Inverted ZnSe/CdSe core–shell nanobelts with type-I behavior: preparation, photoelectrochemical and photocatalytic performances

Abstract

ZnSe nanobelts were prepared on a gold-coated silicon substrate by a thermal evaporation method, and inverted ZnSe/CdSe core–shell nanobelts were formed by coating a narrow-gap CdSe shell outside the as-prepared wide-gap ZnSe nanobelt through a cation replacement process. ZnSe/CdSe core–shell nanobelts showed enhanced luminescence performance and extended visible light absorption compared with pristine ZnSe nanobelts. Photoelectrochemical (PEC) characterization indicated that the inverted core–shell nanobelts had higher photocurrent, lower resistance and better photocurrent stability under visible light irradiation than the pristine ZnSe nanobelts, which can be attributed to the passivation of surface defects of the ZnSe nanobelts by the CdSe shell and type-I localization, in which both electrons and holes are localized over the entire core–shell nanobelt. The photocatalytic activities of both pristine ZnSe and ZnSe/CdSe nanobelts are significantly improved compared with commercial ZnSe powder, which might be due to the higher specific area of the belt morphology and the anionic surface of the nanobelts. The strategy provides a flexible and straightforward route to the design and preparation of inverted core–shell nanobelts for new opportunities in PEC applications.