Ag quantum dot modified hydrophobic film wrapped cluster-like TiO2, and preparation method and application thereof

Abstract

The application discloses a kind of Ag quantum dot modified hydrophobic film wrapped cluster TiO2 and its preparation method and application, the preparation method of the application includes: one, silver is deposited on titanium dioxide by high vacuum resistance evaporation;Two, solid particles are washed with ethanol and distilled water by centrifugation and dry;Three, immerse in hydrophobic polydimethylsiloxane solution;Four, curing is carried out in oven;Five, solid particles are washed with ethanol and distilled water by centrifugation and dry.Ag quantum dot modified hydrophobic film wrapped cluster TiO2 of the application can degrade volatile organic pollutants in airtight container, and can be used in the field of photocatalytic degradation of volatile organic pollutants.Ag quantum dot modified hydrophobic film wrapped cluster TiO2 of the application can effectively degrade a variety of volatile organic pollutants, wherein the removal rate of toluene can reach 100%, and the mineralization rate is 83%.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials, and mainly relates to a clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film, its preparation method and application. Background Technology

[0002] Volatile organic pollutants (VOCs) are increasing through various sources, including industrial operations, volatilization from plastics and paint products, and the dismantling of electronic waste, exacerbating air pollution problems. Meanwhile, long-term human exposure to VOCs poses a serious threat to human health, such as birth defects, respiratory symptoms, and, in extreme cases, cancer. Therefore, developing efficient and feasible VOC removal technologies is crucial. Various methods are employed for VOC treatment, including physical adsorption, chemical absorption, catalytic oxidation, and biological treatment. Among these methods, photocatalytic degradation technology is considered a clean, mild, and effective removal method. Photocatalytic degradation technology is an effective environmental remediation strategy because it is non-toxic, resistant to photocorrosion, operates under mild conditions, and produces non-toxic and clean final products. Its main principles are as follows:

[0003] TiO2 + hv → h + +e - (1)

[0004] h + +H₂O→H + +OH - (2)

[0005] h + +OH - →OH · (3)

[0006] e - +O2→O2 ·- (4)

[0007] O2 ·- +Organic pollutants → Non-toxic products +CO2↑ (5)

[0008] OH · +Organic pollutants → Non-toxic products +CO2↑ (6)

[0009] In short, the photocatalytic process can be summarized in four steps: 1) absorption of incident ultraviolet or visible light, followed by the generation of e-rays. - / h + Yes; 2) adsorption of volatile organic compounds; 3) redox reactions; and 4) decomposition of volatile organic pollutants. Throughout the process, the decisive steps are the interaction of electrons and holes (e- and hole-). - -h +) charge separation and the promotion of electrons from the valence band to the conduction band. Titanium dioxide is a well-known photocatalyst, which has been widely used in many environmental protection fields due to its photocatalytic and chemical stability, non-toxicity and low cost. However, the wide band gap and the unfavorable photogenerated electron-hole pair recombination of titanium dioxide seriously hinder its practical application in photocatalytic treatment of volatile organic pollutants. In addition, another thorny problem is that titanium dioxide is easily deactivated and is inherently hydrophilic. SUMMARY

[0010] In view of the technical problems of the wide band gap and the unfavorable photogenerated electron-hole pair recombination of titanium dioxide in the prior art and easy deactivation, the purpose of the present application is to provide a Ag quantum dot modified hydrophobic film wrapped cluster-like TiO2, a preparation method and application thereof.

[0011] The technical scheme adopted by the present application is as follows:

[0012] A preparation method of Ag quantum dot modified hydrophobic film wrapped cluster-like TiO2, comprising the following steps:

[0013] 1) Synthesis of Ag-TiO2 by high vacuum evaporation deposition method:

[0014] P25 powder is weighed and stirred and dispersed in ethanol, then uniformly applied on the ultrasonically cleaned glass slide, and TiO2 is formed on the glass slide after natural air drying. High-purity silver is added to a molybdenum boat, and the molybdenum boat and the glass slide are placed in a vacuum chamber, respectively. The glass slide is close to the vacuum port of the vacuum chamber, and the vacuum chamber is evacuated until the high vacuum level is reached. The high-purity silver in the molybdenum boat is evaporated into gas atoms by resistance heating, and the gas atoms condense on the surface of TiO2 on the glass slide to form Ag quantum dots;

[0015] 2) The solid product obtained in step 1) is scraped off from the glass slide, and then washed with ethanol and double distilled water by centrifugation, respectively, to obtain Ag-TiO2;

[0016] 3) The Ag-TiO2 obtained in step 2) is added to chloroform, and then polydimethylsiloxane (PDMS, Aldrich, CAS No.: 70131-67-8) is added. The mixture is heated and stirred under a rotary evaporator until the solvent is evaporated to dryness;

[0017] 4) The solid particles obtained in step 3) are subjected to solidification treatment in an oven, and then washed with ethanol and double distilled water by centrifugation, respectively, and dried in a vacuum oven, i.e. the preparation is completed.

[0018] Further, in step 1), the purity of high-purity silver is more than 99.9%, and the pressure reaches (0.5-5) x 10 -4Pa controls the high vacuum resistance deposition time to control the silver content in titanium dioxide. The amount of Ag deposited on TiO2 is 1-10% of the mass of TiO2, preferably 5-7%.

[0019] Further, in step 3), the dispersion concentration of Ag-TiO2 in chloroform is 0.1-0.5 g / mL, preferably 0.2-0.3 g / mL, the mass of polydimethylsiloxane is 1-50% of the mass of TiO2, preferably 1-10%, the rotation speed of the rotary evaporator is 100-200 rpm, and the heating temperature is 50-60℃.

[0020] Furthermore, in step 4), the curing temperature is 80-95℃ and the curing time is 1-2 hours.

[0021] This invention also provides the application of the aforementioned Ag quantum dot-modified hydrophobic film-encapsulated clustered TiO2 in the photocatalytic degradation of volatile organic pollutants. The light source for the photocatalytic degradation is a 200-400W mercury lamp, and the photocatalytic degradation of volatile organic pollutants is carried out under conditions of 50-100% relative humidity and room temperature. The volatile organic pollutants are one or more of acetaldehyde, toluene, benzene, and chlorobenzene.

[0022] This invention focuses on the modification of titanium dioxide. By modifying titanium dioxide with noble metals, electrons in the conduction band can be effectively separated into metal nanoparticles, which helps to prevent electrons from being drawn into the metal nanoparticles. - and h + Therefore, by depositing titanium dioxide together with noble metals such as silver nanoparticles, the photocatalytic performance of titanium dioxide is improved, aiming to reduce the band gap energy by acting in an effective electron trap and effectively mitigate electron-hole recombination.

[0023] Furthermore, the reaction interface microenvironment and catalytic performance can be affected by catalyst wettability. Therefore, hydrophobic surfaces are obtained through modification with polydimethylsiloxane (PDS), a low-surface-energy material. PDS possesses low surface energy, strong adhesion, non-toxicity, low cost, and excellent chemical and thermal stability. With decreasing surface energy, PDS exhibits remarkable properties, including maintaining the optical transparency of the catalytic surface and forming a waterproof barrier. The significant adsorption affinity of PDS can promote degradation by concentrating contaminants onto the catalytic surface. PDS-modified titanium dioxide exhibits good hydrophobicity and self-cleaning ability while ensuring the original photocatalytic performance of titanium dioxide. Loading with silver and PDS allows titanium dioxide to exhibit a synergistic effect of hydrophobicity and photocatalytic performance, extending its service life and improving recyclability and regenerability.

[0024] This invention has the following outstanding features and beneficial effects:

[0025] (1) The present invention reduces the band gap energy by the effect of silver deposition in an effective electron trap and effectively mitigates electron-hole recombination.

[0026] (2) Compared with unmodified titanium dioxide, the photocatalytic degradation rate of silver-loaded titanium dioxide is significantly improved.

[0027] (3) In this invention, titanium dioxide is modified with polydimethylsiloxane, which gives it good hydrophobicity and self-cleaning ability, while ensuring photocatalytic performance.

[0028] (4) The present invention also demonstrates the synergistic effect of hydrophobicity and photocatalytic performance to extend the service life of photocatalytic degradation of volatile organic pollutants and improve recyclability and regenerability.

[0029] The Ag quantum dot-modified hydrophobic film-encapsulated clustered TiO2 of the present invention can be used in the field of photocatalytic degradation of volatile organic pollutants. Attached Figure Description

[0030] Figure 1 Comparison of scanning electron microscope (SEM) images of P25 powder raw material, 5-Ag-TiO2 product, TiO2 / PDMS-10 product and 5-Ag-TiO2 / PDMS-10 product in Example 1 (sub-image a: P25, sub-image b: 5-Ag-TiO2, sub-image c: TiO2 / PDMS-10, sub-image d: 5-Ag-TiO2 / PDMS-10);

[0031] Figure 2 The image shown is a transmission electron microscope (TEM) image of 5-Ag-TiO2 / PDMS-10 from Example 1.

[0032] Figure 3 The graph shows the photocatalytic degradation rate of toluene for the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10 in Example 4, and the five materials with different silver loadings obtained in Example 2.

[0033] Figure 4 The graph shows the photocatalytic degradation rate of toluene mineralization of the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10 in Example 4, and the five materials with different silver loadings obtained in Example 2.

[0034] Figure 5 The graph shows the photocatalytic degradation rate of toluene by the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10 in Example 4, and the four materials with different PDMS loadings obtained in Example 3.

[0035] Figure 6The graph shows the photocatalytic degradation rate of toluene mineralization of the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10 in Example 4, and the four materials with different PDMS loadings obtained in Example 3.

[0036] Figure 7 This is a cyclic rate diagram of the photocatalytic degradation of toluene using P25, 5-Ag-TiO2, TiO2 / PDMS-10, and 5-Ag-TiO2 / PDMS-10 for five cycles, respectively, in Example 5.

[0037] Figure 8 This is a mineralization rate diagram from Example 5, showing the photocatalytic degradation of toluene in cyclic experiments involving five cycles of P25, 5-Ag-TiO2, TiO2 / PDMS-10, and 5-Ag-TiO2 / PDMS-10.

[0038] Figure 9 The graph shows the reaction rate of toluene degradation by the hydrophobic silver-loaded titanium dioxide photocatalyst 5-Ag-TiO2 / PDMS-10 obtained in Example 1 under different relative humidities.

[0039] Figure 10 The graph shows the reaction mineralization rate of the hydrophobic silver-loaded titanium dioxide photocatalyst 5-Ag-TiO2 / PDMS-10 under different relative humidities during the photocatalytic degradation of toluene.

[0040] Figure 11 The reaction rate diagram of the photocatalytic degradation of different volatile organic pollutants by the hydrophobic silver-loaded titanium dioxide photocatalyst 5-Ag-TiO2 / PDMS-10 obtained in Example 1 is shown.

[0041] Figure 12 The graph shows the reaction mineralization rate of the hydrophobic silver-loaded titanium dioxide photocatalyst 5-Ag-TiO2 / PDMS-10 obtained in Example 1, which degrades different volatile organic pollutants.

[0042] Figure 13 The graph shows the photocatalytic degradation rate of toluene by clustered TiO2 coated with different hydrophobic films modified with Ag quantum dots in Example 8.

[0043] Figure 14 The graph shows the mineralization rate of toluene in the photocatalytic degradation of clustered TiO2 encapsulated by different hydrophobic films modified with Ag quantum dots in Example 8. Detailed Implementation

[0044] The beneficial effects of the present invention are verified using the following examples:

[0045] Example 1:

[0046] I. Synthesis of Ag-TiO2 using a high-vacuum evaporation deposition method

[0047] Weigh 1g of P25 powder and pour it into ethanol. Stir at 700rpm magnetically for 10 minutes and then sonicate for 30 minutes to disperse it evenly. Spread the evenly dispersed mixture evenly onto a glass slide that has been ultrasonically cleaned. After allowing it to air dry, place it in a vacuum chamber. Simultaneously, place a molybdenum boat with high-purity silver (99.9% purity) inside the vacuum chamber. The glass slide is placed closer to the vacuum vent of the vacuum chamber than the molybdenum boat.

[0048] Turn on the vacuum pump to reduce the air pressure inside the vacuum chamber to a high vacuum level, reaching 1.33 × 10⁻⁶. -4 Pa, the molybdenum ship is heated by resistance, and the high-purity silver (99.9%) in the molybdenum ship evaporates into gas atoms through resistance heating. The gas atoms pass through and condense on the TiO2 surface on the glass slide to form Ag quantum dots. After the required time is reached, the resistance heating is turned off to stop the evaporation process. High-purity nitrogen gas is slowly introduced into the vacuum chamber to restore the pressure to normal. The vacuum chamber door is then opened, and the deposited sample is taken out.

[0049] The deposition quality of Ag on TiO2 was controlled by changing the deposition time. The deposition quality of Ag was determined by measuring the change in mass before and after deposition using a microbalance. The solid product on the glass slide was scraped off and collected.

[0050] 2. The solid product obtained in step 1 was washed three times by centrifugation with ethanol and double-distilled water at 10,000 rpm, and then dried in a vacuum drying oven at 60°C for 24 h to obtain a TiO2 product with Ag deposited on it, which was labeled as Ag-TiO2.

[0051] III. Obtaining the hydrophobic layer using the impregnation method. The Ag-TiO2 (1.0 g) obtained in step II was added to 5 mL of chloroform, followed by a certain amount of polydimethylsiloxane (PDMS, Aladdin, CAS No.: 70131-67-8). The mixture was heated and stirred in a rotary evaporator at 60 °C and 100 rpm until evaporated to dryness. The mass of the loaded PDMS was calculated using the volume of PDMS added and its density (0.97 g / mL).

[0052] IV. The obtained solid particles were cured in an oven at 90°C for 1 hour.

[0053] 5. The obtained solid particles were centrifuged three times at 10,000 rpm with ethanol and double-distilled water, respectively, and dried in a vacuum oven at 60°C for 24 hours. Finally, the target product, Ag quantum dot-modified hydrophobic film-encapsulated clustered TiO2, was obtained. The product was named x-Ag-TiO2 / PDMS-y, where x represents the mass percentage of Ag deposition on TiO2 relative to the mass of TiO2 (%), and y represents the mass percentage of PDMS feed relative to the mass of TiO2 (%). That is, x and y represent the mass percentages of Ag and PDMS relative to TiO2, respectively.

[0054] For example, 5-Ag-TiO2 / PDMS-10 means that the amount of Ag deposited on TiO2 is 5% of the mass of TiO2; the mass of PDMS fed is 10% of the mass of TiO2 product, and so on.

[0055] Experiment 1: Following the preparation method of Example 1, the deposition quality of Ag on TiO2 was controlled by changing the deposition time in step one. When the deposition amount of Ag on TiO2 was controlled to be 5% of the mass of TiO2, the 5-Ag-TiO2 product was obtained by centrifugation, washing, and drying in step two. Steps three to five were omitted.

[0056] Experiment 2: Following the preparation method of Example 1, no high-purity silver was added to the molybdenum ship in step one, i.e., the Ag deposition process was omitted. Then, in step three, the amount of PDMS was controlled so that the mass of PDMS was 10% of the mass of TiO2 product. After passing through step four (curing), step five (centrifugation and washing), and drying, TiO2 / PDMS-10 product was obtained.

[0057] Experiment 3: Following the preparation method of Example 1, in step one, the deposition quality of Ag on TiO2 was controlled by changing the deposition time, and the deposition amount of Ag on TiO2 was controlled to be 5% of the mass of TiO2. In step two, the product was washed by centrifugation and dried. Then, in step three, the amount of PDMS was controlled so that the mass of PDMS was 10% of the mass of TiO2 product. After curing in step four and washing by centrifugation and drying in step five, the 5-Ag-TiO2 / PDMS-10 product was obtained.

[0058] The comparison results of scanning electron microscope (SEM) images of the above-mentioned P25 powder raw material, 5-Ag-TiO2 product, TiO2 / PDMS-10 product, and 5-Ag-TiO2 / PDMS-10 product are summarized in the following table. Figure 1 See in the middle, respectively Figure 1 The results are shown in sub-images a, b, c, and d. Transmission electron micrographs of the 5-Ag-TiO2 / PDMS-10 product are shown below. Figure 2 .

[0059] from Figure 1 It can be observed that, compared with (a) P25 and (b) 5-Ag-TiO2, (c) TiO2 / PDMS-10 and (d) 5-Ag-TiO2 / PDMS-10, PDMS loading results in more uniform dispersion of TiO2 particles and the formation of a thin film surrounding them. The formation of this film demonstrates the successful loading of PDMS, thereby improving the lifespan and renewability of titanium dioxide photocatalysis. Figure 2 As can be seen from the figure, the black particles are evenly distributed, indicating that Ag quantum dots were successfully and uniformly loaded onto the TiO2 surface. The uniform loading of silver nanoparticles can effectively reduce electron-hole recombination and improve the photocatalytic effect of titanium dioxide. The successful loading of PDMS and silver has a synergistic promoting effect on the photocatalytic degradation of volatile organic pollutants by titanium dioxide.

[0060] Example 2:

[0061] The difference between Example 2 and Example 1 is that in step one, the silver content in titanium dioxide is controlled by adjusting the high-vacuum resistance deposition time. Other conditions are the same as in Experiment 3 of Example 1. 1-Ag-TiO2 / PDMS-10, 3-Ag-TiO2 / PDMS-10, and 5-Ag-TiO2 / PDMS-10 were prepared.

[0062] Five materials with different silver loadings, including 7-Ag-TiO2 / PDMS-10 and 10-Ag-TiO2 / PDMS-10.

[0063] Example 3:

[0064] The difference between Example 3 and Example 1 is that in step three, different amounts of polydimethylsiloxane were added to control the polydimethylsiloxane content in titanium dioxide. Other conditions were the same as in Experiment 3 of Example 1. Four materials with different PDMS loadings were prepared: 5-Ag-TiO2 / PDMS-1, 5-Ag-TiO2 / PDMS-10, 5-Ag-TiO2 / PDMS-30, and 5-Ag-TiO2 / PDMS-50.

[0065] Example 4: The hydrophobic silver-loaded titanium dioxide photocatalysts prepared in Examples 1, 2, and 3, as well as P25, 5-Ag-TiO2, and TiO2 / PDMS-10 controls, were subjected to the following experiments:

[0066] The photocatalytic degradation of toluene was carried out in a closed optical reactor (effective volume 276 mL), covered by a quartz glass window with a diameter of 6.5 cm. A 300 W mercury lamp, placed vertically 20 cm above the reactor, served as the light source. The photoreaction temperature was maintained at 25 ± 0.2 °C using a cooling water jacket circulation system. Before illumination, 50 mg of photocatalyst was uniformly dispersed on a 3.5 cm diameter glass fiber located at the center of the reactor. After sealing, high-purity air with a relative humidity (RH) of 50% was introduced into the reactor and ventilated for 30 minutes to ensure the required concentration was reached. Subsequently, toluene was injected into the reactor to achieve a concentration of 800 ppm. After adsorption under dark conditions for 60 minutes to reach adsorption-desorption equilibrium, the mercury lamp was turned on. Gas samples were taken at preset time points and monitored by gas chromatography with a flame ionization detector. The yield of CO2 generated during the photocatalytic process was analyzed using gas chromatography equipped with a thermal conductivity detector. Mineralization rate = C CO2 / (n×C0)×100%, where C CO2 The molar concentration of carbon dioxide produced is represented by , n represents the number of carbon atoms in the pollutant molecule, and C0 represents the initial molar concentration of the pollutant.

[0067] The photocatalytic degradation rate and photocatalytic degradation mineralization rate of toluene for the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10, and the five materials with different silver loadings obtained in Example 2 are shown in the figure. Figure 3 and Figure 4 As shown. By Figure 3 and 4 It can be seen that with the increase of silver loading, the C / C0 (i.e., the ratio of the remaining toluene concentration to the initial concentration) in the dark state gradually decreases, indicating that the toluene adsorption gradually increases due to the increase of Ag loading. During the photocatalytic degradation process, the degradation rate of Ag-TiO2 / PDMS is significantly higher than that of P25, Ag-TiO2, and TiO2 / PDMS, and its degradation effect is also superior to the other three, as can be seen from the C / C0 ratio. Among Ag-TiO2 / PDMS with different silver loadings, we can observe that its degradation rate first increases and then decreases with increasing loading. Among them, 5-Ag-TiO2 / PDMS-10 exhibits the best degradation effect, indicating that a suitable specific surface area and a larger pore size are beneficial for promoting photocatalytic degradation.

[0068] The photocatalytic degradation rate and mineralization rate of toluene for the original sample P25, 5-Ag-TiO2, TiO2 / PDMS-10, and four materials with different PDMS loadings obtained in Example 3 are shown in the figure below. Figure 5 and Figure 6 As shown. By Figure 5 and 6It can be seen that among materials with different PDMS loadings, the degradation effect of the material first increases and then decreases as the PDMS loading increases. Furthermore, when the PDMS loading exceeds 30 wt%, its degradation effect is even worse than that of P25, indicating that excessive PDMS will lead to a significant reduction in the active sites on the material surface, thus affecting its degradation effect.

[0069] Example 5:

[0070] To better illustrate the reusability of the photocatalytic degradation of Ag-TiO2 / PDMS materials, we conducted a cycle test to demonstrate their usable lifetime. Following the steps in Example 4, we performed five cycles of photocatalytic degradation of toluene on P25, 5-Ag-TiO2, TiO2 / PDMS-10, and 5-Ag-TiO2 / PDMS-10 respectively. The experimental results are shown in [Figure 4]. Figure 7 and Figure 8 As shown.

[0071] Depend on Figure 7 and 8 It can be seen that the removal rate of toluene by 5-Ag-TiO2 / PDMS-10 remained almost unchanged after 5 cycles. Although 5-Ag-TiO2 showed good degradation performance in the first cycle, its degradation effect gradually deteriorated with each cycle. While TiO2 / PDMS did not degrade as effectively as Ag-TiO2, it maintained a relatively stable effect after 5 cycles. Therefore, this indicates that Ag loading can improve the degradation effect of TiO2, and PDMS loading can extend the lifespan of TiO2.

[0072] Example 6:

[0073] The hydrophobic silver-loaded titanium dioxide photocatalyst material 5-Ag-TiO2 / PDMS-10 obtained in Example 1 was subjected to photocatalytic degradation experiments of toluene under five different relative humidity conditions (RH 0%, 25%, 50%, 75%, and 100%). The photocatalytic experimental procedures were repeated in Example 4. The experimental results are shown in [Figure 4]. Figure 9-10 As shown.

[0074] Depend on Figure 9 and 10 It can be seen that humidity has little effect on the degradation of 5-Ag-TiO2 / PDMS-10, indicating that the PDMS loading makes the material hydrophobic, which is beneficial for TiO2 to maintain a good degradation effect under high humidity conditions. The fact that the removal rate was less than 100% at RH=0% may be due to the lack of hydroxyl radicals.

[0075] Example 7:

[0076] The hydrophobic silver-loaded titanium dioxide photocatalyst 5-Ag-TiO2 / PDMS-10 obtained in Example 1 was used to degrade different volatile organic pollutants (toluene, chlorobenzene, acetaldehyde, or benzene) according to the photocatalytic degradation method in Example 4. Figure 11 and 12 It is evident that the hydrophobic silver-loaded titanium dioxide photocatalyst has a significant effect on volatile organic compounds (VOCs). 5-Ag-TiO2 / PDMS-10 can completely remove toluene and acetaldehyde, achieving a mineralization rate of over 80%. However, some residues remain after the degradation of chlorobenzene and benzene, with a mineralization rate of around 70%. The photocatalytic degradation efficiency of these four VOCs, from highest to lowest, is acetaldehyde, toluene, benzene, and chlorobenzene.

[0077] Example 8:

[0078] In Experiment 3 of Example 1, PDMS was replaced with an equal mass of polytetrafluoroethylene (PTFE, Aladdin, CAS No.: 9002-84-0) or octaphenyl-POSS (Aladdin, CAS No.: 5256-79-1), with all other conditions remaining unchanged. The final products were labeled Ag-TiO2-PTFE and Ag-TiO2-POSS, respectively. The 5-Ag-TiO2 / PDMS-10 product from Experiment 3 of Example 1 was abbreviated as Ag-TiO2 / PDMS.

[0079] The Ag-TiO2-PTFE, Ag-TiO2-POSS, and Ag-TiO2 / PDMS were subjected to photocatalytic degradation of toluene according to the photocatalytic degradation method in Example 4. The experimental results are shown in [Figure 4]. Figure 13-Figure 14 As shown. By Figure 13 and 14 It is evident that the photocatalytic effect of PDMS-loaded materials is superior to that of PTFE-loaded materials and octaphenyl POSS-loaded materials, with PTFE showing the worst performance. This is because the bonding between PTFE and TiO2 may not be as tight as the other two materials, as PTFE itself is inert and does not readily form chemical bonds with TiO2. Octaphenyl POSS, on the other hand, can potentially bind to the TiO2 surface through covalent or non-covalent interactions, thereby enhancing its stability and resulting in a relatively better performance. PDMS is a material with good hydrophobic properties, and its flexibility and good adhesion make it easy to load onto the TiO2 surface. PDMS can provide a certain degree of protection, preventing contaminants from adhering to the TiO2 surface while maintaining and enhancing its photocatalytic activity. PDMS also has good transparency, which facilitates light penetration and thus improves photocatalytic efficiency.

Claims

1. A method for preparing clustered TiO2 encapsulated by an Ag quantum dot-modified hydrophobic film, characterized in that... Includes the following steps: 1) Synthesis of Ag-TiO2 via high-vacuum evaporation deposition: Weigh out P25 powder and pour it into ethanol. Stir and disperse evenly, then spread it evenly on an ultrasonically cleaned glass slide. After air drying, TiO2 will form on the glass slide. Add high-purity silver to a molybdenum boat. Place the molybdenum boat and the glass slide into a vacuum chamber, with the glass slide close to the vacuum port of the vacuum chamber. Evacuate the vacuum chamber until a high vacuum level is reached. Evacuate the high-purity silver in the molybdenum boat into gas atoms by resistance heating. The gas atoms condense on the TiO2 surface of the glass slide to form Ag quantum dots. 2) Scrape the solid product obtained in step 1) off the glass slide, and then wash it by centrifugation with ethanol and double-distilled water respectively to obtain Ag-TiO2; 3) Add the Ag-TiO2 obtained in step 2) to chloroform, followed by polydimethylsiloxane. Heat and stir the mixture in a rotary evaporator until the solvent evaporates to dryness. 4) The solid particles obtained in step 3) are cured in an oven, then washed by centrifugation with ethanol and double-distilled water respectively, and dried in a vacuum oven to complete the preparation.

2. The method for preparing clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film as described in claim 1, characterized in that... In step 1), the purity of the high-purity silver is above 99.9%, and the vacuum is applied to achieve a pressure of (0.5-5)×10⁻⁶. -4 Pa, controlling the high vacuum resistance deposition time to control the silver content in titanium dioxide, the amount of Ag deposited on TiO2 is 5-7% of the mass of TiO2.

3. The method for preparing clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film as described in claim 1, characterized in that... In step 3), the dispersion concentration of Ag-TiO2 in chloroform is 0.1-0.5 g / mL, the mass of polydimethylsiloxane is 1-50% of the mass of TiO2, the rotation speed of the rotary evaporator is 100-200 rpm, and the heating temperature is 50-60℃.

4. The method for preparing clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film as described in claim 2, characterized in that... In step 3), the dispersion concentration of Ag-TiO2 in chloroform is 0.2-0.3 g / mL, and the mass of polydimethylsiloxane is 1-10% of the mass of TiO2.

5. The method for preparing clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film as described in claim 1, characterized in that... In step 4), the curing temperature is 80-95℃ and the curing time is 1-2 hours.

6. A clustered TiO2 coated with an Ag quantum dot-modified hydrophobic film, prepared by any one of claims 1-4.

7. The application of the Ag quantum dot-modified hydrophobic film-encapsulated clustered TiO2 as described in claim 5 in the photocatalytic degradation of volatile organic pollutants.

8. The application as described in claim 7, characterized in that... The light source for photocatalytic degradation is a 200-400W mercury lamp. The photocatalytic degradation of volatile organic pollutants is carried out under conditions of relative humidity of 50-100% and room temperature.

9. The application as described in claim 7, characterized in that... The volatile organic pollutants are one or more of acetaldehyde, toluene, benzene, and chlorobenzene.

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