Pyrolysis preparation of ZnO/BiOI composite photocatalyst with enhanced photocatalytic performance

Photocatalytic degradation has emerged as an effective and practical method for eliminating dyes from contaminated water. In this study, a ZnO/BiOI heterojunction photocatalyst was synthesized by the calcination of zinc nitrate and bismuth iodide. The photodegradation of rhodamine B (RhB) utilizing the as-prepared ZnO/BiOI composite demonstrated that this composite exhibited significantly enhanced photocatalytic activity compared to both BiOI and ZnO alone. With the optimized proportion, the ZnO/BiOI-0.5 composite showed the highest rate constant with approximately 31 times higher than that of ZnO and about 142 times higher than that of BiOI. The improved catalytic performance of the composite was due to the formation of a heterojunction structure between ZnO and BiOI. The primary active species identified in this study were superoxide radicals (•O 2 − ), hydroxyl radicals (•OH) and holes (h + ). Moreover, mass spectroscopic analysis and toxicity evaluation were conducted to probe the degradation pathway and toxicity of the degradation intermediates of RhB. One-pot preparation of a ZnO/BiOI n-n heterojunction photocatalyst for the efficient photodegradation of rhodamine B (RhB). • ZnO/BiOI n-n heterojunction composite was prepared via a one-step calcination method. • ZnO/BiOI composite showed greatly improved photocatalytic activity. • The improved catalytic activity resulted from enhanced charge separation and transfer. • RhB was oxidized to less toxic intermediates, which can be further degraded to H 2 O and CO 2 .