Fabrication of N-doped TiO ₂ /activated carbon fiber composites with enhanced photocatalytic activity

N-doped TiO 2 powders were synthesized via a sol-gel processing, and N-doped TiO 2 /activated carbon fiber (ACF) composites have been fabricated using the impregnating method. The prepared powders and composites were characterized using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet visible absorption spectroscopy, N 2 adsorption-desorption, and scanning electron microscopy. The results show that N-doped TiO 2 powders prepared are anatase phase, and the mean size of the particles is about 15 nm when calcined at 500℃. Nitrogen atoms were incorporated into the surface of TiO 2 mainly as interstitial nitrogen and molecularly chemisorbed γ-N 2 molecules. N-doped TiO 2 powders exhibit an evident red shift in the band edge and an obvious increase in visible region absorption, and the powders are homogeneously dispersed on the surface of ACF. The photocatalytic degradation of methylene blue shows that N-doped TiO 2 /ACF composites exhibit enhanced visible light photocatalytic activity. This could be attributed to the synergistic effect between strong adsorption of the ACF and visible light photocatalytic activity by N-doped TiO 2 .