Gas-phase photocatalytic oxidation has become an interesting and active domain in catalysis recently because of its potential application in the degradation of volatile organic compounds (VOCs). TiO_2 is the most commonly studied photocatalyst due to its good activity, chemical stability, commercial availability and inexpensiveness. A wide variety of VOCs such as alkanes, alkenes, aromatics, oxygenates and halides are successfully oxidized at ambient conditions over TiO_2 under UV or near-UV radiation using air or oxygen as the oxidant. In a recent literature, it has been reported that the photocatalytic activity of TiO_2 is dependent on its crystalline phase as well as phase composition and a mixture of anatase and rutile in an approximate proportion of 70/30 is more active than either of the two pure crystalline phases during degradation of p-coumaric acid in aqueous solution. Calcining at high temperature is a facile way to prepare TiO_2 with bicrystalline , but nanosized samples are impossible to be obtained in that way, let alone the ratio of the two phases being difficult to control. In this work, a novel hydrothermal method to prepare nanosized TiO_2 with controllable crystalline phase composition, and the effect of the crystalline phase composition on the activity for gas phase photo-oxidation of hexane are introduced.
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