(304a) Nanosculpting of Electrodeposited Multilayered Nanowires and Nanotubes

The electrochemical fabrication of compositionally modulated, multilayered nanowires, and to a lesser extent nanotubes, has been widely studied, but not the selective etching of them. We will present results on the electrochemical etching of one of the nanolayers that comprise the nanowires/tubes. In contrast to etching multilayered nanowires/tubes by a chemical route, an electrochemical method can result in novel intermediate structures ranging from bamboo-like wires and tubes to complete etching to form disks and rings. As a model system, nanolayers of Au and Co-rich CoAu were electrodeposited in a sandwich fashion into nanoporous alumina and polycarbonate membranes. The Co-rich layers were selectively etched potentiostatically and the current transients inspected. The current response indicated when the surface area of the nanowires/tubes is enhanced due to shape change under diffusion controlled dissolution and signaled when the layers were completely etched. Cyclic voltammetry was also employed to characterize and track the etching process. SEM confirmed the partially etched and completely etched nanostructures.