Electrochemical actuation behaviors of bulk nanoporous palladium in acid and alkaline solutions

•Np-Pd shows different electrochemical actuation behaviors in acid/alkaline solutions.•ξ exhibits inverse signs associated with H/OH-adsorption/desorption in KOH solutions.•Strain amplitude of np-Pd can be regulated by being triggered in different solutions.

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 H2SO4) 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 H2SO4 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 (ξ) 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.

Graphical abstractBulk nanoporous Pd rod fabricated by dealloying shows distinct electrochemical actuation behaviors in acid and alkaline solutions.Download high-res image (95KB)Download full-size image