Photocatalytic and photoelectrochemical studies of visible-light active α-Fe2O3–g-C3N4 nanocomposites

Abstract

Nanocrystalline hematite iron oxide (α-Fe₂O₃) and graphitic carbon nitride (g-C₃N₄) were prepared and used as precursors to synthesise α-Fe₂O₃–g-C₃N₄ composite photocatalysts of various compositions by a wet impregnation method. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and photoluminescence spectroscopy (PL). The efficiency of the photocatalysts was evaluated by photoelectrochemical measurements and photodegradation of direct red 81 (DR81) as a target textile pollutant under visible light irradiation. The α-Fe₂O₃–g-C₃N₄ composites exhibited remarkably improved visible-light induced photocatalytic activity. The composite photocatalysts with optimal α-Fe₂O₃ content with the highest photocatalytic activity was found to be 2%-α-Fe₂O₃–g-C₃N₄. The synergistic enhancement in the photocatalytic degradation of composite photocatalysts might be due to an increase in the visible-light absorption efficiency and rapid photoinduced charge separation. A possible photocatalytic mechanism has been proposed for the photocatalytic activity of α-Fe₂O₃–g-C₃N₄ composite photocatalysts.