Pyrolysis process from precursor to prepare a BCN compound

C₃N₆H₆ (H₃BO₃)₂ was synthesized with C₃N₆H₆ and H₃BO₃ as raw materials in aqueous solution, which was then used as the precursor for preparation of a BCN compound by pyrolysis in flowing N₂ atmosphere. The pyrolysis process was investigated by means of TG-DSC-MS coupling technique, FT-IR, XRD and SEM. The results indicate that the precursor C₃N₆H₆ (H₃BO₃)₂ is a 3D supramolecular compound which is constructed by different hydrogen-bonding interactions between C₃N₆H₆ and H₃BO₃ molecules. With the increase of pyrolysis temperature, C₃N₆H₆ and H₃BO₃ unit in the precursor is gradually decomposed, accompanied by the release of H₂O, NH₃, CO₂, and NO₂ gases. After 1000°C, the pyrolysis process has completed and B-N, B-C, and C-N chemical bonds established in the products, which means the formation of turbostratic-structure BCN compounds with atomic-level hybrid of B, C, and N elements. A novel nitrogen-rich BCN compound with an approximate composition of B₃CN₃ was obtained from the pyrolysis at 1900°C. The B₃CN₃ compound shows bar-like or fibrous morphology similar to the precursor, but there is an obvious reduction in its crystal size compared with the precursor.