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 + V-O] 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 + V-O] as photocatalyst. (C) 2011 Elsevier B.V. All rights reserved.