Ti3+ self-doped TiO2 as a photocatalyst for cyclohexane oxidation under visible light irradiation

Abstract Most of TiO 2 have been reported to photocatalyze the selective oxidation of cyclohexane under ultraviolet light illumination. In this work, the Ti 3+ self-doped TiO 2 submicrometer-sized particles (Ti 3+ /TiO 2 SMP) were used as catalyst for visible-light driven photocatalytic cyclohexane oxidation for the first time. The structure and properties of the Ti 3+ /TiO 2 SMP were studied by X-ray diffraction (XRD), UV–visible diffuse reflection (UV–Vis DRS), Scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), Solid state photoluminescence spectrum (PL) and X-ray photoelectron spectroscopy (XPS) characterization techniques. The Ti 3+ /TiO 2 SMP exhibited good visible-light driven photocatalytic performances for cyclohexane oxidation with cyclohexanone being the dominate product. The effects of solvent, temperature, time and oxygen pressure were further studied to identify the optimal conditions for the formation of cyclohexanone. In the optimal conditions, the cyclohexane oxidation over the Ti 3+ /TiO 2 SMP photocatalyst using carbon tetrachloride as solvent presented a 95.1% selectivity to cyclohexane. Finally, control experiments were carried out using different radical scavengers. It was found that the active substances to play a major role are the hole (h + ) and superoxide radical (O 2− ).