Measurements were presented of the diffusion of bridging O vacancy (OV) crossover Ti rows via OV pairs. Using a high-resolution scanning tunnelling microscope, it was shown that the OVs could be moved along the bridging O rows driven by the scanning tunnelling microscopy tip at voltages higher than 3.0V on TiO2(110)-(1x1) surface. It was found that the combination of OV pairs led to the formation of OV pairs which could diffuse crossover Ti rows under the mediation of OVs in adjacent bridging O rows. The deduced diffusion activation energy for the diffusive OV pairs from experiments was in agreement with first-principles calculations. The reaction activation energy of the OV pairs with O2 was lower than that of the OVs by 82meV.

Formation and Diffusion of Oxygen-Vacancy Pairs on TiO2(110)-(1x1). Cui, X., Wang, B., Wang, Z., Huang, T., Zhao, Y., Yang, J., Hou, J.G.: Journal of Chemical Physics, 2008, 129[4], 044703