Visible-light-induced Fe-doped BiVO4 photocatalyst for contaminated water treatment

Abstract

A monoclinic–tetragonal heterostructured BiVO4 photocatalyst doped with varying quantities of Fe was synthesized by a microwave–hydrothermal method and employed in the photodegradation of ibuprofen and inactivation of Escherichia coli under irradiation with visible light. An improvement in the photocatalytic activity for the Fe-doped BiVO4 was confirmed relative to that determined for the undoped BiVO4. The in-gap state formed between the valence band and conduction band of BiVO4 as a result of doping, as established by first principles DFT calculations, facilitates an easy transition of electrons from the valence band to the conduction band. This transition enhances the tendency of electron–hole separation and improves the visible light absorption capacity, thereby improving the photocatalytic activity. Among the various concentrations of Fe dopant examined, the highest visible light photoactivity is demonstrated for the 1wt% Fe-doped BiVO4 photocatalyst, which degrades 80% of ibuprofen within 180min and inactivates 90% of Escherichia coli within 5h. No decrease in the efficiency of the 1wt% Fe-doped BiVO4 photocatalyst was observed during the degradation of ibuprofen over three consecutive cycles, thereby demonstrating the stability of the semiconductor towards photocorrosion. Possible mechanisms for both the enhanced photocatalytic activity and the degradation of ibuprofen are proposed on the basis of the experimental observations.