In situ fabrication of a 2D/2D WO3/Bi5O7I S-scheme heterojunction with enhanced spatial charge separation and tetracycline degradation

Abstract

Constructing an interfacial optimized heterojunction with plentiful connections and strong electric field interactions is an effective method to promote the efficiency of spatial charge separation and photocatalytic activity. Herein, a 2D/2D WO₃/Bi₅O₇I heterojunction with an S-scheme structure was prepared by a simple calcination method. WO₃ nanosheets were uniformly anchored to the surface of porous Bi₅O₇I nanoplates. The prepared 2D/2D WO₃/Bi₅O₇I heterojunction showed excellent performance and long-term cycling stability in the photocatalytic degradation of tetracycline. In particular, 15% WO₃/Bi₅O₇I exhibited the best tetracycline degradation activity, which was 8.93 and 4.47 times that of pristine WO₃ and Bi₅O₇I, respectively. The enhanced photocatalytic performance is attributed to the intimate interfacial contact between the photocatalysts, resulting in an internal electric field at the 2D/2D WO₃/Bi₅O₇I heterojunction interface. This facilitated the separation and utilization of photo-generated charge carriers, thus suppressing the high recombination rates in Bi₅O₇I. A possible S-scheme charge transfer pathway is proposed at the interface of the 2D/2D WO₃/Bi₅O₇I heterojunction.