Fe and Cu co-doped graphitic carbon nitride as an eco-friendly photo-assisted catalyst for aniline degradation

A novel bimetallic coordinated g-C₃N₄ with Fe₂O₃ composite catalyst (FeCu-g-C₃N₄) was synthesized by simple calcination of Fe³⁺/Cu²⁺/melamine precursor. Its catalytic performance was analyzed via photodegrading aniline. The X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the composition and structure of the catalysts. Results indicated that Fe mainly distributed in the Fe(III)-N coordination form and partly in Fe₂O₃ lattice, and Cu inserted at the interstitial positions of g-C₃N₄ in the Cu(I)-N form. The great optical property was also proved by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence (PL) spectroscopy, and photocurrent responses. The heterogeneous photo-assisted catalyst exhibited excellent performance in activation of H₂O₂, resulting in 80% decomposition of aniline with low metal leaching in 6 h. The incorporation of Cu elevated the performance of degradation compared to that only iron doped. A synergistic catalytic effect between solid Cu(I) and Fe(III) accelerated the reduction of Fe(III). The ·OH and ¹O₂ were confirmed as major reactive oxygen species (ROS) identified by scavenging experiments and ESR, and e^- was the most essential since it not only led to the generation of ROS but also participated in the circulation of Fe³⁺/Fe²⁺, Cu²⁺/Cu⁺, and Fe³⁺/Cu⁺. Furthermore, the possible catalytic mechanism was proposed based on the analysis.