A method for preparing ferrohydrate / mesocrystalline TiO2 and its application

Abstract

The application discloses a preparation method and application of a ferrihydrite / mesoporous TiO2, and comprises the following steps: dissolving FeCl3*6H2O and NaAc in ethylene glycol, stirring, storing, cooling, and obtaining black precipitate; centrifuging, washing and drying the black precipitate to obtain black nano Fe3O4; adding Fe(NO3)3*9H2O into a reaction container, stirring, adding the black nano Fe3O4, stirring, adding NaOH to adjust pH, stirring, adding distilled water, aging, washing with water, and drying to obtain magnetic ferrihydrite; mixing TiF4, H2O, NH4NO3 and NH4F to prepare a precursor solution, dropping the solution onto a silicon chip, heating and calcining, and keeping warm to obtain powder; calcining the powder in an O2 / Ar atmosphere, grinding to obtain mesoporous TiO2; ultrasonic treating the mesoporous TiO2, adding the magnetic ferrihydrite, adjusting pH, heating, keeping warm, and filtering, washing and drying to obtain ferrihydrite / mesoporous TiO2. The ferrihydrite / mesoporous TiO2 prepared by the preparation method can efficiently degrade volatile organic pollutants (VOCs).

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a method for preparing and applying ferrohydrate / mesocrystalline TiO2. Background Technology

[0002] In modern industry and daily life, the release of volatile organic pollutants (VOCs) has an increasingly significant impact on the environment and human health. VOCs are a class of volatile organic compounds, including solvents, volatile organic chemicals, and fuel combustion products. They can be released into the atmosphere through various activities such as industrial production, vehicle exhaust, paint, printing, and cleaning agents. The emission of these harmful substances has attracted widespread attention because they not only damage the environment but also have adverse effects on human health. Therefore, developing effective VOCs control and purification technologies has become an urgent task for environmental protection and public health.

[0003] Traditional VOCs treatment methods include physical adsorption, chemical adsorption, pyrolysis, and biological treatment. However, these methods have limitations, such as low treatment efficiency, complex equipment, and high operating costs. Therefore, developing efficient, economical, and environmentally friendly VOCs treatment technologies is crucial.

[0004] Photocatalysis is a widely studied and applied method for the degradation of VOCs. In the photocatalytic process, the photocatalyst absorbs light energy and reacts with oxygen or other oxidants to produce reactive oxygen species, such as hydroxyl radicals (·OH) and peroxide anions (·O2). - This process degrades organic pollutants. Among photocatalytic materials such as TiO2, ZnO, WO3, CdS, and ZnS, TiO2 is widely used due to its excellent photocatalytic activity, chemical stability, low cost, and environmental friendliness.

[0005] Ferrous ore (Fh) is a Fe mineral with an average diameter of 2nm-6nm. 3+ Magnetic materials, specifically iron hydroxides, have been widely used in various industrial fields for many years, such as wastewater treatment and pollutant degradation. Due to their extremely large specific surface area and high surface activity, they not only promote the adsorption of VOCs on the surface but also... 3+ It is also considered an "electron sacrificial agent" that can rapidly separate electrons and holes generated by the catalyst. However, even so, there are some limitations in practical applications, such as poor catalyst stability and the generation of reactive oxygen species (such as hydroxyl radicals ·OH and superoxide radicals ·O2). - Insufficient hydrogen peroxide (H2O2, etc.) is insufficient to destroy the molecular structure of organic pollutants and convert them into simpler inorganic or low molecular weight organic compounds.

[0006] Therefore, how to fully utilize the excellent photocatalytic activity, chemical stability, low cost and environmental friendliness of TiO2, as well as solve the problem of poor stability in the catalytic process of ferrous hydrate (Fh), is currently the focus of research. Summary of the Invention

[0007] The main objective of this invention is to propose a method for preparing and applying ferrohydrate / mesocrystalline TiO2, aiming to solve the problems of poor stability in existing ferrohydrate (Fh) catalysis processes and how to fully utilize the photocatalytic material TiO2.

[0008] To achieve the above objectives, this invention proposes a method for preparing ferrohydrate / mesocrystalline TiO2, comprising the following steps:

[0009] Preparation of black nano Fe3O4: FeCl3·6H2O and NaAc were dissolved in ethylene glycol, stirred, stored at 170-190℃ for 5-7 h, cooled, and a black precipitate was obtained. The black precipitate was centrifuged, washed with an organic solvent, and dried to obtain black nano Fe3O4.

[0010] Preparation of magnetic ferromagnetic ore: Add Fe(NO3)3·9H2O to the reaction vessel and stir. Add the black nano Fe3O4 and stir. Add alkaline solution to adjust the pH to 7-8 and stir. Add distilled water, age, wash with water, and dry to obtain magnetic ferromagnetic ore.

[0011] Preparation of mesocrystalline TiO2: TiF4, H2O, NH4NO3 and NH4F are mixed to prepare a precursor solution. The precursor solution is dropped onto a silicon chip to form a thin layer. The precursor solution on the thin layer is heated and calcined, and kept at the temperature to obtain powder. The powder is calcined in an O2 / Ar atmosphere and ground to obtain mesocrystalline TiO2.

[0012] Preparation of ferrohydrate / mesocrystalline TiO2: The mesocrystalline TiO2 was ultrasonically treated, the magnetic ferrohydrate was added, the pH value was adjusted, the mixture was heated, kept warm, filtered, washed, and dried to obtain ferrohydrate / mesocrystalline TiO2.

[0013] Optionally, in the step of preparing black nano Fe3O4, the mass ratio of FeCl3·6H2O to NaAc is 1:2.

[0014] Optionally, in the step of preparing black nano-Fe3O4, drying is performed using a vacuum drying oven; and / or,

[0015] The drying temperature is 50–70°C.

[0016] Optionally, in the step of preparing magnetic ferrophosphate, the aging temperature is 60–70°C; and / or,

[0017] The aging time is 70-74 hours.

[0018] Optionally, in the step of preparing magnetic ferrophosphate, the drying temperature is 65–75°C.

[0019] Optionally, in the step of preparing mesocrystalline TiO2, the molar ratio of TiF4, H2O, NH4NO3 and NH4F is 1:(115-120):(6.5-7.0):(3-5).

[0020] Optionally, in the step of preparing mesocrystalline TiO2, the thickness of the thin layer does not exceed 1 mm.

[0021] Optionally, in the step of preparing mesocrystalline TiO2, the heating rate is 8–12 °C / min. -1 ; and / or,

[0022] The heat preservation time is 1.5h to 2.5h; and / or,

[0023] The calcination temperature in the O2 / Ar atmosphere is 480–520°C; and / or,

[0024] The calcination time in the O2 / Ar atmosphere is 7-9 hours.

[0025] Optionally, in the step of preparing ferrohydrate / mesocrystalline TiO2, the pH value is 6.9–7.1; and / or,

[0026] Water bath heating is used, wherein the temperature of the water bath heating is 75–85°C; and / or,

[0027] The heat preservation time is 2.5h to 3.5h.

[0028] Optionally, the ferroalloy / mesocrystalline TiO2 is prepared by the ferroalloy / mesocrystalline TiO2 preparation method described above.

[0029] The beneficial effects of this invention are as follows:

[0030] The technical solution provided by this invention uses a hydrothermal synthesis method to load prepared magnetic ferrohydrate onto the surface of a mesocrystalline TiO2 (TMC) substrate, forming a stable electron transport channel. TMC is a highly ordered and stable structure composed of TiO2 nanocrystals with a unique edge trap state, i.e., an edge effect, which can effectively achieve exciton dissociation and ultimately realize the spatial separation of photogenerated carriers. Magnetic ferrohydrate is a magnetic material, and its combination with TMC can achieve efficient light absorption and carrier separation, thereby improving the efficiency and stability of the photocatalytic reaction. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The catalyst prepared in Example 1 of this invention is shown in in-situ DRIFTS spectra under darkness and ultraviolet-visible light.

[0033] Figure 2 Here is a SEM image of the catalyst prepared in Example 2 of this invention;

[0034] Figure 3 This is the XRD pattern of the catalyst prepared in Example 3 of this invention;

[0035] Figure 4 This is a performance diagram of the catalyst prepared in Example 1 of the present invention.

[0036] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Given the poor stability of ferrohydrate (Fh) catalysis, this invention proposes a method for preparing ferrohydrate / mesocrystalline TiO2, comprising the following steps:

[0039] S1. Preparation of black nano Fe3O4: FeCl3·6H2O and NaAc are dissolved in ethylene glycol, stirred, stored at 170-190℃ for 5-7 h, cooled, and a black precipitate is obtained. The black precipitate is centrifuged, washed with organic solvent, and dried to obtain black nano Fe3O4.

[0040] In this step, the mass ratio of FeCl3·6H2O to NaAc is 1:2, so that FeCl3·6H2O is fully dissolved in sodium acetate; the black precipitate after washing is dried in a vacuum drying oven; the drying temperature is 50-70℃, preferably 60℃.

[0041] S2. Preparation of magnetic ferromagnetic ore: Add Fe(NO3)3·9H2O to the reaction vessel and stir. Add the black nano Fe3O4 and stir. Add alkaline solution to adjust the pH to 7-8 and stir. Add distilled water, age, wash with water, and dry to obtain magnetic ferromagnetic ore.

[0042] In this step, the alkaline solution is NaOH solution or KOH solution; the aging temperature is 60-70℃, preferably 65℃; the aging time is 70-74h. After aging within this temperature and time range, the nano-Fe3O4 can be fully aged to obtain magnetic ferromagnetic ore; the drying temperature is 65-75℃, preferably 70℃. Drying within this temperature range can dry the moisture on the magnetic ferromagnetic ore without damaging its nanoparticle structure.

[0043] S3. Preparation of mesocrystalline TiO2: TiF4, H2O, NH4NO3 and NH4F are mixed to prepare a precursor solution. The precursor solution is dropped onto a silicon chip to form a thin layer. The precursor solution on the thin layer is heated and calcined, and kept at the temperature to obtain powder. The powder is calcined in an O2 / Ar atmosphere and ground to obtain mesocrystalline TiO2.

[0044] In this step, the molar ratio of TiF4, H2O, NH4NO3, and NH4F is 1:(115-120):

[0045] (6.5~7.0):(3~5), with a preferred molar ratio of 1:117:6.6:4; the thickness of the thin layer does not exceed 1 mm; the heating rate is 8~12℃ min. -1 The heat preservation time is 1.5h to 2.5h; the calcination temperature in the O2 / Ar atmosphere is 480 to 520℃, preferably 500℃; the calcination time in the O2 / Ar atmosphere is 7 to 9h, preferably 8h, to completely remove surface residues, and then the material is thoroughly ground for later use.

[0046] S4. Preparation of ferrohydrate / mesocrystalline TiO2: The mesocrystalline TiO2 is ultrasonically treated, the magnetic ferrohydrate is added, the pH value is adjusted, the mixture is heated, kept warm, filtered, washed, and dried to obtain ferrohydrate / mesocrystalline TiO2.

[0047] In this step, the pH value is 6.9–7.1. After adjusting the pH value, the TMC mixed with magnetic Fh is placed into a high-pressure reactor with a polytetrafluoroethylene liner and heated in a water bath at a temperature of 75–85°C, preferably 80°C. The holding time is 2.5–3.5 h, preferably 3 h. By heating in a water bath within this temperature and time range and holding the temperature, the hydrothermal synthesis reaction can be fully carried out, resulting in a light yellow Fh / TMC powder.

[0048] The photocatalytic activity of TiO2 is related to its phase composition, specific surface area, crystal size, and exposed crystal surface. To enhance the generation and separation of photogenerated carriers and correspondingly improve the catalytic activity of TiO2, this invention first prepares a substrate mesocrystalline TiO2. Mesocrystalline TiO2 (TMC) is a highly ordered and stable structure composed of TiO2 nanocrystals, possessing a unique edge trap state (edge ​​effect), which can effectively achieve exciton dissociation and ultimately realize the spatial separation of photogenerated carriers. Then, using a hydrothermal synthesis method, the prepared magnetic ferrite is loaded onto the surface of the substrate mesocrystalline TiO2 (TMC), forming a stable electron transport channel. TMC, a highly ordered and stable structure composed of TiO2 nanocrystals, possesses a unique edge trap state (edge ​​effect), which can effectively achieve exciton dissociation and ultimately realize the spatial separation of photogenerated carriers. Magnetic ferrite is a magnetic material; its combination with TMC can achieve efficient light absorption and carrier separation, thereby improving the efficiency and stability of the photocatalytic reaction.

[0049] This invention further proposes an application of ferroalloy / mesocrystalline TiO2, which is prepared by the method described above. Using the ferroalloy / mesocrystalline TiO2 prepared by this invention as a photocatalyst in photocatalytic reactions can achieve efficient light absorption and carrier separation, thereby improving the efficiency and stability of the photocatalytic reaction. This catalyst has potential advantages in applications such as the efficient degradation of VOCs.

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0051] Example 1

[0052] S1. Dissolve 8.0 g FeCl3·6H2O and 16.0 g NaAc in 40 mL ethylene glycol at room temperature. After stirring for about 30 min, transfer the solution to a 50 mL polytetrafluoroethylene-lined autoclave and store at 180 °C for 6 h, then allow it to cool naturally to ambient temperature. Centrifuge the black precipitate, wash thoroughly with ethanol, and finally dry it in a vacuum drying oven at 60 °C to obtain black nano-Fe3O4.

[0053] S2. Add 50 mL of 0.5 mol / L Fe(NO3)3·9H2O to a 500 mL beaker and stir at room temperature for 10 min. Then add 0.7 g of the prepared nano-Fe3O4. Stir for 10 min to prepare magnetic Fh. Adjust the pH to 7-8 with 1 mol / L NaOH. Stir for 20 min, add distilled water to 125 mL, and age at 65 °C for 72 h. Wash several times with water and dry at 70 °C to obtain magnetic Fh.

[0054] S3. A precursor solution was prepared by mixing TiF4, H2O, NH4NO3, and NH4F in a molar ratio of 1:117:6.6:4. This precursor was then dropped onto a silicon chip to form a thin layer no more than 1 mm thick. The precursor solution was then calcined in air at a heating rate of 10 °C / min. -1 The heating temperature was 5℃, and the holding time was 2h. Finally, the obtained powder was calcined at 500℃ in an O2 / Ar atmosphere for 8h to completely remove surface residues and then thoroughly ground for later use, denoted as TMC.

[0055] S4. First, ultrasonically treat TMC for 30 minutes, then add a certain amount of magnetic Fh and adjust the pH value to 7±0.1. Place the mixture in a high-pressure reactor with a polytetrafluoroethylene liner, and maintain the hydrothermal temperature at 80℃ for 3 hours. Subsequently, filter, wash, and dry to obtain a light yellow Fh / TMC powder.

[0056] Example 2

[0057] Compared with Example 1, the only difference is that S2 has been changed, and all other steps are the same, specifically:

[0058] S2. Dissolve Fe(NO3)3·9H2O in deionized water, then add KOH solution, adjust the pH to 7.4-7.6, stir, and centrifuge the resulting colloid. Discard the supernatant, wash the obtained solid with deionized water, shake well, centrifuge, and discard the supernatant. Repeat this process 5 times, and then dry at 40℃. The resulting black powder is Fh.

[0059] Example 3

[0060] Compared with Example 1, the only difference is that S4 has been changed; all other steps are the same. Specifically:

[0061] S4. First, sonicate the TMC for 30 min. Then, slowly and simultaneously titrate 8 mL of Fe(NO3)3 (1M, 40 mL) and 4 mL of NaOH (6M, 20 mL) into 10 mL of TMC containing 0.086 g, 0.129 g, and 0.172 g respectively, controlling the pH value at 7 ± 0.1. After continuous stirring for 3 h, centrifuge, wash, and dry to obtain materials with 20%, 30%, and 40% Fh / TMC.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that S1 has been changed, and everything else is the same, specifically:

[0064] S1. Preparation of nano-magnetic Fe3O4 by co-precipitation method: A certain amount of divalent ferric salt (FeSO4·7H2O) and trivalent ferric salt (FeCl3·6H2O) solutions were mixed in a molar ratio of 1:2, with a total ferric salt concentration of 0.5 mol / L. The mixture was added to a three-necked flask, and 200 mL of distilled water was added. The temperature was controlled at 30℃ under a N2 atmosphere. Then, 0.25 mol NaOH was slowly added dropwise to the three-necked flask, and the pH was adjusted to 10. The mixture was then stirred vigorously and heated in a high-temperature water bath for a certain period of time. After the mixture gradually turned from orange-red to black, the reaction was stopped after stirring for another 15 min. The obtained Fe3O4 particles were centrifuged and washed repeatedly with distilled water until the pH reached 7. The supernatant was removed, and the product was kept at 80℃ for 30 min to age it. After grinding, nano-magnetic Fe3O4 particles were obtained.

[0065] Comparative Example 2

[0066] Compared with Example 1, the only difference is that step S2 is omitted, and black nano Fe3O4 is used instead of magnetic ferrite in step S4. All other aspects are the same.

[0067] Comparative Example 3

[0068] Compared with Example 1, the only difference is that step S3 is omitted, and ordinary TiO2 is used instead of mesocrystalline TiO2 in step S4; all other aspects are the same.

[0069] Test methods and results

[0070] The Fh / TMC powder obtained in Example 1 above was tested under darkness and ultraviolet-visible light to obtain diffuse reflectance Fourier transform infrared (DRIFTS) spectra. Figure 1 The Fh / TMC powder obtained in Example 2 above was observed using a scanning electron microscope to obtain... Figure 2 The Fh / TMC powder obtained in Example 3 above was subjected to X-ray diffraction testing to obtain... Figure 3The Fh / TMC powder obtained in Example 1 was dissolved in n-hexane and sonicated for a period of time to ensure complete dispersion. The powder was then dropped onto a polyethylene film and dried. The catalyst was spread evenly in a clean Pyrex reaction cell, and 30 μL of deionized water was dripped along the wall. The cell was connected to a photocatalytic degradation system for VOCs. Before the photocatalytic reaction, the system was evacuated to remove air, then air was introduced, and the system was stabilized for a period of time to allow sufficient adsorption of VOCs molecules on the catalyst surface. The photocatalytic degradation performance of VOCs was tested using a 300W xenon lamp (PLS-SXE300). The product was analyzed by an online gas chromatograph equipped with an FID detector. Figure 4 The catalysts prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to photocatalytic degradation performance tests on VOCs. The methods were the same as above, and their degradation efficiencies at 5 min, 10 min, 15 min and 20 min were tested respectively. The results are shown in Table 1 below.

[0071] Table 1. Performance Test Table for Photocatalytic Degradation of VOCs

[0072]

[0073] Depend on Figure 1 It can be seen that the Fh / TMC catalyst produces benzyl alcohol intermediate during the adsorption stage, and the amount of this intermediate gradually decreases under light irradiation; from Figure 2 It can be seen that the Fh / TMC catalyst has a micron-sized bulk structure; from Figure 3 It can be seen that the Fh / TMC catalyst was successfully synthesized. These peaks only show the peaks of TMC, with almost no characteristic peaks of Fh observed, indicating that Fh has very poor crystallinity and the peak intensity is very weak, which is consistent with descriptions in many literatures. Figure 4 It can be seen that the Fh / TMC catalyst has high catalytic efficiency, reaching over 95% in the initial stage, but the catalytic efficiency decreases over time. Table 1 shows that Examples 1-3 exhibit higher degradation rates compared to Comparative Examples 1-3 at the same catalytic time.

[0074] In summary, the ferrohydrate / mesocrystalline TiO2 prepared by the method provided by this invention can be used as a photocatalyst. The combination of magnetic ferrohydrate and TMC can achieve efficient light absorption and carrier separation, thereby improving the efficiency and stability of the photocatalytic reaction.

[0075] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing ferrohydrate / mesocrystalline TiO2, characterized in that, Includes the following steps: Preparation of black nano Fe3O4: FeCl3·6H2O and NaAc were dissolved in ethylene glycol, stirred, stored at 170~190℃ for 5~7h, cooled, and a black precipitate was obtained. The black precipitate was centrifuged, washed with organic solvent, and dried to obtain black nano Fe3O4. Preparation of magnetic ferromagnetic ore: Add Fe(NO3)3·9H2O to the reaction vessel and stir. Add the black nano Fe3O4 and stir. Add alkaline solution to adjust the pH to 7-8 and stir. Add distilled water, age, wash with water, and dry to obtain magnetic ferromagnetic ore. Preparation of mesocrystalline TiO2: TiF4, H2O, NH4NO3 and NH4F are mixed to prepare a precursor solution. The precursor solution is dropped onto a silicon chip to form a thin layer. The precursor solution on the thin layer is heated and calcined, and kept at the temperature to obtain powder. The powder is calcined in an O2 / Ar atmosphere and ground to obtain mesocrystalline TiO2. Preparation of ferrohydrate / mesocrystalline TiO2: The mesocrystalline TiO2 was ultrasonically treated, the magnetic ferrohydrate was added, the pH value was adjusted, the mixture was heated, kept warm, filtered, washed and dried to obtain ferrohydrate / mesocrystalline TiO2. In the step of preparing ferrohydrate / mesocrystalline TiO2, the pH value is 6.9~7.1; and / or, Water bath heating is used, wherein the temperature of the water bath heating is 75~85°C; and / or, The heat preservation time is 2.5h to 3.5h.

2. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing black nano Fe3O4, the mass ratio of FeCl3·6H2O to NaAc is 1:

2.

3. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing black nano-Fe3O4, drying is performed using a vacuum drying oven; and / or, The drying temperature is 50~70℃.

4. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing magnetic ferrohydrate, the aging temperature is 60-70°C; and / or, The aging time is 70-74 hours.

5. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing magnetic ferromagnetic ore, the drying temperature is 65~75℃.

6. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing mesocrystalline TiO2, the molar ratio of TiF4, H2O, NH4NO3 and NH4F is 1:(115~120):(6.5~7.0):(3~5).

7. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing mesocrystalline TiO2, the thickness of the thin layer does not exceed 1 mm.

8. The method for preparing ferrohydrate / mesocrystalline TiO2 as described in claim 1, characterized in that, In the step of preparing mesocrystalline TiO2, the heating rate is 8~12°C min. -1 ; and / or, The heat preservation time is 1.5h to 2.5h; and / or, The calcination temperature in the O2 / Ar atmosphere is 480~520°C; and / or, The calcination time in the O2 / Ar atmosphere is 7-9 hours.

9. An application of ferrohydrate / mesocrystalline TiO2, characterized in that, The ferroalloy / mesocrystalline TiO2 is prepared by the method described in any one of claims 1 to 8 and is used in the photocatalytic degradation of VOCs.

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