Selectivity of gold nanoparticles on the photocatalytic activity of TiO2 for the hydroxylation of benzene by water

The influence of gold nanoparticles on the photocatalytic activity (500 W-medium pressure Hg lamp) of TiO2 anatase for the conversion of benzene to phenol has been studied. Au/TiO2 samples (Au loading ranging from 0.25 to 2.20 wt%) were prepared by the deposition–precipitation method and characterized by chemical analysis, TEM, XRD, and Raman spectroscopy. Photocatalytic tests revealed that the presence of gold nanoparticles initially decreases the reaction rate but for longer reaction times it becomes beneficial and promotes phenol formation almost doubling the reaction yield with respect to unmodified TiO2, without increasing the percentage of hydroquinone, resorcinol and benzoquinone byproducts.