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 efficiency 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)3·5H2O 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 (·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 vacancies (OVs), which effectively promote the adsorption of organic pollutants, boost light responsiveness, and expedite the separation of photoinduced e-/h+ pairs.