Enhanced photocatalytic activity of a-Fe₂ O₃/g-C₃ N₄ composite materials for degradation of toluene in aqueous solution under visible light irradiation

The photocatalytic oxidation method can be used to effectively remove volatile organic com-pounds present in water and has the ability to degrade even at low concentrations. This study presents the analysis of photoexcited charge carriers with a proposed Z-scheme interface of the a-Fe₂ O₃/g-C₃ N₄ composite for better photocatalytic degradation of toluene in aqueous solution. The a-Fe₂ O₃/g-C₃ N₄ heterojunction synthesized by the solvothermal method by combining a-Fe₂ O₃ microspheres constructed from several nanospheres with g-C₃ N₄ nanosheets. The prepared samples were characterized by different techniques such as X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron, scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, UV-Vis diffuse reflectance spec-troscopy, and photoluminescence in order to analyze their elemental composition and optical properties. The degradation of toluene as a volatile organic compound candidate is analyzed to determine the photocatalytic efficiency. It is observed that narrowing the band gap in the hete-ro-composite structure increases the charge carrier mobility and reduces the recombination rate. Furthermore, the electrons migrate from the conduction band of a-Fe₂ O₃ to the valence band of g-C₃ N₄ due to the shift in the interfacial interaction band position. The 60% a-Fe₂ O₃/g-C₃ N₄ composite exhibits the highest photocatalytic activity among all samples and more than 90% degradation of toluene in water is achieved.