The Preparation And Characteristics Of Noble Metal(Au, Ag) SERS Substrates Based On ZnO Nanofilms

In this thesis, we mainly studied the synthesis and application of noble metal (M=Au, Ag) SERS (Surface Enhence Raman Scatting)substrates based on ZnO nanometer thin films, such as Au/ZnO mace-like hollow hierarchical micro-nanostructures, Au/ZnO nanocomposite materias, and Ag/ZnO nanosheet arrays. The major contents can be summarized as follows:1. ZnO net-like nanosheets were firstly prepared through an electrodeposition method. Au nanoparticles were attached to on the surfaces and edges of ZnO nanosheets through the second electrodeposition, the sample was used as nanocomposite SERS substrate, and the morphology, structural and Raman effect of the SERS substrate were characterized, Experimental results show that ZnO nanosheets were mutually hinged and vertically grown on ITO substrate, and Au nanoparticles were grown along the (111) crystal orientation, the Au/ZnO nanocomposite material has better Raman activity.2. ZnO nanorod arrays were firstly prepared through an eletrodeposition method, and then, the prepared ZnO nanorod arrays were employed as working electrode. A graphite flake was used as anode. The second electrodeposition was carried out in the certain concentration electrolyte under the constant current density at room temperature. Au/ZnO mace-like hollow hierarchical micro-nanostructures and Ag/ZnO nanosheet arrays were consequently obtained. The experimental results show that the gold catalyzed etching is more favorable for ZnO nanorod arrays decorated with noble metal (M=Au, Ag) nanoparticles. Especially, for Ag/ZnO nanosheet arrays, this phenomenon of the gold catalyzed etching to ZnO was very serious, almost all ZnO nanorods were etched. At the same time, solution concentration can control the morphologies of nanocomposite SERS substrates. Therefore, in order to prepare morphology controllable SERS substrates, the appropriate electrolyte concentration and Au catalytic conditions are essential. The Raman properties of the prepared M/ZnO nanocomposite SERS substrates were studied, which show that the M/ZnO nanocomposites have higher Raman enhancement effect than the noble metal (M=Au, Ag) SERS substrates and semiconductor (ZnO) SERS substrates. The SERS substrates can be used for the detection of harmful substances in food.