Unique Porous Oxide Shell on Liquid Gallium Nanoparticles.

The oxide "skin" that is easily formed on the surface of liquid gallium plays an important role in controlling the wettability of gallium. However, the oxidation mechanism of liquid gallium is still under debate. Herein, experiments and reactive molecular dynamics simulations were performed to systematically investigate the oxidation mechanism of gallium nanoparticles (GNPs). This study reveals the cracking and wrinkling behaviors of oxide "skin" during the oxidation process, which is kinetically driven by the synergistic effect of oxidation and liquid core flow. The wrinkling behavior facilitates the morphological transformation of GNPs from a core-shell structure to a spherical crown-like structure. A higher temperature would transform the nucleation mode of oxide from chain-like to island-like, leading to "crater" oxides. Our findings are favorable for the understanding of the atomic-scale oxidation mechanism of GNPs, which could have a practical significance for the production of patterned circuit filling materials.