Investigation of charge carrier dynamics in beaded ZnO nanowire decorated with SnS2/IrOx cocatalysts for enhanced photoelectrochemical water splitting

Abstract

We report the synthesis of shape-modulated ZnO nanowires (NWs) and their role to achieve competent photoelectrochemical water splitting (PEC-WS) performance. The carrier dynamics of smooth (s-) and beaded ZnO NW (b-ZnO NW) photoanodes were investigated using time-resolved, temperature-controlled (room-temperature and low-temperature) photoluminescence spectroscopy. The enhanced PEC-WS performance obtained with the bZnO NWs was related to the reduced density of surface recombination states, superior crystallinity, and enhanced carrier lifetime, which improved carrier separation. Furthermore, an effective type-II aligned structure with bZnO NWs encapsulated in SnS2 and IrOx co-catalyst for enhanced PEC-WS performance and viability have been demonstrated. The optimized IrOx/15 nm SnS2/b-ZnO NW photoanodes demonstrated higher PEC-WS performance (0.58 mA/cm2 at 1.23 V vs RHE) with feasible photostability retention. We believe that our structural modulation approach, in-depth understanding of the carrier dynamics, and demonstration of a co-catalystenabled core-shell structure will be beneficial for obtaining highly efficient PEC-WS performances in ZnObased photoanodes.