Defect-engineered TiO2/BiOCl core-shell S-scheme heterojunction: Boosting photocatalytic degradation via optimizing charge dynamics and enhancing light absorption capacity

Herein, Ti-deficient TiO 2 was combined with oxygen-deficient BiOCl to construct a core-shell structured TiO 2 /BiOCl S-scheme heterojunction. The defect-engineered TiO 2 and BiOCl exhibited significantly enhanced tetracycline (TC) removal efficiency, which were 4.4 and 2.5 times higher than those over the defect-free TiO 2 (TiO 2 -R) and BiOCl (BiOCl-R) samples, respectively. The optimized TiO 2 /BiOCl-2 photocatalyst demonstrated the highest degradation efficiency, outperforming single BiOCl and TiO 2 by 3.2 and 2.9 times, respectively. In-depth explorations showed that the enhanced photocatalytic activity originated from the establishment of an interfacial electric field at the core/shell interface, the enhanced light utilization efficiency, and the established S-scheme charge transfer pathway. More importantly, TiO 2 /BiOCl-2 also manifested superior photocatalytic degradation efficiency when subjected to complex reaction environments. By taking into account the contributions of involved reactive species and produced intermediates, both the reaction mechanism and toxicity assessment were thoroughly explored. The present work showcases an effective strategy to improve photocatalytic efficiency by virtue of the synergy between core-shell heterojunction and defect engineering.