Speaker
Description
Dealloying corrosion has become a popular method for obtaining highly functional nanoporous gold (NPG) substrates1. The selective dissolution of Ag from AgAu solid solutions in acidic environments leads to the formation of an open-pore, bicontinuous 3D, nanoporous structure. Using thin film precursors, as opposed to solid-solution alloys, facilitates easier integration of NPG into energy stor-age and catalytic devices owing to the inherent substrate-support feature2,3. High-resolution studies of dealloyed thin films could guide optimization efforts by revealing the effect of as-deposited struc-ture and dealloying conditions on the morphology and chemical structure of dealloyed substrates.
In this investigation, we focus on studying NPG made by dealloying AgAu thin films deposited via magnetron sputtering. Using scanning electron microcopy (SEM) and electron backscatter diffrac-tion (EBSD), we uncovered the different morphologies attained due to non-equilibrium AgAu com-positions created by the sputtering process. Atom probe tomography (APT) was used to study the influence of dealloying conditions on nanoligament compositions, at the atomic-scale4. We correlate our findings to subtleties in the dealloying mechanism of AgAu, that are introduced by the thin-film properties of AgAu. Significant findings include the different electrochemical regimes of dealloying and the formation of Au-rich segregates at grain boundaries.
