Synthesis of fluorine-doped titania-coated activated carbon under low temperature with high photocatalytic activity under visible light

Fluorine-doped anatase titania sols were synthesized by hydrolysis of titanium-n-butoxide in the presence of abundant acidic aqueous solution and using ammonium fluoride as fluorine precursors, under mild condition. The prepared fluorine-doped titania nanoparticles were loaded on activated carbon in a rotatory evaporator under vacuum to form a composite photocatalyst. X-ray diffraction, Fourier transform infrared spectrum analysis, UV–visible spectroscopy, scanning electron microscope and Brunauer–Emmett–Teller adsorption measurement were used to characterize these as-prepared powders. The photocatalytic activity of the sample was evaluated by degrading phenol under visible light. Results showed that the composite photocatalyst was porous due to its nano–microstructure. The number of hydroxyl groups on the titania surface was enhanced after fluorine doping. Compared with pure titania–activated carbon and Degussa P25, the as-prepared composite powders exhibited much higher photocatalytic activity, although absorption response range into the visible region was not detected by diffuse reflection spectra.