Synthesis of porous wires from directed assemblies of nanospheres.

A method is reported for the fabrication of wires with extended pore structures. Nanospheres are initially infiltrated into the one-dimensional channels of alumina or polymer porous membranes. Metal is then electrochemically deposited within the channels. Removal of the membrane and nanospheres results in porous wires. The production of 1-mum diameter wires with 300- or 500-nm diameter pores and 300-nm diameter wires with 140-nm pores illustrates the utility of this approach. Contacts between the spheres and the channel wall result in openings on the surface of the wires, and contacts between the spheres themselves produce openings between adjacent pores. Some short-range ordering of the spheres within the channels, as reflected in the wire pore structure, is evident. Characterization of the porous wires by electron microscopy is presented, and the potential applications of materials is discussed.