Synthesis of open-ended, cylindrical Au-Ag alloy nanostructures on a Si/SiOx surface

Dip-pen nanolithography (DPN) in conjunction with wet chemical etching was used to synthesize a new class of open-ended, cylindrical Au-Ag alloy nanostructures on a Si/SiOx surface. Ag nanostructures were prepared by depositing dot MHA features on Ag-coated Si/SiOx, 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.