A eutectic mixture of choline chloride and urea as an assisting solvent in the synthesis of flower-like hierarchical BiOCl structures with enhanced photocatalytic activity

Flower-like hierarchical BiOCl structures were successfully synthesized in the presence of a eutectic mixture of choline chloride and urea through a solvothermal process. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption analysis, photo-electrochemical analysis and UV-vis diffuse reflectance spectroscopy (DRS). During the reaction process, the eutectic mixture of choline chloride and urea acted not only as the solvent and the template, but also as a chlorine source for the fabrication of flower-like BiOCl. In addition, the photocatalytic activity toward the degradation of RhB in aqueous solution was also investigated. The results showed that the flower-like BiOCl exhibited enhanced photocatalytic activity for the degradation of RhB under sunlight illumination. Meanwhile, the flower-like BiOCl catalyst performed without obvious decrease in activity after five cycles. Furthermore, the main reactive species in the catalytic oxidation reaction were detected through radical trapping experiments.