Novel Ag-Bridged Z-Scheme CdS/Ag/BiWO Heterojunction: Excellent Photocatalytic Performance and Insight into the Underlying Mechanism.

The construction of semiconductor heterojunction photocatalysts that improve the separation and transfer of photoinduced charge carriers is an effective and widely employed strategy to boost photocatalytic performance. Herein, we have successfully constructed a CdS/Ag/BiWO Z-scheme heterojunction with an Ag-bridge as an effective charge transfer channel by a facile process. The heterostructure consists of both CdS and Ag nanoparticles anchored on the surface of BiWO nanosheets. The photocatalytic efficiency of the CdS/Ag/BiWO system was studied by the decontamination of tetracycline (TC) and Rhodamine B (RhB) under visible light irradiation (λ ≥ 420). The results exhibited that CdS/Ag/BiWO shows markedly higher photocatalytic performance than that of CdS, BiWO, Ag/BiWO, and CdS/BiWO. The trapping experiment results verified that the O and h radicals are the key active species. The results of photoluminescence spectral analysis and photocurrent responses indicated that the CdS/Ag/BiWO heterojunctions exhibit exceptional efficiency in separating and transferring photoinduced electron-hole pairs. Based on a series of characterization results, the boosted photocatalytic activity of the CdS/Ag/BiWO system is mostly due to the successful formation of the Ag-bridged Z-scheme heterojunction; these can not only inhibit the recombination rate of photoinduced charge carriers but also possess a splendid redox capacity. The work provides a way for designing a Z-scheme photocatalytic system based on Ag-bridged for boosting photocatalytic performance.