Samantha Meenach, Department of Chemical and Materials Engineering, Arizona State University, Biodesign Institute, 1001 S. McAllister Ave., Tempe, AZ 85287, Jared Burdick, Department of Chemistry, Arizona State University, Biodesign Institute, 1001 S. McAllister Ave., Tempe, AZ 85287, and Joseph Wang, Department of Chemical and Materials Engineering and Department of Chemistry, Arizona State University, Biodesign Institute, 1001 S. McAllister Ave., Tempe, AZ 85287.
With the increasing interest in nanotechnology, the development of novel materials for applications in nanoscale electronics, optical sensing, and mechanical and magnetic devices is on the rise. Here, we report the synthesis of nanowires incorporating nanoporous gold and polypyrrole into composite nanowires to be used in a wide variety of applications. Nanoporous gold nanowires were fabricated by the electrodeposition of a single-phase binary gold/silver alloy of various compositions into an alumina membrane template. This template fabrication can be used for the preparation of many types of nanowires including hybrid metal-polymer nanowires. The subsequent etching of the less noble metal silver from the nanowires with nitric acid created nanoporous gold nanowires. Upon the dealloying of the nanowires, the conductive polymer polypyrrole was electropolymerized into the porous template where it filled the spaces in the nanoporous gold. The nanowires were then released from the membrane template and characterized using scanning electron microscopy (SEM) imaging and energy dispersive x-ray analysis (EDX) experiments. Through SEM we were able to confirm the successful etching of the silver from the alloy nanowire as well as the addition of polypyrrole into the nanowire matrix. It was discovered that the addition of polypyrrole both increased the rigidity of the nanoporous nanowires and prevented them from becoming aggregated in aqueous solution. The nanowires were fabricated in alumina membranes with a specified pore diameter of 200 nm and were found to be approximately 200 to 300 nm in diameter and 4 to 5.5 μm in length. Through EDX experiments we were able to confirm that as the amount of gold in the gold/silver alloy is increased, the amount of gold in the nanoporous gold-polypyrrole nanowires increased while the amount of nitrogen in the wires decreased. This decrease in nitrogen corresponds to a decrease in the amount of polypyrrole in the nanowires. Overall, it is possible to incorporate other conductive polymers or metals through electrodeposition into the nanoporous gold matrix for the creation of other pseudoalloy nanowires. These nanowires can subsequently be used in a wide variety of nanotechnology applications, further enhancing the development of this field.