Aspartic acid synthesis of crystalline gold nanoplates, nanoribbons, and nanowires in aqueous solutions

Abstract

A facile, environmentally benign shape-controlled synthesis of anisotropic crystalline gold nanostructures at room temperature has been developed using aspartic acid (Asp) as the reducing, particle-stabilizing, and shape-directing agents. Great latitude in the control of particle size and shape, including formation of hitherto unreported nanoribbons and nanowires, could be accomplished through simple manipulation of the experimental conditions. The gold precursor concentration [HAuCl4] and the concentration ratio of aspartic acid to gold precursor, R ([Asp]/[HAuCl4]), were found to be critical factors in morphosynthesis. Their effects on crystal growth into different final morphologies were examined and correlated with the growth kinetics. The experimental results also suggested a growth mechanism where the difference in rates between reduction of the gold precursor on {111} and {100} family of planes, competition between the reduction and capping functions of Asp, and Asp surface coverage determined the morphology of the nanostructure formed. © 2008 American Chemical Society.