A Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst, its preparation method and application

Abstract

This invention discloses a Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite catalyst, its preparation method, and its application, belonging to the fields of nanocomposite materials and photocatalysis technology. TiO₂ nanorods and Bi₂VO₅ nanoparticles are deposited on Bi₂O₂CO₃ nanosheets, forming TiO₂ / Bi₂O₂CO₃ and Bi₂VO₅ / Bi₂O₂CO₃ bis-binary heterojunction composite catalysts. In these catalysts, the (101) crystal plane of TiO₂ and the (111) crystal plane of Bi₂VO₅ are in close contact with the (110) crystal plane of Bi₂O₂CO₃. The catalyst of this invention exhibits excellent catalytic performance in the photocatalytic degradation of tetracycline, achieving a tetracycline degradation rate of 62% after 1.5 hours of illumination.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials and photocatalysis technology, specifically relating to a Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst, its preparation method, and its application. Background Technology

[0002] Catalysis technology refers to the use of photocatalysts to absorb and convert light energy, enabling it to participate in a series of reactions such as organic degradation, water splitting, carbon dioxide reduction, and organic synthesis. Since these reactions only require light energy as an energy source without the need for other types of energy input, if stable sunlight-driven photocatalytic reactions can be achieved, this technology holds promise as a key technology for low-cost, green, and sustainable development.

[0003] Photocatalytic degradation of tetracycline has become an important research topic in chemistry, particularly catalysis, due to its green nature, low pollution, and the ease of separation of byproducts. TiO2, with its advantages of high efficiency, non-toxicity, and low cost, is most often used to manufacture charge carriers in the photocatalytic degradation of organic pollutants; however, its wide band gap and low electron-hole separation efficiency limit its practical application. Bi2O2CO3, as a typical layered Bi-based semiconductor material, is considered an excellent semiconductor photocatalyst due to its chemical stability and unique chemical properties. However, the low separation efficiency of photogenerated electrons and holes in traditional Bi2O2CO3 photocatalysts limits its practical application. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst, its preparation method and application, which will be used for photocatalytic degradation of tetracycline.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst, wherein TiO2 nanorods and Bi2VO5 nanoparticles are deposited on Bi2O2CO3 nanosheets by a one-step hydrothermal method to form TiO2 / Bi2O2CO3 and Bi2VO5 / Bi2O2CO3 dual binary heterojunction composite catalysts, wherein the (101) crystal plane of TiO2 and the (111) crystal plane of Bi2VO5 in the TiO2 / Bi2O2CO3 and Bi2VO5 / Bi2O2CO3 dual binary heterojunction composite catalysts are in close contact with the (110) crystal plane of Bi2O2CO3.

[0007] Furthermore, the TiO2 nanorods have a size of 61.9-108.3 nm, the sheet-like Bi2O2CO3 has a size of 243.6-83.2 nm, and the Bi2VO5 has a size of 6.6-14.3 nm.

[0008] Furthermore, the molar ratio of Bi2O2CO3, TiO2, and Bi2VO5 is 2-4:13-15:2-4.

[0009] Preferably, the molar ratio of Bi2O2CO3, TiO2, and Bi2VO5 is 3:14:3.

[0010] Secondly, the present invention provides a method for preparing a Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst, comprising the following steps:

[0011] Using potassium titanate nanowires as a precursor, Bi(NO3)3·5H2O and NH4VO3 were added to a urea aqueous solution, and a one-step hydrothermal method was used to synthesize a Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite photocatalyst.

[0012] In this process, Bi(NO3)3·5H2O nucleates and grows in the urea solution to form Bi2O2CO3 nanosheets, potassium titanate nanowires grow in situ to form TiO2 nanorods and are deposited on the Bi2O2CO3 nanosheets, and Bi2VO5 particles generated by the reaction of NH4VO3 and Bi(NO3)3·5H2O are also deposited on the Bi2O2CO3 nanosheets.

[0013] Furthermore, the above technical solution specifically includes the following steps:

[0014] (1) The potassium titanate nanowire precursor is mixed with the urea solution and then ultrasonicated to obtain a precursor solution;

[0015] (2) Add Bi(NO3)3·5H2O and NH4VO3 to the precursor solution, stir evenly, and react at 180-220℃ for 14-18h. After washing with water, centrifugation and drying, Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite photocatalyst is obtained.

[0016] Furthermore, in the above technical solution, the preparation method of the potassium titanate nanowire precursor includes the following steps:

[0017] At room temperature, P25 (abbreviation for titanium dioxide P25) is mixed evenly with potassium hydroxide aqueous solution and reacted at 190-210℃ for 22-26 hours. The solid in the product is separated, washed with water until the solid is neutral, and dried to obtain the final product.

[0018] Furthermore, in the above technical solution, the molar ratio of the potassium titanate nanowire precursor, the Bi(NO3)3·5H2O and the NH4VO3 is 1.6-2:0.4-0.6:0.1-0.3.

[0019] Thirdly, the present invention provides the application of the above-mentioned composite catalyst in the photocatalytic degradation of tetracycline.

[0020] Beneficial effects:

[0021] This invention utilizes potassium titanate nanowires as a precursor and employs a one-step hydrothermal method to rationally construct a Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite photocatalyst. The heterojunction interface is constructed by growing Bi₂VO₅ nanoparticles and TiO₂ nanorods on Bi₂O₂CO₃ nanosheets, respectively. The (101) crystal plane of TiO₂ and the (111) crystal plane of Bi₂VO₅ are in close contact with the (110) crystal plane of Bi₂O₂CO₃, forming the bis-binary heterojunction interface. The coupling between titanium dioxide and bismuth oxycarbonate, and between bismuth vanadate and bismuth oxycarbonate, induces the transfer of photogenerated electrons and holes among the three semiconductors, thereby improving the separation efficiency of photogenerated electrons and holes. The synergistic effect of the heterojunction interface promotes the separation and transfer of photogenerated electrons and holes, enhancing the catalytic reaction performance.

[0022] The Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst of the present invention exhibits enhanced photocatalytic activity in the photocatalytic degradation of tetracycline. After 1.5 h of illumination, it photodegraded 62% of tetracycline, demonstrating high photocatalytic degradation activity for tetracycline.

[0023] This invention constructs a Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst system. By utilizing the synergistic effect of the heterojunction interface, it promotes the separation and transfer of photogenerated electrons and holes, and realizes the photocatalytic high-efficiency degradation of tetracycline. Attached Figure Description

[0024] Figure 1 XRD characterization of the Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite photocatalyst.

[0025] Figure 2 The image shows the electron microscopy (TEM) characterization of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst. In the image, a is the TEM image of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst, and b is the HRTEM lattice spacing diagram of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst.

[0026] Figure 3 The figure shows the photocatalytic degradation performance of tetracycline by the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst. Figure a shows the photocatalytic activity of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst, b shows the first-order kinetic fitting curve of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst, and c shows the comparison of the reaction constant K values ​​of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite photocatalyst. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: Preparation of Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst.

[0029] At room temperature, 16.8 g of potassium hydroxide was added to 30 mL of deionized water, followed by 1 g of P25. After mixing thoroughly, the vessel was sealed and kept at 200 °C for 24 h. After naturally cooling to room temperature, the product was centrifuged and filtered. The precipitate was washed with water until the pH was about 7, and then centrifuged and dried to obtain the potassium titanate precursor.

[0030] 30 mL of deionized water was added to a 50 mL polytetrafluoroethylene reactor, along with 0.05 g of potassium titanate precursor. After stirring for 10 min, 2.4 g of urea was added, and the mixture was sonicated for 30 min. Subsequently, 0.2172 g of Bi(NO3)3·5H2O and 0.0130 g of NH4VO3 were added under stirring. The reactor was then sealed and kept at 200 °C for 16 h. After cooling to room temperature, the catalyst was washed with water, centrifuged, and dried at 80 °C for 12 h to obtain the Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst.

[0031] The potassium hydroxide used in this invention is analytical grade, with a purity ≥96.0%; urea is analytical grade, with a purity ≥99%; ammonium metavanadate is analytical grade, with a purity ≥99.0%; and bismuth nitrate pentahydrate is analytical grade, with a purity ≥99%. The XRD pattern of the Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite catalyst prepared in this invention is shown below. Figure 1As shown, the XRD pattern of the Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite catalyst exhibits diffraction peaks similar to those of the bismuth oxycarbonate sample (standard card NO. 41-1488) at 23.9°, 30.3°, 32.7°, 52.2°, and 56.9°, and diffraction peaks similar to those of the bismuth vanadate sample (standard card NO. 47-0734) at 11.4°, 23.5°, and 28.7°, indicating that the synthesized sample successfully combines bismuth oxycarbonate and bismuth vanadate. The Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite catalyst does not show diffraction peaks similar to those of titanium dioxide.

[0032] Figure 2 The morphological characterization of the Bi2VO5 / TiO2 / Bi2O2CO3 bi-binary heterojunction composite catalyst is presented, from... Figure 2 In diagram a, we can clearly see many titanium dioxide nanorods stacked on the bismuth oxycarbonate nanosheets, and bismuth vanadate particles growing on the titanium dioxide nanorods. Figure 2 b indicates that the crystal planes of bismuth oxycarbonate (110), titanium dioxide (101), and bismuth vanadate (111) are in close contact, effectively forming a heterogeneous interface between bismuth oxycarbonate, titanium dioxide, and bismuth vanadate.

[0033] Example 2: Photocatalytic degradation of tetracycline.

[0034] The composite catalyst prepared in Example 1 was used for the photocatalytic degradation of tetracycline.

[0035] Photocatalytic degradation of tetracycline was carried out in a specially designed quartz reactor. The reaction used pre-dissolved 20 mg / L tetracycline as the reactant and was conducted under circulating water cooling. 100 mL of tetracycline was accurately measured and placed in the reactor. After thorough mixing, 3 mL of the solution was taken, and 20 mg of the catalyst prepared in Example 1 was added. The suspension was magnetically stirred in the dark for 30 min to establish adsorption-desorption equilibrium. Measurements were taken using a UV-Vis spectrophotometer, with a maximum absorption wavelength of 357 nm. The BTV-15 sample exhibited the best photocatalytic activity, degrading 62% of TC within 90 min.

[0036] from Figure 3 As can be seen, the photocatalytic degradation rate of the synthesized catalyst gradually increases with increasing reaction time. The BTV-15 composite catalyst exhibited the strongest reactivity compared to the BTV-10 and BTV-20 composite catalysts, achieving a tetracycline degradation rate of 62% after 1.5 hours of reaction. Figure 3 b indicates that the Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bi-binary heterojunction composite catalyst follows first-order kinetics. Figure 3c shows that after 1.5 hours of reaction, the K value for BTV-10 is 0.0095, the K value for BTV-15 is 0.0105, and the K value for BTV-20 is 0.0073.

[0037] By constructing heterojunctions between semiconductors, not only can the defects of individual semiconductors be compensated, which is beneficial for preparing advanced catalysts for target reactions, but also a deeper understanding of the structure-activity relationship between catalyst structure and reaction performance can be achieved. This invention prepares potassium titanate nanowires via a one-step hydrothermal method, and further synthesizes a Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ bis-binary heterojunction composite catalyst via hydrothermal synthesis. The synergistic effect of the heterojunction interface achieves maximum separation of photogenerated electrons and holes, further enhancing the photocatalytic degradation activity of tetracycline under illumination.

[0038] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Various changes that can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ dual binary heterojunction composite catalyst, characterized in that, TiO2 nanorods and Bi2VO5 nanoparticles were deposited on Bi2O2CO3 nanosheets using a one-step hydrothermal method to form TiO2 / Bi2O2CO3 and Bi2VO5 / Bi2O2CO3 bis-binary heterojunction composite catalysts. In the TiO2 / Bi2O2CO3 and Bi2VO5 / Bi2O2CO3 bis-binary heterojunction composite catalysts, the (101) crystal plane of TiO2 and the (111) crystal plane of Bi2VO5 are in close contact with the (110) crystal plane of Bi2O2CO3.

2. The Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ dual binary heterojunction composite catalyst according to claim 1, characterized in that, The TiO2 nanorods have a size of 61.9-108.3 nm, the Bi2O2CO3 nanosheets have a size of 243.6-83.2 nm, and the Bi2VO5 nanoparticles have a size of 6.6-14.3 nm.

3. The Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ dual binary heterojunction composite catalyst according to claim 1, characterized in that, The molar ratio of Bi2O2CO3, TiO2, and Bi2VO5 is 2-4:13-15:2-4.

4. The Bi₂VO₅ / TiO₂ / Bi₂O₂CO₃ dual binary heterojunction composite catalyst according to claim 3, characterized in that, The molar ratio of Bi2O2CO3, TiO2, and Bi2VO5 is 3:14:

3.

5. A method for preparing the Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: Using potassium titanate nanowires as a precursor, Bi(NO3)3·5H2O and NH4VO3 were added to urea solution, and a one-step hydrothermal method was used to synthesize a Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst. In this process, Bi(NO3)3·5H2O nucleates and grows in the urea solution to form Bi2O2CO3 nanosheets, potassium titanate nanowires grow in situ to form titanium dioxide nanorods and are deposited on the Bi2O2CO3 nanosheets, and Bi2VO5 particles generated by the reaction of NH4VO3 and Bi(NO3)3·5H2O are also deposited on the Bi2O2CO3 nanosheets.

6. The preparation method of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst according to claim 5, characterized in that, Specifically, the steps include the following: (1) The potassium titanate nanowire precursor is mixed with the urea solution and then ultrasonicated to obtain a precursor solution; (2) Add Bi(NO3)3·5H2O and NH4VO3 to the precursor solution, stir evenly, and react at 180-220℃ for 14-18h. After washing with water, centrifuging and drying, the Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst is obtained.

7. The preparation method of the Bi2VO5 / TiO2 / Bi2O2CO3 dual binary heterojunction composite catalyst according to claim 6, characterized in that, The method for preparing the potassium titanate nanowire precursor includes the following steps: At room temperature, P25 is mixed evenly with potassium hydroxide aqueous solution and reacted at 190-210℃ for 22-26 hours. The solid in the product is separated, washed with water until the solid is neutral, and dried to obtain the final product.

8. The preparation method of the Bi2VO5 / TiO2 / Bi2O2CO3 bis-binary heterojunction composite catalyst according to claim 6, characterized in that, The molar ratio of the potassium titanate nanowire precursor, the Bi(NO3)3·5H2O and the NH4VO3 is 1.6-2:0.4-0.6:0.05-0.

15.

9. The application of the composite catalyst according to any one of claims 1-4 or the composite catalyst prepared by the preparation method according to any one of claims 5-8 in the photocatalytic degradation of tetracycline.

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