Synthesis, characterization and enhanced photocatalytic performance of Ag2S-coupled ZnO/ZnS core/shell nanorods

A series of composite photocatalysts comprised of ZnO nanorods core and ZnS-Ag2S heterostructural shell layer with different Ag2S/ZnS molar ratios have been synthesized via the combination of a low-temperature hydrothermal growth and cation exchange technique. The core/shell nanorods, with the diameters of about 150 nm and the lengths of ranging from a few 100 nm to several micrometers, were fabricated by coating the ZnO nanorods with a layer of ZnS and Ag2S composite shell mainly consisting of nanocrystals with the diameters of about 5-8 nm. The characterization from SEM, TEM, EDX, XPS, and UV-Vis DRS reveals that the molar ratio of Ag2S/ZnS in shell layer strongly affects the morphologies, distribution of components, photo absorption, and photocatalytic performance of the ZnO/ZnS-Ag2S core/shell nanorods. Due to the coupling with low bandgap material Ag2S, the ZnO/ZnS-Ag2S nanorods have a much higher solar-simulated light absorption capability than that of ZnO/ZnS. As a result, the as-prepared ZnO/ZnS-Ag2S 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-Ag2S core/shell nanorods may be ascribed to the heterostructure, which enhanced the separation of photo-induced electron-hole pairs. (C) 2013 Elsevier B.V. All rights reserved.