Cu2O-decorated CdS nanostructures for high efficiency visible light driven hydrogen production

Abstract

Cu2O-decorated CdS nanostructures are developed as highly efficient photocatalysts for hydrogen evolution from visible-light driven photocatalytic water splitting. The type II heterojunctions formed at the Cu2O/CdS interfaces facilitate charge separation that promotes photocatalytic water splitting and thus markedly improves the hydrogen evolution efficiency. For Cu2O decorated CdS nanobeads (NB), a milli-molar level specific hydrogen evolution rate of 4.76 mmol/h g is achieved, 72 times that achieved by plain CdS NBs, under irradiation of a 400 W light source using a mixture of Na2S and NaSO3 as the sacrificial reagent. The improvements in hydrogen evolution acquired from the Cu2O decoration for CdS NBs are much greater than those attained for CdS nanoparticles (NPs) and CdS nanowires (NWs). The success of using CdS NBs as the hosting base for Cu2O decoration is attributed to the much better exposed CdS surfaces after the treatment, enabling direct contact of CdS with the reactant solution for hydrogen evolution, while the Cu2O surfaces are also exposed to contact the sacrificial reagent for scavenging holes.