Synthesis and improved photoelectrochemical performances of Bi9O7.5S6/CdS heterojunction

Layered bismuth oxychalcogenides have recently emerged as promising photoelectric materials due to their visible-light bandgaps, effective charge separation, high carrier mobility, and long carrier lifetime. In order to verify the potential application of Bi9O7.5S6 for water splitting, Bi9O7.5S6/CdS composite film was prepared by combining the knife-coating and chemical bath deposition (CBD) methods. The structure, morphology and band positions were completely checked and revealed a type Ⅱ heterojunction structure in Bi9O7.5S6/CdS composite film. The thickness-dependent optical, impedance and photoelectrochemical properties have been also studied. Under the irradiation of AM 1.5 G simulated sunlight, a stable photocurrent density of ∼ 259.73 μA/cm2 has been obtained for the Bi9O7.5S6/CdS photoanode at 0 V vs. Ag/AgCl, which is about 5-fold and 40-fold higher than that of bare CdS and Bi9O7.5S6 photoanodes due to the formation of the type Ⅱ heterojunction between Bi9O7.5S6 and CdS. This work demonstrates the promising prospects of layered bismuth oxychalcogenide as cost effective, highly stable and efficient photocatalysts for water splitting.