Electric Field Coupling in the S-Scheme CdS/BiOCl Heterojunction for Boosted Charge Transport toward Photocatalytic CO2 Reduction

Step-scheme (S-scheme) photocatalysts have received much attention owing to the enhanced photocatalytic redox ability. However, the carrier transport driven only by the interfacial electric field of the S-scheme heterojunction is not efficient enough to satisfy the highly active CO2 reduction. In this study, we realize the coupling of multiple electric fields and the accelerating of charge transfer in the CdS/BiOCl heterojunction by regulating the contact interface of CdS and BiOCl. The photoreduction CO2 test results show that all composites exhibit a higher photocatalytic activity than pure CdS and BiOCl, indicating the inherent advantages of the S-scheme heterojunction. More importantly, the CdS/BiOCl composites (Cx-B001) assembled by the {001}facet-exposed BiOCl nanosheets show significantly boosted photocatalytic activity compared to the counterpart (Cx-B010) constructed by the {010}-facet-exposed BiOCl nanosheets. The enhanced CO2 reduction activity of Cx-B001 is attributed to the more effective charge transport, which is synergistically driven by the electric field at the heterojunction interface and the polarization electric field in the BiOCl phase. This work may provide some useful insights into the design of highly efficient S-scheme photocatalysts.