The Impact of the Manufacturing and Corrosion Steps of the AuCu Master Alloy on the Catalytic Activity of Nanoporous Gold for CO Oxidation

Nanoporous gold (npAu) fabricated from a AuCu alloy is a complex procedure mostly because of the passivated outer surface and the inhibited corrosion phenomena observed in those materials as a consequence of the formation of a Pm¯3m (AuCu3). To further deepen our understanding of the leaching of Cu in these materials, a series of experiments were performed to study the corrosion process and finally start giving an answer to this problem. Here we compare different corrosion methods, beginning with free corrosion (as the standard synthetic route for npAu) and finishing with an optimized potentiostatic dealloying (four-step method) procedure. In order to distinguish between the structural and chemical effects affecting the catalytic activity, a series of experiments employing scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with Energy-dispersive X-ray spectroscopy (EDXS), and X-ray photoelectron spectroscopy (XPS) were performed before and after catalytic CO oxidation. The data reveals a clear influence in key synthetic steps in the master alloy synthesis (thermal treatment), as well as in the dealloying procedure.