Synthesis of Open-ended, Cylindrical Au-Ag Alloy Nanostructures on a Si/SiO_x Surface

Dip-pen nanolithography (OPN) in conjunction with wet chemical etching was used to synthesize a new class of open-ended, cylindrical Au-Ag alloy nanostructures on a Si/SiO_x surface. Ag nanostructures were prepared by depositing dot MHA features on Ag-coated Si/SiO_x, followed by etching with ferri/ferrocyanide solution. When these Ag nanostructures are reacted with HAuCl₄, electroless plating of Au occurs on the sidewalls of the silver features along with concomitant oxidation of the Ag. This results in the formation of novel open-ended, cylindrical Au-Ag alloy nanostructures. Insight into the mechanism for this process is provided. © 2004 American Chemical Society