Synthesis of ZnO nanosheets decorated with Au nanoparticles and its application in recyclable 3D surface-enhanced Raman scattering substrates

Abstract

Au decorated ZnO (Au/ZnO) nanosheets were prepared by ultra-thin liquid layer electrodeposition and galvanic reduction route. Polycrystalline Zn backbones with dense single-crystalline ZnO nanosheets covering the surface were electrodeposited on SiO₂ by controlling the ion concentration and deposition potential. The Zn/ZnO micro/nanostructure was used as a template and reducing reagent for preparing Au/ZnO composite nanosheets via a low-cost and convenient galvanic reduction method. The coverage and size of Au nanoparticles (NPs) on ZnO nanosheets surface can be changed by tuning the concentration of Au precursor. The Au protrusions and gaps between them contribute to 3D SERS “hot spots” which can be modulated by simply controlling the HAuCl₄ concentration. The substrates can be easily self-cleaned and reactivated by UV irradiation to eliminate the single-use problem of traditional SERS substrates. This study suggested that the Au decorated ZnO nanosheets would be promising as high SERS-active substrates with UV-cleanable and regenerated property.