Surface Decoration of ZnO Nanorod Arrays by Electrophoresis in the Au Colloidal Solution Prepared by Laser Ablation in Water

A simple and green strategy is presented to decorate ZnO nanorod array, based on electrophoresis deposition in the Au colloidal solution prepared by laser ablation in water and subsequent further laser irradiation. The surface of nanorods is homogeneously decorated with Au nanoparticles. The Au nanoparticles have good interfacial connection and strong binding with ZnO nanorods. The decoration morphology can be easily controlled by the size of Au colloids. Further experiments have revealed that suitable electrophoretic potential, small Au colloid's size, and enough inter-nanorod's spacing are crucial to formation of a homogeneous and strong surface decoration. Such Au nanoparticle-decorated ZnO nanorod array is functionalized and exhibits excellent surface-enhanced Raman scattering performance and shows the possibility of molecule-level detection. This study provides a new opportunity for the controllable surface modification of ID semiconductor nanostructures and deepens the understanding of the physical mechanism of electrophoretic deposition.