Crystallographic facets and shapes of gold nanorods of different aspect ratios

Crystal structures of gold nanorods synthesized electrochemically using mic elles as a capping material have been studied by high-resolution transmissi on electron microscopy. Short gold nanorods with aspect ratios of 3-7 are e nclosed mainly by (100) and (110) facets and their axial growth direction i s [001], whereas long gold nanorods of aspect ratios 20-35 are dominated by (111) and (110) facets and their growth axial direction is (112). The shor t rods are the dominant constituents, whereas the long rods are observed oc casionally. Spherical-like Au particles with equivalent mass to the short r ods are dominated by (111) and (100) facets with shapes of truncated octahe dra, icosahedra and decahedra. The unique (110) facets of Au nanorods are e xpected to have interesting surface properties. (C) 1999 Elsevier Science B .V. All rights reserved.