Hydrangea‐Like Bi 4 O 5 I 2 /Na 0.5 Bi 0.5 TiO 3 Type‐II Heterojunctions For Efficient Photocatalytic Degradation of Bisphenol A

ABSTRACT Heterojunctions hold great promise for photocatalysis due to their enhanced photo‐generated electron‐hole separation efficiency. However, the development of heterojunctions with robust interfacial contact and broad visible light response remains a critical challenge. Herein, hydrangea‐like Bi 4 O 5 I 2 /Na 0.5 Bi 0.5 TiO 3 heterojunctions with an intimate interface were rationally constructed via a facile coprecipitation method. The as‐prepared heterojunctions exhibited exceptional visible light‐driven photocatalytic performance in degrading various refractory organic pollutants, including bisphenol A (BPA), tetracycline, and Rhodamine B, outperforming the parent compounds Bi 4 O 5 I 2 and Na 0.5 Bi 0.5 TiO 3 alone. Notably, the optimized heterojunction catalyst achieved complete (100%) photocatalytic removal of BPA under visible light irradiation. The enhanced activity originates from the synergy of heterojunction formation and uniform hydrangea‐like morphology, which promotes photo‐generated electron‐hole separation/transfer and inhibits their recombination. Mechanistically, the heterojunction follows a Type‐II charge transfer pathway, where photo‐generated electrons preferentially migrate and accumulate on the conduction band of Na 0.5 Bi 0.5 TiO 3 , while photo‐generated holes transfer to and enrich on the valence band of Bi 4 O 5 I 2 . These accumulated electrons efficiently reduce adsorbed O 2 molecules to generate O 2 · − , which serves as the primary active species driving BPA degradation. This study provides a useful guideline for the design and application of bismuth‐based heterojunctions in environmental remediation.