Enhanced photocatalytic NOx decomposition of visible-light responsive F-TiO2/(N,C)-TiO2 by charge transfer between F-TiO2 and (N,C)-TiO2 through their doping levels.

Composite type photocatalyst F-TiO 2 /(N,C)-TiO 2 consisted of anatase-type TiO 2 with fluorine-doping (F-TiO 2 ) and TiO 2 with nitrogen and carbon-doping ((N,C)-TiO 2 ) was prepared by simple physical mixing to exhibit higher visible-light responsive photocatalytic nitrogen oxide (NO x ) decomposition activity than those of F-TiO 2 and (N,C)-TiO 2 . Transient absorption measurement clarified that the composite possessed longer carrier lifetime compared to that of each material (F-TiO 2 or (N,C)-TiO 2 ), resulting in higher photocatalytic activity. In the composite, photoexcited holes and electrons, which are not in impurity level but in valence and conduction band, respectively, should photocatalytically decompose NO x , judging from the redox potential of O 2 /O 2 ･− and the band positions of F-TiO 2 and (N,C)-TiO 2 . The mechanism for higher visible-light photocatalytic activity, or longer carrier lifetime can be explained by charge transfer between F-TiO 2 and (N,C)-TiO 2 through their impurity levels. The charge transfer should make photoexcited carries spatially separated to enhance the photocatalytic activity. [ABSTRACT FROM AUTHOR]