Chemical etching preparation of the Bi2WO6/BiOI p–n heterojunction with enhanced photocatalytic antifouling activity under visible light irradiation

In this paper, a novel Bi2WO6/BiOI heterojunction photocatalyst was prepared based on a chemical etching method and used in photocatalytic antifouling. The as-prepared Bi2WO6/BiOI photocatalyst was composed of Bi2WO6 and BiOI, exhibiting a three-dimensional hierarchical microsphere structure. Experimental results indicated that the molar percentage of Bi2WO6 to BiOI leaded to different morphologies and photocatalytic activities of Bi2WO6/BiOI composites. 30%Bi2WO6/BiOI exhibited an improved photocatalytic performance under visible light irradiation compared to pure Bi2WO6, pure BiOI, and other Bi2WO6/BiOI composites. Almost all (99.99%) of Pseudomonas Aeruginosa (P. aeruginosa), Escherichia Coli (E. coli) and Staphylococcus Aureus (S. aureus) could be killed and the degradation efficiency of methyl blue (MB) could achieve 100% within 60 min in the presence of 30%Bi2WO6/BiOI. In addition, after six circulating photocatalytic antifouling experiments, 30%Bi2WO6/BiOI exhibited no significant loss of photocatalytic performance, verifying its stability and reusability, which was especially important for its application. Moreover, a possible photocatalytic mechanism was proposed based on active species trapping experiments, demonstrating that the superoxide radicals (O-center dot(2)-) and the holes (h(+)) were the main reactive species in this system. The obviously enhanced photocatalytic activity of the 30%Bi2WO6/BiOI heterojunction photocatalyst could be mainly attributed to the formation of the p-n heterojunction, accelerating the separation of photogenerated charge carriers. This work provides a valuable information on the design of novel heterojunction photocatalysts with excellent photocatalytic properties used in marine antifouling. (C) 2015 Elsevier B.V. All rights reserved.