Surface reconstruction effects on the structural evolution of gold nanorods

INOR 1021

Michael Bockstaller, Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, Heidrun Keul, Institute for Technical and Macromolecular Chemistry and DWI, RWTH Aachen University, Pauwelstr. 8, Aachen, 52056, Germany, and Martin Moeller,, Deutsches Wollforschungsinstitut an der RWTH Aachen e.V, Pauwelsstrasse 8, Aachen, D-52056, Germany.
Single-crystalline gold nanorods synthesized by the Ag(I)-mediated seeded-growth method were used as seeds for the preferential overgrowth of gold on particular crystallographic facets by systematic variation of the conditions during overgrowth. Interestingly, secondary overgrowth is found to inevitably result in a loss of particle shape anisotropy. A mechanism based on surface reconstruction is proposed to rationalize the “shape-reversal” that is generally observed in the nanorod growth process, that is, the initial increase and subsequent decrease of particle anisotropy with increasing reaction time. High-resolution electron microscopy analysis of gold nanorods reveals clear evidence for (1 x 2) missing row surface reconstruction of high energetic {110} facets that form during the initial phase during particle growth.