This grant looks at the formation mechanism, coarsening behavior, and applications of nanoporous gold (NPG). NPG is formed by dissolving silver from gold/silver alloys in acid, a dealloying process that leaves behind an open sponge of nearly pure gold. By varying the experimental conditions such as the pre-alloyed composition and post-dealloying annealing time, the size of the spongy ligaments is tunable over length scales from 5 nm to many microns. For this research NPG is a model system for studying nanoscale surface kinetics. NPG films will be grown by electron beam evaporation, and the time evolution of the porosity will be characterized by SEM and TEM. Coarsening behavior will be examined to measure surface diffusivity as a function of chemical environment. The research includes refinement of a general-purpose atomistic simulation program. %%% NPG holds great promise in applications where high surface open structures are advantageous, e.g. sensors and electrodes. A simple MEMS hydrogen fuel cell will be built with NPG coated with platinum catalyst as the electrodes. ***
