Preparation of Nanoporous Palladium by Dealloying: Anodic Polarization Behaviors of Pd-M (M=Fe, Co, Ni) Alloys

Abstract

Anodic polarization behaviors of Pd-M (M = Fe, Co, Ni) alloys in H 2 SO 4 solution are investigated for the preparation of nanoporous palladium by dealloying. For Pd 0.2 Co 0.8 alloy, the current monotonically increased with the increase in potential. However, anodic polarization curves for Pd 0.2 Fe 0.8 and Pd 0.2 Ni 0.8 alloys showed passive regions at high potentials, although the standard electrode potentials for Fe, Co, Ni are similar. As a result, nanoporous Pd was successfully fabricated via electrolysis under a constant potential (= +0.5 V vs standard calomel electrode) only when the starting alloy was Pd-Co. Passivation, as well as standard electrode potentials, must be considered for the efficient production of nanoporous Pd. The preparation of nanoporous structure on the surface of bulk Pd was also demonstrated using alloying/dealloying process involving Co electrodeposition, thermal alloying and subsequent dealloying.