Tri-layer nanoporous silver | gold | silver by etching without sacrificing materials through the Kirkendall effect

In our previous work, we used the Kirkendall effect to demonstrate a novel sustainable method for fabricating metal/metal nanocomposites of the same element, such as tri-layer nanoporous Ag | Ag | Ag, without losing sacrificial materials. Here, we extend this new method to create metal/metal/metal nanocomposites of dissimilar elements, such as tri-layer nanoporous Ag | Au | Ag. Simply applying an oxidative and reductive current to a Au ₃₅Ag ₆₅ at. % alloy in a chloride-ion-containing electrolyte enables the plating and stripping of AgCl, resulting in a tri-layer nanoporous Ag | Au | Ag. We used various characterization techniques, including electron microscopy and small-angle X-ray scattering, to confirm the structure and porosity of the fabricated materials. This sustainable synthesis approach not only reduces the loss of material during dealloying but also opens new avenues for developing metal/metal nanocomposites made of dissimilar nanoporous metal layers stacked together, offering significant implications for applications in catalysis and beyond, in which the synergistic effect between the underlying nanoporous metal layers could enhance the properties of the nanocomposite.