Nanoporous Cu Prepared through Dealloying by Selectively Etching an Alkaline Metal with Saline

A facile, benign, and rapid dealloying method was employed to synthesize nanoporous Cu using an ammonium chloride (NH4Cl) saline solution and Mg as an etchant and a sacrificial metal, respectively. The large difference between the standard electrode potentials of Mg and Cu (-2.36 and +0.34 V, respectively) resulted in rapid etching at 10 nm/min and 303 K. Dealloying for 15 min yielded a nanoporous Cu foil, exhibiting a specific surface area of 24.1 m2/g. The raw materials Mg and NH4Cl are naturally abundant; Mg is classified as a biodegradable metal, while NH4Cl is recognized as a safe material by the United States Food and Drug Administration. No harmful byproducts were produced during dealloying. Therefore, the proposed dealloying method is environmentally benign and addresses the issue of the hazardous chemical waste produced via conventional electrochemical dealloying methods.