Photocatalytic removal of organic pollutants by SiO2 modified BiOCl nanosheets with abundant oxygen vacancies

In this demonstration, SiO2/BiOCl composites were fabricated by loading SiO2 nanoparticles onto the surface of BiOCl nanosheets through a conventional hydrothermal approach. SiO2/BiOCl photocatalysts were studied by specific surface area analysis, X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflection spectroscopy (UV-Vis DRS) and electron spin resonance (ESR) techniques. In light of the rich pore structures of BiOCl modified by SiO2, the photogenerated carriers separation efficiency of SiO2/BiOCl is significantly improved. Therefore, SiO2/BiOCl composite nanosheets show high ef-ficiency towards degradation of perfluorooctanoic acid (PFOA) and rhodamine B (RhB), and the composites display exceptional stability. In comparison to the pure BiOCl, photocatalytic degradation activity of 4.4 % SiO2/ BiOCl (mass ratio of SiO2/Bi(NO3)3 & sdot;5H2O is 4.4 %) for RhB and PFOA increases by 100 % and 50 %, respectively. The result from the radical capture experiments suggests that holes (h+) and superoxide radicals (& sdot;O2-) play a crucial role as the primary active species in degradation of organic pollutants. The enhanced photocatalytic efficiency of the SiO2/BiOCl composites can be primarily ascribed to the construction of numerous oxygen va-cancies (OVs), which effectively promote the adsorption of organic pollutants, boost light responsiveness, and expedite the separation of photoinduced e -/h+ pairs.