La3+ doped BiOBr microsphere with enhanced visible light photocatalytic activity

In this work, La3+ doped BiOBr microspheres have been prepared via 1-hexadecy1-3-methy-limidazolium bromine ([C(16)mim]Br) assisted solvothermal process. In this process, [C(16)mim]Br acted not only as the template but also the Br source and was good for the even dispersion of La3+. The morphology and compositional characteristics of the La3+ doped BiOBr microspheres were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The photocatalytic activity of the La3+ doped BiOBr microspheres was evaluated by the degradation of rhodamine B (RhB), colorless antibiotic agent ciprofloxacin (CIP) under visible light irradiation. The as-prepared La3+ doped BiOBr microspheres exhibited much higher photocatalytic activity than pure BiOBr, and the 1 wt% La3+ doped BiOBr showed the highest photocatalytic activity. The enhanced photocatalytic activities were ascribed to the narrowed band gap and the efficient separation of electron hole pairs. The free radical trapping experiments suggested that the holes were the main active specie for the photocatalytic degradation. A possible photocatalytic mechanism of La3+ doped BiOBr has been proposed. (C) 2016 Elsevier B.V. All rights reserved.