Efficient interfacial charge transfer of BiOCl-In2O3 step-scheme heterojunction for boosted photocatalytic degradation of ciprofloxacin

Abstract

• Step-scheme In 2 O 3 -BiOCl heterojunctions were synthesized by molten salt method. • Molten-salt method without organic solvent for the BiOCl-In 2 O 3 composites could endow clean surface, which is beneficial to the adsorption of reactants in the photocatalytic degradation process. • In 2 O 3 -BiOCl heterojunctions exhibited excellent photocatalytic degradation of ciprofloxacin. • Boosting photocatalytic performance is due to the formation of step-scheme heterojunction. • • O 2− and H + played critical roles in photocatalytic degradation process of ciprofloxacin. BiOCl as a representative layered bismuth-based photocatalyst with Sillén-structure has aroused wide public concern on photocatalytic degradation. However, the photocatalytic efficiency of pristine BiOCl is currently restricted by its low optical absorption and charge separation efficiency. Herein, step-scheme (S-scheme) heterojunctions of In 2 O 3 nanoparticle and BiOCl micron-sheet were constructed by a convenient molten salt method by using a LiNO 3 -KNO 3 system. The In 2 O 3 -BiOCl heterojunctions exhibit higher optical absorption performance from 380 nm to 700 nm than the pristine BiOCl and enhanced photocatalytic property toward ciprofloxacin (CIP) degradation under Xenon lamp illumination. The sample 20%In 2 O 3 -BiOCl showed the highest photodegradation efficiency, attaining 91% removal of CIP within 35 min, which was 39.6 times and 3.2 times higher than that of pristine In 2 O 3 and BiOCl, respectively. The improved photodegradation property mainly resulted from the novel S-scheme mechanism, which boosted highly efficient separation of the photo-induced carriers. The photoluminescence spectrometric test and transient photocurrent response results demonstrated that In 2 O 3 -BiOCl composite exhibited efficient separation of photo-generated charge carriers. This work would provide new insights into the design of novel S-scheme photocatalytic systems with applicability in photocatalytic water treatment.