CO2 Adsorption and Reactivity on Rutile TiO2(110) in Water: An Ab Initio Molecular Dynamics Study

Atomic-scale understanding of CO2 adsorption and reactivity on TiO2 is important for the development of new catalysts for CO2 conversion with improved efficiency and selectivity. Here, we employ Car-Parrinello molecular dynamics combined with metadynamics simulations to explore the interaction dynamics of CO2 and rutile TiO2(110) surface explicitly treating water solution at 300 K. We focus on understanding the competitive adsorption of CO2 and H2O, as well as the kinetics of CO and bicarbonate (HCO3-) formation. Our results show that adsorption configurations and possible reaction pathways are greatly affected by proper description of the water environment. We find that in aqueous solution, CO2 preferentially adsorbs at the bridging oxygen atom O-b, while Ti-sc sites are saturated by H2O molecules that are difficult to displace. Our calculations predict that further conversion reactions include spontaneous protonation of adsorbed CO2 and detachment of OH- to form a CO molecule that is significantly facilitated in the presence of a surface Ti3+ polaron. In addition, the mechanisms of HCO3 formation in bulk water and near TiO2(110) surface are discussed. These results provide atomistic details on the mechanism and kinetics of CO2 interaction with TiO2(110) in a water environment.