A new and environmentally benign precursor for the synthesis of mesoporous g-C3N4 with tunable surface area

An environmentally benign and widely available precursor, guanidinium chloride, has been employed, for the first time, for the synthesis of mesoporous g-C3N4 materials via a nanocasting method using 12 nm colloid silica as a hard template. A series of mesoporous g-C3N4 (C3N4-G-r) samples with bimodal pore systems (1.8 and 13.4 nm), and high surface areas (146–215 m2 g−1) along with large pore volumes (0.57–0.84 m3 g−1), depending on the amount of templates, have been successfully prepared. Several techniques including X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and CHN elemental analysis have confirmed the formation of graphitic structures and extremely high nitrogen content of the synthesized C3N4-G-r materials. In Friedel–Crafts acylation reaction between hexanoyl chloride and benzene, C3N4-G-r samples, especially C3N4-G-1.0 with a large surface area of 215 m2 g−1, have demonstrated high catalytic conversions, affording a maximum yield of 86% of n-hexanophenone in 4 h at 80 °C.