Reverse Semi-Combustion Driven by Titanium Dioxide-Ionic Liquid Hybrid Photocatalyst.

Unprecedented metal-free photocatalytic CO conversion to CO (up to 228±48 μmol g h) was displayed by TiO@IL hybrid photocatalysts prepared by simple impregnation of commercially available P25-titanium dioxide with imidazolium-based ionic liquids (ILs). The high activity of TiO@IL hybrid photocatalysts was mainly associated to (i) TiO@IL red shift compared to the pure TiO absorption, and thus a modification of the TiO surface electronic structure; (ii) TiO with IL bearing imidazolate anions lowered the CO activation energy barrier. The reaction mechanism was postulated to occur via CO photoreduction to formate species by the imidazole/imidazole radical redox pair, yielding CO and water.