Fabrication of nanoporous palladium by dealloying and its thermal coarsening

Nanoporous Pd with an average ligament size of 5-20 nm was fabricated by dealloying Pd0.2Co0.8 alloy. An electrochemical potential of +0.5V (vs saturated calomel electrode) on the initial alloy led to Co dissolution in H2SO4 aqueous solution. However, unlike nanoporous Au fabrication from Au-Ag alloy, the free corrosion of Pd0.2Co0.8 alloy in H2SO4 did not result in a nanoporous structure; the electrochemical potential must have been applied to generate a nanoporous structure from the Pd-Co alloy. Thermal coarsening of nanoporous Pd is also investigated. Heating nanoporous Pd increased the ligament size up to 650 nm. it is suggested that a solid state process like recrystallization, rather than melting, is responsible for the thermal coarsening of nanoporous Pd. (C) 2008 Elsevier B.V. All rights reserved.