A photocatalytic material, a preparation method therefor and an application thereof

Abstract

The application relates to a kind of photocatalytic materials and its preparation method and application, including (1) titanium salt solution and precipitant are mixed under stirring to pH is 2-3, then ultrasonic treatment is carried out, TiO2 Nanoparticle is obtained after drying, vacuum calcination;(2) the mixture is prepared by dispersing TiO2 Nanoparticle in anhydrous ethanol, active carbon fiber is treated in silane reagent, then is immersed in the mixture, after taking out, drying, calcination, photocatalytic material is obtained.The photocatalytic material prepared by the application has stable catalytic interface, and can maintain good catalytic effect and long-term use stability when used for high humidity VOCs gas treatment.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment technology, specifically relating to a photocatalytic material, its preparation method, and its application. Background Technology

[0002] Volatile organic compounds (VOCs) are among the major pollutants in the atmosphere, characterized by their wide range of sources, high volatility, and easy diffusion. Currently, technologies for treating and controlling VOC-containing gases fall into two main categories: destruction methods and recovery methods. Destruction methods include catalytic oxidation, biodegradation, and photocatalysis, while recovery methods include adsorption, absorption, condensation, and membrane treatment technologies. Although these methods each have their advantages, most are energy-intensive, require stringent operating conditions, or generate large amounts of waste requiring further treatment. Photocatalytic oxidation, as a mild and clean advanced oxidation technology, can utilize solar energy to degrade VOCs into CO2, offering advantages such as high treatment efficiency and low operating costs, making it suitable for the removal of most VOCs. However, in the treatment of VOC gases with high humidity, the catalytic efficiency of the target pollutant often decreases due to water vapor occupying most of the adsorption sites, especially with long-term operation at relative humidity above 50%. Therefore, suitable photocatalytic materials are crucial for solving this technical problem in the treatment of high-humidity VOC gases.

[0003] CN110180520A discloses a method for preparing recyclable mesoporous carbon@TiO2 / carbon fiber (CFs) photocatalytic material, comprising the following steps: (1) dissolving ethylene glycol in acetone to obtain solution A; (2) adding mesoporous carbon spheres to solution A and ultrasonically dispersing them uniformly to obtain suspension B; (3) adding tetrabutyl titanate to suspension B and ultrasonically dispersing them uniformly to obtain suspension C; (4) transferring suspension C to a high-pressure reactor and immersing carbon fibers in suspension C, and the reactants undergo a solvothermal reaction under magnetic stirring to generate solvothermal product D; (5) ultrasonically washing and drying solvothermal product D to obtain mesoporous carbon@TiO2 / carbon fiber photocatalytic material. This invention prepares photocatalytic materials through solvothermal reaction, solving the problem of separation and recovery of powdered photocatalysts in actual use. However, the photocatalytic material prepared by this method does not consider the influence of high humidity environment on the application effect. Since water vapor occupies most of the adsorption sites on the catalyst surface, the effect will decay after long-term use.

[0004] The literature "Preparation of TiO2 Visible Photocatalyst by Vacuum Activation Method and Study on its Long-Term Effect" (Wu Sanding et al., Journal of Zhejiang Sci-Tech University, Vol. 35, No. 6, November 2016) uses commercial TiO2 (Degussa P25) as raw material and prepares TiO2 visible photocatalysts by a simple one-step vacuum activation method. 3+A self-doped TiO2 visible-light catalyst was used. Methyl orange was used as a simulated target pollutant, and its catalytic performance and long-term effectiveness were investigated under visible light. Results showed that, under visible light irradiation, vacuum-activated P25 significantly improved the degradation efficiency of methyl orange compared to pure P25. Cyclic testing results indicated that the efficiency of TiO2 in degrading methyl orange was significantly higher than that of pure P25. 3+ It is relatively reactive and easily oxidized. This catalyst is designed to degrade the pollutant methyl orange, and it requires repeated regeneration via vacuum activation, resulting in relatively high energy consumption.

[0005] The literature "Highly Efficient Photocatalytic Oxidation of Formaldehyde by Oxygen-Vacant TiO2 and Its Reaction Pathway" (Li Yuhan et al., Science Communications, 2022, Vol. 65, No. 8: 718-728) describes the preparation of titanium dioxide (TiO2) with abundant surface oxygen vacancies using a one-step calcination method, and its application to the treatment of formaldehyde, a typical air pollutant. The results show that in a fluidized bed test environment, the maximum effective removal rate of formaldehyde can reach 95.05%, which is 1.31 times higher than the baseline sample (72.52%). The study indicates that oxygen-vacant TiO2 not only enhances the light absorption range but also utilizes oxygen vacancies to capture photogenerated electrons, effectively inhibiting the recombination of photogenerated electrons and holes, thereby improving photocatalytic activity. Real-time dynamic monitoring of the formaldehyde degradation reaction process by the catalyst was performed using in-situ infrared spectroscopy. Combined with density functional theory (DFT) calculations, it was shown that oxygen vacancies on the TiO2 surface can effectively enhance the adsorption and activation of formaldehyde molecules. The large number of delocalized electrons present can be injected into the C=O bonds in the formaldehyde molecules and activate and break them, thereby effectively reducing the accumulation of formic acid during formaldehyde oxidation and accelerating the efficient oxidation and removal of formaldehyde. However, this method does not consider the issue of material performance degradation under high humidity environments, and its long-term stability, in particular, needs improvement. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a photocatalytic material, its preparation method, and its applications. The photocatalytic material prepared by this invention possesses a stable catalytic interface and maintains good catalytic performance and long-term stability when used for treating high-humidity VOCs gases.

[0007] The present invention provides a method for preparing a photocatalytic material, comprising the following steps:

[0008] (1) The titanium salt solution and the precipitant were mixed under stirring until the pH was 2-3, then subjected to ultrasonic treatment, and then dried and calcined under vacuum to obtain TiO2 nanoparticles;

[0009] (2) TiO2 nanoparticles were dispersed in anhydrous ethanol to obtain a mixture. Activated carbon fibers (ACFs) were treated in silane reagent and then immersed in the mixture. After being removed, dried and calcined, the photocatalytic material was obtained.

[0010] In this invention, the titanium salt mentioned in step (1) is at least one of TiCl4, TiOSO4, and TiSO4, and the concentration of the titanium salt solution is 0.1-1.0 mol / L. Preferably, the titanium salt solution is filtered using a microfiltration membrane with a pore diameter of 0.10 μm-0.20 μm.

[0011] In this invention, the precipitant in step (1) is at least one of urea solution, NH4OH solution, etc., with a solution concentration of 0.01-0.05 mol / L.

[0012] In this invention, the stirring in step (1) can be carried out by various conventional stirring methods to mix the two evenly, preferably by magnetic stirring, and the stirring time is 12-36h.

[0013] In this invention, the power of the ultrasonic treatment in step (1) is 200-600W, preferably 300-400W, and the treatment time is 10-100min, preferably 20-60min.

[0014] In this invention, the drying temperature in step (1) is 80-200℃ and the drying time is 4-12h.

[0015] In this invention, the vacuum calcination temperature in step (1) is 300-600℃, the vacuum degree is 0.135-0.0135Pa, and the calcination time is 2-4h. Further, the heating rate is preferably 1-4℃ / min.

[0016] In this invention, the mass-to-volume ratio of TiO2 nanoparticles to anhydrous ethanol in step (2) is 1 mg:(0.5-1) mL.

[0017] In this invention, the activated carbon fiber in step (2) is at least one of polypropylene-based carbon fiber, viscose-based carbon fiber, pitch-based carbon fiber, etc., preferably pitch-based carbon fiber.

[0018] In this invention, the silane mentioned in step (2) is at least one of n-octyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluorooctyltrimethoxysilane, and trichlorooctadecylsilane, preferably heptadecafluorodecyltrimethoxysilane. The concentration of the silane reagent is 0.1-2.0 mol / L, preferably 0.25-1.0 mol / L. The specific method for preparing the silane reagent is as follows: dissolve ethylenediamine hydrochloride in Tris-HCl solution to obtain a buffer solution of 3-5 g / L, and then dissolve the silane in the buffer solution to prepare a silane reagent with a concentration of 0.1-2.0 mol / L.

[0019] In this invention, step (2) involves placing activated carbon fibers (ACFs) in a silane reagent and treating them under stirring conditions for 6-30 hours.

[0020] In this invention, the immersion treatment in the mixture in step (2) takes 2-16 hours, preferably 4-10 hours.

[0021] In this invention, after step (2), the product is dried at a temperature of 60-100℃ for 3-10 hours.

[0022] In this invention, the calcination temperature in step (2) is 300-850℃, preferably 500-800℃; the calcination time is 4-20h, preferably 8-18h. The calcination is carried out in an inert atmosphere, and the carrier gas is any one of N2, Ar, He, etc.

[0023] The photocatalytic material described in this invention is prepared using the method described above. The prepared photocatalytic material consists of oxygen-vacant TiO2 nanoparticles immobilized on a silane-treated activated carbon fiber substrate, exhibiting a stable catalytic interface.

[0024] This invention also provides the application of the above-mentioned photocatalytic material for the photocatalytic treatment of high-humidity VOCs gas, which has good catalytic effect and long-term stability.

[0025] In the application of this invention, the high humidity refers to the humidity of VOCs gas not less than 50% under normal temperature and pressure, preferably 60%-80%.

[0026] In the application of this invention, VOCs refer to organic compounds with a boiling point of less than or equal to 250°C at normal pressure and a vapor pressure of more than 0.5 kPa at 25°C, preferably at least one of toluene, acetone, etc.

[0027] In the application of this invention, the photocatalytic conditions are: the wavelength of the light source is 420-750nm and the power is 400-600W.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The inventors of this application discovered in their research that existing photocatalytic materials are not effective in treating VOCs gases in high humidity conditions. In particular, some materials, although they can maintain good performance during initial use, show a significant decline in performance after long-term use. To address this, the inventors of this application prepared a photocatalytic material for treating VOCs gases in high humidity by immobilizing TiO2 nanoparticles containing oxygen vacancies onto ACFs treated with silane reagents. This not only effectively avoids the adverse effects of high humidity on the photocatalytic material, but also maintains a good catalytic effect and exhibits good long-term stability.

[0030] (2) TiO2 nanoparticles and activated carbon fibers are bonded by C-Ti bonds, and Ti in TiO2 +4 When activated carbon fibers are reduced to Ti +2 This not only expands the response wavelength range of photocatalytic materials, enhances their visible light sensing effect and interfacial charge transfer, and improves VOCs catalytic effect; but also, in particular, improves the stability of catalysts for long-term use in high humidity environments. Attached Figure Description

[0031] Figure 1 The image shows the X-ray photoelectron spectrum of the material prepared in Example 1 of this invention. Detailed Implementation

[0032] The photocatalytic material, its preparation method, and application effects of the present invention are further illustrated below with specific embodiments. These embodiments are carried out based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0034] Example 1

[0035] Dissolve 119g of TiSO4 in 1L of deionized water and stir until dissolved. Filter the solution through a 0.20μm microfiltration membrane to obtain a 0.5mol / L TiSO4 solution.

[0036] A 0.05 mol / L NH4OH solution was prepared by dissolving 0.08 g of NH4OH in 50 mL of water.

[0037] TiSO4 solution and NH4OH solution were mixed with stirring until the pH reached 2.5, and then magnetically stirred for 24 h. The mixture was then ultrasonically treated at 300 W for 25 min, and then dried at 80 °C for 10 h. The mixture was then placed in an alumina magnetic boat and then placed in a vacuum tube furnace. The mixture was calcined at 450 °C for 2 h under a vacuum of 0.1 Pa and a heating rate of 2 °C / min to obtain TiO2 nanoparticles containing oxygen vacancies.

[0038] A buffer solution was prepared by dissolving 0.2 g of ethylenediamine hydrochloride in 50 mL of Tris-HCl solution. A 1.0 mol / L silane reagent was prepared by dissolving n-octyltrimethoxysilane in the buffer solution. Pitch-based ACFs were then immersed in the silane reagent and stirred at room temperature for 25 h to obtain silane-treated activated carbon fibers.

[0039] 20 mg of the prepared TiO2 nanoparticles were dispersed in 15 mL of anhydrous ethanol to obtain a mixture. Activated carbon fibers treated with silane reagent were impregnated in the mixture for 7.5 h. After removal, the mixture was placed in an oven at 75 °C for 8.5 h and then calcined in a tube furnace at 650 °C under N2 atmosphere for 9 h to obtain the photocatalytic material. Figure 1 The full-range XPS spectra of TiO2 / ACFs were shown, revealing distinct C1s, Ti2p, and O1s characteristic peaks. Figure 1 The small peak centered at 487.5 eV corresponds to the Ti2p3 / 2 state, indicating that Ti... +2 The presence of [a specific substance] is suggested. The strong absorption peak at 284.6 eV indicates that after the formation of the C-Ti bond, electrons around the Ti atoms delocalized on the carbon fiber surface, enhancing the electronegativity of the carbon atoms, thereby promoting charge transfer at the interface and improving photocatalytic activity and stability.

[0040] Example 2

[0041] Dissolve 189g of TiCl4 in 1L of deionized water and stir until dissolved. Filter the solution through a 0.2μm microfiltration membrane to obtain a 1.0mol / L TiCl4 solution.

[0042] A 0.04 mol / L urea solution was prepared by dissolving 0.12 g of urea in 50 mL of water.

[0043] TiCl4 solution and urea solution were mixed with stirring until the pH reached 2.0, and then magnetically stirred for 30 h. The mixture was then ultrasonically treated at 300 W for 30 min, and dried at 100 °C for 8 h. The mixture was then placed in an alumina magnetic boat and then placed in a vacuum tube furnace. The mixture was calcined at 350 °C for 4 h under a vacuum of 0.1 Pa and a heating rate of 2.5 °C / min to obtain TiO2 nanoparticles containing oxygen vacancies.

[0044] A buffer solution was prepared by dissolving 0.2 g of ethylenediamine hydrochloride in 50 mL of Tris-HCl solution. Then, 0.25 mol / L of silane reagent was prepared by dissolving n-octyltrimethoxysilane in the buffer solution. Pitch-based ACFs were immersed in the silane reagent and stirred at room temperature for 10 h to obtain silane-treated activated carbon fibers.

[0045] 20 mg of the prepared TiO2 nanoparticles were dispersed in 20 mL of anhydrous ethanol to prepare a mixture. Activated carbon fibers treated with silane reagent were immersed in the mixture for 5 h. After removal, the mixture was placed in an oven at 75 °C for 8 h and then calcined in a tube furnace at 700 °C under N2 atmosphere for 8.5 h to obtain the photocatalytic material.

[0046] Example 3

[0047] Dissolve 32g of TiOSO4 in 1L of deionized water and stir until dissolved. Filter the solution through a 0.2μm microfiltration membrane to obtain a 0.2mol / L TiOSO4 solution.

[0048] A 0.03 mol / L urea solution was prepared by dissolving 0.09 g of urea in 50 mL of water.

[0049] TiOSO4 solution and urea solution were mixed with stirring until the pH reached 3.0, and then magnetically stirred for 18 hours. The mixture was then ultrasonically treated at 350 W for 45 minutes, and dried at 120 °C for 6 hours. The mixture was then placed in an alumina magnetic boat and then placed in a vacuum tube furnace. The furnace was calcined at 600 °C under a vacuum of 0.1 Pa for 2 hours with a heating rate of 2.5 °C / min to obtain TiO2 nanoparticles containing oxygen vacancies.

[0050] A buffer solution was prepared by dissolving 0.2% ethylenediamine hydrochloride in 50 mL of Tris-HCl solution. Then, 3.0 mol / L silane reagent was prepared by dissolving n-octyltrimethoxysilane in the buffer solution. Pitch-based ACFs were immersed in the silane reagent and stirred at room temperature for 20 h to obtain silane-treated activated carbon fibers.

[0051] 20 mg of the prepared TiO2 nanoparticles were dispersed in 10 mL of anhydrous ethanol to prepare a mixture. Activated carbon fibers treated with silane reagent were immersed in the mixture for 6 h. After removal, the mixture was placed in an oven at 85 °C for 7 h and then calcined in a tube furnace at 350 °C under N2 atmosphere for 14 h to obtain the photocatalytic material.

[0052] Example 4

[0053] Same as Example 1, except that silane was replaced with heptadecafluorodecyltrimethoxysilane to obtain the final photocatalytic material.

[0054] Example 5

[0055] Same as Example 1, except that silane was replaced with trifluorooctyltrimethoxy to obtain the final photocatalytic material.

[0056] Example 6

[0057] Same as Example 1, except that silane was replaced with trichlorooctadecylsilane to obtain the final photocatalytic material.

[0058] Example 7

[0059] Same as Example 1, except that: pitch-based carbon fiber is replaced with polypropylene-based carbon fiber to obtain the final photocatalytic material.

[0060] Example 8

[0061] Same as Example 1, except that pitch-based carbon fiber is replaced with viscose-based carbon fiber to obtain the final photocatalytic material.

[0062] Comparative Example 1

[0063] Same as Example 1, except that: the TiO2 nanoparticles were not treated with oxygen-containing vacancy treatment, that is, TiO2 nanoparticles without oxygen vacancies were used to obtain the final photocatalytic material.

[0064] Comparative Example 2

[0065] Same as Example 1, except that step (2) is not performed, and the oxygen-vacant TiO2 nanoparticles obtained in step (1) are directly used as photocatalytic materials.

[0066] Comparative Example 3

[0067] Same as Example 1, except that: step (1) was not subjected to ultrasonic treatment, and the final photocatalytic material was obtained.

[0068] Comparative Example 4

[0069] Same as Example 1, except that: step (1) did not use vacuum calcination, but only high-temperature calcination to obtain the final photocatalytic material.

[0070] Comparative Example 5

[0071] Same as Example 1, except that the activated carbon fibers were not treated with silane reagents to obtain the final photocatalytic material.

[0072] Comparative Example 6

[0073] Similar to Example 1, except that the concentration of the silane reagent was adjusted to 4.0 mol / L to obtain the final photocatalytic material. The results showed that excessive concentration caused shrinkage and agglomeration during sintering, adversely affecting the specific surface area and pore volume of the catalyst, thus reducing the photocatalytic performance of the material.

[0074] Comparative Example 7

[0075] Same as Example 1, except that anhydrous ethanol was replaced with a 75% ethanol solution to obtain the final photocatalytic material.

[0076] Comparative Example 8

[0077] Similar to Example 1, except that: silane reagent is first added to the mixture prepared by dispersing TiO2 nanoparticles in anhydrous ethanol, and then activated carbon fibers are immersed in the mixture to obtain the final photocatalytic material.

[0078] Test Example 1

[0079] The photocatalytic materials prepared in the embodiments and comparative examples of the present invention were used for the treatment of high-humidity VOCs gas: the VOCs in the gas were toluene with a concentration of 1000 mg / m³. 3 The relative humidity is 70%.

[0080] 0.4 g of catalyst was placed in a 50 mL double-layer quartz cold trap photocatalytic purification device. After high humidity VOCs gas was introduced, the sample was irradiated for 1.5 h with a 420 nm wavelength xenon lamp (CEL-HXF300) with a power of 500 W. The CO2 in the system was detected by a gas chromatograph (GC-9790plus, Fuli). The CO2 generation rate is shown in Table 1.

[0081] Table 1. Test results of different embodiments and comparative examples

[0082]

[0083]

[0084] Test Example 2

[0085] The photocatalytic materials prepared in the embodiments and comparative examples of the present invention were used for the treatment of high-humidity VOCs gas: the VOCs in the gas were acetone, with a concentration of 1000 mg / m³. 3 The relative humidity is 60%.

[0086] 0.4 g of catalyst was placed in a 50 mL double-layer quartz cold trap photocatalytic purification device. After high humidity VOCs gas was introduced, the sample was irradiated for 1.5 h with a 600 nm wavelength and 500 W xenon lamp (CEL-HXF300). The CO2 in the system was detected by a gas chromatograph (GC-9790plus, Fuli). The CO2 generation rate is shown in Table 2.

[0087] Table 2. Test results of different embodiments and comparative examples

[0088]

[0089]

[0090] As shown in Tables 1 and 2, the photocatalytic material prepared by this invention has a stable catalytic interface and can maintain good catalytic effect and long-term stability when used for high-humidity VOCs gas treatment. However, the effects are not ideal when any of the technical features of this invention are missing.

Claims

1. A method for producing a photocatalytic material, characterized by The method comprises the following steps: (1) mixing a titanium salt solution and a precipitant under stirring to pH 2-3, and then performing ultrasonic treatment, and then drying and vacuum calcining to obtain TiO2 nanoparticles; the vacuum calcining temperature is 300-600℃, the vacuum degree is 0.135-0.0135 Pa, and the calcining time is 2-4h; the temperature rising speed is 1-4℃ / min; (2) dispersing the TiO2 nanoparticles into anhydrous ethanol to obtain a mixture, treating the activated carbon fiber in a silane reagent, and then immersing the activated carbon fiber in the mixture, and then taking out and drying and calcining to obtain a photocatalytic material; the concentration of the silane reagent is 0.1-2.0mol / L; the calcining temperature is 300-850℃, and the calcining time is 4-20h; the calcining is performed in an inert atmosphere.

2. The method of claim 1, wherein: In step (1), the titanium salt is at least one of TiCl4, TiOSO4 and TiSO4, and the concentration of the titanium salt solution is 0.1-1.0mol / L.

3. The method of claim 2, wherein: In step (1), the titanium salt solution is subjected to filtration treatment, and the filtration is performed by using a microfiltration membrane with a filter hole diameter of 0.10-0.20μm.

4. The method of claim 1, wherein: In step (1), the precipitant is at least one of urea solution and NH4OH solution, and the concentration of the solution is 0.01-0.05mol / L.

5. The method of claim 1, wherein: In step (1), the stirring is performed by using magnetic stirring, and the stirring time is 12-36h.

6. The method of claim 1, wherein: In step (1), the ultrasonic treatment is performed at a power of 200-600W for 10-100min.

7. The method of claim 6, wherein: In step (1), the ultrasonic treatment is performed at a power of 300-400W for 20-60min.

8. The method of claim 1, wherein: In step (1), the drying temperature is 80-200℃, and the drying time is 4-12h.

9. The method of claim 1, wherein: In step (2), the mass / volume ratio of the TiO2 nanoparticles to anhydrous ethanol is 1mg:(0.5-1)mL.

10. The method of claim 1, wherein: In step (2), the activated carbon fiber is at least one of polypropylene-based carbon fiber, viscose-based carbon fiber and pitch-based carbon fiber.

11. The method of claim 10, wherein: In step (2), the activated carbon fiber is pitch-based carbon fiber.

12. The method of claim 1, wherein: In step (2), the silane is at least one of n-octyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluorooctyltrimethoxysilane and trichlorooctadecylsilane.

13. The method of claim 12, wherein: In step (2), the silane is heptadecafluorodecyltrimethoxysilane.

14. The method of claim 1 or 12 or 13, wherein: The concentration of the silane reagent is 0.25-1.0mol / L.

15. The method of claim 1, 12, or 13, wherein: The preparation method of the silane reagent is as follows: dissolving ethylenediamine hydrochloride in Tris-HCl solution to obtain a buffer solution with a concentration of 3-5g / L, and then dissolving the silane in the buffer solution to prepare a silane reagent with a concentration of 0.1-2.0mol / L.

16. The method of claim 1, wherein: In step (2), the activated carbon fiber is treated in the silane reagent under stirring, and the stirring time is 6-30h.

17. The method of claim 1, wherein: In step (2), the immersion in the mixture is performed for 2-16h.

18. The method of claim 17, wherein: The immersion time is 4-10h.

19. The method of claim 1, wherein: In step (2), the taking out is followed by drying, and the drying temperature is 60-100℃, and the drying time is 3-10h.

20. The method of claim 1, wherein: In step (2), the calcining temperature is 500-800℃, and the calcining time is 8-18h.

21. The method of claim 1 or 20, wherein: The carrier gas in the inert atmosphere is any one of N2, Ar and He.

22. A photocatalytic material, characterized by The method is prepared by any one of claims 1-21.

23. Use of a photocatalytic material produced according to the method of any one of claims 1 to 21, characterized in that: The photocatalytic treatment for VOCs gas with high humidity has good catalytic effect and long-term use stability; the high humidity refers to the humidity of VOCs gas being not less than 50% at normal temperature and pressure.

24. The use according to claim 23, characterized in that: The high humidity refers to the humidity of VOCs gas being 60%-80% at normal temperature and pressure.

25. The use according to claim 23, characterized in that: The VOCs refer to organic matters with boiling point less than or equal to 250 DEG C at normal pressure and vapor pressure more than 0.5 kPa at 25 DEG C.

26. The use according to claim 25, characterized in that: The VOCs refer to at least one of toluene and acetone.

27. The use according to claim 23, characterized in that: The photocatalytic condition is that the wavelength of the light source is 420-750 nm and the power is 400-600 W.

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