Synthesis and characterization of N-doped TiO2 loaded onto activated carbon fiber with enhanced visible-light photocatalytic activity

Abstract

Nano-sized TiO₂ particles are only excited under ultraviolet light irradiation and are difficult to be separated and recovered from the solution after the degradation reaction is complete. In this work, we have reported that N-doped TiO₂ particles prepared via a sol–gel method were loaded onto activated carbon fiber (ACF) to fabricate a series of novel N-doped TiO₂/ACF photocatalysts. The prepared N-doped TiO₂ particles were in the anatase phase and the mean size of the particles was about 15 nm when heat-treated at 500 °C. Nitrogen atoms were incorporated into the surface of TiO₂ mainly as interstitial nitrogen and molecularly chemisorbed γ-N₂ molecules, and a little as substitutional nitrogen. N-doped TiO₂ particles exhibit an evident red shift in the band edge and an obvious increase in visible region absorption, and the particles as a single particle are homogeneously dispersed on the surface of ACF. The results of the photocatalytic degradation of methyl orange show that N-doped TiO₂/ACF photocatalysts exhibit enhanced visible light photocatalytic activity. This could be attributed to the synergistic effect between the strong adsorption of the ACF and the visible light photocatalytic activity by N-doped TiO₂. The photocatalysts could be used for multiple degradation cycles without a decrease in the photocatalytic activity.