Selective photocatalytic reduction CO2 to CH4 on ultrathin TiO2 nanosheet via coordination activation

Ultrathin TiO 2 nanosheet (NST) with abundant Ti 3+ sites is developed as a photocatalyst which exhibits a high yield (147.2 μmol g −1 h −1 ) and selectivity (96.8%) for CO 2 to CH 4 . The results of in situ FTIR, in situ EPR and density functional theory (DFT) calculation suggest that CO 2 would be selectively activated on NST surface via forming the bridging Ti···CO 2 − ···Ti coordination species which not only lowers the activation energy barrier, but also determines the selectivity of CH 4 . Additionally, NST with the better separation and transfer ability for photogenerated electrons-holes can fleetly supply the electrons to CO 2 molecules for high efficiently producing CH 4 via the Ti-C coordination bond. Finally, a possible mechanism of the synergistic effect about coordination-activation and photocatalysis is discussed at a molecule level. This work would offer a perspective for designing an effective photocatalyst and tailoring the selectivity of products by coordination activation.