Preparation of highly visible light active Fe-N co-doped mesoporous TiO2 photocatalyst by fast sol-gel method

A novel fast sol-gel method, using polyethylene glycol and polyacrylamide as bi-templates, to prepare the pure, Fe-doped, N-doped, and Fe-N co-doped mesoporous TiO2 samples has been developed. The reaction time is reduced to a few hours for the present work. The IR spectrum has been used to investigate the reaction mechanism of the fast sol-gel method. The results indicate that the fast sol-gel process has been achieved due to the polymerization crosslink between hydrolysates of Ti alkoxides and templates by the intermolecular hydrogen bond. The prepared samples have been characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N-2 adsorption-desorption, and UV-vis spectroscopy. The results show that the samples have a typical ordered mesoporous structure. The crystallite size, pore size, and surface area of Fe-N co-doped TiO2 are about 13.6, 18.4 nm, and 172.08 m(2) g(-1), respectively. The iron species as the Fe3+ oxidation state are substitutionally doped into the TiO2 lattice, and the doped nitrogen atom is incorporated into the TiO2 lattice as the interstitial N. The co-doping of nitrogen and iron can enhance the absorption of visible region and inhibit the recombination of photogenerated charge carriers, leading to higher photocatalytic activity for the co-doped sample than pure TiO2 and solely doped with iron or nitrogen for degradation of methyl orange under visible light irradiation.