Adsorption CO2 on the perfect and oxygen vacancy defect surfaces of anatase TiO2 and its photocatalytic mechanism of conversion to CO

The adsorption energies for physisorption and the most stable chemisorption of CO2 on the neutral charge of perfect anatase [TiO2] (0 0 1) are −9.03 and −24.66 kcal/mol on the spin-unpolarized and −12.98 and −26.19 kcal/mol on the spin-polarized surface. The small activation barriers of 1.67 kcal/mol on the spin-unpolarized surface and of 6.66 kcal/mol on the spin-unpolarized surface were obtained. The adsorption mechanism of CO2 on the oxygen vacancy defect [TiO2 + VO] surface of anatase TiO2 using density functional theory calculations was investigated. The energetically preferred conversion of CO2 to CO was found either on the spin-unpolarized or spin-polarized surfaces of oxygen vacancy defect surface [TiO2 + VO] as photocatalyst.