Controllable one-pot synthesis of a nest-like Bi2WO6/BiVO4 composite with enhanced photocatalytic antifouling performance under visible light irradiation

Abstract

In this study, a novel visible-light-sensitive Bi₂WO₆/BiVO₄ composite photocatalyst was controllably synthesized through a facile one-pot hydrothermal method. The Bi₂WO₆/BiVO₄ composite exhibited a perfect nest-like hierarchical microsphere structure, which was constructed by the self-assembly of nanoplates with the assistance of polyvinylpyrrolidone (PVP). The growth mechanism of the Bi₂WO₆/BiVO₄ composite and the effect of its structure on its photocatalytic performance was investigated and proposed. Experimental results showed that the Bi₂WO₆/BiVO₄ composites displayed enhanced photocatalytic antifouling activities under visible light irradiation compared to pure Bi₂WO₆ and BiVO₄. Bi₂WO₆/BiVO₄-1 exhibited the best photocatalytic antifouling performance, and almost all (99.99%) Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were killed within 30 min. Moreover, the Bi₂WO₆/BiVO₄-1 composite exhibited excellent stability and reusability in the cycled experiments. The photocatalytic antifouling mechanism was proposed based on the active species trapping experiments, revealing that the photo-induced holes (h⁺) and hydroxyl radicals (˙OH) could attack the cell wall and cytoplasmic membrane directly and lead to the death of bacteria. The obviously enhanced photocatalytic activity of the Bi₂WO₆/BiVO₄-1 composite could be mainly attributed to the formation of heterojunctions, accelerating the separation of photo-induced electrons and holes. Furthermore, the large BET surface area combined with the wide photoabsorption region further improved the photocatalytic performance of the Bi₂WO₆/BiVO₄-1 composite. This study provides a new strategy to develop novel composite photocatalysts with enhanced photocatalytic performance for marine antifouling and water purification.