Fabrication of one dimensional hierarchical WO/BiOI heterojunctions with enhanced visible light activity for degradation of pollutants.

One-dimensional (1D) hierarchical WO/BiOI p-n (WB) heterojunctions with different mass percentages of WO were fabricated through a precipitation process. Various analytical techniques were employed to characterize the resulting WB composites, and their photocatalytic properties were measured by the degradation of rhodamine B (RhB) and methylene blue (MB) under irradiation of visible light. The WB heterojunctions showed largely enhanced photocatalytic performance as compared to the pure photocatalysts. Notably, the degradation rate constant of RhB by WB-10 was 3.3 and 33.6 times higher than those of pure BiOI and WO, respectively. The enhanced activity could be attributed to the hierarchical p-n heterostructures, which can supply more reaction sites and effectively promote the separation of photogenerated charge carriers, as confirmed by PL and photocurrent. Trapping experiments implied that holes (h) and superoxide anion radicals (˙O ) were the dominant active species for organic pollutants decomposition on the WB composites. This work may benefit the construction of hierarchical heterostructures with high photocatalytic efficiency.