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–Ag 2 S heterostructural shell layer with different Ag 2 S/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 Ag 2 S 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 Ag 2 S/ZnS in shell layer strongly affects the morphologies, distribution of components, photo absorption, and photocatalytic performance of the ZnO/ZnS–Ag 2 S core/shell nanorods. Due to the coupling with low bandgap material Ag 2 S, the ZnO/ZnS–Ag 2 S nanorods have a much higher solar-simulated light absorption capability than that of ZnO/ZnS. As a result, the as-prepared ZnO/ZnS–Ag 2 S 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–Ag 2 S core/shell nanorods may be ascribed to the heterostructure, which enhanced the separation of photo-induced electron–hole pairs.