Solvent-free selective photocatalytic oxidation of benzyl alcohol over modified TiO2

Heterogeneous photocatalysis offers a promising route to realize green oxidation processes in organic synthesis. In this research, the solvent-free selective photocatalytic oxidation of benzyl alcohol to benzaldehyde in the presence molecular oxygen was studied by using TiO2 and modified TiO2 as photocatalysts. The surface modification of TiO2 by transition metal clusters dramatically enhanced the photocatalytic oxidation activity. Ir/TiO2 prepared by photodeposition showed a remarkably high activity for the photocatalytic oxidation of benzyl alcohol, and an average reaction rate of 14538 μmol h−1 gcat−1 could be obtained. The effect of preparation method, iridium loading and reaction conditions on the catalytic performance of Ir/TiO2 is investigated in detail. Based on the catalytic and characterization results, the problem of product selectivity and the reaction mechanism of the photocatalytic oxidation of benzyl alcohol over Ir/TiO2 are discussed.