Enhancement of the intrinsic photocatalytic activity of TiO2 in the degradation of 1,3,5-triazine herbicides by doping with N,F

The presence of N and F in TiO2 improved the intrinsic properties of the catalyst and demonstrated enhanced kinetic UV photoreactivity in atrazine degradation by a factor of 3 as compared to undoped TiO2. This high activity is induced from the significant modification of nanocrystal morphology due to the presence of fluorine during sol-gel synthesis. The change in the morphology leads to the enhanced presence of 001 facets reasonably coexisting with 101 facets, which favored stabilization of charge separation, as proof from PL measurements. Minor effects are present on the adsorption of atrazine and reaction products, and on the pathways of atrazine transformation. The modification in the nanomorphology of TiO2 crystals is mainly affecting the rate of generation of OH radicals and in turn the specific activity in atrazine conversion. Therefore, doping may not only introduce activity in the visible light region, but is shown to improve the performances of intrinsic TiO2 itself, an aspect which is typically not considered in investigating the performances of codoped TiO2 samples. © 2015 Elsevier B.V.