Synthesis of cadmium sulfide quantum dot-decorated barium stannate nanowires for photoelectrochemical water splitting

Abstract

We report the fabrication of cadmium sulfide (CdS) quantum dot-decorated barium stannate (BaSnO₃) nanowires and their application as photoanodes for photoelectrochemical water splitting. First, polycrystalline BaSnO₃ nanowires, which have a perovskite structure, were prepared by electrospinning their polyvinylpyrrolidone polymer precursors and calcining the resultant polymer fibres. Then, CdS quantum dots were decorated onto the BaSnO₃ nanowires by a wet-chemical method. Our results show that the hybrid photoanode made of the CdS quantum dot-decorated BaSnO₃ nanowires exhibits a high photocurrent density up to 4.8 mA cm⁻² at 0 V (vs. saturated calomel electrode), which corresponds to a hydrogen generation rate of 71.8 μmol (h cm²)⁻¹ with a faradaic efficiency of around 80%. Its favourable performance was attributed to the effective charge separation at the type II staggered gap heterojunction formed at the BaSnO₃/CdS interface, and the low charge recombination in BaSnO₃ nanowires during transport. Our findings indicate that the water splitting performance of photoelectrochemical cells can be highly improved by rationally building a type II band alignment heterojunction with sensitizing quantum dots and wide band gap semiconductor nanowires which have a low charge recombination rate during transport.