Formation of ultrafine nanoporous gold related to surface diffusion of gold adatoms during dealloying of Al2Au in an alkaline solution

Nanoporous gold (NPG) with ultrafine ligaments/channels (less than 10 nm) can be obtained by the dealloying of Al2Au in an alkaline solution at room temperature. The surface diffusivity of Au adatoms was evaluated as 2.1 × 10−23, 2.3 × 10−21 and 1.6 × 10−19 m2 s−1 for the dealloying at 253, 298 and 368 K, respectively. The measurement of activation energy demonstrates that the formation and coarsening of NPG are governed by the Au diffusion at alloy/solution interfaces regardless of dealloying media.