Nanocrystalline Fe/TiO2 visible photocatalyst with a mesoporous structure prepared via a nonhydrolytic sol-gel route

Fe-doped nanocrystalline TiO2 (Fe/TiO2) with a mesoporous structure was prepared via a facile nonhydrolytic sol-gel (NSG) route. During photodegradation of methylene blue under visible light irradiation, as-prepared Fe/TiO2 exhibited a higher activity than either the undoped TiO2 or the Fe/TiO2 obtained via the traditional hydrolytic sol-gel route. The correlation of the photocatalytic performance to the structural characteristics is discussed based on detailed characterizations. The promoting effect of the Fe-doping on the photocatalytic activity could be attributed to the formation of intermediate energy levels that allow Fe/TiO2 to be activated easily in the visible area. The optimum Fe-content in Fe/TiO2 is determined as 0.1% (Fe/Ti molar ratio). The nonhydrolytic sol-gel method is superior to the traditional hydrolytic sol-gel method owing to the controllable reaction rate and lack of surface tension, which ensures the formation of mesopores and well-crystallized anatase in the Fe/TiO2 sample, leading to a higher activity since the reactant molecules are easily adsorbed and the recombination between the photoelectrons and the holes is effectively inhibited. Meanwhile, the nonhydrolytic sol-gel process could strengthen the incorporation of Fe-dopants in the TiO2 network, which may further enhance the promoting effect of Fe-doping on the photocatalytic activity.