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. Bi 5 O 7 I 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/Bi 5 O 7 I 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 Bi 5 O 7 I, the spatial separation of carriers and their subsequent transfer efficiency have been prominently enhanced, rendering the BiOI/Bi 5 O 7 I heterostructures possessed with a powerful photoredox capacity, thereby improving the photocatalytic activity of BiOI.