Internal structure of Al hollow nanoparticles generated by laser ablation in liquid ethanol

Al nanoparticles (NPs) are synthesized by laser ablation of a bulk Al target immersed into liquid ethanol saturated with H2 at atmospheric pressure. The nanoparticles possess a well-distinguished core–shell structure. High resolution transmission electron microscopy shows several layers inside the Al nanoparticle: oxide layer, amorphous Al, single crystal, and a cavity in the center. Formation of the cavity is attributed to the sharp increase of hydrogen dissolution in Al upon its melting and its release after the solidification and crystallization of the aluminium core.