September 27, 2006
Interschool Lab, 7th floor, Schapiro/CEPSR
Hosted by: Irving Herman - CISE
Speaker: Jeffrey W Kysar, Columbia University
Nanoporous materials have many potential applications due to their very high surface area to volume ratio. Nanoporous gold is of particular interest because of its resistance to corrosion as well as the ability to tailor the gold surface to be sensitive to various chemical and biological species. Nanoporous gold can be synthesized by subjecting a homogeneous solid solution alloy of gold and silver to a process known as dealloying, during which the silver is selectively removed from the alloy. This is commonly accomplished by immersion of the alloy into nitric or perchloric acid. In the process, the surface diffusion of the gold component is significantly enhanced which enables the remaining gold to adopt the form of a open nanoporous network of voids. The connecting ligaments and cell sizes are of the order of 10 nm to 100 nm in size depending upon processing parameters. The ratio of the volume of gold to the overall volume is between 25% and 35%. Nanoporous gold has been synthesized in bulk form, and more recently in thin film form. In this talk, we will discuss experiments in which nanoporous gold films have been synthesized with two different methods. The mechanical properties and robustness of nanoporous gold films will be examined. In addition, results in which nanoporous gold is incorporated with homogeneous gold films to make nanostructured freestanding thin films will be discussed. Finally, an array of potential applications for nanoporous gold films and nanostructures constructed from them will be explored.