Green Preparation of High Surface Area Cu-Au Bimetallic Nanostructured Materials by Co-Electrodeposition in a Deep Eutectic Solvent

In this work we present an electrodeposition method in a deep eutectic solvent (DES) to prepare bimetallic high surface area nanostructures of Cu and Au with tunable structure and composition. The metal electrodeposition performed in green choline chloride within a urea deep eutectic solvent allows us to tailor the size, morphology and elemental composition of the deposits. We combine electrochemical methods with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) to characterize the electrodeposited nanostructured materials. We assess the increase of the electroactive surface area through the analysis of the lead underpotential deposition (UPD) on the prepared films. We observe a 5 to 15-fold increase of the active surface area compared to flat surfaces of polycrystalline Cu or Au. Our work reports, for the first time, a green route for the electrodeposition of Cu-Au bimetallic nanostructures in a deep eutectic solvent.