Fabrication and photocatalytic performance of BiOI-CuWO4 heterojunction flexible films

We prepared CuWO 4 films and BiOI-CuWO 4 heterojunction films on the surface of copper wire mesh using a simple and low-cost anodization method and immersion method. The light absorption measurement of these films indicated that, compared to the single CuWO 4 films, the BiOI-CuWO 4 heterojunction films exhibited a significant enhancement in light absorption capacity in both the ultraviolet and visible light regions, and its bandgap width continuously decreased with an increase in the number of immersion cycles. The heterojunction formation also enhanced the separation and transfer of photogenerated charge carriers within the films, leading to an increased photocatalytic activity for the degradation of methylene blue (MB) under simulated sunlight. The activity of the heterojunction films was improved by approximately 57% at most compared to the single CuWO 4 films. Their photocatalytic activity remained at a high level after multiple repeated evaluations, ensuring stable performance during long-term use. Active species trapping experiments demonstrated that superoxide radicals play a crucial role in the photocatalytic degradation process. The photogenerated charge carrier transfer mechanism we propose suggests that the photogenerated electrons generated in BiOI transfer to the conduction band of CuWO 4 , while the photoinduced holes produced in the valence band of CuWO 4 transfer to the valence band of BiOI simultaneously, achieving the spatial separation and transfer of photogenerated electrons and holes.