Surfactant-Promoted Reductive Synthesis of Shape-Controlled Gold Nanostructures

We describe a surfactant-promoted reductive route for the shape-controlled synthesis of gold nanostructures by hydrothermal treatment of chloroauric acid in the presence of the surfactant hexadecyltrimethylammonium bromide (CTAB) without using reducing agent. The results show that the cationic surfactant CTAB provides the dual function of promoting Au-III reduction to Au-0 and size- and shape-controlled synthesis of the gold nanocrystals. More importantly, the benefit of the present work stems from the first report on the controlled synthesis of gold nanostructures by hydrothermal treatment of chloroauric acid in the presence of the surfactant CTAB without using reducing agent. The kinetics of the reduction could be manipulated through changes in the CTAB concentration to produce gold nanostructures with shapes ranging from three-dimensional (313) octahedra, triangles, to two-dimensional (213) hexagonal nanoplates in high yields. Growth of gold nanostructures in the CTAB solution with concentration was monitored by microscopic and spectroscopic techniques.