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 CO 2 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 CO 2 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 CO 2 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.

Solar-driven CO2 with H2O conversion into valuable chemical fuels has attracted considerable attention. However, the low separation efficiency of photogenerated carriers and deficient surface-active sites on catalysts result in low CO2 reduction activity. Herein, the bulk Bi2O2(OH)­(NO3) material was exfoliated to atomically thin nanosheets for shortening the migration distance of photoinduced carriers and enlarging the specific surface area. Photoreduction CO2 test results showed that the CO yield of nanosheets could be enhanced up to nearly six times compared to that of the bulk catalyst. Moreover, a series of ultrathin Bi2O2(OH)1+x (NO3)1–x nanosheets were constructed based on the surface regulation of the OH– concentration on ultrathin nanosheets. The optimized catalyst had an elevated CO yield of 16.7 μmol/g after irradiation for 3 h, about 10 times higher than that of the bulk catalyst. Further theoretical calculations revealed that the superficial NO3 – has stronger charge accumulation/depletion behavior with the adjacent Bi atom than surface OH–, conducive to the transfer of photogenerated charge from the bulk phase to the catalyst surface. This work may provide a powerful strategy for the design of a surface-controlled 2D ultrathin photocatalyst for efficient CO2 reduction.