fig8

Figure 8. ETEM observations showing the dynamics of H₂O molecules absorbed on TiO₂ (1 × 4) (001) surface under gaseous environments^[77]. (A) HAADF-STEM image of the TiO₂ (1 × 4) (001) surface viewed along the [010] direction. The image was collected at 700 °C in vacuum. (B) Atomic structure of the adsorbed H₂O molecules on TiO₂ (1 × 4) (001) surface (gray, Ti; red, O; cyan, H). (C) ETEM images showing the same area of TiO₂ (001) surface at 700 °C under oxygen and water vapor conditions, respectively. Scale bar, 1 nm. (D) Dynamic structural evolution of the TiO₂ (1 × 4) (001) surface in the water-gas shift reaction. Scale bar, 2 nm. (E) Enlarged ETEM images of the dotted rectangle region in (D). Scale bar, 0.5 nm. (F) Intensity profiles along the lines across the Ti rows of (E) marked in the inset. Blue arrows denote intensity valleys corresponding to the twin protrusions.