We have studied the dynamic relationship between acetone and bridge-bonded oxygen (O b) vacancy (V O) defect sites on the TiO 2(110)-1 - 1 surface using scanning tunneling microscopy (STM) and density function theory (DFT) calculations. We report an adsorbate-assisted V O diffusion mechanism. The STM images taken at 300 K show that acetone preferably adsorbs on the V O site and is mobile. The sequential isothermal STM images directly show that the mobile acetone effectively migrates the position of V O by a combination of two acetone diffusion channels: one is the diffusion along the O b row and moving as an alkyl group, which heals the initial V O; another is the diffusion from the O b row to the five-coordinated Ti 4+ row and then moving along the Ti 4+ row as an acetone, which leaves a V O behind. The calculated acetone diffusion barriers for the two channels are comparable and agree with experimental results.
- Porous Materials
- and Catalysis