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

• Published in: Chemistry of materials Vol. 12; no. 12; pp. 3906 - 3912
• Main Author: Gillan, Edward G
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.12.2000
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Chemistry; Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...); Exact sciences and technology; Inorganic chemistry and origins of life; Miscellaneous; Preparations and properties; Technical ceramics; Organic azide; Chemical preparation; Triazine derivatives; Manufacturing; Precursor; Carbon Nitrides; Non oxide ceramics
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm000570y

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)(N3)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., C3N4. Under applied nitrogen gas pressure, (C3N3)(N3)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 °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 sp2 carbon bonding in a conjugated doubly bonded network. Electron microscopy reveals that these powders have a glassy microstructure with large irregular pores and voids. C3N4 and C3N5 are thermally stable up to 600 °C 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.