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

Nanocrystalline hematite iron oxide (alpha-Fe2O3) and graphitic carbon nitride (g-C3N4) were prepared and used as precursors to synthesise alpha-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 alpha-Fe2O3-g-C3N4 composites exhibited remarkably improved visible-light induced photocatalytic activity. The composite photocatalysts with optimal alpha-Fe2O3 content with the highest photocatalytic activity was found to be 2%-alpha-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 alpha-Fe2O3-g-C3N4 composite photocatalysts.