Enhanced photocatalytic formation of hydroxyl radicals on fluorinated TiO2

Direct experimental evidence of the higher concentration of hydroxyl radicals generated on fluorinated titanium dioxide (F - TiO2) under irradiation was obtained by spin-trapping EPR measurements. The faster photoinduced bleaching of the azo dye Acid Red 1 (AR1) observed in the presence of F - TiO2 was explained by the high affinity of the azo double bond towards . OH radicals. Moreover, the pronounced decrease of the AR1 bleaching rate by addition of 2-propanol, as hydroxyl radicals scavenger, on F - TiO2 and not on naked TiO2 demonstrated that on. fluorinated titania AR1 is mainly degraded via . OH radical attack.