature keeping is carried out in the range of 300-1100℃, the time length of each stage temperature keeping is controlled in the range of 1-5h, and the sintering is completed, and then the furnace is cooled to below 200℃. the cleaning adopts a solvent rinsing method, and the cleaning is performed until the pH value is 5.5-7.5; the alkaline solution is at least one of NaOH solution, Na2CO3 solution and NaHCO3 solution with a mass concentration of 10%-40%; the acid solution is at least one of H2SO4 solution, H3PO4 solution, HCl solution and H2C2O4 solution with a mass concentration of 10%-30%; the solvent is water and acetone.

6. The method according to claim 1, characterized in that: the molar ratio of the tin source to the complexing agent is (3-7):10; the molar ratio of the tin source to the antimony source is 10:(1-5); the tin source includes at least one of potassium stannate trihydrate, tin dichloride hydrate, stannous sulfate, tin nitrate and stannous oxalate; the complexing agent includes at least one of sodium citrate and thiourea; the antimony source includes antimony trichloride. The solvothermal reaction is performed at a temperature of 120-300 ℃ for 6-20 h. The heat treatment is performed at a temperature of 300-600 ℃ in an air atmosphere for 1-3 h, and the heating rate is 2-5 ℃ / min. ​ ​ 7. The preparation method of the microporous Sn02-Sb / Ti@C composite anode according to claim 1 or 6, characterized in that: ​ 8. The method according to claim 1, wherein the method is characterized by: ​ 9. A microporous Sn02-Sb / Ti@C composite anode, characterized in that: The method for preparing the compound according to any one of claims 1-8.

10. The use of a microporous SnO2-Sb / Ti@C composite anode according to claim 9, characterized in that: It is applied to electrocatalytic oxidation degradation of organic high-salt wastewater.

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