Controllable synthesis of hexagonal and orthorhombic YFeO3 and their visible-light photocatalytic activities

Single phase hexagonal and orthorhombic YFeO3 were prepared by a citric acid assisted sol-gel process. The prepared samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area measurement, transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy (DRS). The phase composition can be effectively controlled by changing the calcination temperature. It is found that the hexagonal form exhibits a narrow optical band gap in comparison with the orthorhombic one, and shows stronger visible-light photocatalytic activity than the orthorhombic one. Both the narrow optical band gap and unique porous structure are responsible for the high visible-light photocatalytic activity of the hexagonal form. (C) 2012 Elsevier B.V. All rights reserved.