Hydrothermal synthesis of silver nanocubes with tunable edge lengths and their size dependent SERS behaviors

Silver nanocubes (NCs) with different edge lengths were successfully prepared by a facile hydrothermal method with glucose as a reducing agent. The average edge length of the silver NCs could be tailored from 45 to 75 nm by changing the amount of glucose and the reaction time. Even larger silver NCs with average edge length of 105 nm could be synthesized by a secondary hydrothermal growth process. The experiment results of the size-dependent surface plasmon resonance properties of these silver NCs were directly compared with theoretical calculations. The surface-enhanced Raman scattering (SERS) efficiency of these silver NCs was further evaluated by using rhodamine 6G and 4-mercaptobenzoic acid as Raman probe molecules. It was demonstrated that the intensity of SERS signal was related to the sizes of the samples, and the highest signal was observed by selecting the 105 nm silver NCs as substrates. Moreover, the silver NCs showed significant advantage on improving the homogeneity of the SERS intensity.166