Photocatalytic decomposition of phenol over N–TiO₂–SiO₂catalyst under natural sunlight

Gel-derived TiO2–SiO2 and N–TiO2–SiO2 mixed oxides with the TiO2 : SiO2 weight ratio of 95 : 5 are synthesised and employed for phenol removal under UVA light and natural sunlight in this study. Both SiO2 and N are interestingly found to improve the specific surface area of resulting catalysts up to 169 m2 g−1. Meanwhile, only N is observed to shift significantly the light absorption of derived catalyst to visible range. Optimisation between specific surface area and crystallinity in TiO2–SiO2 mixed oxide is found to give rise to the superior photoactivity of TiO2–SiO2 catalyst in comparison with TiO2 counterpart. Under natural sunlight in Hochiminh City on October 2007, N–TiO2–SiO2 presents the outstanding photoactivity towards decomposition of 10 ppm phenol aqueous solution with the efficiency up to 100% as compared to those of 65 and 48% for bare TiO2–SiO2 and bare TiO2, respectively.