The synthesis of 18O labeled TiO2 was accomplished using hydrothermal technique. The labeled TiO2 was characterized by X-ray diffraction, Raman spectroscopy and secondary ion mass spectrometry depth profiling. UV irradiation on 18O labeled TiO2 dispersed in cyclohexane leads to the formation of cyclohexanone with near 90% selectivity. Relative abundance of 18O isotope incorporated in cyclohexanone produced from 18O isotope labeled TiO2 is about 35 times larger than that obtained from natural TiO2. In addition, we have found that relative abundance of 18O isotope decreases from 20% to 8.5% as the reaction time increases. Our experimental results clearly suggest that photo-induced oxygen exchange occurs between liquid cyclohexane and solid 18O labeled TiO2. We propose a multi-step mechanism to account for the cyclohexane oxidation, which is quite analogous to the thermal-induced oxygen exchange between gas molecule and solid oxide known as Mars van Krevelen mechanism.

Photo-induced oxygen exchange between cyclohexane and solid oxide surface of Ti<sup>18</sup>O<sub>2</sub>

243rd National Meeting (2012)

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Photo-induced oxygen exchange between cyclohexane and solid oxide surface of Ti18O2

Photo-induced oxygen exchange between cyclohexane and solid oxide surface of Ti¹⁸O₂