Seed-Morphology-Directed Synthesis of Concave Gold Nanocrystals with Tunable Sizes

We report the fabrication of concave gold (Au) nanocrystals with a set of morphologies and controlled sizes via seeded growth. Starting with Au seeds with a well-defined morphology and uniform size, cubic and rodlike Au nanocrystals with a noticeable concave feature could be successfully obtained, respectively. We also track the growth process and record the shape evolution process. The effect of several reaction parameters on product morphology, such as capping agent and concentration of Ag+, are systematically investigated. Their optical and electrochemical properties are investigated via UV-vis extinction spectroscopy and cyclic voltammetry, respectively. Compared to spherical counterparts, the current concave Au nanocrystals exhibit a noticeable red shift of the absorbance peak in UV-vis extinction spectra and characterized electrochemical behavior of stepped facets, illustrating the morphological advantage.