ZnO/ZnS–PdS core/shell nanorods: Synthesis, characterization and application for photocatalytic hydrogen production from a glycerol/water solution

Abstract

The composite photocatalysts comprised of ZnO nanorods core and ZnS–PdS heterostructural shell layer with different PdS/ZnS molar ratios were prepared via the combination of a low-temperature hydrothermal growth and cation exchange technique. The SEM and TEM results reveal that the ZnO nanorods, with the diameters of about 150nm and the lengths of ranging from a few hundred nanometers to several micrometers, were coated by a layer of ZnS and PdS composite shell mainly consisting of nanocrystal in size of 5–8nm. The molar ratios of PdS/ZnS in shell layer strongly affect the morphology, distribution of components, photo absorption and photocatalytic activity of the ZnO/ZnS–PdS core/shell nanorods. With coupling low band gap PdS, the ZnO/ZnS–PdS nanorods have a much higher light absorption capability than ZnO/ZnS. As a result, the as-prepared ZnO/ZnS–PdS nanocomposites exhibited much higher catalytic efficiency for the hydrogen production from glycerol aqueous solution. The superior photo absorption properties and photocatalytic performance of the ZnO/ZnS–PdS core/shell nanorods may be ascribed to the heterostructure, which enhanced the separation of photoinduced electron–hole pairs and improved the charge transfer ability and meanwhile, efficiently inhibited the recombination of photoinduced electron–hole pairs.