Formation of nanoporous Au by dealloying AuCu thin films in HNO3

AuCu thin films were dealloyed in concentrated HNO3 solution at temperatures of 5–35 °C. X-ray diffraction and scanning electron microscopy analysis showed that interior grain regions undergo partial Cu dissolution before being assimilated into a ligament/void network that was initiated at grain boundaries. The compressive stress generated by removal of the smaller Cu atom yielded an activation energy for ligament growth of 25.4 ± 2.37 kJ mol−1, which is less than half that reported for AgAu alloys.

Research highlights
► AuCu films dealloyed in nitric acid.
► Ligament/void network initiated at grain boundaries.
► Interior grain regions undergo partial Cu dissolution before being assimilated into network.
► Compressive stress generated by removal of the smaller Cu atom.
► Activation energy for ligament growth was 25.4 ± 2.37 kJ/mol−1, less than half that for AgAu alloys.