Formation of ultrafine spongy nanoporous metals (Ni, Cu, Pd, Ag and Au) by dealloying metallic glasses in acids with capping effect

The formation of ultrafine spongy nanoporous Ni, Cu, Pd, Ag and Au obtained by dealloying Mg-based metallic glasses in citric acid, tartaric acid, malic acid and amber acid is systematically investigated. The nanoporosity can generally be tuned by the capping efficiency of the acids, the precursor composition and dealloying conditions. Capping effect dominated dealloying is responsible for the novel nanoporosity via significantly increasing the activation energy of the surface diffusion process. This work demonstrates that capping agents involved dealloying is efficient to obtain ultrafine spongy nanoporosity and is important to further understand the dealloying mechanisms.