Nanosheets loaded on tetrahedral surfaces form a Z-type Bi2MoO6/γ-Bi2O3 heterojunction to enhance the photocatalytic degradation activity of lomefloxacin and Rhodamine B

Abstract

The Bi₂MoO₆ nanosheets are loaded on to γ-Bi₂O₃ tetrahedron surfaces to form Bi₂MoO₆/γ-Bi₂O₃ heterojunctions using a simple calcination method. The photocatalytic degradation efficiencies of the lomefloxacin and the Rhodamine B using the optimum sample are 96% and 99%, respectively, much higher than that of pure phase samples. When the waters from different regions in China were used as solvents, the removal efficiencies of the lomefloxacin and the Rhodamine B are still higher than 88% and 90%, respectively, which shows excellent prospects for practical applications. The photocatalytic degradation efficiencies of these two pollutants are higher than 91% and 95% in the five cycling tests, and the crystal structure of the sample is not changed after cycling. Based on the first-principles calculation, Bi₂MoO₆ and γ-Bi₂O₃ form a Z-type energy band structure which accelerates the separation of the photogenerated charge carriers. The Bi₂MoO₆ valence band potential of 3.25 V and the γ-Bi₂O₃ conduction band potential of −0.21 V are reserved to generate ˙OH⁻ and O₂⁻, respectively, for the photocatalytic reaction. The degradation of the lomefloxacin is ascribed to the shedding of functional groups and bond breaking with the final products being CO₂, F⁻, H₂O, and NO₃⁻. This research shows that Bi₂MoO₆/γ-Bi₂O₃ heterojunctions can be employed to purify domestic and textile industrial sewage.