An atomic view of dealloying

Nanomaterials The dealloying of metals to create nanoporous materials with bicontinuous surfaces is often modeled as a surface dissolution and diffusion process, but many of the details lack experimental verification. Liu et al. used liquid-cell high-resolution scanning transmission electron microscopy to follow the nitric acid–driven dissolution of silver from gold-silver alloy (Au0.2Ag 0.8) nanospheres, nanocubes, and fivefold twin nanorods. Whereas the nanoparticles had more surface defects than the nanorods and began to dissolve immediately, the nanorods had an induction period in which surface dealloying created defects that then allowed bulk silver to dealloy. Dealloying led to large decreases in particle volumes that were attributed to the inward movement of exterior atoms, creating a denser, less porous outer shell. Nano Lett. 10.1021/acs.nanolett.9b05216 (2020).