Bulk nanoporous platinum for electrochemical actuation

Bulk nanoporous Pt samples with a remarkably fine ligament size down to 2 nm and a good mechanical robustness were fabricated for the first time by electrochemical dealloying Pt₁₅Cu₈₅ master alloy in 1M H₂SO₄ at 60°C. Attributing to the ultrafine nanostructure, the as-prepared np-Pt shows an electrochemical active specific surface area as high as 25 m²/g. The active surface area remains almost invariable even after 15% macroscopic compressive strain. Furthermore, np-Pt shows a considerably high thermal stability due to the low surface diffusivity of Pt. The high surface-to-volume ratio and mechanical robustness makes np-Pt a promising surface- or interface-controlled functional materials in particular when not only excellent electrochemical performances but also good mechanical performance are demand. In this work, we demonstrated the potential application of np-Pt as an electrochemical actuation material. In-situ dilatometry experiments revealed the surface adsorption/desorption of OH species on np-Pt causes significant strain variations. Our np-Pt electrochemical actuator shows an operating voltage down to 1.0V, a large reversible strain amplitude of 0.37% and a strain energy density of 1.64 MJ/m³.