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

Klyukin, Konstantin, Alexandrov, Vitaly
The Journal of Physical Chemistry C 2017 v.121 no.19 pp. 10476-10483
adsorption, aqueous solutions, bicarbonates, carbon dioxide, catalysts, molecular dynamics, oxygen, titanium dioxide
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 Ob, while Ti₅c 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.