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

Abstract

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 150nm and the lengths of ranging from a few 100nm 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 5–8nm. 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.