A Handbook for Graphitic Carbon Nitrides: Revisiting the Thermal Synthesis and Characterization Towards Experimental Standardization

Abstract Graphitic carbon nitrides (g-C3N4s) have continued to attract attention as metal-free, low-cost semiconductor catalysts. Herein, a systematic synthesis and characterization of g-C3N4s prepared using four conventional precursors (urea (U), dicyandiamide (DCDA), semicarbazide hydrochloride (SC-HCl), thiosemicarbazide (TSC)) an unexplored one (thiosemicarbazide (TSC-HCl)) is presented. Equal conditions (e.g. heating cooling rates, temperature, atmosphere, reactor type/volume etc.) mitigated the experimental error, offering fair comparability for library g-C3N4s. The highest g-C3N4 amount per mole precursor was obtained D-C3N4 (~37.85 g), while lowest S-C3N4 (~0.78 g). HCl addition TSC increased production yield (~5-fold) oxygen content (T-C3N4~3.17% vs TCl-C3N4~3.80%); however, it had negligible effect on level sulphur doping (T-C3N4~0.52% TCl-C3N4~0.45%). darkest in color (reddish brown), band gap energies were S-C3N4(2.00 eV) < T-C3N4(2.74 TCl-C3N4(2.83 ≤ D-C3N4(2.84 U-C3N4(2.97 eV). experimentally derived conduction position S-C3N4(-0.01 closer Fermi energy than others, attributable high atom (~5.11%). displayed smallest crystallite size (~3.599 nm by XRD) but largest interlayer distance (~0.3269 nm). Furthermore, BET surface areas 138.52 (U-C3N4), 22.24 (D-C3N4), 18.63 (T-C3N4), 10.51 (TCl-C3N4), 9.31 m2/g (S-C3N4). For first time, this comprehensive handbook gives glimpse researcher planning g-C3N4-based research. It also introduces novel oxygen-sulphur co-doped (TCl-C3N4) new halogen-free catalyst with relatively (~24.09