Controlled Synthesis of Nanoscale Icosahedral Gold Particles at Room Temperature

The shape of nanocrystals determines surface atomic arrangement and coordination, influencing their chemical and physical properties. We present a novel and facile approach to synthesize gold icosahedra by employing glucose as reducing reagent and sodium dodecyl sulfate as directing agent in the environmentally benign medium of water at room temperature. The size of the icosahedra can be controlled in the range of 30250 nm by altering reaction conditions. High-resolution microscopy and diffraction studies indicate the icosahedra are composed of rotational twins that owe likely to assemblage of tetrahedral units. The gold icosahedra particles catalytic properties are probed in the borohydride reduction of p-nitrophenols and exhibit a size-dependence reaction property. Comparison studies with spherical particles prepared by the Turkevich method, coupled with poisoning experiments, infer that the shape has a strong influence in the abundance of active surface sites as well as their activities. The properties of nanoscale icosahedra particles has promising applications for further catalytic processes, surface enhancement spectroscopic methods, chemical or biological sensing, and the fabrication of nanoscale devices.