Unveiling the Atomic Structures of the Minority Surfaces of TiO₂ Nanocrystals

Determining the atomic structures of minority surfaces of TiO 2 is of critical importance in terms of accurately interpreting their demonstrated properties. Unlike well-studied majority surfaces [such as anatase TiO 2 (101)], the structures of the more attractive minority surfaces and edges are poorly known, which hampers the further understanding of their unique behaviors. Herein, through the aberration-corrected scanning transmission electron microscope, the atomic structures of the five minority surfaces [(100), (001), (102), (103), and (301)] and edges between six facets are experimentally determined. Several unique configurations are unveiled on the (301) and (102) surfaces. Intriguingly, the defective (103) and (102) surfaces are identified as distinct structures, completely different from the early predictions of stoichiometric surfaces, which are further confirmed by first-principles calculations. With the calculations based on density functional theory, the intrinsic electronic properties of the minority surfaces are also revealed. This work provides new information on minority surfaces and edges, which contributes to advancing our knowledge in surfaces and better understanding their versatile performances.