Synthesis of Nitrogen-Rich Carbon Nitride Networks from an Energetic Molecular Azide Precursor

Nitrogen-rich carbon nitrides are produced as amorphous, bulk solids from the slow thermal decomposition of 2,4,6-triazido-1,3,5-triazine [(C 3 N 3 )(N 3 ) 3 ]. This energetic molecular azide is thermally unstable and readily decomposes at 185 °C in a high-pressure reactor to produce carbon nitride materials, e.g., C 3 N 4 . Under applied nitrogen gas pressure, (C 3 N 3 )(N 3 ) 3 decomposes to yield a solid with one of the highest reported nitrogen-to-carbon ratios corresponding to C 3 N 5 . This azide precursor also decomposes upon rapid heating to 200 °C to form graphite nanoparticles without any retained nitrogen. Spectroscopic evidence (infrared, nuclear magnetic resonance, and ultraviolet−visible) demonstrates that the carbon−nitrogen solids have significant sp 2 carbon bonding in a conjugated doubly bonded network. Electron microscopy reveals that these powders have a glassy microstructure with large irregular pores and voids. C 3 N 4 and C 3 N 5 are thermally stable up to 600 °C and sublime to produce carbon nitride thin films on SiO 2 and Si substrates. A discussion on possible azide decomposition pathways and carbon nitride structures is presented.