The Z-scheme photocatalyst S-BiOBr/Bi2Sn2O7 with 3D/0D interfacial structure for the efficient degradation of organic pollutants

Abstract

The establishment of heterojunction photocatalysts with significant degradation ability is identified as an effective strategy to address refractory pollutants. S-BiOBr nano-flowers were successfully synthesized by the isomorphous replacement combined self-assembly methods, and then Bi2Sn2O7 was deposited in-situ on the surface to construct a 3D/0D interfacial Z-scheme S-BiOBr/Bi2Sn2O7 heterojunction. The S-BiOBr/Bi2Sn2O7 maintained high activity on the degradation of rhodamine B, tetracycline and the inactivation of Spirulina, and three-dimensional excitation-emission matrix fluorescence spectroscopy was used to track the dynamic degradation process of pollutants. Mechanism analysis revealed that the h+ and O2− radicals played a leading role in the photocatalytic process, and OH played an assisting role. This enhanced activity can be attributed to the formation of oxygen vacancies at the interface when BiOBr is doped with S, which not only promoted the upward shift of the conduction band and thus improving the oxidation ability, but also narrowed the bandgap and thus boosting the visible light harvesting of BiOBr. Semiconductor produced photogenerated electron-hole pairs are effectively separated, and the redox ability of photogenerated carriers is maintained. These results provide a reasonable design method of high-efficiency heterojunction photocatalysis for refractory pollutants’ removal from wastewater.