Enhanced visible light photocatalytic reduction of Cr (VI) by Bi2WO6 nanosheet/CuFe2O4 nanofiber heterojunctions

Heterojunction formation is among the important approaches to improve visible light activity of photocatalysts, to achieve cheaper and more sustainable pollutant removal, at larger scale. In this study, Bi₂WO₆ NS/x% CuFe₂O₄ NF (x = 1, 2, 5 and 10) composites were prepared using electrospinning and hydrothermal synthesis, to achieve improved photocatalytic Cr (VI) removal under visible light. The effects of the composite formation on their structural, optical and photocatalytic properties were studied. Pure CuFe₂O₄ and Bi₂WO₆ phases were achieved, as reflected by X-ray diffraction (XRD) analysis, with some variations in peak parameters in the Bi₂WO₆ NS/CuFe₂O₄ NF composites, which confirmed the incorporation of the CuFe₂O₄ NFs into the Bi₂WO₄ NS. From photoluminescence studies, lower emission peaks were observed in the Bi₂WO₆ NS/CuFe₂O₄ NF composites than that in pure Bi₂WO₆ NS, indicating the achievement of suppressed recombination of charge carriers in the composites. Hence, Cr (VI) removal rate was significantly improved with the Bi₂WO₄ NS/ CuFe₂O₄ NF composite formation, where each of them shows higher activity than both Bi₂WO₆ NS and CuFe₂O₄ NF. The highest removal rates of 90.35% and 96.04% were achieved with the sample Bi₂WO₄ NS/2% CuFe₂O₄ NF, after 60 and 120 min of visible light irradiations respectively.