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

Ultrathin TiO2 nanosheet (NST) with abundant Ti3+ sites is developed as a photocatalyst which exhibits a high yield (147.2 mu mol g(-1) h(-1)) and selectivity (96.8%) for CO2 to CH4. The results of in situ FTIR, in situ EPR and density functional theory (DFT) calculation suggest that CO2 would be selectively activated on NST surface via forming the bridging Ti center dot center dot center dot CO2-center dot center dot center dot Ti coordination species which not only lowers the activation energy barrier, but also determines the selectivity of CH4. Additionally, NST with the better separation and transfer ability for photogenerated electrons-holes can fleetly supply the electrons to CO2 molecules for high efficiently producing CH4 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.

Automated summary

Ultra-thin TiO2 nanosheet (NST) with abundant Ti3+ sites has been developed as a photocatalyst for high yield and selectivity in the conversion of CO2 to CH4. The NST selectively activates CO2 on its surface, forming bridging Ti dot CO2-Ti coordination species to lower the activation energy barrier and determine the selectivity for CH4 production via Ti-C coordination bond.