Enhanced visible-light-driven photocatalytic activities of Bi2Fe4O9/g-C3N4 composite photocatalysts

Highlights: • The novel Bi₂Fe₄O₉/g-C₃N₄ composite photocatalysts have been designed and prepared. • Combination of Bi₂Fe₄O₉ and g-C₃N₄ could enhance the visible-light-driven photocatalytic degradation for RhB. • The effects of Bi₂Fe₄O₉/g-C₃N₄ weight ratios on photocatalytic performance in the composite have been discussed. • The Z-scheme photocatalytic mechanism was proposed and discussed in detail. - Abstract: A series of Bi₂Fe₄O₉/g-C₃N₄ composite photocatalysts are prepared via a facile mixing-calcination method. The crystal structures of composites are investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The Field Emission Scanning Electron Microscope (FE-SEM) in combination with Energy Dispersive X-ray Spectroscopy (EDS) mapping analysis and Transmission Electron Microcopy (TEM) images illustrate the uniform distribution of constituent elements and clear interface between Bi₂Fe₄O₉ and g-C₃N₄ component. The visible-light-driven photocatalytic rates of Rhodamine B over Bi₂Fe₄O₉/g-C₃N₄ composites increase and then decrease with the increase of g-C₃N₄ content. The effects of Bi₂Fe₄O₉/g-C₃N₄ weight ratios on photocatalytic performance are thoroughly discussed. Meanwhile, the active species trapping experiments and the electrochemical impedance spectra as well as the electronic energy-band structure estimation analysis demonstrate that the photocatalytic mechanism for Bi₂Fe₄O₉/g-C₃N₄ composites is ascribed to the Z-scheme. In addition, the recyclability and stability experiments of the composite are also studied.