Synthesis and visible photocatalytic activities of a Au@Ag@ZnO triple layer core-shell nanostructure

We report a facile route for the synthesis of a Au@Ag@ZnO triple layer core-shell nanostructure with Au as core, Ag as intermediate layer and ZnO as an outer shell. The thickness and surface plasmon resonance (SPR) absorption peak of the Ag shell of Au@Ag bimetal has been controlled by the concentration of AgNO3. In the Au@Ag@ZnO nanostructure two major absorption peaks were seen, one due to SPR of Au and other due to the combined effect of Ag and a ZnO layer. The photoluminescence study shows that the Au@Ag@ZnO has better charge separation compared to the ZnO and Au@ZnO nanostructure. The visible photocatalytic activity for the degradation of methyl orange dye was found to be much higher in the case of the Au@Ag@ZnO core-shell structure than ZnO or Au@ZnO or TiO2.