Rare noble metal / Ti (at) TiO2-x self-supporting gas purification material, preparation and application thereof and air purifier

Abstract

The invention belongs to the field of gas purification, and particularly relates to a rare noble metal / Ti (at) TiO2-x self-supporting gas purification material, preparation and application of the rare noble metal / Ti (at) TiO2-x self-supporting gas purification material and an air purifier, and the rare noble metal / Ti (at) TiO2-x self-supporting gas purification material comprises a Ti (at) TiO2-x material and rare noble metal nanoparticles loaded on the Ti (at) TiO2-x material; the Ti (at) TiO2-x material comprises a titanium mesh and a hollow tube-shaped anatase phase TiO2-x with oxygen-rich defects, wherein the hollow tube-shaped anatase phase TiO2-x grows on the titanium mesh in situ; the rare and noble metal nanoparticles are nanoparticles containing at least one of Pt, Ag, Pd and Ce. According to the self-supporting material, the TiO2-x material with the special physicochemical characteristics grows on a titanium mesh in situ, and rare and noble metal particles are loaded in the TiO2-x material. Researches show that the material with physicochemical characteristics can meet the use requirements of gas photocatalysis, and excellent gas pollutant photocatalysis effect and stability can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of air purification, and in particular relates to the field of air photocatalytic purification materials. Background Art

[0002] Industrialization and the upgrading of confined spaces have led to the emergence of volatile organic compounds (VOCs) and pathogenic microorganisms as core air pollutants threatening human health. VOCs (such as formaldehyde and benzene derivatives) are not only highly carcinogenic and teratogenic, but their photochemical products (ozone and secondary organic aerosols) can also induce respiratory illnesses. The spread of pathogenic microorganisms (bacteria, viruses, etc.) in the air can trigger infections such as influenza. Traditional physical adsorption methods (such as activated carbon) suffer from rapid saturation failure and the risk of secondary release. UV light sterilization is ineffective against VOCs and produces ozone as a byproduct. Photocatalytic oxidation technology, due to its broad-spectrum degradation and sterilization capabilities, is considered an ideal solution, but existing material systems face significant bottlenecks in industrial application.

[0003] The current mainstream photocatalytic material is based on titanium dioxide (TiO2), which produces strong oxidative active species (•OH, •O2 - ) degrades VOCs into CO2 and H2O and destroys microbial nucleic acids and cell membranes. For example, patent publication number CN108906017A discloses a method for preparing a photocatalytic material for air purification, which contains modified titanium dioxide. Another example is patent publication number CN102127348A, which discloses a method for preparing a nano-titanium dioxide photocatalytic air purification coating.

[0004] Although the prior art discloses many solutions for using titanium dioxide for catalytic air purification, there are still significant defects in material design and application:

[0005] One issue is performance degradation caused by carrier dependence. 90% of commercial products use a TiO2 slurry coated on a high-molecular-weight polymer carrier (PET / PP nonwoven fabric). This technology results in a TiO2 coating thickness of 10-50μm on the polymer substrate, resulting in insufficient light penetration and a catalyst utilization rate of less than 40%. Furthermore, UV irradiation causes polymer chain scission and embrittlement, resulting in a carrier lifespan of typically less than 12 months. Furthermore, VOC degradation intermediates (carboxylic acids, aldehydes) and microbial debris clog the pores, reducing catalytic efficiency by more than 60%.

[0006] The second issue is low visible light response and carrier separation efficiency. Pure TiO2 utilizes only 4% of the ultraviolet light in the solar spectrum. Although visible light absorption can be expanded through doping (N, C), the quantum efficiency is generally less than 20%. While precious metal (Pt, Ag) deposition can improve carrier separation efficiency, traditional physical coating methods cause nanoparticle agglomeration, resulting in less than 30% exposure of active sites.

[0007] The third issue is the shedding of active components and secondary contamination. TiO2 prepared by the coating method has a weak bond with the carrier, and airflow erosion causes the catalyst to peel off (laboratory accelerated testing shows a shedding rate of >15%), resulting in nanoparticle contamination.

[0008] In summary, existing photocatalytic materials are limited by problems such as carrier failure, low light utilization efficiency and precious metal agglomeration, and the air purification effect and purification stability need to be further improved. Summary of the Invention

[0009] In view of the problems of existing photocatalytic materials such as carrier failure, low light utilization rate and noble metal agglomeration, the present invention proposes a rare noble metal / Ti@TiO 2-x The self-supporting gas purification material aims to provide a material that can adapt to gas purification requirements and has excellent gas purification effect and stability.

[0010] The second purpose of the present invention is to provide the rare metal / Ti@TiO 2-x The invention relates to a preparation method of a self-supporting gas purification material and an application of the self-supporting gas purification material in polluted gas purification.

[0011] The third object of the present invention is to provide a method comprising the rare metal / Ti@TiO 2-x Air purifier with self-supporting gas purification material.

[0012] Gas photocatalysis (such as air purification and VOC degradation) and liquid photocatalysis (such as wastewater treatment) share similar fundamental principles. However, the significant differences in their reaction environments (gas-solid vs. liquid-solid) present many unique challenges. Specifically, first, the low concentration of reactants in the gas phase leads to poor mass transfer efficiency. Pollutant concentrations in the atmosphere are much lower than those in the liquid phase. Efficiently capturing and transporting low-concentration gas molecules to the active sites of the catalyst is a primary challenge. Second, there are issues with the gas-phase reaction interface and product desorption. In the liquid phase, the solvent acts as a medium, bringing reactants closer to the interface and facilitating product diffusion. However, in the gas phase, only gas molecules in direct contact with the catalyst surface can participate in the reaction, and the effective reaction area is much smaller than in the liquid phase. Third, there are challenges with light source penetration and energy efficiency. Traditional powder catalysts often aggregate to increase surface area, resulting in inefficient illumination of deep-layered catalysts and low light energy utilization. Fourth, the gas-phase reaction pathway and byproduct control are more complex. Since intermediate products are less susceptible to solvation or diffusion, they are more susceptible to complex side reactions on the catalyst surface. Fifth, catalyst immobilization and pressure drop. Liquid-phase reactions can use a slurry system (powder suspension), but in gas-phase reactions, the powder is blown away by the airflow, so the catalyst must be immobilized. Traditional coating-based immobilization (catalyst powder coated on a carrier) has problems such as easy coating shedding, covering of active components, and increased airflow resistance (pressure drop), making it unsuitable for practical application.

[0013] To address the problems faced by gas photocatalysis, the existing technology mainly uses polymers as binders to adhere photocatalytic materials. However, the catalytic activity and stability of this solution are not ideal. There is no solution in the industry that can effectively adapt to the characteristics of gas photocatalytic treatment. To address this problem, the present invention provides the following solutions:

[0014] A rare precious metal / Ti@TiO 2-x Self-supporting gas purification materials, including Ti@TiO 2-x Materials and loaded rare and precious metal nanoparticles;

[0015] The Ti@TiO 2-x The material includes titanium mesh and oxygen-defect-rich hollow tubular anatase TiO in situ grown on the titanium mesh. 2-x ;

[0016] The rare metal nanoparticles are nanoparticles containing at least one of Pt, Ag, Pd, and Ce.

[0017] The present invention provides a self-supporting material, which in situ grows TiO with special physical and chemical characteristics on a titanium mesh. 2-x The present invention studies show that the material with the above physical and chemical characteristics can adapt to the requirements of gas photocatalysis and can obtain excellent photocatalytic effect and stability of gas pollutants.

[0018] In the present invention, the pore size of the titanium mesh is (1mm~5mm)×(1mm~5mm), and the thickness is 0.4~1.0mm. 2-x In the material, the oxygen-defect-rich empty tubular anatase phase TiO 2-x The diameter of Ti@TiO is 30~80 nm, and it grows along the Z-axis direction of the titanium mesh. 2-x The thickness of the material is 1~5μm.

[0019] In the present invention, TiO 2-x Refers to TiO2 with oxygen defects. There is no special requirement for x, for example, 0 <x<2。

[0020] The rare metal / Ti@TiO 2-x In the self-supporting gas purification material, the D50 particle size of the rare metal nanoparticles is 10-50 nm; the content thereof is 0.05-1 Wt.%; further, it can be 0.05-0.1 Wt.%.

[0021] The present invention also provides a rare metal / Ti@TiO 2-x A method for preparing a self-supporting gas purification material, comprising:

[0022] Step 1: Temperature-controlled voltage-variable electrochemical oxidation

[0023] The titanium mesh is subjected to temperature-controlled variable-voltage electrochemical oxidation, which includes a high-voltage oxidation process at a voltage of 40 to 60 V and a subsequent low-voltage oxidation process at a voltage of 5 to 20 V;

[0024] The system temperature during the voltage-variable electrochemical oxidation process is controlled below 10°C, and the high-pressure oxidation process lasts for 1 to 4 hours.

[0025] Step 2: Ti@TiO 2-x Material preparation

[0026] The electrochemical oxidation material of step 1 is subjected to a first-stage heat treatment in an oxygen-containing atmosphere to obtain a first-stage material; the first-stage material is subjected to a second-stage heat treatment in a hydrogen-containing atmosphere to obtain Ti@TiO 2-x material; or a section of the material is electrochemically reduced to obtain Ti@TiO 2-x Material;

[0027] The temperature of the first heat treatment is 300~700℃; the temperature of the second heat treatment is 400~650℃;

[0028] Step 3: Precious Metal Loading

[0029] Ti@TiO prepared in step 2 2-x The material is used as a carrier, and rare metal nanoparticles are loaded on its surface to prepare the rare metal / Ti@TiO 2-x Self-supporting gas purification material.

[0030] The present invention innovatively performs temperature-controlled voltage-variable electrochemical oxidation at the specific temperature and time, followed by gas-variable heat treatment or one-stage roasting-electrochemical reduction treatment to produce Ti@TiO 2-x The material is then subsequently loaded with rare metals, so that the material with the special physical and chemical characteristics can be prepared, and can adapt to the requirements of gas photocatalysis and can show excellent gas purification efficiency and stability.

[0031] In the present invention, there is no special requirement for the electrolyte in the temperature-controlled voltage-variable electrochemical oxidation (electrochemical oxidation) treatment process, and it can be, for example, a mixed solution including a fluorine-containing inorganic salt and an aqueous solvent.

[0032] The aqueous solvent is water or a mixed solvent of water and an organic solvent; the organic solvent is at least one of C1 to C4 alcohol, acetone, and THF.

[0033] In the present invention, when a water-organic solvent mixed solvent is selected as the solvent, the ratio of water to organic solvent can be reasonably adjusted as needed, for example, the mass fraction ratio can be 1-3:100.

[0034] The fluorine-containing inorganic salt includes at least one of sodium fluoride and ammonium fluoride.

[0035] The mass fraction of the fluorine-containing inorganic salt solute in the electrolyte is 0.1~0.3 Wt.%.

[0036] In the present invention, during the temperature-controlled variable-pressure electrochemical oxidation process, controlling the variable-pressure electrochemical oxidation treatment mechanism, temperature and treatment time of the treatment process can be beneficial to constructing physicochemical structures such as active sites that are compatible with gas photocatalysis, thereby improving the gas purification effect and stability.

[0037] In the present invention, the temperature of the temperature-controlled voltage-variable electrochemical oxidation process is 0-8°C; further, it can be 0-5°C.

[0038] In step 1, before high-voltage oxidation, the titanium mesh can be pre-activated in an electrolyte at a voltage of 5 to 20 V (or 10 to 15 V). In the present invention, the low-high-low three-stage voltage transformation process is used to further optimize the titanium mesh structure and Ti@TiO 2-x The physical and chemical structure helps to further improve the air purification effect of the obtained material.

[0039] In the present invention, the low-pressure pre-activation time may be 3 to 15 minutes; for example, further may be 5 to 10 minutes.

[0040] Preferably, after low-pressure pre-activation, ultrasonic treatment is performed in acid solution, and then the subsequent high-pressure oxidation process is performed. In the present invention, the low-high-low three-stage pressure change treatment is adopted, and further combined with the ultrasonic treatment of acid solution, which helps to further optimize the titanium mesh structure and Ti@TiO 2-x The physical and chemical structure helps to further improve the air purification effect of the obtained material.

[0041] In the present invention, the acid solution may be any inorganic acid, for example, hydrochloric acid with a concentration of 0.1 to 5 M, and further 1 to 3 M.

[0042] In the present invention, the ultrasonic treatment time can be 10 to 30 minutes.

[0043] In the present invention, the voltage of the high-voltage oxidation process is 45-55V.

[0044] In the present invention, the high-pressure oxidation process may last for 2.5 to 3.5 hours.

[0045] In the present invention, the voltage of the low-voltage oxidation process is 10-15V.

[0046] In the present invention, the low-pressure oxidation process may last for 3 to 15 minutes; further, it may last for 10 to 15 minutes.

[0047] An optional Ti@TiO 2-x Material preparation plan (Scheme A): Subjecting the electrochemical oxidation material under the special parameters to the two-stage gas-changing heat treatment, and further coordinating with the joint control of temperature, will help to further construct the physical and chemical structure such as active sites adapted to gas photocatalysis, thereby improving the gas purification effect and stability.

[0048] In step 2, the oxygen-containing atmosphere is at least one of air, oxygen, an oxygen-diluent mixture, and an air-diluent mixture; the diluent is at least one of nitrogen and a rare gas.

[0049] In the present invention, the oxygen partial pressure in the oxygen-containing atmosphere can be reasonably controlled as needed, for example, it can be 1-30v%; further, it can be 15-25v%.

[0050] In the present invention, the temperature of the first heat treatment can be 350-650°C.

[0051] The holding time of the first heat treatment is 1 to 3 hours.

[0052] In the present invention, the hydrogen-containing atmosphere is hydrogen or a mixture of hydrogen and a diluent gas. The diluent gas is as shown above.

[0053] In the present invention, the hydrogen partial pressure in the hydrogen-containing atmosphere can be reasonably controlled as needed, for example, it can be 1-30v%; further, it can be 1-5v%.

[0054] In the present invention, the temperature of the second heat treatment can be 450-550°C.

[0055] The holding time of the second heat treatment is 0.5-3 hours, and can further be 1-2 hours.

[0056] Another method of preparing Ti@TiO 2-x Material solution (Scheme B): The electrochemically oxidized material of step 1 is subjected to a first-stage heat treatment in an oxygen-containing atmosphere to obtain a first-stage material (the preparation method of the first-stage material is the same as that of Scheme A); the first-stage material is then subjected to an electrochemical reduction treatment to obtain Ti@TiO 2-x Material.

[0057] The electrochemical reduction method of the present invention can be conventional. For example, in the electrochemical reduction, the electrochemical reduction solution is a C1-C6 organic acid aqueous solution, and the electrochemical reduction current density is 1-15 mA / cm 2; The electrochemical reduction time is 1~10min.

[0058] The C1-C6 organic acid may be, for example, at least one of formic acid and acetic acid.

[0059] The concentration of the organic acid in the organic acid aqueous solution may be 1 to 30 wt.%.

[0060] In the present invention, the Ti@TiO 2-x The material is loaded with rare metal nanoparticles. For example, as an optional solution, the Ti@TiO 2-x The material is loaded with rare metal nanoparticles, and the steps are as follows: Ti@TiO 2-x The precursor liquid of the material and rare metal nanoparticles is mixed, and then a reducing agent is added for reduction treatment. 2-x The rare metal nanoparticles are reduced and deposited on the material to obtain the rare metal / Ti@TiO 2-x Self-supporting gas purification material.

[0061] The precursor material is a water-soluble compound of rare metal nanoparticles; for example, it can be at least one of nitrate, chloride, acetate, etc.

[0062] The reducing agent is a component capable of reducing the precursor raw material to a zero-valent state, such as sodium borohydride, ascorbic acid and its salts, etc. The amount used is 1 to 5 times the theoretical reaction amount for reducing the precursor raw material to a zero-valent state.

[0063] The present invention also provides a rare metal / Ti@TiO 2-x The application of self-supporting gas purification materials is to use them as photocatalysts for catalytic degradation of pollutants in polluted gases. The rare metal / Ti@TiO 2-x The self-supporting gas purification material is the rare noble metal / Ti@TiO 2-x Self-supporting gas purification material.

[0064] In the application of the present invention, the polluted gas is polluted air; the pollutants therein include at least one of volatile organic compounds and microorganisms.

[0065] The present invention also provides an air purifier, comprising a purification active material or an air purifier prepared by purifying active materials; the rare metal / Ti@TiO 2-x The self-supporting gas purification material is the rare noble metal / Ti@TiO 2-x Self-supporting gas purification material.

[0066] Beneficial effects

[0067] 1) The present application develops a new type of self-supporting gas purification material, which is Ti@TiO 2-x carrier and loaded with rare and precious metals. Through the synergistic control of components and microstructure, the performance of photocatalytic removal of VOCs in air and disinfection of pathogenic microorganisms is significantly improved. The material shows the advantages of high efficiency, low cost, no pollution and long period.

[0068] 2) The present application discloses a preparation method of rare and precious metal / Ti@TiO 2-x self-supporting gas purification material. This multi-step synthesis strategy effectively solves the key technical bottleneck in material construction, so that the three-dimensional curved surface structure of flexible titanium net has uniform current density distribution during electrochemical treatment, thereby forming hollow tubular titanium dioxide nanotubes with specific crystal face orientation and very tight interface bonding. This method can prepare anatase Ti@TiO 2-x carrier rich in oxygen vacancies and highly ordered in the vertical direction, and its high dispersion and regular crystal structure provide a good platform for subsequent surface modification. After loading rare and precious metals, they are uniformly dispersed on the surface of TiO 2-x , with low shedding rate under airflow scouring. Experimental results show that the composite material has superior performance in photocatalytic degradation of VOCs and inactivation of pathogenic microorganisms, and its purification and disinfection efficiency is significantly improved compared with traditional materials. From the perspective of industrial application, the preparation process has mild conditions and parameters easy to control, and has the feasibility of large-scale production, with broad engineering transformation prospects. BRIEF DESCRIPTION OF DRAWINGS

[0069] Figure 1 Picture of palladium-loaded O-vacancy-rich anatase Ti@TiO 2-x self-supporting material prepared in Example 1.

[0070] Figure 2 Picture of silver-loaded O-vacancy-rich anatase Ti@TiO 2-x self-supporting material prepared in Example 4A.

[0071] Figure 3 Picture of the material prepared in Comparative Example 7.

[0072] Figure 4 Transmission electron microscopy image of the material prepared in Comparative Example 7.

[0073] Figure 5 UV-Vis absorption spectrum of the material prepared in Example 1, Comparative Example 9, Comparative Example 7 and Example 4B.

[0074] Figure 6 IPCE comparison chart of the material prepared in Comparative Example 9, Comparative Example 7 and Example 4B. DETAILED DESCRIPTION

[0075] The following specific examples are intended to further illustrate the present invention in detail, rather than to further limit the scope of protection of the claims of the present invention.

[0076] Unless otherwise specified, the reagents involved in the following examples are commercial reagents purchased directly from the market.

[0077] The present invention provides a Ti@TiO based on rare metal loading 2-x The self-supporting gas purification material comprises a high-purity self-supporting titanium mesh substrate and a hollow tubular anatase phase TiO2 rich in oxygen vacancies supported on the titanium mesh. 2-x , and uniformly loaded on Ti@TiO 2-x Rare and precious metal nanoparticles on the material;

[0078] Hollow tubular anatase phase TiO 2-x Vertically loaded on a high-purity self-supporting titanium mesh substrate;

[0079] Rare metal nanoparticles are uniformly loaded on Ti@TiO 2-x In terms of materials;

[0080] Rare and precious metal nanoparticles (including but not limited to Pt, Ag, Pd, Ce, etc.) are single metal nanoparticles or multi-component alloy nanoparticles, and the particle size is 10-50 nm;

[0081] Titanium mesh substrate, hollow tubular TiO 2-x There are clear heterogeneous interfaces among the three materials:

[0082] The rare metal loaded Ti@TiO 2-x The metal content in the self-supporting gas purification material is 0.05~1Wt.%.

[0083] The present invention proposes a material synthesis strategy combining carrier-catalyst integrated design, oxygen vacancy and rare metal energy level matching, and anti-pollution interface design to develop a rare metal-loaded Ti@TiO 2-x Self-supporting gas purification material. The self-supporting material described in the present invention has made a breakthrough in solving technical bottlenecks such as carrier failure, low light utilization rate and noble metal agglomeration of photocatalytic air purification materials.

[0084] In the present invention, the supporting substrate is a high-purity titanium mesh with a pore size of 1 mm to 5 mm × 1 mm to 5 mm and a thickness of 0.4 to 1.0 mm.

[0085] The air purification material of the present invention comprises Ti@TiO 2-xSelf-supporting gas purification materials loaded with rare metal nanomaterials to induce energy level synergistic effect are the key to efficient and stable photocatalytic removal of VOCs and disinfecting pathogenic microorganisms. On this basis, further research on Ti@TiO 2-x By optimizing and regulating the size of the self-supporting structure, the composition and content of the rare metal nanoparticles, the performance of the material can be further improved.

[0086] In the present invention, the rare metal loaded Ti@TiO 2-x The metal content in self-supporting gas purification materials can be further optimized to 0.05-0.5 wt.%. Research has shown that this optimal content not only provides an excellent ratio of rare and precious metals, but also synergizes with oxygen vacancies to induce energy levels, adapting to the photocatalytic reaction characteristics of removing VOCs from the air and disinfecting pathogenic microorganisms, while offering the advantages of high efficiency, low cost, pollution-free operation, and a long cycle time.

[0087] In the present invention, the hollow tubular TiO 2-x The diameter is 30~80 nm, the length is 1~5 μm, and the hollow tubes are closely arranged perpendicular to the substrate;

[0088] The present invention also aims to provide the rare metal loaded Ti@TiO 2-x In the preparation method of the self-supporting gas purification material, during the implementation of this method, the three-dimensional curved surface structure of the flexible titanium mesh easily leads to uneven current density distribution during electrochemical treatment, making it difficult to form a uniform TiO 2-x Nanotubes, and the interface bonding strength is insufficient and easy to fall off; In addition, rare metals in TiO 2-x The surface is easy to migrate and agglomerate, and the air flow erosion shedding rate is high. In response to the problems faced by the preparation of this new material, the present invention provides an optional rare metal loaded Ti@TiO 2-x A method for preparing a self-supporting gas purification material, comprising:

[0089] Step 1:

[0090] The Ti@TiO2 precursor material was prepared using an electrochemical treatment process: the titanium mesh was electrochemically oxidized, and the system temperature T1 during the electrochemical oxidation process was controlled (less than 10°C). The first electrochemical treatment duration was H1 and the oxidation voltage was U1, forming a Ti@TiO2 induction layer. Subsequently, ultrasonic exfoliation was performed in an HCl solution to expose the "induction pits." The second electrochemical treatment duration was H2 and the oxidation voltage was U2, forming a Ti@TiO2 growth layer. The third electrochemical treatment duration was H3 and the oxidation voltage was U3, forming a Ti@TiO2 precursor layer.

[0091] Finally, the anatase Ti@TiO2 with rich O vacancies was obtained by two-stage gasification treatment at temperatures T2 and T3, or by pre-heat treatment at temperature T2 followed by electrochemical reduction. 2-x Self-supporting material.

[0092] The solute in the electrochemical oxidation process is a fluorine-containing inorganic salt with a mass fraction of 0.1-0.3 wt.%, and the solution in the electrolyte is ethylene glycol and water (the mass fraction of water is 2-3 wt.%). The electrolyte in the electrochemical reduction process is an aqueous solution of a C1-C6 organic acid with a volume fraction of 1-30 wt.%.

[0093] Step 2:

[0094] The above synthesized O vacancy-rich anatase phase Ti@TiO 2-x The self-supporting material is vertically immersed in a solution containing a certain concentration of rare metals, and adsorbed in the dark for T4 hours at a stirring speed of R1. Subsequently, a certain concentration of reducing agent solution is added to the reaction system, and the reaction is continued at a stirring speed of R2 for T5 hours. The rare metal-loaded Ti@TiO 2-x Self-supporting gas purification material.

[0095] The concentration of metal ions in the rare metal solution is 0.01M~0.1M, and the concentration of the reducing agent solution is 0.1M~0.5M.

[0096] In the present invention, in step 1, the solute in the electrolyte is a fluorine-containing inorganic salt with a mass fraction of 0.1-0.3 wt.%, and the solution in the electrolyte is ethylene glycol and water (the mass fraction of water is 2-3 wt.%).

[0097] The electrolyte is an aqueous solution of a fluorine-containing inorganic salt, wherein the fluorine-containing inorganic salt includes at least one of sodium fluoride and ammonium fluoride;

[0098] Temperature T1 is 0~8℃.

[0099] During electrochemical treatment, the voltage of the first electrochemical oxidation process (low-voltage pre-activation) is 5~20V, the voltage of the second electrochemical oxidation process is 40~60V (high-voltage oxidation process), and the voltage of the third electrochemical oxidation process is 5~20V (low-voltage oxidation process).

[0100] The first electrochemical oxidation time is 3~15min, the second electrochemical oxidation time is 1~4h; the third electrochemical oxidation time is 3~15min;

[0101] During ultrasonic stripping, the ultrasonic time is 10~30min and the HCl concentration is 1~3M.

[0102] The first heat treatment temperature T2 is 300~700℃, and can further be 350~650℃. The atmosphere of the first heat treatment is air, the holding time is 1~3h, and the heating rate is 1~2℃ / min; it can further be 480~520℃.

[0103] The temperature T3 of the second heat treatment is 400~650℃, and can be further 450~550℃, the atmosphere is 1~10% H2 / Ar mixed gas, the holding time is 0.5~3h, and the heating rate is 1~3℃ / min; it can be further 480~520℃.

[0104] The electrochemical reduction solution is a C1~C6 organic acid aqueous solution, and the current density of the electrochemical reduction is 1~15mA / cm 2 ; The electrochemical reduction time is 1~10min.

[0105] The preferred preparation scheme of the present invention innovatively uses temperature-controlled variable-pressure electrochemical oxidation and variable-gas heat treatment. Temperature-controlled variable-pressure electrochemical oxidation first creates regular "induced pits" on the surface of the titanium mesh, and completely removes the initial oxide layer through acid-added ultrasonic cleaning, retaining only the induced surface pattern, laying the foundation for the subsequent growth of highly ordered nanotube arrays. Then, on the pretreated titanium surface, a highly ordered long nanotube array is grown. Finally, the grown nanotubes are "finely trimmed" to thin the barrier layer, repair the top morphology, and release internal stress: this helps to release the internal stress in the nanotube array and enhance its mechanical stability and bonding with the substrate. This is conducive to the preparation of highly ordered, large-area uniform TiO2 nanotube arrays that are firmly bonded to the substrate. In addition, the preparation method innovatively uses two-stage variable-gas treatment to introduce O vacancies, so that the titanium and oxygen atoms can be fully arranged to form a complete, high-quality crystal structure, while avoiding contamination caused by templates or other organic residues in the precursor. In addition, the two-stage gas change treatment avoids the generation of deep energy level defects as electron-hole pair recombination centers by direct H2 / Ar treatment, and also avoids the reduction of TiO2 to low-valent titanium oxides such as Ti2O3, ensuring that the basic semiconductor properties of the material are not destroyed.

[0106] In the present invention, under the synthesis conditions, the desired anatase phase Ti@TiO rich in O vacancies can be successfully obtained. 2-x The self-supporting material is advantageous for combination with subsequent processes, and further advantageous for subsequent high dispersion and high stability loading of rare metals, and is advantageous for preparing the material with the structure required by the present invention.

[0107] In the present invention, the rare metal raw materials include but are not limited to at least one of sulfates, copper nitrate and copper acetate of elements such as Pt, Ag, Pd and Ce;

[0108] The metal ion concentration in the rare noble metal solution is 0.01M~0.1M;

[0109] The reducing agent solution includes at least one of sodium borohydride, ascorbic acid, and sodium citrate;

[0110] The reducing agent solution is 0.1M~0.5M.

[0111] In the present invention, anatase Ti@TiO 2-x The self-supporting material is vertically immersed in a solution containing a certain concentration of rare metals to ensure that the Ti@TiO 2-x The metal ions are uniformly adsorbed on the surface of the self-supporting material and reach saturation. The stirring speed R1 is 500-800 rpm, and the adsorption time T4 is 8-16 hours. The adsorption process must be protected from light.

[0112] In the present invention, when adding the reducing agent to the reaction system after light-shielded adsorption, it must be added slowly and dropwise at a rate of 8 to 12 mL / min. The reducing agent is used in an amount of 40 to 60 mL, the stirring speed R2 during reduction is 600 to 1000 rpm, and the reduction time T5 is 20 to 50 min.

[0113] In the present invention, under the reducing conditions, the anatase phase Ti@TiO 2-x Stably anchor rare metal quantum dots on self-supporting materials,

[0114] This is conducive to constructing a physical and chemical structure suitable for photocatalytic removal of VOCs in the air and disinfecting pathogenic microorganisms, and is conducive to the preparation of materials with high activity, long life and low cost.

[0115] The present invention also provides a rare metal loaded Ti@TiO 2-x The application of self-supporting gas purification materials is to use them as air purification materials for photocatalytic removal of VOCs in the air and disinfecting pathogenic microorganisms.

[0116] In the application of the present invention, in addition to the rare metal loaded Ti@TiO 2-x In addition to the self-supporting gas purification material, other application methods can be well known.

[0117] This proposal also discloses a rare metal-loaded Ti@TiO 2-x A self-supporting gas purification material module includes air purification materials, ultraviolet light, and an air circulation fan. The self-supporting gas purification material prepared by the process described herein can be used directly or obtained through secondary processing based on the preparation method provided in this technical solution. The device achieves photocatalytic removal of VOCs and the elimination of pathogenic microorganisms in the air through a photocatalytic mechanism.

[0118] Example 1

[0119] Step 1: Temperature-controlled electrochemical oxidation

[0120] A high-purity titanium mesh (pore size 3 mm × 5 mm, purity ≥ 99.99%) of 18 cm × 18 cm × 0.5 mm was sequentially cleaned in 2 M HCl, ethanol, acetone, and ultrapure water, and then dried at 60 °C.

[0121] Ti@TiO2 precursors were prepared using an electrochemical process: a high-purity titanium mesh served as the anode and a high-purity titanium sheet as the cathode (with the plates maintaining the same area). An ammonium fluoride-containing ethylene glycol solution (0.25 wt% ammonium fluoride and 2 wt% water) was used as the electrolyte. Electrochemical treatment was performed in a double-layer quartz glass reactor with circulating cooling water. The temperature of the solution was controlled between 4 and 8°C (T1). The first electrochemical oxidation step was performed at a voltage of 10 V for 5 minutes. After the oxidation, the material was ultrasonically exfoliated in 1.5 M HCl for 15 minutes. After three washes with water and ethanol, the material was dried at 60°C to obtain an induction layer. A second electrochemical oxidation step was then performed at a voltage of 50 V for 3.5 hours to obtain a growth layer. Finally, a third electrochemical oxidation step was performed at a voltage of 10 V for 5 minutes to obtain the Ti@TiO2 precursor layer.

[0122] Step 2: Gas treatment

[0123] The Ti@TiO2 precursor layer in step 1 was heated to temperature T2 (350°C) in air at a heating rate of 2°C / min and heat-treated at this temperature (first stage heat treatment) for 2 hours. Then, the atmosphere was switched to a 5v% H2 / Ar mixed gas and heat-treated at temperature T3 (500°C) for 1 hour (second stage heat treatment). 2-x Self-supporting material.

[0124] Step 3: Pd Load

[0125] The Ti@TiO prepared in step 1 2-x The self-supporting material was vertically immersed in a 0.01M chloropalladic acid solution and adsorbed in the dark for 12 hours at a stirring speed of 700 rpm. Subsequently, a 0.1M sodium borohydride solution was added dropwise to the reaction system at a rate of 10 mL / min (a total of 50 mL was added, and the amount of reducing agent was 1.5 to 2 times the theoretical amount of reducing the precious metal to zero valence). The reaction was continued at a stirring speed of 800 rpm for 30 minutes to finally obtain Pd-loaded Ti@TiO 2-x Self-supporting gas purification material (Pd loading is 0.05wt.%).

[0126] Electrochemical detection

[0127] On the electrochemical workstation, Pt as the counter electrode, Ag / AgCl as the reference electrode, and Pd-loaded O-vacancy-rich anatase Ti@TiO 2-x A three-electrode system was constructed using the self-supporting material (cut into 1 cm × 1 cm pieces) as the working electrode to test its photoelectrochemical performance. The electrolyte was 0.5 M Na₂SO₄. LSV performance was tested at a scan rate of 5 mV / s. All tests were performed under 300 W Xe lamp illumination.

[0128] Rare metal-loaded Ti@TiO 2-x Modular assembly of self-supporting gas purification materials:

[0129] Two parallel 18 cm × 18 cm rare metal loaded Ti@TiO 2-x The self-supporting gas purification material is fixed vertically on a plastic bracket with a distance of 10 cm between them, and a 19W UV disinfection lamp is placed between them. The above device is then placed in a 19cm×19cm plastic ventilation duct, and an air circulation fan is placed on one side. The rare metal loaded Ti@TiO 2-x The module of the self-supporting gas purification material. Air enters the duct through the circulating fan, flows through the self-supporting gas purification material, and is discharged from the other side. The catalytic performance of the material is evaluated by measuring the concentration of pathogenic microorganisms or VOCs in the room after a certain period of time. The initial concentration of microbial pathogens is 1.5×10 7 cfu / mL, VOCs concentration is 500ppb.

[0130] Example 2

[0131] Compared with Example 1, the only difference is that the conditions of step 1 are changed. The experimental groups are:

[0132] Group A: The first electrochemical oxidation treatment was not performed, and the second and third electrochemical oxidation treatments were performed directly. The time of the third electrochemical oxidation was extended to 10 minutes. Other operations and parameters were the same as those in Example 1.

[0133] Group B: After the first electrochemical treatment, ultrasonic stripping was not performed and subsequent electrochemical treatment was performed directly. Other operations and parameters were the same as those in Example 1.

[0134] Group C: The voltage of the first electrochemical treatment was 15 V, the time was 8 min, and the ultrasonic treatment time after treatment was 20 min; the voltage of the second section was 45 V, and the treatment time was 3 h; the voltage of the third electrochemical oxidation process was 15 V, and the time was adjusted to 10 min; other operations and parameters were the same as in Example 1.

[0135] Example 3

[0136] Compared with Example 1, the only difference is that the conditions of step 2 are changed, and the Ti@TiO2 precursor layer of step 1 is pre-heated to temperature T2 (650°C) in air at a heating rate of 2°C / min and heat-treated at this temperature for 1 hour, and then the atmosphere is switched to a 10% H2 / Ar mixed gas, and the heat treatment is continued at temperature T3 (450°C) for 1.5 hours.

[0137] Example 4

[0138] Compared with Example 1, the only difference is that the conditions of step 3 are changed. The experimental groups are:

[0139] Group A: Compared with Example 1, the only difference is that the chloropalladic acid solution in step 3 is replaced with a silver nitrate solution of the same concentration, and the other operations and parameters are the same as those in Example 1.

[0140] Group B: Compared with Example 1, the only difference is that in step 3, the chloropalladium acid solution in step 3 is replaced with 0.01M chloropalladium acid + 0.01M copper sulfate solution, and the total loading amount of palladium / copper precious metal is 0.06wt.%; other operations and parameters are the same as those in Example 1.

[0141] Example 5

[0142] Compared with Example 1, the only difference is that the conditions of step 2 are changed. The difference is that after the first stage of heat treatment, the material is cooled with the furnace, and then electrochemical reduction is used to reduce the material after the first stage of heat treatment to prepare the Ti@TiO 2-x Materials. During electrochemical reduction, the reduction time is 5 min and the reduction current density is 5 mA / cm 2 The electrolyte in the electrochemical reduction process is formic acid solution with a volume fraction of 10%.

[0143] Comparative Example 1

[0144] Compared with Example 1, the only difference is that the temperature T1 during the electrochemical oxidation process is controlled at 25-30° C., and other operations and parameters are the same as in Example 1.

[0145] Comparative Example 2

[0146] Compared with Example 1, the only difference is that the time of the second electrochemical oxidation process is 5.5 hours, and the other operations and parameters are the same as Example 1.

[0147] Comparative Example 3

[0148] Compared with Example 1, the difference is only that in Step 2, only single-stage hydrogen atmosphere treatment is carried out, the difference is that the temperature T2 is raised and the atmosphere during the holding process is 5v% H2 / Ar mixed atmosphere, and other operations and parameters are the same as those in Example 1.

[0149] Comparative Example 4

[0150] Compared with Example 1, the difference is only that in Step 2, only single-stage oxygen-containing atmosphere treatment is carried out, the difference is that the temperature T3 is raised and the atmosphere during the holding process is air, and other operations and parameters are the same as those in Example 1.

[0151] Comparative Example 5

[0152] Compared with Example 1, the difference is only that in Step 2, the temperature T2 and T3 are both 350℃, and other operations and parameters are the same as those in Example 1.

[0153] Comparative Example 6

[0154] Compared with Example 1, the difference is only that in Step 2, after the temperature T2, the product and sodium borohydride are mixed in a weight ratio of 1:1, and then the calcination treatment is carried out under Ar atmosphere at temperature T3, and other operations and parameters are the same as those in Example 1.

[0155] Comparative Example 7

[0156] Compared with Example 1, the difference is only that Step 3 is not carried out.

[0157] Comparative Example 8

[0158] Compared with Example 1, the difference is only that a commercial TiO2 air purification material is used for testing.

[0159] Comparative Example 9

[0160] Compared with Example 1, the difference is only that Step 3 is not carried out, and in Step 2, no temperature T3 treatment is carried out, and other operations and parameters are the same as those in Example 1.

[0161] Comparative Example 10

[0162] Compared with Example 1, the difference is only that the temperature T3 is raised and the holding process is carried out in Ar atmosphere, and other operations and parameters are the same as those in Example 1.

[0163] The test results of each case are shown in Table 1:

[0164] Table 1: Staphylococcus albus killing efficiency (1h) and toluene, formaldehyde removal efficiency (1.5h) of each catalyst

[0165]

[0166] In summary, it can be seen from Examples 1 to 5 and Comparative Examples 1 to 10 that the material synthesis strategy combining carrier-catalyst integrated design, oxygen vacancy and rare metal energy level matching, and anti-pollution interface design can help solve the problems of photocatalytic materials being limited by carrier failure, low light utilization, and noble metal agglomeration. 2-x The self-supporting gas purification material can improve its catalytic activity and stability in photocatalytic removal of VOCs in the air and disinfecting pathogenic microorganisms.

[0167] In addition, it can be seen from Examples 1 and 2 that the gas purification effect of the obtained material can be enhanced by using the preferred three-stage temperature-controlled and pressure-controlled electrochemical oxidation described in the present invention, in combination with ultrasonic treatment after the first-stage oxidation.

[0168] It can be seen from Examples 1, 3 and 4 that the gas purification effect of the obtained material can be enhanced by adopting the gas change treatment and precious metal loading of the present invention.

[0169] It can be seen from Examples 1 and 5 that by adopting the two-stage gas conversion treatment described in the present invention, or the single-stage heat treatment followed by electrochemical reduction treatment, and further coordinating with other processes, a material with excellent air purification effect can be obtained.

[0170] The above describes the specific embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A rare metal / Ti@TiO 2-x A self-supporting gas purification material, characterized in that Contains Ti@TiO 2-x Materials and loaded rare and precious metal nanoparticles; The Ti@TiO 2-x The material includes titanium mesh and oxygen-defect-rich hollow tubular anatase TiO in situ grown on the titanium mesh. 2-x ; The rare metal nanoparticles are nanoparticles containing at least one of Pt, Ag, Pd, and Ce.

2. The rare metal / Ti@TiO according to claim 1 2-x A self-supporting gas purification material, characterized in that The titanium mesh has a pore size of (1 mm to 5 mm) × (1 mm to 5 mm) and a thickness of 0.4 to 1.0 mm; The Ti@TiO 2-x In the material, the oxygen-defect-rich empty tubular anatase phase TiO 2-x The diameter is 30~80 nm, it grows along the Z-axis direction of the titanium mesh, and the thickness is 1~5 μm; The rare metal / Ti@TiO 2-x In the self-supporting gas purification material, the D50 particle size of the rare metal nanoparticles is 10-50 nm, and the content thereof is 0.05-1 Wt.%.

3. A rare metal / Ti@TiO according to claim 1 or 2 2-x The method for preparing a self-supporting gas purification material is characterized in that the steps include: Step 1: Temperature-controlled voltage-variable electrochemical oxidation The titanium mesh is subjected to temperature-controlled variable-voltage electrochemical oxidation, which includes a high-voltage oxidation process at a voltage of 40 to 60 V and a subsequent low-voltage oxidation process at a voltage of 5 to 20 V; The system temperature during the voltage-variable electrochemical oxidation process is controlled below 10°C, and the high-pressure oxidation process lasts for 1 to 4 hours. Step 2: Ti@TiO 2-x Material preparation The electrochemical oxidation material of step 1 is subjected to a first-stage heat treatment in an oxygen-containing atmosphere to obtain a first-stage material; the first-stage material is subjected to a second-stage heat treatment in a hydrogen-containing atmosphere to obtain Ti@TiO 2-x material; or a section of the material is electrochemically reduced to obtain Ti@TiO 2-x Material; The temperature of the first heat treatment is 300~700℃; the temperature of the second heat treatment is 400~650℃; Step 3: Precious Metal Loading Ti@TiO prepared in step 2 2-x The material is used as a carrier, and rare metal nanoparticles are loaded on its surface to prepare the rare metal / Ti@TiO 2-x Self-supporting gas purification material.

4. The rare metal / Ti@TiO according to claim 3 2-x The method for preparing a self-supporting gas purification material is characterized in that: The electrolyte in the temperature-controlled voltage-variable electrochemical oxidation process is a mixed solution comprising a fluorine-containing inorganic salt and an aqueous solvent; The aqueous solvent is water or a mixed solvent of water and an organic solvent; the organic solvent is at least one of a C1 to C4 alcohol, acetone, and THF; The fluorine-containing inorganic salt includes at least one of sodium fluoride and ammonium fluoride; The mass fraction of the fluorine-containing inorganic salt solute in the electrolyte is 0.1~0.3 Wt.%.

5. The rare metal / Ti@TiO according to claim 3 2-x The method for preparing a self-supporting gas purification material is characterized in that: In step 1, before the high-voltage oxidation, a low-voltage pre-activation process with a voltage of 5 to 20 V is also included; wherein the time of the low-voltage pre-activation is 3 to 15 minutes.

6. The rare metal / Ti@TiO according to claim 5 2-x The method for preparing a self-supporting gas purification material is characterized in that: After low-pressure preactivation, ultrasonic treatment is performed in acid solution, followed by a subsequent high-pressure oxidation process; The high-pressure oxidation process lasts for 2.5 to 3.5 hours; the subsequent low-pressure oxidation process lasts for 3 to 15 minutes.

7. The rare metal / Ti@TiO according to claim 3 2-x The method for preparing a self-supporting gas purification material is characterized in that: In step 2, the oxygen-containing atmosphere is at least one of air, oxygen, an oxygen-diluent mixture, and an air-diluent mixture; the diluent is at least one of nitrogen and a rare gas; The holding time of the first heat treatment is 1 to 3 hours; The hydrogen-containing atmosphere is hydrogen or a mixture of hydrogen and diluent gas; The holding time of the second heat treatment is 0.5~3h; Electrochemical reduction: The solution for electrochemical reduction is a C1~C6 organic acid aqueous solution, and the current density of electrochemical reduction is 1~15mA / cm 2 ;Electrochemical reduction time is 1~10min; In step 3, the Ti@TiO 2-x The material is loaded with rare metal nanoparticles, and the steps are as follows: Ti@TiO 2-x The precursor liquid of the material and rare metal nanoparticles is mixed, and then a reducing agent is added for reduction treatment. 2-x The rare metal nanoparticles are reduced and deposited on the material to obtain the rare metal / Ti@TiO 2-x Self-supporting gas purification materials; The precursor material is a water-soluble compound of rare and precious metal nanoparticles; The reducing agent is a component that can reduce the precursor raw material to a zero-valent state; the amount of the reducing agent used is 1 to 5 times the theoretical reaction amount for reducing the precursor raw material to a zero-valent state.

8. A rare precious metal / Ti@TiO 2-x The application of the self-supporting gas purification material as a photocatalyst for catalytic degradation of pollutants in polluted gas is characterized in that: The rare metal / Ti@TiO 2-x The self-supporting gas purification material is the rare metal / Ti@TiO according to any one of claims 1 to 2 2-x Self-supporting gas purification material, and / or rare metal / Ti@TiO prepared by the preparation method according to any one of claims 3 to 7 2-x Self-supporting gas purification material.

9. The rare metal / Ti@TiO according to claim 8 2-x Application of the self-supporting gas purification material, characterized in that, The polluted gas is polluted air; the pollutants therein include at least one of volatile organic compounds and microorganisms.

10. An air purifier comprising a purification active material or prepared by purifying an active material; characterized in that: The rare metal / Ti@TiO 2-x The self-supporting gas purification material is the rare metal / Ti@TiO according to any one of claims 1 to 2 2-x Self-supporting gas purification material, and / or rare metal / Ti@TiO prepared by the preparation method according to any one of claims 3 to 7 2-x Self-supporting gas purification material.

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