CO2 adsorption on TiO2(101) anatase: A dispersion-corrected density functional theory study

Adsorption, diffusion, and dissociation of CO2 on the anatase (101) surface were investigated using dispersion-corrected density functional theory. On the oxidized surface several different local minima were identified of which the most stable corresponds to a CO2 molecule adsorbed at a five-fold coordinated Ti site in a tilted configuration. Surface diffusion is characterized by relatively small activation barriers. Preferential diffusion takes place along Ti rows and involves a cartwheel type of motion. The presence of a bridging oxygen defect or a surface interstitial Ti atom allows creation of several new strong binding configurations the most stable of which have bent CO2 structures with simultaneous bonding to two surface Ti atoms. Subsurface oxygen vacancy or interstitial Ti defects are found to enhance the bonding of CO2 molecules to the surface. CO2 dissociation from these defect sites is calculated to be exothermic with barriers less than 21 kcal/mol. The use of such defects for catalytic activation of CO2 on anatase (101) surface would require a mechanism for their regeneration. (C) 2011 American Institute of Physics. [doi:10.1063/1.3638181]