In situ TEM observation of liquid-state Sn nanoparticles vanishing in a SiO₂ structure: a potential synthetic tool...

Precise design of hollow nanostructures can be realized via various approaches developed in the last two decades, endowing nanomaterials with unique structures and outstanding performances, showing their usefulness in a broad range of fields. Herein, we demonstrate the formation of SnO₂@SiO₂ hollow nanostructures, for the first time, by interaction between liquid state Sn cores and SiO₂ shell structures inside Sn@SiO₂ core-shell nanoparticles with real-time observation via in situ transmission electron microscopy (TEM). Based on the in situ results, designed transformation of the nanoparticle structure from core-shell Sn@SiO₂ to yolk-shell Sn@SiO₂ and hollow SnO₂@SiO₂ is demonstrated, showing the controllable structure of core-shell Sn@SiO₂ nanoparticles via fixing liquid-state Sn inside a SiO₂ shell which has a certain Sn containing capacity. The present approach expands the toolbox for the design and preparation of yolk-shell and hollow nanostructures, thus providing us with a new strategy for fabrication of more complicated nanostructures.