In Situ Fabrication of Z-scheme BiOI/Bi ₅ O ₇ I Heterostructure with Enhanced Photocatalytic Redox Ability for Water Purification

Bismuth oxide iodide (BiOI), as a visible light semiconductor material, is widely utilized for photocatalytic removal of water pollutants. Nevertheless, due to its intrinsic high electron-hole pair recombination rate, bare BiOI typically exhibits limited photocatalytic performance. Bi₅O₇I shares similar crystal structures and identical elemental composition with BiOI, which could facilitate the formation of a stable interface when constructing a heterostructure between the two materials. In this study, a Z-scheme BiOI/Bi₅O₇I heterostructure was fabricated via an in situ thermal annealing strategy to suppress the recombination of photoexcited charge carriers and enhance the photo-oxidation activity of bare BiOI. The photoredox efficiencies of tetracycline and phenol were significantly improved after the formation of the heterostructure, which was mainly driven by the established Z-scheme charge carrier transfer mechanism. In virtue of the synergistic effect and the formed interface bonding between BiOI and Bi₅O₇I, the spatial separation of carriers and their subsequent transfer efficiency have been prominently enhanced, rendering the BiOI/Bi₅O₇I heterostructures possessed with a powerful photoredox capacity, thereby improving the photocatalytic activity of BiOI.