Rare and precious metals / Ti@TiO 2-x Self-supporting gas purification materials, their preparation, application, and air purifiers

Abstract

This invention belongs to the field of gas purification, specifically relating to a rare and precious metal / Ti@TiO 2‑x Self-supporting gas purification materials, their preparation, application, and air purifiers, including rare and precious metals / Ti@TiO 2‑x Self-supporting gas purification materials include Ti@TiO 2‑x The material and the rare and precious metal nanoparticles it supports; the Ti@TiO 2‑x The materials include titanium mesh, and oxygen-rich, hollow tubular anatase phase TiO2 grown in situ on the titanium mesh. 2‑x The rare and precious metal nanoparticles are nanoparticles containing at least one of Pt, Ag, Pd, and Ce. This invention provides a self-supporting material in which TiO₂ with the aforementioned special physicochemical properties is grown in situ on a titanium mesh. 2‑x The material is loaded with rare and precious metal particles. Research in this invention shows that the material with the described physicochemical properties is suitable for the application requirements of gas photocatalysis, and can achieve excellent photocatalytic effects and stability against gaseous pollutants.

Description

Technical Field

[0001] This invention belongs to the field of air purification technology, specifically relating to the field of air photocatalytic purification materials. Background Technology

[0002] Industrialization and the increasing prevalence of enclosed spaces have led to volatile organic compounds (VOCs) and pathogenic microorganisms becoming core air pollutants threatening human health. VOCs (such as formaldehyde and benzene compounds) are not only highly carcinogenic and teratogenic, but their photochemical products (ozone, secondary organic aerosols) can induce respiratory diseases. Meanwhile, the spread of pathogenic microorganisms (bacteria, viruses, etc.) in the air can trigger infectious events (such as influenza). Traditional physical adsorption methods (activated carbon) suffer from rapid saturation and deterioration, and the risk of secondary release. Ultraviolet (UV) sterilization is ineffective against VOCs and produces ozone byproducts. 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] Current mainstream photocatalytic materials are based on titanium dioxide (TiO2), which generate highly reactive oxidizing species (•OH, •O2) through ultraviolet light excitation. - This process degrades VOCs into CO2 and H2O and disrupts microbial nucleic acids / cell membranes. For example, patent document CN108906017A discloses a method for preparing a photocatalytic material for air purification, which includes modified titanium dioxide. Another example is patent document CN102127348A, which discloses a method for preparing a nano-titanium dioxide photocatalytic air-purifying coating.

[0004] Although existing technologies disclose many schemes for using titanium dioxide for air catalytic purification, significant shortcomings still exist in material design and application:

[0005] One issue is the performance degradation caused by carrier dependence. 90% of commercial products use polymer carriers (PET / PP nonwoven fabric) coated with TiO2 slurry. The TiO2 coating thickness on the polymer substrate in this technology is 10~50μm, which is insufficient for light penetration and the utilization rate of the underlying catalyst is <40%. At the same time, the polymer undergoes chain scission and embrittlement under ultraviolet irradiation, and the carrier life is usually <12 months. In addition, VOCs degradation intermediates (carboxylic acids, aldehydes) and microbial residues clog the pores, resulting in a catalytic efficiency degradation of >60%.

[0006] Secondly, the visible light response and carrier separation efficiency are low. Pure TiO2 only utilizes 4% of the ultraviolet light in the solar spectrum. Although the visible light absorption can be extended by doping (N, C), the quantum efficiency is generally <20%. While noble metal (Pt, Ag) deposition can improve carrier separation efficiency, the traditional physical coating method leads to nanoparticle agglomeration, and the exposure rate of active sites is less than 30%.

[0007] Thirdly, there is the issue of active component shedding and secondary pollution. The TiO2 prepared by the coating method has weak bonding with the support, and the airflow erosion causes catalyst stripping (laboratory accelerated testing shows a shedding rate >15%), resulting in nanoparticle pollution.

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

[0009] To address the limitations of existing photocatalytic materials, such as support failure, low light utilization, and noble metal agglomeration, this invention proposes a rare noble metal / Ti@TiO2 method. 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 objective of this invention is to provide the aforementioned rare and precious metal / Ti@TiO 2-x Preparation method of self-supporting gas purification material and its application in polluted gas purification.

[0011] A third objective of this invention is to provide a solution containing the aforementioned rare and precious metal / Ti@TiO 2-x Air purifier with self-supporting gas purification materials.

[0012] Gas photocatalysis (such as air purification and VOCs degradation) and liquid catalysis (such as wastewater treatment) are similar in basic principles, but the significant difference in their reaction environments (gas-solid vs. liquid-solid) brings many unique challenges. Specifically: First, the concentration of gaseous reactants is low, resulting in poor mass transfer efficiency. The concentration of pollutants in the atmosphere is much lower than that in the liquid phase. How to efficiently "capture" and transport low-concentration gas molecules to the active sites of the catalyst is a primary challenge. Second, there is the problem of desorption from the gas-phase reaction interface and products. In the liquid phase, the solvent can act as a medium, helping reactants approach the interface and promoting 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 system. Third, there is the issue of light source penetration and energy utilization. Traditional powder catalysts are often piled up to increase specific surface area, resulting in the deep catalyst layers not being effectively irradiated, leading to low light energy utilization. Fourth, the gas-phase reaction pathway and byproduct control are more complex. Because intermediate products are not easily solvated or diffused, they are more likely to undergo complex side reactions on the catalyst surface. Fifth, catalyst immobilization and pressure drop. Liquid-phase reactions can use slurry systems (powder suspension), but in gas-phase reactions, the powder is blown away by the gas flow, so the catalyst must be immobilized. Traditional coating-based immobilization (coating catalyst powder onto a support) has problems such as easy coating detachment, coverage of active components, and increased gas flow resistance (pressure drop), which are not conducive to practical applications.

[0013] To address the challenges of gas photocatalysis, existing technologies primarily employ polymers as binders to adhere photocatalytic materials. However, this approach suffers from unsatisfactory catalytic activity and stability. Currently, there is no effective solution in the industry that can effectively adapt to the characteristics of gas photocatalytic treatment. To address this issue, this invention provides the following solution:

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

[0015] The Ti@TiO 2-x The materials include titanium mesh, and oxygen-rich, hollow tubular anatase phase TiO2 grown in situ on the titanium mesh. 2-x ;

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

[0017] This invention provides a self-supporting material in which TiO with the aforementioned special physicochemical properties is grown in situ on a titanium mesh. 2-x The material is loaded with rare and precious metal particles. Research in this invention shows that the material with the described physicochemical properties is suitable for the application requirements of gas photocatalysis, and can achieve excellent photocatalytic effects and stability against gaseous pollutants.

[0018] In this invention, the titanium mesh has a aperture of (1mm~5mm) × (1mm~5mm) and a thickness of 0.4~1.0mm. The Ti@TiO₂... 2-x In the material, oxygen-rich defect-filled hollow tubular anatase phase TiO 2-x The diameter is 30~80 nm, and it grows along the Z-axis of the titanium mesh. (Ti@TiO) 2-x The thickness of the material is 1~5μm.

[0019] In this invention, TiO 2-x This refers to TiO2 with oxygen vacancies. The 'x' value has no specific requirements, for example, 0. <x<2。

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

[0021] The present invention also provides the aforementioned rare and precious metal / Ti@TiO 2-x The preparation method of self-supporting gas purification material includes the following steps:

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

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

[0024] Among them, the system temperature during the voltage-switching electrochemical oxidation process is controlled to be below 10℃, and the high-pressure oxidation process takes 1~4h;

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

[0026] The electrochemical oxidation material from 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 then subjected to a second-stage heat treatment in a hydrogen-containing atmosphere to obtain Ti@TiO. 2-x Materials; or by electrochemically reducing a section of material to obtain Ti@TiO. 2-x Material;

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

[0028] Step 3: Rare and precious metal loading

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

[0030] This invention innovatively employs temperature-controlled voltage-switching electrochemical oxidation at specific temperatures and times, followed by gas-switching heat treatment or a single-stage calcination-electrochemical reduction treatment to obtain Ti@TiO. 2-x The material is then loaded with rare and precious metals to prepare the material with the special physicochemical properties mentioned above, which can meet the requirements of gas photocatalysis and exhibit excellent gas purification efficiency and stability.

[0031] In this invention, there are no special requirements for the electrolyte in the temperature-controlled and voltage-switching electrochemical oxidation (electrochemical oxidation) process. For example, it can be a mixed solution including fluorine-containing inorganic salts and water-containing solvents.

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

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

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

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

[0036] In this invention, the temperature-controlled voltage-switching electrochemical oxidation process controls the voltage-switching electrochemical oxidation mechanism, temperature, and processing time, which facilitates the construction of physicochemical structures such as active sites adapted to gas photocatalysis, thereby improving gas purification effect and stability.

[0037] In this invention, the temperature of the temperature-controlled voltage-variable electrochemical oxidation process is 0~8℃; more specifically, it can be 0~5℃.

[0038] In step 1, before high-pressure oxidation, the titanium mesh can be pre-activated in an electrolyte at a low-pressure level of 5-20V (or further, 10-15V). In this invention, the low-high-low three-stage transformer treatment helps to further optimize the titanium mesh structure and Ti@TiO₂. 2-x The physical structure helps to further improve the air purification effect of the obtained material.

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

[0040] Preferably, after low-pressure pre-activation, ultrasonic treatment is performed in an acid solution, followed by a subsequent high-pressure oxidation process. In this invention, the low-high-low three-stage variable pressure treatment, combined with ultrasonic treatment in an acid solution, helps to further optimize the titanium mesh structure and Ti@TiO₂. 2-x The physical structure helps to further improve the air purification effect of the obtained material.

[0041] In this invention, the acid solution can be any inorganic acid, for example, hydrochloric acid with a concentration of 0.1~5M, and more specifically, hydrochloric acid with a concentration of 1~3M.

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

[0043] In this invention, the voltage for the high-pressure oxidation process is 45~55V.

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

[0045] In this invention, the voltage for the low-pressure oxidation process is 10~15V.

[0046] In this invention, the low-pressure oxidation process can take 3 to 15 minutes; more specifically, it can take 10 to 15 minutes.

[0047] An optional Ti@TiO2 of the present invention 2-x Material preparation scheme (Scheme A): The electrochemical oxidation material under the special parameters is subjected to the two-stage gas-changing heat treatment, and further combined with the joint control of temperature, which helps to further construct the active sites and other physicochemical structures adapted to gas photocatalysis, which is beneficial to improve the gas purification effect and stability.

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

[0049] In this invention, the partial pressure of oxygen 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 this invention, the temperature of the first stage of heat treatment can be 350~650℃.

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

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

[0053] In this invention, the partial pressure of hydrogen 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 this invention, the temperature of the second heat treatment stage can be 450~550℃.

[0055] The heat treatment holding time for the second stage is 0.5 to 3 hours, and can be further extended to 1 to 2 hours.

[0056] Another preparation of Ti@TiO in this invention 2-x Material Scheme (Scheme B): The electrochemical oxidation material from 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 in Scheme A); then the first-stage material is subjected to 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 solution for electrochemical reduction is an aqueous solution of a C1-C6 organic acid, and the current density for electrochemical reduction is 1-15 mA / cm². 2The electrochemical reduction time is 1~10 min.

[0058] Organic acids of C1 to C6 can be, for example, at least one of formic acid and acetic acid.

[0059] The concentration of organic acids in aqueous solutions can be 1 to 30 wt.

[0060] In this invention, conventional methods can be used to process the Ti@TiO₂. 2-x Loading rare and precious metal nanoparticles onto materials, for example, as an alternative approach, using a liquid-phase reduction method on Ti@TiO₂. 2-x Loading rare and precious metal nanoparticles onto the material involves the following steps: loading Ti@TiO₂... 2-x The precursor materials, including the Ti@TiO3 nanoparticles, are mixed in a liquid phase, followed by reduction treatment with a reducing agent. 2-x Rare and precious metal nanoparticles were deposited on the material by reduction to obtain the aforementioned rare and precious metal / Ti@TiO. 2-x Self-supporting gas purification material.

[0061] The precursor material is a water-soluble compound of rare and precious metal nanoparticles; for example, it can be at least one of nitrates, chlorides, acetates, etc.

[0062] The reducing agent is a component capable of reducing the precursor to a zero-valent state, such as sodium borohydride, ascorbic acid, and its salts. Its dosage is 1 to 5 times the theoretical reaction amount required to reduce the precursor to a zero-valent state.

[0063] This invention also provides a rare and precious metal / Ti@TiO 2-x The application of self-supporting gas purification materials, using them as photocatalysts for the catalytic degradation of pollutants in polluted gases, includes the rare and precious metal / Ti@TiO₂. 2-x The self-supporting gas purification material is the rare and precious metal / Ti@TiO described in this invention. 2-x Self-supporting gas purification material.

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

[0065] This invention also provides an air purifier, comprising or prepared from a purification active material; the rare and precious metal / Ti@TiO 2-x The self-supporting gas purification material is the rare and precious metal / Ti@TiO described in this invention. 2-x Self-supporting gas purification material.

[0066] Beneficial effects

[0067] 1) This invention develops a novel self-supporting gas purification material, which is based on Ti@TiO 2-x Using a carrier and loading rare and precious metals, the performance of this material in photocatalytic removal of VOCs from the air and elimination of pathogenic microorganisms was significantly improved through synergistic regulation of its components and microstructure. This material exhibits advantages such as high efficiency, low cost, no pollution, and long production cycle.

[0068] 2) This invention discloses a rare and precious metal / Ti@TiO 2-x A method for preparing self-supporting gas purification materials. This multi-step synthesis strategy effectively solves the key technical bottlenecks in material construction, enabling the three-dimensional curved structure of flexible titanium mesh to exhibit uniform current density distribution during electrochemical treatment, thereby forming hollow tubular titanium dioxide nanotubes with uniform surface and specific crystal orientation, and exhibiting very tight interfacial bonding. This method can prepare anatase Ti@TiO3-rich materials with highly ordered vertical arrangement of oxygen vacancies. 2-x The support, with its high dispersion and well-ordered crystal structure, provides a good platform for subsequent surface modification. After loading rare and precious metals, it forms a suitable substrate for TiO₂. 2-x The surface is uniformly dispersed, resulting in a low rate of shedding due to airflow erosion. Experimental results show that this composite material exhibits superior performance in photocatalytic degradation of VOCs and inactivation of pathogenic microorganisms, with significantly improved purification and disinfection efficiency compared to traditional materials. From an industrial application perspective, the preparation process is mild, with easily controllable parameters, making large-scale production feasible and possessing broad prospects for engineering transformation. Attached Figure Description

[0069] Figure 1 The palladium-supported anatase phase Ti@TiO prepared in Example 1 is shown. 2-x Image of self-supporting material.

[0070] Figure 2 Silver-loaded anatase phase Ti@TiO prepared in Example 4A 2-x Image of self-supporting material.

[0071] Figure 3 Image of the material prepared for Comparative Example 7.

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

[0073] Figure 5 The UV-Vis absorption spectra of the materials prepared in Example 1, Comparative Example 9, Comparative Example 7 and Example 4B are shown.

[0074] Figure 6 Comparison of IPCE values ​​for materials prepared in Comparative Example 9, Comparative Example 7, and Example 4B. Detailed Implementation

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

[0076] Unless otherwise specified, the reagents used in the following examples are commercially available reagents purchased directly from the market.

[0077] This invention provides a Ti@TiO based on rare and precious metals. 2-x Self-supporting gas purification materials include high-purity self-supporting titanium mesh substrates and hollow tubular anatase TiO₂ phases loaded on the titanium mesh with oxygen-rich vacancies. 2-x and uniform loading on Ti@TiO 2-x Rare and precious metal nanoparticles in the material;

[0078] Hollow tubular anatase phase TiO 2-x Vertical load is applied to a high-purity self-supporting titanium mesh substrate;

[0079] Rare and precious metal nanoparticles 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, with a particle size of 10~50nm.

[0081] Titanium mesh substrate, hollow tubular TiO 2-x There are clear heterogeneous interfaces among the three: rare and precious metal nanoparticles;

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

[0083] This invention proposes a material synthesis strategy that combines integrated support-catalyst design, energy level matching between oxygen vacancies and rare and precious metals, and anti-fouling interface design, and develops a rare and precious metal-supported Ti@TiO₂. 2-x Self-supporting gas purification material. The self-supporting material described in this invention has made a breakthrough in solving technical bottlenecks such as carrier failure, low light utilization, and precious metal agglomeration in photocatalytic air purification materials.

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

[0085] The air purification material of this invention, in Ti@TiO3 rich in O vacancies 2-xSelf-supported gas purification materials loaded with rare and precious metal nanomaterials to induce synergistic energy level effects are the core key to efficient and stable photocatalytic removal of VOCs and elimination of pathogenic microorganisms. Based on this, further research was conducted on Ti@TiO₂... 2-x The performance of the material can be further improved by optimizing and controlling the size of the self-supporting structure and the composition and content of rare and precious metal nanoparticles.

[0086] In this invention, the rare and precious metal-supported Ti@TiO 2-x In self-supporting gas purification materials, the metal content can be further set at 0.05~0.5 Wt.%. Studies have shown that at this optimal content, not only is there an excellent proportion of rare and precious metals, but it can also synergize with the O-vacancy induced energy level, adapting to the reaction characteristics of photocatalytic removal of VOCs and elimination of pathogenic microorganisms in the air, and has the advantages of high efficiency, low cost, no pollution, and long cycle.

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

[0088] The present invention also aims to provide the aforementioned rare and precious metal-supported Ti@TiO. 2-x In the preparation method of self-supporting gas purification materials, 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 TiO2 surface. 2-x Nanotubes, but with insufficient interfacial bonding, are prone to detachment; furthermore, rare and precious metals in TiO2... 2-x The surface is prone to migration and aggregation, and the shedding rate is high due to airflow erosion. To address the problems faced in the preparation of this novel material, this invention provides an optional rare and precious metal-supported Ti@TiO₂. 2-x The preparation method of self-supporting gas purification material includes the following steps:

[0089] Step 1:

[0090] Ti@TiO2 precursor materials were prepared using an electrochemical treatment process: Titanium mesh was electrochemically oxidized, with the system temperature T1 controlled to be less than 10℃ during the oxidation process. The first electrochemical treatment lasted for H1 hours with an oxidation voltage of U1, forming a Ti@TiO2 induced layer. Subsequently, ultrasonic exfoliation was performed in HCl solution to expose the "induced pits." A second electrochemical treatment lasted for H2 hours with an oxidation voltage of U2, forming a Ti@TiO2 growth layer. A third electrochemical treatment lasted for H3 hours with an oxidation voltage of U3, forming the Ti@TiO2 precursor layer.

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

[0092] In the electrochemical oxidation process, 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 (water mass fraction of 2~3 wt.%). In the electrochemical reduction process, the electrolyte is an aqueous solution of 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 was vertically immersed in a solution containing a certain concentration of rare and precious metals. Adsorption was carried out in the dark for 4 hours at a stirring speed of R1. Subsequently, a reducing agent solution of a certain concentration was added to the reaction system, and the reaction was continued at a stirring speed of R2 for 5 hours. The rare and precious metal-supported Ti@TiO₂ was then formed. 2-x Self-supporting gas purification material.

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

[0096] In this 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 (with a water mass fraction of 2~3 Wt.%).

[0097] The electrolyte is an aqueous solution containing fluorine-containing inorganic salts, wherein the fluorine-containing inorganic salts include 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-pressure pre-activation) is 5~20V, the voltage of the second electrochemical oxidation process is 40~60V (high-pressure oxidation process), and the voltage of the third electrochemical oxidation process is 5~20V (low-pressure oxidation process).

[0100] The first electrochemical oxidation period lasts 3-15 minutes; the second electrochemical oxidation period lasts 1-4 hours; and the third electrochemical oxidation period lasts 3-15 minutes.

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

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

[0103] The temperature T3 of the second stage heat treatment is 400~650℃, or more specifically 450~550℃, with an atmosphere of 1~10% H2 / Ar mixed gas, a holding time of 0.5~3h, and a heating rate of 1~3℃ / min; or more specifically 480~520℃.

[0104] The electrochemical reduction solution is an aqueous solution of C1-C6 organic acids, and the current density for electrochemical reduction is 1-15 mA / cm². 2 The electrochemical reduction time is 1~10 min.

[0105] The preferred preparation method of this invention innovatively employs temperature-controlled pressure-switching electrochemical oxidation and gas-switching heat treatment. Temperature-controlled pressure-switching electrochemical oxidation first creates regular "induced pits" on the surface of a titanium mesh, and then 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 a highly ordered nanotube array. Then, a highly ordered long nanotube array is grown on the pretreated titanium surface. Finally, the grown nanotubes undergo "fine trimming," thinning the barrier layer, repairing the top morphology, and releasing internal stress: this helps release the internal stress in the nanotube array, enhancing its mechanical stability and adhesion to the substrate. This facilitates the preparation of highly ordered, large-area uniform TiO2 nanotube arrays that are firmly bonded to the substrate. Furthermore, this preparation method innovatively uses a two-stage gas-switching process to introduce O vacancies, allowing titanium and oxygen atoms to fully arrange themselves, forming a complete, high-quality crystal structure, while avoiding contamination caused by template agents or other organic residues in the precursor. In addition, the two-stage gas-changing treatment avoids the direct treatment of H2 / Ar to generate deep-level defects that become recombination centers for electron-hole pairs, and also avoids TiO2 being reduced to low-valence titanium oxides such as Ti2O3, thus ensuring that the basic semiconductor properties of the material are not destroyed.

[0106] In this invention, under the aforementioned synthesis conditions, the desired O-vacancy-rich anatase phase Ti@TiO can be successfully obtained. 2-x Self-supporting materials facilitate integration with subsequent processes, thereby enabling high dispersion and stable loading of rare and precious metals, and facilitating the preparation of materials with the structure required by this invention.

[0107] In this invention, the rare and precious metal raw materials include, but are not limited to, at least one of the following: sulfates of Pt, Ag, Pd, Ce, copper nitrate, and copper acetate.

[0108] The concentration of metal ions in the rare and precious 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 this invention, anatase phase Ti@TiO rich in O vacancies is pre-filled with... 2-x The self-supporting material is vertically immersed in a solution containing a certain concentration of rare and precious metals to ensure the stability of Ti@TiO₂. 2-x The self-supporting material surface exhibits uniform and saturated adsorption of metal ions. The stirring speed R1 is 500~800 rpm, the adsorption time T4 is 8~16 h, and light must be avoided during adsorption.

[0112] In this invention, when adding the reducing agent to the reaction system where adsorption has been completed in the dark, it must be added slowly drop by drop at a rate of 8-12 mL / min. The amount of reducing agent used is 40-60 mL, the stirring speed R2 during reduction is 600-1000 rpm, and the reduction time T5 is 20-50 min.

[0113] In this invention, under the aforementioned reduction conditions, Ti@TiO in the O-vacancy-rich anatase phase can be synthesized. 2-x Rare and precious metal quantum dots are stably anchored on self-supporting materials.

[0114] This facilitates the construction of physicochemical structures suitable for photocatalytic removal of VOCs from the air and elimination of pathogenic microorganisms, and makes it easier to prepare materials that combine high activity, long lifespan, and low cost.

[0115] The present invention also provides a rare and precious metal-supported Ti@TiO. 2-x The self-supporting gas purification material is used as an air purification material for photocatalytic removal of VOCs and elimination of pathogenic microorganisms in the air.

[0116] In the applications described in this invention, besides Ti@TiO supported by the aforementioned rare and precious metals... 2-x Apart from self-supporting gas purification materials, other application methods are all well-known.

[0117] This solution also discloses a rare and precious metal-supported Ti@TiO₂. 2-x The self-supporting gas purification material module includes air purification material, ultraviolet light, and an air circulator. It can be obtained either directly using the self-supporting gas purification material prepared by the process described in this invention, or through secondary processing based on the preparation method provided in this technical solution. This device achieves photocatalytic removal of VOCs and elimination of pathogenic microorganisms from the air through a photocatalytic mechanism.

[0118] Example 1

[0119] Step 1: Temperature-controlled electrochemical oxidation

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

[0121] Ti@TiO2 precursor materials were prepared using an electrochemical process: a high-purity titanium mesh was used as the electrochemical anode, and a high-purity titanium sheet was used as the electrochemical cathode (with consistent electrode area). An ethylene glycol solution containing ammonium fluoride (0.25 wt% ammonium fluoride and 2 wt% water) was used as the electrolyte. Electrochemical treatment was carried out in a double-layered quartz glass reactor with circulating cooling water. The temperature of the solution system was controlled at 4–8 °C (labeled T1) during the electrochemical treatment. The first stage of electrochemical oxidation was performed at a voltage of 10 V for 5 min. After oxidation, the material was ultrasonically exfoliated in 1.5 M HCl for 15 min, washed three times each with water and ethanol, and then dried at 60 °C to obtain the induced layer. A second stage of electrochemical oxidation was then performed at a voltage of 50 V for 3.5 h to obtain the growth layer. Finally, a third stage of electrochemical oxidation was performed at a voltage of 10 V for 5 min to obtain the Ti@TiO2 precursor layer.

[0122] Step 2: Gasification Treatment

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

[0124] Step 3: Pd load

[0125] The Ti@TiO2 obtained in step 1 2-x The self-supported material was vertically immersed in a 0.01 M palladium chloroacetate solution and adsorbed in the dark for 12 hours with stirring at 700 rpm. Subsequently, a 0.1 M sodium borohydride solution (totaling 50 mL, the amount of reducing agent being 1.5 to 2 times the theoretical amount to reduce the noble metal to zero valence) was added dropwise to the reaction system at a rate of 10 mL / min. The reaction was continued with stirring at 800 rpm for 30 min, finally obtaining Pd-supported Ti@TiO. 2-x Self-supporting gas purification material (Pd loading is 0.05 wt.%).

[0126] Electrochemical detection

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

[0128] Ti@TiO supported by rare and precious metals 2-x Module assembly of self-supporting gas purification materials:

[0129] Two parallel 18cm×18cm rare and precious metal-loaded Ti@TiO₂ 2-x The self-supporting gas purification material is vertically fixed to a plastic bracket, with a 10cm gap between them, and a 19W ultraviolet disinfection lamp is placed between them. The device is then placed inside a 19cm x 19cm plastic ventilation duct, with an air circulation fan placed on one side. This completes the assembly of the rare and precious metal-loaded Ti@TiO₂. 2-x The module is a self-supporting gas purification material. Air enters the duct via a circulating fan, flows through the self-supporting gas purification material, and is then exhausted from the other side. The catalytic performance of the material is evaluated by testing the concentration of pathogenic microorganisms or VOCs in the room after a certain period of time. The initial concentration of pathogenic microorganisms is 1.5 × 10⁻⁶. 7 cfu / mL, VOCs concentration is 500 ppb.

[0130] Example 2

[0131] Compared to Example 1, the only difference is that the conditions in step 1 are changed, and the experimental groups are as follows:

[0132] Group A: The first stage of electrochemical oxidation treatment is not performed. The second and third stages of electrochemical oxidation treatment are performed directly. The time of the third stage of electrochemical oxidation is extended to 10 min. Other operations and parameters are the same as in Example 1.

[0133] Group B: After the first electrochemical treatment, ultrasonic stripping is not performed; subsequent electrochemical treatment is performed directly. All other operations and parameters are the same as in Example 1.

[0134] Group C: The voltage of the first electrochemical treatment was 15V, the time was 8min, and the ultrasonic treatment time after treatment was 20min; the voltage of the second stage was 45V, the treatment time was 3h; the voltage of the third electrochemical oxidation process was 15V, and the time was adjusted to 10min; 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. The Ti@TiO2 precursor layer of step 1 is preheated to temperature T2 (650°C) in air at a heating rate of 2°C / min and heat-treated at this temperature for 1 hour. Then the atmosphere is switched to 10% H2 / Ar mixed gas and heat-treated at temperature T3 (450°C) for 1.5 hours.

[0137] Example 4

[0138] Compared to Example 1, the only difference is that the conditions in step 3 are changed, and the experimental groups are as follows:

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

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

[0141] Example 5

[0142] Compared to Example 1, the only difference is that the conditions of step 2 are changed. Specifically, after the first heat treatment, the material is cooled in the furnace, and then electrochemical reduction is used to reduce the material after the first heat treatment to prepare the Ti@TiO. 2-x Materials. During electrochemical reduction, the reduction time was 5 minutes, and the reduction current density was 5 mA / cm². 2 The electrolyte in the electrochemical reduction process is a 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 in the electrochemical oxidation process is controlled at 25~30℃, and all 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 second electrochemical oxidation process takes 5.5 hours, while the other operations and parameters are the same as in Example 1.

[0147] Comparative Example 3

[0148] Compared with Example 1, the only difference is that in step 2, only a single-stage hydrogen atmosphere treatment is performed. The difference is that the atmosphere during the temperature rise T2 and the heat preservation process is a 5v%H2 / Ar mixed atmosphere. All other operations and parameters are the same as in Example 1.

[0149] Comparative Example 4

[0150] Compared with Example 1, the only difference is that in step 2, only a single-stage oxygen-containing atmosphere treatment is performed. The difference is that the atmosphere during the temperature rise T3 and the heat preservation process is air. All other operations and parameters are the same as in Example 1.

[0151] Comparative Example 5

[0152] Compared with Example 1, the only difference is that in step 2, the temperature of both T2 and T3 is 350°C, while the other operations and parameters are the same as in Example 1.

[0153] Comparative Example 6

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

[0155] Comparative Example 7

[0156] Compared to Example 1, the only difference is that step 3 is not performed.

[0157] Comparative Example 8

[0158] The only difference from Example 1 is that commercial TiO2 air purification materials were used for testing.

[0159] Comparative Example 9

[0160] Compared with Example 1, the only difference is that step 3 is not performed, and in step 2, temperature T3 is not processed. All other operations and parameters are the same as in Example 1.

[0161] Comparative Example 10

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

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

[0164] Table 1. Staphylococcus aureus disinfect efficiency (1h) and toluene and formaldehyde removal efficiency (1.5h) of each catalyst

[0165]

[0166] In summary, as demonstrated in Examples 1-5 and Comparative Examples 1-10, the material synthesis strategy combining integrated support-catalyst design, energy level matching between oxygen vacancies and rare and precious metals, and anti-fouling interface design helps solve problems in photocatalytic materials such as support failure, low light utilization, and precious metal agglomeration. The developed rare and precious metal-supported O-vacancy-rich Ti@TiO₂... 2-x The self-supporting gas purification material can improve its catalytic activity and stability in photocatalytic removal of VOCs from the air and elimination of pathogenic microorganisms.

[0167] Furthermore, as can be seen from Examples 1 and 2, the preferred three-stage temperature and pressure controlled electrochemical oxidation described in this invention, combined with ultrasonic treatment after the first stage of oxidation, can enhance the gas purification effect of the obtained material.

[0168] As can be seen from Examples 1, 3 and 4, the gas-changing treatment and precious metal loading described in this invention can enhance the gas purification effect of the obtained material.

[0169] As can be seen from Examples 1 and 5, by using the two-stage gas-changing treatment described in this invention, or the single-stage heat treatment followed by electrochemical reduction treatment, and further combined with other processes, materials with excellent air purification effects can be obtained.

[0170] The specific embodiments of the present invention have been described above. 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 should be included within the protection scope of the present invention.

Claims

1. A rare / noble metal / Ti@TiO 2-x Process for the preparation of a self-supporting gas purification material, characterized in that the steps The method comprises the following steps: Step 1: temperature-controlled variable-voltage electrochemical oxidation The titanium mesh is subjected to temperature-controlled variable-voltage electrochemical oxidation, which comprises a high-voltage oxidation process at a voltage of 40-60 V and a subsequent low-voltage oxidation process at a voltage of 5-20 V; before the high-voltage oxidation, a low-voltage pre-activation process at a voltage of 5-20 V is further included; wherein the time of the low-voltage pre-activation is 3-15 min; wherein the temperature of the system during the variable-voltage electrochemical oxidation process is controlled to be below 10℃, and the time of the high-voltage oxidation process is 1-4 h; the electrolyte of the temperature-controlled variable-voltage 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 C1-C4 alcohol, acetone and THF; the fluorine-containing inorganic salt comprises 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.%; After the low-voltage pre-activation, ultrasonic treatment is performed in an acid solution, and then a subsequent high-voltage oxidation process is performed; Step 2: Ti@TiO 2-x Material preparation The electrochemical oxidation material of step 1 is subjected to a first heat treatment in an oxygen-containing atmosphere to obtain a first-stage material; the first-stage material is subjected to a second heat treatment in a hydrogen-containing atmosphere to obtain Ti@TiO 2-x material; or the first-stage material is subjected to an electrochemical reduction treatment to obtain Ti@TiO 2-x material. The temperature of the first-stage heat treatment is 300-700℃, and the temperature of the second-stage heat treatment is 400-650℃; Step 3: rare and precious metal loading Ti@TiO prepared in step 2 2-x The material is a carrier, and rare and precious metal nanoparticles are loaded on the surface of the carrier to prepare the rare and precious metal / Ti@TiO 2-x Self-supporting gas purification material The rare and precious metal nanoparticles are nanoparticles comprising at least one of Pt, Ag, Pd and Ce, or Pd and Cu.

2. The precious metal / Ti@TiO 2-x Process for the preparation of a self-supporting gas purification material, characterized in that, The time of the high-voltage oxidation process is 2.5-3.5 h, and the time of the subsequent low-voltage oxidation process is 3-15 min.

3. The precious metal / Ti@TiO 2-x Process for the preparation of a self-supporting gas purification material, characterized in that, In step 2, the oxygen-containing atmosphere is at least one of air, oxygen, oxygen-dilution gas mixed gas and air-dilution gas mixed gas; the dilution gas is at least one of nitrogen and noble gas; The holding time of the first-stage heat treatment is 1-3 h; The hydrogen-containing atmosphere is hydrogen or hydrogen-dilution gas mixed gas; The holding time of the second-stage heat treatment is 0.5-3 h; In the electrochemical reduction: the solution for electrochemical reduction is C1~C6 organic acid aqueous solution, the current density for electrochemical reduction is 1~15mA / cm 2 ; the electrochemical reduction time is 1~10min; In step 3, the Ti@TiO 2-x The rare and precious metal nanoparticles are loaded on the material by the following steps: the Ti@TiO 2-x The rare and precious metal nanoparticles are loaded on the material by the following steps: the Ti@TiO 2-x The rare and precious metal nanoparticles are loaded on the material by the following steps: the Ti@TiO 2-x Self-supporting gas purification material The precursor raw material is a water-soluble compound of the rare and precious metal nanoparticles; The reducing agent is a component capable of reducing the precursor raw material to 0 valence state; the amount thereof is 1-5 times the theoretical reaction amount for reducing the precursor raw material to 0 valence state.

4. A rare / noble metal / Ti@TiO 2-x The use of a self-supporting gas purification material as a photocatalyst for the catalytic degradation of pollutants in polluted gases, characterized in that, The rare and noble metal / Ti@TiO 2-x The self-supporting gas purification material is a rare and noble metal / Ti@TiO 2-x The self-supporting gas purification material.

5. The precious metal / Ti@TiO of claim 4 2-x Use of a self-supporting gas purification material, characterized in that The contaminated gas is contaminated air; wherein the contaminants include at least one of volatile organic compounds and microorganisms.

6. An air cleaner comprising or prepared by a purification active material; characterized in that, The rare and noble metal / Ti@TiO 2-x The self-supporting gas purification material is a rare and noble metal / Ti@TiO 2-x The self-supporting gas purification material.

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