Sodium flux-assisted low-temperature high-pressure synthesis of carbon nitride with high nitrogen content

Carbon nitride powders with high nitrogen content have been synthesized via a new, high-pressure (7.7 GPa) and relatively low-temperature (400–500 °C) procedure that involves a chemical reaction of hexachlorobenzene (C6Cl6) and sodium azide (NaN3) in an enclosed system for 50–70 h in the presence of a sodium flux. The obtained powder product was characterized by X-ray powder diffraction, infrared and electron energy loss spectroscopy. The nitrogen–carbon atomic ratio of the material was 1.24 ± 0.15, which is consistent with C3N4 stoichiometry and represents the most nitrogen-rich carbon nitride yet prepared under high-pressure. Scanning electron microscopy and high-resolution transmission electron microscopy studies revealed that the material obtained was predominantly amorphous with some fraction of nanocrystallites with the reticular distance between the lattice planes approximately 0.326 nm.