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

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.