Significant improvement of photocatalytic activity of porous graphitic-carbon nitride/bismuth oxybromide microspheres synthesized in an ionic liquid by microwave-assisted processing

Graphitic-carbon nitride/bismuth oxybromide (g-C3N4/BiOBr) porous microspheres have been successfully synthesized by a one-pot ethylene glycol (EG) assisted microwave process in the presence of 1-hexadecyl-3-methylimidazolium bromine ([C16mim]Br). The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and UV-vis diffuse reflectance spectroscopy (DRS). During the reaction process, the ionic liquid acts not only as solvent and Br source but also as a template for fabrication of g-C3N4/BiOBr porous microspheres. In addition, the photocatalytic activity of the g-C3N4/BiOBr is evaluated by degrading Rhodamine B (RhB) and ciprofloxacin (CIP) under visible-light irradiation. It is found that 12.75 wt% g-C3N4/BiOBr microspheres exhibit higher photocatalytic activity than that of the as-prepared BiOBr. A possible photocatalytic mechanism based on the relative band positions of g-C3N4/BiOBr has been proposed.