Synthesis of Z–scheme Bi2S3/RGO/BiVO4 photocatalysts with superior visible light photocatalytic effectiveness for pollutant degradation

Abstract

The design and synthesis of Z-scheme heterojunctions is one of the effective methods to enhance the photocatalytic performance. Herein, the Z-scheme Bi2S3/RGO/BiVO4 composites were prepared by a one-pot hydrothermal method. 0.1Bi2S3/0.5%RGO/BiVO4 shows the best photocatalytic activity of glyphosate degradation under visible light irradiation, and its apparent reaction rate constant (0.01658 min−1) is 7.6, 4.6, and 2.9 times higher than BiVO4 (0.00219 min−1), 0.1Bi2S3/BiVO4 (0.00363 min−1), and 0.5%RGO/BiVO4 (0.00566 min−1). Reduced graphene oxide (RGO) acts as the electron-transfer mediator, and the photoinduced electrons in the conductance band (CB) of BiVO4 migrate through the electron mediator RGO to recombine with the photogenerated holes in the valence band (VB) of Bi2S3 at the interface, promoting the separation and transfer of electrons and holes. Glyphosate was effectively degraded by the electrons in the CB of Bi2S3 and the holes in the VB of BiVO4 with strong oxidation–reduction capacity, thus improving the photocatalytic activity. The major reactive active species detected by active-species-trapping tests and electron paramagnetic resonance are holes, hydroxyl radicals, and superoxide anion radicals. After four cycles, Bi2S3/RGO/BiVO4 still maintained its photocatalytic performance of about 96%. This research provides a new idea for the photocatalytic reaction using Z-scheme heterojunctions under visible-light irradiation.