Design of High-Surface-Area Bimetallic Ag-Cu Nanostructures with a Tunable Ratio Obtained via Selective Leaching of AlAgCu Alloys

Abstract

Nanostructured metals are promising for applications as energy materials. Often, several metal components must be combined to obtain the desired properties. However, preparing high-surface-area bimetallic metals with a desired spatial distribution can be challenging. We developed a novel synthesis route to make nanostructured Ag x Cu10‑x with control over the Ag:Cu molar ratio, covering the full range from x = 0 to x = 10. We used a dealloying synthesis route based on leaching Al from an AlAgCu mixed phase. We introduced a quenching step after alloying and before leaching to suppress the formation of side phases, which is beneficial for the leaching step. High-surface-area AgCu samples with a tunable Ag:Cu ratio and Ag and Cu mixed on tens of nanometer scale were obtained. The AgCu samples were applied as catalysts in the electrochemical reduction of CO2, showing a clear dependence of the selectivity on the Cu content. An optimum in C2H4 production was found for a Cu content between 50 and 70 atom % in the nanostructures. After catalysis, the molar ratios had not changed significantly, showing the stability of these catalysts. This work shows the usefulness of a method to prepare nanostructured catalyst covering the full Ag:Cu ratio.