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

Abstract

Adsorption, diffusion, and dissociation of CO(2) 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 CO(2) 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 CO(2) structures with simultaneous bonding to two surface Ti atoms. Subsurface oxygen vacancy or interstitial Ti defects are found to enhance the bonding of CO(2) molecules to the surface. CO(2) 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 CO(2) on anatase (101) surface would require a mechanism for their regeneration.

Photocatalytic Conversion of CO2 into Renewable Hydrocarbon Fuels: State‐of‐the‐Art Accomplishment, Challenges, and Prospects

“…Oxygen vacancy is an intrinsic defect in metal oxides, which is the most reactive site on the surface and able to modify the structure of the materials and change the electronic and chemical properties of the surface . The surface oxygen vacancies sites of semiconductors play an important role in CO 2 activation CO 2 molecules prefer to adsorb at oxygen vacancy sites with one oxygen atoms of the CO 2 located at bridging oxygen vacancy defects . The attraction between an oxygen vacancy and a CO 2 molecule may lower the reactive barrier due to the generation of an unexpected affinity interaction.…”

Synthesis and Surface Modification of TiO2-Based Photocatalysts for the Conversion of CO2

“…As a result of the structural transformation, the lowest unoccupied molecular orbital (LUMO) level of the metal oxide decreases lowering its activation energy [39]. However, density functional theory (DFT) calculations performed by Sorescu et al [43] demonstrated that CO2 preferentially binds to the metal oxide surface in a linear geometry. This is most probably due to the low binding energy (−46 kJ/mol) associated with the linear configuration, the considerable energy required to bend CO2 (38.6 kcal/mol) and the significant deformation the metal oxide surface undergoes when binding to bent CO2 [42,43].…”

Ni‐Nanocluster Modified Black TiO2 with Dual Active Sites for Selective Photocatalytic CO2 Reduction

“…Additionally, several theoretical studies have demonstrated that subsurface oxygen vacancy or interstitial defects enhance the bonding of CO 2 adsorption on reduced TiO 2 anatase surfaces . Yang et al illustrated that CO 2 adsorption on reduced anatase TiO 2 was attributable to an electrostatic competition between attractive (Ti−O) and repulsive (Ti−C) interactions according to their density functional theory calculations .…”