Abstract
Abstract In this study,we use the silver-assisted method to synthesis gold nanorods and control the aspect ratio. Under this kind of seed-mediated growth, we can tune the aspect ratio from 1.8 to 5. Among those gold nanorods we synethsis, we choose gold nanorods with longitudinal surface resonance wavelength between 750nm to 800nm as the seed for synthesizing Au-CdSe core-shell nanorods.In order to adapt cation exchange process, we have to control three major steps：(1)Au-Ag core-shell nanorods synthesis (2) Au-Ag2Se core-shell nanorods synthesis (3) Au-CdSe core-shell nanorods synthesis. In step (1), To get well coverage of Ag shell, we choose PVP and C16TAB as the ligand for synthsizing Au-Ag core-shell nanorods. As the result, we can control the shell thickness at about 3 nm for next step synthesis. In step(2), we choose selenourea as the source for producing Ag2Se shell,meanwhile in the expect of maintain the shell structure, we also control the amount of selenourea we use. By characterizing with HR-TEM and XRD, we finally confirm the heterostructure we produce is Au-Ag2Se core-shell nanorod. In last step, we perform the cation exchange process for transforming Ag2Se shell to CdSe, also increasing the CdSe shell thickness.