Enhanced photocatalytic performance of BiOClxI1-x solid solution benefited from effective separation of photogenerated carriers

In this study, BiOClxI1-x solid solution photocatalysts were fabricated by a hydrothermal method. The structure, morphology, optical performance, surface chemical microstructure and photogenerated carriers separation efficiency of BiOClxI1-x catalysts were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), UV–Vis diffuse reflection spectroscopy (UV–Vis DRS), X-ray photoelectron spectrometer (XPS) and surface photo-voltage spectroscopy (SPS). For the BiOClxI1-x solid solution, molar ratio of Cl−/I− can be adjusted to achieve the regulation of morphology and oxygen vacancies (OVs) concentration for the sake of improving the separation efficiency of photogenerated carriers. Rhodamine B (RhB) and tetracycline (TC) were used as simulated pollutants to investigate the photocatalytic performance of BiOClxI1-x samples under the irradiation of a 500 W Xe lamp. When the molar ratio of Cl−/I− is 1, the sample shows the highest degradation activity for removal of RhB and TC. The degradation rate constants of RhB and TC on BiOCl0.5I0.5 is 24 and 10 times of that on BiOI, respectively. The photocatalytic degradation of fluorinated compounds by BiOCl, BiOI and BiOCl0.5I0.5 was assessed by destroying perfluorooctanoic acid (PFOA) under ultraviolet (UV) light irradiation. The major active species in BiOClxI1-x photocatalytic system were investigated, and a photocatalytic enhancement mechanism of BiOClxI1-x was reasonably elaborated considering the above experimental observations.