Ultrasmall C-TiO2-X nanoparticle/g-C3N4 composite for CO2 photoreduction with high efficiency and selectivity

The photoreduction of CO2 to CO offers a promising sustainable and clean approach for a global new energy program. Coupling this reductive process with a matched water photo-oxidation pathway is an attractive avenue to accelerate the half-reaction of CO2 reduction. Herein, we propose a three-component photocatalyst design strategy for reducing CO2 to CO coupled with water oxidation via a two-electron/two-step pathway. Employing polyoxotitanium ([Ti17O24(OPri)(20)]) as a titanium source, ultrasmall TiO2-x nanoparticles coated with ultrathin carbon layers (C-TiO2-x) were fabricated and loaded on to a g-C3N4 matrix through chemical bonding (C-TiO2-x@g-C3N4) for the first time. The optimized C-TiO2-x@g-C3N4 photocatalyst showed a very high activity of 12.30 mmol g(-1) (204.96 mmol g(TiO2)(-1)) CO generation within 60 h visible-light irradiation, which represents the highest CO production rate to date among the reported TiO2-based materials under similar conditions. The excellent adsorption capability of C-TiO2-x@g-C3N4 for photons, H+ protons, and CO2 molecules together with efficient charge separation and the two-electron/two-step oxidative pathway lead to the high reactivity.