Indirect Z-scheme TiO₂/BC/g-C₃N₄ for efficient photocatalytic reduction of Cr(VI) in aqueous solution

BACKGROUND: There is increasing concern regarding the rising issue of Cr(VI) pollution in aqueous solutions. It is crucial to find an effective technology for the removal of Cr(VI) in aqueous solutions. In this work, a novel TiO2/BC/g-C3N4 heterostructure photocatalyst was successfully prepared by a simple hydrothermal method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, photoluminescence, ultraviolet-visible diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic reduction behavior of Cr(VI) on the TiO2/BC/g-C3N4 heterostructure was investigated under visible light irradiation, and the possible mechanism of photocatalytic reduction of Cr(VI) was elucidated.RESULTS: The TiO2/BC/g-C3N4 heterostructure photocatalyst exhibited better photoreduction activity for Cr(VI) under visible light irradiation. After 100 min irradiation with visible light, the TiO2/BC/g-C3N4 photocatalyst achieved a removal efficiency of 89% for Cr(VI). Compared with TiO2, TiO2/BC and TiO2/BC/g-C3N4, the photocatalytic removal efficiency of Cr(VI) on the TiO2/BC/g-C3N4 increased by 40%, 20% and 10% respectively. The photocatalytic reduction of Cr(VI) was dependent on the initial concentration of Cr(VI), catalyst dosage, pH value and atmosphere. Moreover, TiO2/BC/g-C3N4 presented excellent stability and reusability after five cycles.CONCLUSION: The TiO2/BC/g-C3N4 heterojunction enables highly efficient photocatalytic reduction of Cr(VI) under visible light irradiation. This enhancement is primarily attributed to the construction of an indirect Z-scheme TiO2/BC/g-C3N4 heterojunction, which significantly improves the separation efficiency of photo- generated charge carriers during the photochemical process. Furthermore, the presence of BC enhances the adsorption performance of Cr(VI) on TiO2/BC/g-C3N4, thereby facilitating its photocatalytic reduction.(c) 2023 Society of Chemical Industry.