Nanoporous gold by dealloying of an amorphous precursor

Nanoporous gold has been produced by the electrochemical dealloying of a Au40Cu28Ag7Pd5Si20 metallic glass. Suitable conditions of potential and temperature of dealloying have been established from polarization curves and dealloying has been conducted at the critical potential of 1.05 V in three different electrolytes: 1 M HNO3, 1 M HClO4 and 1 M H2SO4. The resulting material after 6 h of dealloying was constituted by ligaments made of pure Au and pores. The morphology was determined by SEM: ligaments of about 100 nm was observed and their size appears slightly larger (130 nm) when HNO3 is used. In the first stages of dealloying (30-300 s), nanopores and nanocrystals, randomly oriented, were found by HRTEM. From these observations a diffusivity value for crystal growth was estimated. A change in growth mechanism was suggested when impingement occurs for long dealloying times. It is suggested that the ligament and pore morphology can be tailored in order to obtain materials with different chemical and physical properties