Fabrication of highly visible-light-responsive ZnFe2O4/TiO2 heterostructures for the enhanced photocatalytic degradation of organic dyes

Abstract

In this study, a novel visible-light-sensitive ZnFe₂O₄–TiO₂ photocatalyst has been fabricated by coupling 0.2–2 wt% p-type ZnFe₂O₄ narrow bandgap material with n-type anatase TiO₂ for the enhanced photocatalytic degradation of organic dyes under 465 nm visible light irradiation. Transmission electron microscopy (TEM) and high resolution TEM confirm that ZnFe₂O₄ and TiO₂ are strongly linked with an average particle size of 8–9 nm, leading to a decrease in hole–electron recombination rate as well as the enhanced photocatalytic activity of the ZnFe₂O₄–TiO₂ heterostructures under visible light irradiation. The optimized 1 wt% ZnFe₂O₄ not only significantly extends the absorption edge of TiO₂-based heterostructures to the visible light region but can also retain a stable photodegradation efficiency of >99% for at least 5 cycles. In addition, the photocatalytic activity of ZnFe₂O₄–TiO₂ toward dye decomposition follows the order cationic rhodamine B > neutral methyl red > anionic methyl orange. Our results clearly demonstrate that the coupling of a low loading mass of ZnFe₂O₄ with anatase TiO₂ is a reliable green technology approach to prepare visible-light-responsive heterostructure photocatalysts with great potential for application in the decomposition of organic dyes and other emerging pollutants in the treatment of water and wastewater.