Fabrication and functionalization of tunable nanoporous copper structures by hybrid laser deposition and chemical dealloying

Nanoporous metals exhibit promising potentials for engineering applications in catalysis, sensing and bio-detection due to their large surface-to-volume ratios and excellent thermal and electrical conductivity. In this paper, a hybrid laser deposition and chemical dealloying technique is presented for producing tunable nanoporous structures on a substrate, with a particular focus on the etching process behaviour. It was pointed out that the dealloying conditions were crucial to the formation of nanoporosity structures. Nanopore sizes can be tunable from 40 nm-160 nm by controlling the dealloying conditions, such as electrolyte, concentration, time, temperature and alloy components. The nanoporous Cu structures were further functionalized by oxidation. XRD and XPS analyses demonstrated that the formation of Cu ₂O on the surface of nanoporous copper prohibits the conventional oxidation to form CuO on the surface of the micro or bulk copper. This unique nanostructure exhibits excellent catalysis function for converting CO to CO ₂ gas; its transition temperature decreases with the smaller nanoporous sizes.