In situIR study of surface hydroxyl species of dehydrated TiO2: towards understanding pivotal surface processes of TiO2 photocatalytic oxidation of toluene

Abstract

The surface species on P25–TiO₂ were characterized by FTIR after evacuation at 50–550 °C. The functions of OH groups on P25–TiO₂ catalysts have been tested by the adsorption and photooxidation of toluene in an in situ IR cell. FTIR studies show that the hydroxyl species on P25–TiO₂ are clearly temperature-dependent and P25–TiO₂ has six isolated hydroxyls with bands at 3734, 3715, 3688, 3671, 3658 and 3640 cm⁻¹. The OH groups on P25 play different roles in the photo-oxidation process: surface hydroxyls with bands at 3688, 3671, 3658 and 3640 cm⁻¹ act as adsorption sites while surface hydroxyls with bands at 3734 and 3715 cm⁻¹ act as sources of the ˙OH radical.