Effect of oxygen content on pore structure of porous gold

In this work, by controlling the oxygen content during the annealing, the porous golds with different pore structures were prepared after dealloying of Au25Cu75 alloys. Annealing in 2 ppm O2, a loose oxide film could be observed on the alloy surface, mainly of Cu2O, partly of CuO. As the surface oxide was etched away in concentrated HNO3, the precursor alloy formed a unique concave ligament/pore structure. With the increase of the oxygen content, the oxide film became denser, and the proportion of CuO increased significantly. After dealloying, a macroporous gold was obtained, due to the oxidation, diffusion and dissolution of copper atoms.