Sacrificial Silver Recovery during Nanoporous Gold Formation by Electrolytic Dealloying of Gold-Silver Alloy

Electrolytic dealloying has proven to be a practical technique for fabricating nanoporous metals such as nanoporous Au (NP-Au). This widely studied material has novel properties that are useful in applications ranging from chemical sensing to energy storage. Building off the success of this field, issues concerning the sustainability of fabricating NP-Au through dealloying need to be further explored, such as the large amount of valuable sacrificial Ag material dissolved in solution after dealloying is complete. In this work, an electrolytic cell is created consisting of a Au-Ag alloy foil working electrode and a Ag foil counter and reference electrode immersed in a non-aqueous Ag+ ion electrolyte. When a small overpotential is applied, the working electrode is dealloyed to form NP-Au. Unique to this configuration, Ag removed from the working electrode is simultaneously plated on the counter electrode, resulting in high yield recovery of Ag sacrificial material, which can be used to create new Au-Ag parent alloys. This integrated process of simultaneous dealloying and recovery of the sacrificial material significantly improves the sustainability and economic viability of dealloying. From these results, a generalized electrolytic dealloying fabrication procedure is derived that can be extended to a wide range of nanoporous metals.