Coadsorption properties of CO2 and H2O on TiO2 rutile (110): A dispersion-corrected DFT study

Adsorption and reactions of CO 2 in the presence of H 2 O and OH species on the TiO 2 rutile (110)-(1×1) surface were investigated using dispersion-corrected density functional theory and scanning tunneling microscopy. Th e coadsorbed H 2 O (OH) species slightly increase the CO 2 adsorption energies, primarily through formation of hydrogen bonds, and create new binding configurations that are not present on the anhydrous surface. Proton transfer reactions to CO 2 with formation of bicarbonate and carbonic acid species were investigated and found to have barriers in the range 6.1-12.8 kcalmol, with reactions involving participation of two or more water molecules or OH groups having lower barriers than reactions involving a single adsorbed water molecule or OH group. The reactions to form the most stable adsorbed formate and bicarbonate species are exothermic relative to the unreacted adsorbed CO 2 and H 2 O (OH) species, with formation of the bicarbonate species being favored. These results are consistent with single crystal measurements which have identified formation of bicarbonate-type species following coadsorption of CO 2 and water on rutile (110). © 2012 American Institute of Physics