Efficient visible light degradation of rhodamine B by a photo-electrochemical process based on a Bi2WO6 nanoplate film electrode

In this paper, a Bi2WO6 nanoplate film electrode was prepared by a hydrothermal method, combined with a spin coating technique. A photoelectrochemical (PEC) oxidation system based on this electrode was then constructed to degrade rhodamine B (RhB) in aqueous solution under visible light (lambda > 420 nm). The PEC system based on Bi2WO6 nanoplate film electrode could degrade 87.2% of RhB with concentration of 5 mg/L in 120 min, operated at low voltage and under visible light irradiation, whereas only 36.8% and 39.5% degradation of RhB were observed for electro-oxidation process (EC) and photocatalytic oxidation process (PC), respectively, operated under the same condition. These results revealed a significant synergetic effect on degrading RhB via electro-oxidation and photocatalysis under visible light irradiation. A possible mechanism for this synergetic degradation of RhB was proposed on the basis of characterization results. Meanwhile, the degradation pathway of RhB during PEC under visible light irradiation was also discussed. This study provided an effective approach for aqueous organic pollutant removal by utilizing solar light.