Preparation of ZnO/ZnS thin films for enhancing the photoelectrochemical performance of ZnO

In this work, ZnO/ZnS bilayered films were synthesized by a facile magnetron sputtering deposition. Further, ZnO/ZnS films displayed higher photoelectrochemical (PEC) activities as well as dark current values than ZnO film ones. The mechanism for performance improvement was investigated by both Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) plots. It was revealed that the improved PEC activity was attributed to more efficient charge transfer/separation. Finally, a schematic model was developed to clarify the charge transfer/transport inside the heterojunction (HJ) electrodes.