A Facile One-Step Synthesis of Fe-Doped g-C₃N₄ Nanosheets and Their Improved Visible-Light Photocatalytic Performance

A simple one-step pyrolysis process (compared with the routine method of liquid exfoliation and impregnation) was designed to synthesize Fe-doped graphitic carbon nitride (g-C₃N₄) nanosheets with NH₄Cl as dynamic gas template and FeCl₃ as the Fe source. Results of XPS and DRS indicated that the Fe species might exist at the state of Fe³⁺ and form Fe−N bonds with N atoms, thereby expanding visible light absorption regions and reducing the band gap of g-C₃N₄ nanosheets. Doping certain amounts of Fe could promote the exfoliation and further increase the specific surface area, while excessive Fe might break the sheet structure. The specific surface area of the optimized Fe-doped g-C₃N₄ nanosheets reached 236.52 m² g⁻¹, which was 2.5 times higher than that of g-C₃N₄ nanosheets. Among various photocatalysts prepared, the sample (0.5 wt % FeCl₃) exhibited maximum photocatalytic performance in degradation of Methylene Blue and water splitting under visible light irradiation. The degradation rate of MB was about 1.4 and 1.7 times higher than that of pure g-C₃N₄ nanosheets and bulk g-C₃N₄, respectively. The H₂ production rate was 536 μmol h⁻¹ g⁻¹, which was 1.8 and 6 times higher than that of pure g-C₃N₄ nanosheets and bulk g-C₃N₄, separately.