Nanoporous gold formation by dealloying: A Metropolis Monte Carlo study

A Metropolis Monte Carlo study of the dealloying mechanism leading to the formation of nanoporous gold is presented. A simple lattice-gas model for gold, silver and acid particles, vacancies and products of chemical reactions is adopted. The influence of temperature, concentration and lattice defects on the dealloying process is investigated and the morphological properties are characterized in terms of the Euler characteristic, volume, surface area and the specific surface area. It is shown that a minimal three-parameter model suffices to yield nanoporous gold structures which have morphological properties akin to those found in the experiment. The salient features of the structures found by simulation are that the ligament size of the dealloyed material is of the order of 2–3 nm, the structure is disordered, percolating and entirely connected.