In situ construction of Sn-doped structurally compatible heterojunction with enhanced interfacial electric field for photocatalytic pollutants removal and CO2 reduction

Fabrication of heterojunction photocatalysts is a promising strategy for achieving spatial charge separation, for which the interfacial electric field is the linchpin. However, the current density of interfacial electric field still have room for enhancement. In this study, we first demonstrated the regulation of interfacial electric field between bismuth semiconductors assisted by stannum (Sn) doping, raising the surface charge transfer efficiency from 27.25 % of BiOBr/BiOIO3 to 38.08 % of Sn-BiOBr/BiOIO3 composite. Correspondingly, the visible-light induced degradation rates towards tetracycline, 2, 4-chlorophenol and Rhodamine B exhibited 4.2-, 4.7- and 31.5-fold increase, respectively. Meanwhile, the CO2 photoreduction activity was also improved. The density functional theory calculation results unveiled that the Sn2+/Sn4+ redox couple could cause charge redistribution at interface and a distinctly unidirectional interfacial electric field with the direction from BiOIO3 to Sn-BiOBr was formed. This study provides a universal strategy for the design of bismuth-containing heterojunction with tunable interfacial electric field.