Sn–Cu–Fe‐Doped Graphitic g‐C ₃ N ₄ Hetero Photocatalyst for the Removal of Methylene Blue

This study reports the synthesis of a ternary Sn–Cu–Fe (SCF)–doped g‐C 3 N 4 heterostructured photocatalyst for methylene blue (MB) degradation. Characterizations (Fourier transform infrared [FT‐IR], ultraviolet–visible diffuse reflectance spectroscopy [UV–vis. DRS], x‐ray diffraction [XRD], scanning electron microscopy–energy dispersive x‐ray spectroscopy [SEM–EDS], x‐ray photoelectron spectroscopy [XPS], and electrochemical analyses) confirmed heterojunction formation, band‐gap tuning, and enhanced charge separation. The optimized SCF (3 wt%) + g‐C 3 N 4 showed excellent performance, achieving 99.10% MB removal in 120 min under UV light and ∼70%–75% under visible light. Electrochemical results indicated a negative flat‐band potential (−1.19 V). Radical studies revealed that •OH and •O 2 − species dominate the degradation process. The catalyst maintained over 92% efficiency after five cycles, demonstrating good stability and potential for wastewater treatment.