Figure 1: Structural determination and geometric analysis of round anatase TiO2 single crystals.

(a–c) High-magnification SEM images of the as-prepared anatase TiO2 single crystals viewed from various orientations. The inset in a shows three-dimensional (3D) molecular structure of the organic capping agent (CA). (d) Typical TEM images of a round anatase TiO2 single crystal indexed with [001] incidence. Single-crystal characteristic of anatase TiO2 phase can be confirmed by the SAED pattern in the inset. (e) High-resolution TEM image taken from c with [001] orientation. (f) Schematic illustration of the geometric model of the round anatase TiO2 single crystals. ϕ, Azimuthal angle in spherical coordinate system. (g) Unfolded views of the facets (presented by different colours) of crystals synthesized with CA concentrations of (i) 0, (ii) 0.127 M and (iii) 0.476 M. Scale bars are 1 μm in a–d and 1 nm in e.