Interfacial Engineering of WO3/SnS Heterostructures for Accelerated Charge Carrier Transport in Photoelectrochemical Water Splitting

Abstract Metal oxide and chalcogenide-based heterojunctions provide a practical pathway for boosting the efficiency of photoelectrochemical water splitting. In this report, a WO3/SnS heterojunction was successfully fabricated to enhance the photoelectrochemical water splitting response under solar radiation. A sequential fabrication process was employed to fabricate the working electrodes, in which a WO3 thin layer was deposited by DC sputtering and SnS nanostructures were subsequently formed using glancing angle electron beam evaporation. The optimized WO3/SnS photoanode revealed a significantly higher photocurrent density of 2.02 mA/cm2 at 1 V against Ag/AgCl, substantially outperforming pristine WO3. This improvement can be ascribed to the existence of a type-II heterojunction between WO3 and SnS, which promotes directional charge carrier separation and suppresses bulk and interfacial recombination. The WO3/SnS reveal a notable shift in the value of flat band potential from −0.06 V (WO3) to −0.2 V (WO3/SnS) vs Ag/AgCl with increased donor density, affirming the enhanced charge transport efficiency. This research work introduces a strategy for engineering WO3/SnS photoanodes that enables superior light absorption and efficient charge transfer, paving the way for highly effective solar-driven hydrogen production.