Ambient controlled synthesis of advanced core–shell plasmonic Ag@ZnO photocatalysts

Abstract

Plasmonic Ag@ZnO core–shell hybrids, including hetero-nanowires and hetero-nanoparticles, have been synthesized at room temperature for application in photocatalysis. The morphology, size, crystal structure, and composition of the products were investigated by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. It was found the concentration of Zn(NO₃)₂·6H₂O and the amount of water play crucial roles in the formation of Ag@ZnO core–shell hybrids. The resultant Ag@ZnO core–shell hybrids exhibit much higher photocatalytic activity and stability towards degradation of organic contaminants than pure ZnO nanocrystals under solar light irradiation. The one-dimensional (1D) core–shell hetero-nanowires prepared under optimal conditions (i.e. 0.6 M Zn(NO₃)₂·6H₂O and 14.5 mL water) exhibit the best photocatalytic performance. The drastic enhancement in photocatalytic activity over the Ag@ZnO core–shell hybrids, especially the 1D core–shell hetero-nanowires, could be attributed to the synergistic effects of the surface ZnO and Ag nanowire cores with the surface plasmon resonance and the electron sink effect, as well as the unique 1D core–shell nanostructure for efficient mass transfer. The possible mechanism for degradation of rhodamine B (RhB) under solar light irradiation was discussed. This work provides a very convenient chemical route to prepare stable and highly efficient solar light driven plasmonic core–shell Ag@ZnO photocatalysts for cost-effective water purification.