Research On The Preparation And Photocatalytic Antifouling Properties Of Silver Salt Semiconductor Materials

Marine biofouling causes great damage to offshore engineering facilities,involving more than 4,000 species of marine life.There are many ways to protect metals from biofouling in marine and the most widely used one is commercial antifouling coating.The method is simple and low cost with excellent efficiency.However,due to the presence of biocides in these coatings,the balance of marine biological system is being damaged.Therefore,it is imperative to develop environmental friendly antifouling coatings or new antifouling technologies.In this paper,a new type of photocatalytic sterilization and antifouling technology was selected.AgVO₃ and ZnO were used as the substrate materials,and they were combined with Ag₂MoO₄ and AgBr to form composite photocatalysts with different heterojunction structures to enhance light trapping ability,extend the light absorption area,reduce the recombination of electrons and hole pairs,improve their photocatalytic activity and obtain excellent antibacterial antifouling materials.According to the degradation,antibacterial experimental data and free radical trapping experiments,the photocatalytic antibacterial and antifouling activities of the composites were evaluated,and the corresponding photocatalytic reaction mechanism was proposed,which will provide a theoretical basis for the development of stable,efficient and environmental friendly antibacterial antifouling semiconductor materials.The specific research contents were as follows:（1）The AgVO₃ nanomaterial with one-dimensional rod-like structure was synthesized by hydrothermal method,and then AgBr was loaded on the surface by in-situ growth method.The（501）crystal plane of AgVO₃ and the（200）crystal plane of AgBr were successfully combined to form the AgBr/AgVO₃ composite.The photocatalytic degradation experiments showed that the 0.5 AgBr/AgVO₃ composite had excellent photocatalytic activity,and the degradation rate of RhB reached 92.3%after 150 min under visible light irradiation.In the photocatalytic antibacterial antifouling experiment,it was found that more than 99.9970%of E.coli,P.aeruginosa and S.aureus were killed using 0.5 AgBr/AgVO₃ heterojunction photocatalyst within 30 min,indicating 0.5 AgBr/AgVO₃ composite had excellent antibacterial properties.After 6 cycles of sterilization experiments,The antibacterial rate of 0.5 AgBr/AgVO₃ composite to P.aeruginosa did not decrease significantly,indicating that the composite had good reusability.According to the free radical trapping experiment and the above data,the photocatalytic mechanism of the composites was proposed.（2）AgBr/Ag₂MoO₄@AgVO₃ photocatalysts with different molar ratios were prepared by hydrothermal method and in situ growth method.The effects of different loadings of AgBr and Ag₂MoO₄ on the photocatalytic activity of the prepared composites were investigated.The results showed that 1.0 AgBr/Ag₂MoO₄@AgVO₃photocatalyst had the best degradation effect on RhB solution,and the degradation rate reached 94.9%.In the photocatalytic antibacterial and antifouling experiment,the antibacterial rate of 1.0 AgBr/Ag₂MoO₄@AgVO₃ photocatalyst to all three model bacteria exceeded 99.99%.After 5 cycles,the antibacterial rate of the catalyst against P.aeruginosa still reached 98.5942%,indicating that the material had good antibacterial properties and stability.（3）The AgBr/Ag₂MoO₄@ZnO composites with Z-type structure were synthesized by hydrothermal method and in-situ growth method.The morphology,composition and structure of the prepared composites were characterized by XRD,SEM,XPS and HRTEM.The photodegradation experiments were carried out by selecting ciprofloxacin（CIP）and rhodamine B（RhB）as targets to reveal the photocatalytic activity of the prepared composites.The photocatalytic degradation experiments showed that the degradation rate of CIP by 0.5 AgBr/Ag₂MoO₄@ZnO photocatalyst was 80.5%under visible light irradiation,showing good photocatalytic activity.After 60 min of illumination,more than 99.999%of E.coli,P.aeruginosa and S.aureus were killed.In addition,after 5 cycles of sterilization experiments,the catalyst still showed good stability,indicating that the 0.5 AgBr/Ag₂MoO₄@ZnO composite photocatalyst had excellent photocatalytic activity.The photocatalytic reaction mechanism of the composites was proposed by free radical trapping experiments.