Single-element amorphous palladium nanoparticles formed via phase separation

Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates, which are still unachievable for most of the closest-packed metals. Here, we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.% ± 0.23 at.% from palladium—silicon liquid droplets. In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon. Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake, exhibiting a great potential application for hydrogen separation. Our results provide insight into the formation of amorphous metal at nanoscale.