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Solar driven catalysis by semiconductors is considered as a promising route to mitigate environmental problems caused by the combustion of fossil fuels and water pollution. Surface plasmon resonance (SPR) has offered a new opportunity to overcome the limited efficiency of photocatalysts. Herein we report that the SPR-mediated visible-light-responsive photocatalyst, 0.5 wt.% Au/SO 4 2− –TiO 2 , can achieve over 99% conversion of pollutants (thiophene, thiol, rhodamine B, and phenol) during photocatalytic oxidation with oxygen or air as oxidant under visible light irradiation. The considerable enhancement of photocatalytic activity can be attributed to the synergistic effect of Au SPR and Lewis acidic SO 4 2− –TiO 2 which are beneficial for the efficient separation and transfer of the photo-generated electrons and holes. Such a strategy would be important to the design and preparation of highly photocatalytic active semiconductor catalysts. [ABSTRACT FROM AUTHOR]

Ultrathin TiO 2 nanosheet with abundant Ti3+ is constructed as a photocatalyst for CO 2 conversion in the absence of any sacrificial reagents. The exposed Ti3+ as a Lewis base site may activate CO 2 to form bridging Ti···CO 2 −···Ti, resulting highly CH 4 yield via the synergistic effect of coordination-activation and photocatalysis. • Ultrathin TiO 2 nanosheets (NST) with abundant Ti3+ sites are constructed as a photocatalyst for conversion CO 2. • The catalyst (NST) exhibits a high yield (147.2 μmol g−1 h−1) and selectivity (96.8 %) for CH 4. • CO 2 would be selectively activated on the surface of NST via forming the bridging Ti···CO 2 −···Ti coordination species. • The synergistic effect about coordination-activation and photocatalysis can greatly enhance CH 4 yield efficiency. Ultrathin TiO 2 nanosheet (NST) with abundant Ti3+ 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. [ABSTRACT FROM AUTHOR]