Bacitracin-Controlled BiOI/Bi₅O₇I Nanosheet Assembly and S-Scheme Heterojunction Formation for Enhanced Photocatalytic Performances

Coupling heterojunction is an effective and feasible approach to suppressing the electron-hole recombination of a photocatalyst. However, the heterojunction performance is limited by poor interface contact between two semiconductors. Therefore, an in situ partial conversion procedure was proposed to fabricate the flower-spherical BiOI/Bi5O7I (BBOI) heterojunction using bacitracin as a template. The introduction of bacitracin can regulate the assembly of nanosheets into a flower-spherical structure, which caused the BBOI photocatalysts to have larger specific surface areas than BiOI or Bi5O7I. In particular, the dosage of bacitracin can control the thermal conversion of BiOI to Bi5O7I. The in situ partial conversion of BiOI caused the formation of an intimate S-scheme heterojunction interface between BiOI and Bi5O7I, which efficiently inhibited the combination of photogenerated carriers. Upon visible-light irradiation, BBOI-3 exhibited the highest catalytic ability for the simultaneous reduction of Cr(VI) (100%) and oxidative degradation of tetracycline hydrochloride (TH) (80.0%). This work provides an opinion to construct the high-performance heterojunction photocatalysts to environmental remediation.