Formation of hollow ZnO through low-temperature oxidation of Zn nanoparticles

The hollow phenomenon with the oxidation of Zn nanoparticles was studied by transmission electron microscopy. Hollow ZnO was formed by oxidizing Zn nanoparticles with the diameter less than 20 nm at 423 K for 3.6 ks. Nano-hole in the center of ZnO can be considered as a vacancy cluster, which is formed as the result of the generation and aggregation of vacancies due to faster outward diffusion of Zn across ZnO in air at the initial oxidation stage.