A TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, its preparation method and application

Abstract

The present invention discloses a TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst and its preparation method and application; the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst of the present invention is a composite material, which is composed of Bi nanoparticles, Bi2O2CO3 nanosheets, anatase TiO2 and a thin layer of Ti3C2. The Bi2O2CO3 and TiO2 are uniformly distributed on the thin layer of Ti3C2 to form a heterostructure, and the Bi nanoparticles are distributed between the nanosheets. The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst of the present invention has good photocatalytic activity, can effectively degrade tetracycline hydrochloride under visible light or natural sunlight, and has excellent stability and recyclability.

Description

Technical Field

[0001] The present invention relates to the technical fields of nanomaterials and photocatalysis, and particularly relates to a TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, a preparation method thereof and an application thereof. Background Art

[0002] In recent years, antibiotics have played an important role in the treatment of infections in humans and animals. As one of the main broad-spectrum antibiotic drugs, tetracycline (TC) is produced and used in large quantities worldwide. However, the utilization rate of TC is very low, and it can only be partially metabolized in the body. Moreover, such antibiotics have a stable chemical structure and antibacterial properties and are not easily degraded by the environment, so they gradually accumulate in water bodies, posing a serious threat to the ecological environment and human health. Although physical adsorption, biodegradation, ozonation, non-thermal plasma technology, etc. have been widely studied for the removal of antibiotics in water, they are greatly limited in practical applications due to problems such as complex processes, high costs or secondary pollution. The photocatalysis technology has become the most environmentally friendly and effective method for removing TC from water due to its advantages such as economy, low energy consumption and simple operation.

[0003] Semiconductor materials have been widely used as photocatalysts. Among them, Bi2O2CO3 is composed of interlaced [Bi2O2] 2+ layers and CO3 2− layers, which can generate a large internal electric field and an asymmetric polarization effect, thus being beneficial to charge separation. However, the band gap of Bi2O2CO3 is relatively wide, which greatly limits its application as a visible light-responsive material. At present, methods such as doping metals, forming defects and constructing heterojunctions have been explored to modify the photocatalytic activity of Bi2O2CO3 (Li L.X., Gao H.J., Yi Z., et al. Comparative investigation on synthesis, morphological tailoring and photocatalytic activities of Bi2O2CO3 nanostructures [J]. Colloids and Surfaces a-Physicochemical and Engineering Aspects, 2022, 644.). In addition, some studies have shown that introducing a solid-state electron transfer medium when constructing a Z-scheme heterojunction can not only adjust the energy band structure of the photocatalyst to maximize the redox potential, but also provide its utilization rate by avoiding the recombination of photo-generated electron-hole pairs.

[0004] MXene is a class of emerging metal carbides or metal nitrides with a two-dimensional layered structure. They have a large specific surface area, adjustable surface groups, and excellent electrical conductivity. Therefore, MXene represented by Ti3C2T x is widely used to construct heterojunction photocatalysts with other semiconductor materials. It can be used as a growth carrier and also as a cocatalyst to promote the separation of photo-generated carriers. In addition, it is generally believed that doping noble metal nanoparticles on the surface of semiconductor photocatalysts can form a surface plasmon resonance (SPR) effect, accelerating charge transfer and optimizing the carrier separation performance, thereby improving the photocatalytic activity. Recently, it has been found that inexpensive metal bismuth (Bi) also has SPR characteristics and can be an ideal substitute for noble metals. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, its preparation method and application. The present invention uses thin-layer Ti3C2 as a carrier, and anatase TiO2 is grown on it by an in-situ oxidation method without adding an additional titanium source. Then, using Bi(NO3)3•5H2O as the bismuth source and hexamethylenetetramine as the carbon source and reducing agent, Bi2O2CO3 and elemental Bi are simultaneously loaded on the surface of the obtained TiO2 / Ti3C2 material.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is a composite material, which is composed of Bi nanoparticles, Bi2O2CO3 nanosheets, anatase TiO2 and thin-layer Ti3C2. The Bi2O2CO3 and TiO2 are uniformly distributed on the thin-layer Ti3C2 and form a heterostructure, and the Bi nanoparticles are distributed between the nanosheets (and have a surface plasmon resonance effect).

[0008] The preparation method of the above-mentioned TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst includes the following steps:

[0009] Add the TiO2 / Ti3C2 material composed of anatase TiO2 and thin-layer Ti3C2 and a soluble Bi salt into water and ultrasonically disperse to obtain dispersion A. Dissolve hexamethylenetetramine in water to obtain solution B, then drop solution B into dispersion A, stir to form a dispersion for hydrothermal reaction, and after the reaction is completed, wash and dry to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst;

[0010] The molar ratio of Bi ions in the soluble Bi salt to hexamethylenetetramine is 1:1.2 - 3.

[0011] Preferably, the mass ratio of the TiO2 / Ti3C2 material to the soluble Bi salt is 5 - 60:200 - 300; the ratio of the total mass of the TiO2 / Ti3C2 material and the soluble Bi salt in the dispersion liquid A to the volume of water is 200 - 350:10 - 30 mg / mL; the ratio of the mass of hexamethylenetetramine in the solution B to the volume of water is 70 - 200:5 - 10 mg / mL; the stirring time is 10 - 60 min; the temperature of the hydrothermal reaction is 150 - 200 °C, and the time is 3 - 12 h.

[0012] Preferably, the ultrasonic dispersion time is 5 - 30 min; the water is ultrapure water; the soluble Bi salt is Bi(NO3)3•5H2O.

[0013] Preferably, the washing method is to wash 3 - 5 times successively with ethanol and ultrapure water.

[0014] Preferably, the preparation method of the TiO2 / Ti3C2 composite material is: dispersing the thin-layer Ti3C2 and NaBF4 in a 1 - 1.5 mol / L dilute hydrochloric acid solution, carrying out a hydrothermal reaction at 120 - 200 °C for 1 - 6 h, and after the reaction is completed, washing and drying with ultrapure water;

[0015] The mass ratio of the thin-layer Ti3C2 to NaBF4 is 30 - 100:50 - 160.

[0016] More preferably, the drying is vacuum freeze-drying, and the drying time is more than 6 h.

[0017] More preferably, the mass-volume ratio of the thin-layer Ti3C2, NaBF4 and the dilute hydrochloric acid solution is 1 g:1 - 2 g:100 - 300 mL;

[0018] More preferably, the thin-layer Ti3C2 is obtained by reacting Ti3AlC2 with LiF and concentrated hydrochloric acid in a 35 - 40 °C constant temperature water bath for 24 - 48 h, centrifuging and washing, and then dispersing in water and ultrasonically treating for 30 - 90 min under an argon atmosphere;

[0019] Even more preferably, the mass-volume ratio of the Ti3AlC2, LiF powder and concentrated hydrochloric acid is 1 g:1 - 1.5 g:20 - 30 mL; the mass concentration of the concentrated hydrochloric acid is 36% - 38%.

[0020] The application of the above-mentioned TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst in treating wastewater containing tetracycline hydrochloride includes the following steps:

[0021] Under light irradiation conditions, add the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst to the wastewater containing tetracycline hydrochloride.

[0022] Preferably, the light irradiation is visible light or natural light; the treatment conditions include: the concentration of tetracycline hydrochloride is 5-30 mg / L, the dosage of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is 0.2-1 g / L, and under normal temperature conditions.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) In the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared by the present invention, a Z-scheme heterojunction is formed among Ti3C2, TiO2 and Bi2O2CO3, which regulates the energy band structures of TiO2 and Bi2O2CO3. In addition, Ti3C2 MXene, as a solid-state electron transfer medium, effectively promotes the transfer and separation of photo-generated carriers. Therefore, the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst has excellent photocatalytic activity under visible light;

[0025] (2) In the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared by the present invention, Bi nanoparticles provide the SPR effect and can serve as the collection center of photo-generated electrons, enhancing the absorption of visible light by the catalyst and further improving the photo-generated carrier separation ability, thus realizing the further improvement of photocatalytic performance;

[0026] (3) The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared by the present invention can also effectively degrade tetracycline hydrochloride under natural sunlight, and has excellent stability and recyclability, showing good practical application potential;

[0027] (4) The materials used in the present invention are environmentally friendly and can obtain greater economic benefits with lower investment;

[0028] (5) The materials of the present invention are simple to manufacture, have low equipment requirements, and can be mass-produced in large quantities. Description of the Drawings

[0029] Figure 1X-ray diffraction patterns of the thin-layer Ti3C2, TiO2 / Ti3C2 composite materials, and TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalysts prepared in Example 1, Bi2O2CO3 prepared in Example 8, Bi2O2CO3 / Bi prepared in Example 9, TiO2 / Ti3C2-Bi2O2CO3 prepared in Example 10, and TiO2-Bi2O2CO3 / Bi prepared in Example 11.

[0030] Figure 2 Scanning electron microscope image of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared in Example 1.

[0031] Figure 3 Transmission electron microscope image of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared in Example 1.

[0032] Figure 4 Degradation efficiency graphs of tetracycline hydrochloride under visible light by the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalysts prepared in Examples 1-7, Bi2O2CO3 prepared in Example 8, Bi2O2CO3 / Bi prepared in Example 9, TiO2 / Ti3C2-Bi2O2CO3 prepared in Example 10, and TiO2-Bi2O2CO3 / Bi prepared in Example 11.

[0033] Figure 5 UV-vis DRS spectra of the TiO2 / Ti3C2-Bi2O2CO3 prepared in Example 10 and the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared in Example 1.

[0034] Figure 6 Cyclic test graph of the degradation of tetracycline hydrochloride by the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared in Example 1. Detailed Description of the Specific Embodiments

[0035] In combination with the following examples, the present invention will be further described in detail. However, the embodiments of the present invention are not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to. Reagents or instruments not indicating the manufacturer are regarded as conventional products that can be obtained through commercial purchase.

[0036] Example 1

[0037] (1) Add 40 mL of 37% concentrated hydrochloric acid and 2 g of LiF powder into a polytetrafluoroethylene beaker, stir for 30 min in a 35 °C constant temperature water bath, and the stirring speed is about 400 r / min; then weigh 10 portions of 0.2 g of Ti3AlC2 powder, add them into the above system in portions within 10 min, and continue to react for 24 h under the above conditions. After the reaction, centrifuge the reaction solution, collect the black precipitate and wash it with ultrapure water 5 - 6 times. Then, ultrasonically treat it in ultrapure water under an argon atmosphere for 60 min, centrifuge the dispersion and collect the supernatant, and vacuum freeze-dry it for more than 24 h to obtain thin-layer Ti3C2;

[0038] (2) Weigh 50 mg of the thin-layer Ti3C2 prepared in step (1) and 82.5 mg of NaBF4 into a polytetrafluoroethylene inner liner, then add 7.5 mL of 1 mol / L dilute hydrochloric acid solution, stir for 30 min and ultrasonically treat for 10 min to form a dispersion. Then, place it in a hydrothermal reactor and react at 160 °C for 3 h. After the reaction, naturally cool it to room temperature. Wash the obtained precipitate with ultrapure water 3 - 5 times, and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2 composite material;

[0039] (3) Weigh 25.5 mg of the TiO2 / Ti3C2 composite material obtained in step (2) and 245 mg of Bi(NO3)3•5H2O and add them into a polytetrafluoroethylene inner liner, then add 15 mL of ultrapure water and ultrasonically treat for 20 min to obtain dispersion A. Weigh 98 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then, drop solution B into dispersion A and continue to stir for 30 min to obtain a mixed reaction solution;

[0040] (4) Place the mixed reaction solution obtained in step (3) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 4 h. After the reaction, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water 3 times successively, and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2 - Bi2O2CO3 / Bi photocatalyst.

[0041] The scanning electron microscope of the TiO2 / Ti3C2 - Bi2O2CO3 / Bi composite material obtained in this example is as Figure 2 shown, and the transmission electron microscope image is as Figure 3 shown.

[0042] Use the TiO2 / Ti3C2 - Bi2O2CO3 / Bi photocatalyst obtained in this example for the visible light degradation of tetracycline hydrochloride. The specific steps are as follows:

[0043] (1)Prepare 10 mg / L tetracycline hydrochloride, take 50 mL and put it in a beaker, add 25 mg of catalyst, disperse it by ultrasonic wave and stir it in the dark for 30 min;

[0044] (2)Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0045] (3)Recyclability:

[0046] After each photocatalytic reaction is completed, collect the catalyst by centrifugation, wash it 3 - 5 times with absolute ethanol and ultrapure water respectively, and then freeze-dry it under vacuum. Repeat steps (1) and (2), and the results are as Figure 6 shown.

[0047] Example 2

[0048] (1)Weigh 25.5 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O, add them into a polytetrafluoroethylene inner liner, then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 126 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A, and continue to stir for 30 min to obtain a mixed reaction solution;

[0049] (2)Put the mixed reaction solution obtained in step (1) into a reaction kettle, carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate 3 times successively with ethanol and ultrapure water, and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst.

[0050] Use the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in this example for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0051] (1)Prepare 10 mg / L tetracycline hydrochloride, take 50 mL and put it in a beaker, add 25 mg of catalyst, disperse it by ultrasonic wave and stir it in the dark for 30 min;

[0052] (2)Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0053] Example 3

[0054] (1) Weigh 25.5 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O and add them into a polytetrafluoroethylene inner liner. Then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 154 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A and continue to stir for 30 min to obtain a mixed reaction solution;

[0055] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water successively three times and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst.

[0056] Use the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in this example for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0057] (1) Prepare 10 mg / L tetracycline hydrochloride, take 50 mL and put it in a beaker, add 25 mg of the catalyst, ultrasonically disperse it and stir it in the dark for 30 min;

[0058] (2) Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0059] Example 4

[0060] (1) Weigh 19.1 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O and add them into a polytetrafluoroethylene inner liner. Then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 126 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A and continue to stir for 30 min to obtain a mixed reaction solution;

[0061] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 6 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water successively three times and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst.

[0062] The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in this example was used for the visible-light degradation of tetracycline hydrochloride. The specific steps are as follows:

[0063] (1) Prepare 10 mg / L tetracycline hydrochloride. Take 50 mL and place it in a beaker. Add 20 mg of the catalyst, ultrasonically disperse it, and stir it in the dark for 30 min;

[0064] (2) Use an LED lamp as the visible-light source. Irradiate the system in step (1) under this light source and calculate the removal efficiency. The results are as Figure 4 shown.

[0065] Example 5

[0066] (1) Weigh 19.1 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O and add them to a polytetrafluoroethylene inner lining. Then add 15 mL of ultrapure water and ultrasonically disperse for 20 min to obtain dispersion A. Weigh 126 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A and continue to stir for 30 min to obtain a mixed reaction solution;

[0067] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 12 h. After the reaction, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water three times each, and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst.

[0068] The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in this example was used for the visible-light degradation of tetracycline hydrochloride. The specific steps are as follows:

[0069] (1) Prepare 10 mg / L tetracycline hydrochloride. Take 50 mL and place it in a beaker. Add 20 mg of the catalyst, ultrasonically disperse it, and stir it in the dark for 30 min;

[0070] (2) Use an LED lamp as the visible-light source. Irradiate the system in step (1) under this light source and calculate the removal efficiency. The results are as Figure 4 shown.

[0071] Example 6

[0072] (1) Weigh 19.1 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O, add them to a polytetrafluoroethylene inner liner, then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 126 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then, drop solution B into dispersion A, and continue stirring for 30 min to obtain a mixed reaction solution;

[0073] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle, carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water three times successively, and vacuum freeze-dry for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst.

[0074] The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in this example was used for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0075] (1) Prepare 10 mg / L of tetracycline hydrochloride, take 50 mL and place it in a beaker, add 20 mg of the catalyst, ultrasonically disperse it and stir it in the dark for 30 min;

[0076] (2) Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0077] Example 7

[0078] The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst obtained in Example 1 was used for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0079] (1) Prepare 10 mg / L of tetracycline hydrochloride, take 50 mL and place it in a beaker, add 25 mg of the catalyst, ultrasonically disperse it and stir it in the dark for 30 min;

[0080] (2) Use natural sunlight as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0081] Example 8

[0082] To compare and reflect the effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst on the degradation of tetracycline hydrochloride, the present invention separately studied the photocatalytic effect of Bi2O2CO3.

[0083] (1) Weigh 245 mg of Bi(NO3)3•5H2O and add it to a polytetrafluoroethylene inner liner. Then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 98 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A and continue stirring for 30 min to obtain a mixed reaction solution;

[0084] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water three times successively, and vacuum freeze-dry for more than 6 h to obtain a Bi2O2CO3 photocatalyst.

[0085] Use the Bi2O2CO3 photocatalyst obtained in this example for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0086] (1) Prepare 10 mg / L tetracycline hydrochloride, take 50 mL and place it in a beaker, add 25 mg of the catalyst, ultrasonically disperse it and stir it in the dark for 30 min;

[0087] (2) Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0088] Example 9

[0089] To comparatively reflect the effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst on the degradation of tetracycline hydrochloride, the present invention separately studied the photocatalytic effect of Bi2O2CO3 / Bi.

[0090] (1) Weigh 245 mg of Bi(NO3)3•5H2O and add it to a polytetrafluoroethylene inner liner. Then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 182 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then drip solution B into dispersion A and continue stirring for 30 min to obtain a mixed reaction solution;

[0091] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water three times successively, and vacuum freeze-dry for more than 6 h to obtain a Bi2O2CO3 / Bi photocatalyst.

[0092] Use the Bi2O2CO3 photocatalyst obtained in this example for the degradation of tetracycline hydrochloride under visible light. The specific steps are as follows:

[0093] (1) Prepare 10 mg / L tetracycline hydrochloride. Take 50 mL and place it in a beaker, add 25 mg of the catalyst, disperse it by ultrasonic wave and stir it in the dark for 30 min;

[0094] (2) Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0095] Example 10

[0096] To comparatively reflect the effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst in degrading tetracycline hydrochloride and the SPR effect of Bi nanoparticles, the present invention separately studied the photocatalytic effect of the TiO2 / Ti3C2-Bi2O2CO3 material.

[0097] (1) Weigh 25.5 mg of the TiO2 / Ti3C2 composite material obtained in step (2) of Example 1 and 245 mg of Bi(NO3)3•5H2O, add them to a polytetrafluoroethylene inner liner, then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion liquid A. Weigh 70 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then, drip solution B into dispersion liquid A, and continue to stir for 30 min to obtain a mixed reaction solution;

[0098] (2) Place the mixed reaction solution obtained in step (1) in a reaction kettle, carry out a solvothermal reaction at 180 °C for 4 h. After the reaction is completed, naturally cool it to room temperature. Wash the obtained precipitate successively with ethanol and ultrapure water 3 times, and vacuum freeze-dry it for more than 6 h to obtain the TiO2 / Ti3C2-Bi2O2CO3 photocatalyst.

[0099] Use the TiO2 / Ti3C2-Bi2O2CO3 photocatalyst obtained in this example to degrade tetracycline hydrochloride under visible light. The specific steps are as follows:

[0100] (1) Prepare 10 mg / L tetracycline hydrochloride. Take 50 mL and place it in a beaker, add 25 mg of the catalyst, disperse it by ultrasonic wave and stir it in the dark for 30 min;

[0101] (2) Use an LED lamp as the visible light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0102] Example 11

[0103] To compare and reflect the photocatalytic degradation effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst on tetracycline hydrochloride and the role of Ti3C2 as a solid-state electron transport medium, the photocatalytic effect of the TiO2-Bi2O2CO3 / Bi material was studied separately in this invention.

[0104] (1) Weigh 50 mg of the thin-layer Ti3C2 prepared in step (1) of Example 1 and 82.5 mg of NaBF4 into a polytetrafluoroethylene inner liner, then add 7.5 mL of 1 mol / L dilute hydrochloric acid solution, stir for 30 min and ultrasonicate for 10 min to form a dispersion. Then, place it in a hydrothermal autoclave and react at 160 °C for 12 h. After the reaction, naturally cool it to room temperature. Wash the obtained precipitate with ultrapure water 3-5 times and vacuum freeze-dry it for more than 6 h to obtain TiO2 powder;

[0105] (2) Weigh 25.5 mg of the TiO2 powder obtained in step (1) and 245 mg of Bi(NO3)3•5H2O into a polytetrafluoroethylene inner liner, then add 15 mL of ultrapure water and ultrasonicate for 20 min to obtain dispersion A. Weigh 98 mg of hexamethylenetetramine and dissolve it in 5 mL of ultrapure water to obtain solution B. Then, drop solution B into dispersion A and continue to stir for 30 min to obtain a mixed reaction solution;

[0106] (3) Place the mixed reaction solution obtained in step (2) in a reaction kettle and carry out a solvothermal reaction at 180 °C for 4 h. After the reaction, naturally cool it to room temperature. Wash the obtained precipitate with ethanol and ultrapure water 3 times each and vacuum freeze-dry it for more than 6 h to obtain the TiO2-Bi2O2CO3 / Bi photocatalyst.

[0107] The TiO2-Bi2O2CO3 / Bi photocatalyst obtained in this example was used for the visible-light degradation of tetracycline hydrochloride. The specific steps are as follows:

[0108] (3) Prepare 10 mg / L tetracycline hydrochloride, take 50 mL and put it into a beaker, add 25 mg of the catalyst, ultrasonically disperse it and stir it in the dark for 30 min;

[0109] (4) Use an LED lamp as the visible-light source, irradiate the system in step (1) under this light source, calculate the removal efficiency, and the results are as Figure 4 shown.

[0110] Figure 1are the X-ray diffraction patterns of the thin-layer Ti3C2 (obtained in step (1) of Example 1), TiO2 / Ti3C2 composite material (obtained in step (2) of Example 1), Bi2O2CO3 (Example 8), Bi2O2CO3 / Bi (Example 9), TiO2 / Ti3C2-Bi2O2CO3 (Example 10), TiO2-Bi2O2CO3 / Bi (Example 11), and TiO2 / Ti3C2-Bi2O2CO3 / Bi (Example 1) photocatalysts. From Figure 1 it can be seen that the main characteristic peaks of TiO2, Bi2O2CO3, and Bi simultaneously appear in the XRD pattern of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst and can correspond to the corresponding standard cards, indicating the successful preparation of materials such as TiO2 / Ti3C2-Bi2O2CO3 / Bi.

[0111] Figure 2 and Figure 3 are the scanning electron microscope image and transmission electron microscope image of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, respectively. It can be seen from the figure that anatase TiO2 and Bi2O2CO3 nanosheets grow uniformly on the surface of the thin-layer Ti3C2. In addition, metallic Bi nanoparticles with a diameter of about 100-250 nm can be observed between the nanosheets.

[0112] By Figure 4It can be seen that the degradation efficiency of the TiO2 / Ti3C2-Bi2O2CO3 / Bi (Example 1) photocatalyst of the present invention for tetracycline hydrochloride under visible light can reach nearly 85%. Under the same conditions, compared with Bi2O2CO3, the catalytic effects of the Bi2O2CO3 / Bi and TiO2 / Ti3C2-Bi2O2CO3 photocatalysts on tetracycline hydrochloride are better, indicating that both the construction of the heterostructure and the SPR effect provided by elemental Bi are beneficial to the improvement of the catalytic activity. Compared with Bi2O2CO3 / Bi and TiO2 / Ti3C2-Bi2O2CO3, the catalytic effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi (Example 1) photocatalyst is further improved, indicating that the construction of the heterostructure and the SPR effect synergistically improve the photocatalytic activity of this material. Compared with TiO2-Bi2O2CO3 / Bi, the catalytic effect of TiO2 / Ti3C2-Bi2O2CO3 / Bi (Example 1) is also better, which may be because Ti3C2 acts as a solid-state electron transfer medium here to promote the separation of photogenerated carriers and thus improve the photocatalytic performance of the material. In addition, by comparing Examples 1, 2, and 3, it can be found that the photocatalytic effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is affected by the dosage of the reducing agent; by comparing Examples 4, 5, and 6, it can be found that the photocatalytic effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is affected by the reaction time; and by comparing Examples 1 and 7, it can be found that the photocatalytic effect of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is affected by the light source, but it also shows that the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst prepared by the present invention can effectively degrade tetracycline hydrochloride even under natural sunlight and has good practical application potential.

[0113] Figure 5 Figure 4 is the UV-vis DRS spectra of the TiO2 / Ti3C2-Bi2O2CO3 in Example 10 and the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst in Example 1. It can be seen from this figure that after introducing elemental Bi, the absorption of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst for visible light is further enhanced, which is due to the SPR effect generated by Bi nanoparticles.

[0114] As can be seen from Figure 6 It can be seen that during the 5-cycle reuse process, the degradation rate of tetracycline hydrochloride hardly decreases and remains above 85.0% each time. This indicates that the TiO2 / Ti3C2-Bi2O2CO3 / Bi prepared by the present invention has excellent stability and recyclability.

[0115] The above embodiments are only used to explain the present invention and are not intended to limit the present invention in any form. Those skilled in the art, without departing from the content of the technical solution of the present invention, shall fall within the scope of protection of the technical solution of the present invention for the simplification, modification, substitution and combination made to the above embodiments based on the spirit and technical principle of the present invention.

Claims

1. A TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst, characterized in that, The TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is a composite material, which consists of Bi nanoparticles, Bi2O2CO3 nanosheets, anatase TiO2 and a thin layer of Ti3C2. The Bi2O2CO3 and TiO2 are uniformly distributed on the thin layer of Ti3C2 to form a heterostructure, and the Bi nanoparticles are distributed between the nanosheets. The Bi2O2CO3 and elemental Bi are simultaneously loaded on the surface of the TiO2 / Ti3C2 material using Bi(NO3)3·5H2O as the bismuth source, hexamethylenetetramine as the carbon source and reducing agent. The molar ratio of Bi ions in the bismuth source to hexamethylenetetramine is 1:1.2 - 3.

2. The preparation method of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst according to claim 1, characterized in that, It includes the following steps: Add the TiO2 / Ti3C2 material composed of anatase TiO2 and a thin layer of Ti3C2 and a soluble Bi salt into water and ultrasonically disperse to obtain dispersion A. Dissolve hexamethylenetetramine in water to obtain solution B, then drop solution B into dispersion A, stir to form a dispersion for hydrothermal reaction. After the reaction, wash and dry to obtain the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst. The molar ratio of Bi ions in the soluble Bi salt to hexamethylenetetramine is 1:1.2 - 3.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the TiO2 / Ti3C2 material to the soluble Bi salt is 5 - 60:200 - 300. The ratio of the total mass of the TiO2 / Ti3C2 material and the soluble Bi salt in dispersion A to the volume of water is 200 - 350:10 - 30 mg / mL. The ratio of the mass of hexamethylenetetramine in solution B to the volume of water is 70 - 200:5 - 10 mg / mL. The stirring time is 10 - 60 min. The temperature of the hydrothermal reaction is 150 - 200 °C and the time is 3 - 12 h.

4. The preparation method according to claim 2, characterized in that, The ultrasonic dispersion time is 5 - 30 min. The water is ultrapure water. The soluble Bi salt is Bi(NO3)3·5H2O.

5. The preparation method according to claim 2, characterized in that, The washing method is to wash 3 - 5 times successively with ethanol and ultrapure water.

6. The preparation method according to claim 2, characterized in that, The preparation method of the TiO2 / Ti3C2 composite material is as follows: Disperse the thin layer of Ti3C2 and NaBF4 in a 1 - 1.5 mol / L dilute hydrochloric acid solution, carry out hydrothermal reaction at 120 - 200 °C for 1 - 6 h. After the reaction, wash and dry with ultrapure water. The mass ratio of the thin layer of Ti3C2 to NaBF4 is 30 - 100:50 - 160.

7. The preparation method according to claim 6, characterized in that, The drying is vacuum freeze-drying, and the drying time is more than 6 h.

8. The preparation method according to claim 6, characterized in that, The thin layer of Ti3C2 is obtained by reacting Ti3AlC2 with LiF and concentrated hydrochloric acid in a 35 - 40 °C constant temperature water bath for 24 - 48 h, centrifuging and washing, and then dispersing in water and ultrasonically treating for 30 - 90 min under an argon atmosphere. The mass-volume ratio of Ti3AlC2, LiF powder and concentrated hydrochloric acid is 1 g:1 - 1.5 g:20 - 30 mL. The mass concentration of the concentrated hydrochloric acid is 36% - 38%.

9. Use of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst according to claim 1 in treating wastewater containing tetracycline hydrochloride, characterized in that, It includes the following steps: Under illumination conditions, the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst was added to the wastewater containing tetracycline hydrochloride.

10. The application according to claim 9, characterized in that, The illumination is visible light or natural light; the treatment conditions include: the concentration of tetracycline hydrochloride is 5-30 mg / L, the dosage of the TiO2 / Ti3C2-Bi2O2CO3 / Bi photocatalyst is 0.2-1 g / L, under normal temperature conditions.

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