Mesoporous TiO2 single crystal coated with O vacancies, Ti3+ and OH groups was synthesized by a simple hydrothermal method. Mesoporous form as the growth of TiO2. O vacancies and Ti3+ form with different origins. According to sample's morphology, specific surface areas, CO2 adsorption capacity and photocatalytic activity, OH groups can improve the reaction rate of CO2 photoreduction, and O vacancies and Ti3+ can influence the utilization of phtogenerated carriers. The photocatalytic activity reaches an optimal value with the calcination condition change, which adjusts the amount of these chemical composition: OH groups, O vacancies and Ti3+. (C) 2017 Elsevier B.V. All rights reserved.