Optical identification of oxygen vacancy types in SnO2 nanocrystals

The oxygen vacancies in spherical and cuboid SnO2 nanocrystals prepared by hydrothermal and laser ablation methods are investigated optically. Three oxygen-vacancy-related photoluminescence peaks at ∼430, ∼501, and ∼618 nm are observed, and Raman scattering and density functional calculation disclose that they originate from in-plane, sub-bridging, and bridging oxygen vacancies, respectively. This work reveals that the photoluminescence peaks together with the Raman modes can be used to identify the oxygen vacancy types in SnO2 nanostructures.