Investigation of multielemental catalysts based on decreasing the band gap of titania for enhanced visible light photocatalysis.

ABSTRACT

Novel photocatalysts based on carbon-, nitrogen-, boron-, and fluorine-codoped TiO(2) have been successfully prepared from a single precursor in order to obtain titania with a decreased band gap. Three kinds of catalytic mechanisms are suggested. Initially, boron acts as an initiator to lead the movement of electrons in the valence band, and then nitrogen and fluorine provide electrons in the valence band. Eventually, electrons in the valence band can travel to the conduction band through a carbon bridge. The effect of the calcination temperature was also evaluated for the photodegradation of dyes. Excellent photoactivity results were obtained in the case of samples treated at 400 degrees C and the phase transformation from anatase to rutile did not occur up to calcination temperatures of 800 degrees C. The photodegradation followed the pseudo-first-order kinetic expression. The exceptional visible photoactivities of the prepared catalysts can be predominantly attributed to the effects of doping on titania, reducing its band gap.