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 +0.5 V (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.