In this study, we investigate the photocatalytic behavior of V-doped TiO2 for CO2 reduction in terms of the distribution, concentrations and chemical states of the doped V ions in the TiO2 lattice. In addition, the interfacial charge transfer between the doped TiO2 and CO2 is examined to understand the thermodynamically reductive capability. The V-doped TiO2 contained V2O5 crystallites at the surface after calcination above 300 Â°C. In contrast, V3+ and V4+ ions presented mainly at the inside lattice. High concentrations of V3+/V4+ ions trapped charge carriers to induce recombination, thus inhibiting photocatalytic oxidation. However, higher photocatalytic activity was found in a heavily doped TiO2 for CO2 reduction. Methane (CH4) was the major product of the reduction when water was used as the reductant. The surface embedded V2O5 crystallites which facilitate charge transfer to CO2 are the key for the high reductive activity.