Vanadate Semiconductor Materials: Preparation And Photocatalytic Antibacterial Properties

Marine biofouling is one of the important problems that the marine engineering materials will face in practical application, so it is significant to develop novel and efficient antifouling materials. Based on the good photocatalytic activity and environment friendly property of vanadate semiconductors, series of silver vanadate and bismuth vanadate composites were prepared as antibiofouling and antibacterial materials in this study. Combined with the photocatalysis technique, the photocatalytic antibacterial properties of these composites were investigated, and all of which exhibited excellent antibacterial activities under visible light irradiation. In addition, the relationship between the structure and photocatalytic properties were also studied, and the photocatalytic mechanisms were propsed based on the experimental results. This study has a great significance and scientific value in deeply understanding the potential application of photocatalytic technology in marine antifouling, which will also provide a theoretical support and guidance for the selection of marine antibiofouling materials.The specific results are as follows:(1) Ag2V4O11 nanowires were prepared by the facile hydrothermal method, and Ag/Ag VO3 composites were prepared based on noble metal doping method. The enhanced photocatlyic performance of Ag/Ag VO3 could mainly ascribed to the the surface plasmon resonance(SPR) of Ag. Both Ag2V4O11 and Ag/Ag VO3 showed excellent photocatalytic antibacterial activities under visibile light irradiation due to the large specific surface areas and good visible-light absorption performances. Experimental results indicated that almost all(99.9%) of the bacterial cells were killed after 30 min reaction. In addtion, Ag2V4O11 and Ag/Ag VO3 did not exhibit significant loss of photocatalytic activity after the recycling experiments, indicating the stability and long-time reusability. In addition, the photocatalytic mechanisms were proposed based on the trapping experiments and energy band analysis.(2) A novel composite photocatalyst of Ag VO3/Ag3PO4 was prepared based on the different Ksp of Ag VO3 and Ag3PO4 by semicondutor composite menthod. Experimental results showed that Ag VO3/Ag3PO4 composites were composed of Ag VO3 nanobelts loaded with Ag3PO4 nanoparticles, which exhibited higher photocatalytic activity than bare Ag VO3 and Ag3PO4 under visible light irradiation. The enhanced photodcatalytic properties were mainly owing to the formation of p-n heterojunction, accelerating the separation of the photo-induced electron-hole pairs. Moreover, the photocatalytic antibacterial experiments indicated that almost all(99.9%) of the bacterial cells were killed after 15 min reaction, revealing the excellent photocatalytic properties of Ag VO3/Ag3PO4 composites. In addition, the composites did not exhibit significant loss of photocatalytic activity after 6 recycling experiments, confirming its stability and long-time reusability. The photocatalytic mechanism was also proposed based on the trapping experiments and energy band analysis.(3) A novel Ag@Ag VO3/Bi VO4 composite was prepared by an ion exchange and in-situ growth method based on by semicondutor composite combined with noble mental doping menthod. Experimental results showed that Bi VO4 nanoplates grew in-situ on Ag VO3 nanobelts, wihle the free Ag+ ions could be reduced on the surface of the nanobelts as nano Ag by PVP at the same time. And thus the Ag@Ag VO3/Bi VO4 SPR p-n heterojunction was constructed and displayed excellent photocatalytic properties. An antibacterial rate of 99.99% by Ag@Ag VO3/Bi VO4 was achived in 15 min reaction. The SPR effect by nano Ag and the formation of p-n heterojunction both enhanced the photocatalytic activity and stability of the composites, making it a potential candidate in photocatalytic antibacteria. In addition, the photocatalytic mechanisms were proposed based on the trapping experiments and energy band analysis.(4) A novel visible-light-sensitive Bi2WO6/Bi VO4 composite was synthesized via a hydrothermal method with the assistance of PVP based on semicondutor composite method. The introdunction of Bi VO4 in Bi2WO6 highly enhanced the photocatalytic performace of the composite owing to the formantion of heterojunction. Experimental results showed the higher photocatalytic antibacterial activity of Bi2WO6/Bi VO4 than that of Bi2WO6 and Bi VO4, and the antibacterial rate of marine fouling microorganism P. aeruginosa could achieve 99.99% within 30 min, and it did not exhibit significant loss of photocatalytic activity after 6 recycles, revealing its excellent photocatalytic performance and stability. In addition, the photocatalytic mechanisms were proposed based on the trapping experiments and energy band analysis. Experimental results showed that Bi2WO6/Bi VO4 has a potential application prospect in marine antibiofouling.