Hierarchically Grown Urchinlike CdS@ZnO and CdS@Al2O3 Heteroarrays for Efficient Visible-Light-Driven Photocatalytic Hydrogen Generation

Nanourchin-shaped narrow-band-gap semiconductor photocatalysts with high surface area combined with good crystallinity result in effective photocatalysis. In this work, the impregnating growth of 1D CdS nanowires onto Al2O3 and ZnO templates as cores generates novel urchinlike morphology of CdS@oxide photocatalysts. The CdS@Al2O3 and CdS@ZnO nanourchins explicitly show a major role in enhanced hydrogen generation with apparent quantum yields (AQY) of 11% and 15%, respectively. Mechanistically, the template-based CdS can influence the photocatalytic activity in two ways: (i) direct well-dispersed growth of CdS onto the oxide core, leading to a high surface area for enhanced light absorption, and (ii) charge transfer from the conduction band of highly crystalline CdS to that of the oxide, which facilitate efficient charge separation for hydrogen production. Following these two mechanisms, a simple, low-cost, and environmentally friendly hydrothermal strategy is employed to synthesize novel nanourchin-shaped CdS-based heteroarrays. This new morphology stimulates the surface area per unit volume of the photocatalyst and exhibits promising application for photocatalytic water splitting.