The diffusion of CO2 molecules on a reduced rutile TiO2(110)-(1x1) surface was investigated using scanning tunneling microscopy and density functional theory calculations. The scanning tunneling microscopic features associated with a CO2 molecule at an oxygen vacancy (VO) became increasingly streaky with increasing temperature; indicating thermally activated CO2 diffusion from the VO site. From temperature dependent tunnelling current measurements, the barrier for diffusion of CO2 from the VO site was estimated to be 3.31kcal/mol. The corresponding value from the density functional theory calculations was 3.80kcal/mol. In addition, the density functional theory calculations gave a barrier, for diffusion of CO2 along Ti rows, of only 1.33kcal/mol.

Diffusion of CO2 on the Rutile TiO2(110) Surface. Lee, J., Sorescu, D.C., Deng, X., Jordan, K.D.: Journal of Physical Chemistry Letters, 2011, 2[24], 3114-7