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

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 150 nm 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 5-8 nm. 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 electronhole pairs. (C) 2013 Elsevier B.V. All rights reserved.