Sensitization of vertically grown ZnO 2D thin sheets by MoSx for efficient charge separation process towards photoelectrochemical water splitting reaction

Abstract

Development of advanced materials for photoelectrochemical (PEC) water splitting has become an essential issue for efficient, green, and economical hydrogen production. In this context, vertically grown thin sheets of ZnO is developed, which can function as an efficient photoanode in PEC water splitting reaction. Further, the PEC activity of ZnO is enriched by decorating a newly developed co-catalyst, which is amorphous MoSx through efficient charge transportation. MoSx nanostructure is decorated on the surface of ZnO nanosheet via electrodeposition technique. MoSx adorned ZnO shows enhanced activity towards photoanodic PEC water splitting compared to bare ZnO. ZnO@MoSx can generate photocurrent density nearly three times higher compared to bare ZnO at an applied potential of ‘0.5998’ V vs. RHE. Sensitization of MoSx on ZnO surface results in an enhancement in carrier density; ZnO@MoSx shows nearly 7.4-times higher carrier density compared to bare ZnO. Maximum photoconversion efficiency, 0.934% is achieved in the case of ZnO@MoSx. The determined band alignment of ZnO and MoSx indicate the formation of type-II heterostructure which allow facile charge carrier separation. Efficient charge separation is also confirmed with the help of PL spectroscopy. It further restricts the electron-hole recombination in ZnO, leading to enhanced PEC activity. ZnO@MoSx thin sheets are very stable even up to 1000 s under chopped illumination condition.