Nanoporous foam fabricated by dealloying AgAl thin film through supercritical fluid corrosion

Abstract

In this research, nanoporous silver foams are fabricated through dealloying Ag₃₅Al₆₅ (as atomic percentage, at%) thin films in supercritical (SC) carbon dioxide. The supercritical CO₂ is mixed with either HCl, water or H₂C₂O₄ aqueous solution as the solute in the reaction chamber. Due to the low tension of the supercritical fluid, under the best operating conditions, the surface area of the as-dealloyed Ag₃₅Al₆₅ can reach 4.6 m² g⁻¹, and the porosity volume fraction value can reach 74%, with a smallest average pore size of around 75 nm. In an optimum supercritical CO₂ environment, a lower chemical concentration can be applied and it can take less time to form a uniform nanoporous structure.