Electrochemical actuation behaviors of bulk nanoporous palladium in acid and alkaline solutions
Abstract Metallic actuators have attracted a great deal of attention owing to their potential advantages over piezoelectric ceramics and conducting polymers. Here, we report different electrochemical actuation behaviors of bulk nanoporous palladium (np Pd) fabricated by dealloying in acid (0.5 M H 2 SO 4 and alkaline (1.0 M KOH) solutions. In the 1.0 M KOH solution, the reversible expansion/contraction of np Pd well responds to the adsorption/desorption of involved species (H and OH) In the 0.5 M H 2 SO 4 solution, only continuous contraction can be observed in the potential region involving the H adsorption/desorption, but the reversible strain appears in the potential region related to the OH adsorption/desorption. Moreover, the surface stress charge coefficient (x) exhibits inverse signs associated with the H adsorption (absorption)/desorption and OH adsorption/desorption in the alkaline solution. More importantly, the reversible strain amplitude of np Pd can be regulated by changing the potential scan rate or by being stimulated in different electrolytes.