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 [(C3N3)(N-3)3] This energetic molecular azide is thermally unstable and readily decomposes at 185 degreesC in a high-pressure reactor to produce carbon nitride materials, e.g., C3N4 Under: applied nitrogen gas pressure, (C3N3)(N-3)(3) decomposes to yield a solid with one of the highest reported nitrogen-to-carbon ratios corresponding to C3N5. This azide precursor also decomposes upon rapid heating to 200 degreesC 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. Electronmicroscopy reveals that these powders have a glassy microstructure with large irregular pores and voids. C3N4 and C3N5 are thermally stable up to 600 degreesC and sublime to produce carbon nitride thin films on SiO2 and Si substrates. A discussion on possible azide decomposition pathways and carbon nitride structures is presented.