Enhanced photocatalytic decolorization of methyl orange by gallium-doped α-Fe2O3

Gallium (Ga)-doped hematite (α-Fe2O3) with different molar ratios of Ga/Fe (1%, 2%, 3% and 4%) was prepared by a facile parallel flow co-precipitation method. The photocatalysts prepared were characterized by the Brunauer–Emmett–Teller method, X-ray diffraction, UV/vis diffuse reflectance spectroscopy, and scanning electron microscope. The photo-generated charges separation efficiency of different photocatalysts was investigated using benzoquinone as scavenger. The formation rate of OH radicals produced during the photocatalytic reaction process was studied by a terephthalic acid photoluminescence probing technique. Doping Ga3+ into α-Fe2O3 increases the specific surface area and the separation efficiency of photo-induced charges. The catalytic activity of the photocatalysts for decolorization of methyl orange aqueous solution was investigated. The results show that α-Fe2O3 doped with 3% Ga possesses the best photocatalytic activity. The underlying mechanism is suggested.