From Triazines to Heptazines: Deciphering the Local Structure of Amorphous Nitrogen-Rich Carbon Nitride Materials
Nitrogen-rich carbon nitride (CN x , x ≥ 1) network materials have been produced as disordered structures by a variety of precursor-based methods, many that involve solid-state thermolysis at or above 500 °C. One popular precursor building block is the triazine unit (C3N3), and most postulated amorp...
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Published in | Journal of the American Chemical Society Vol. 130; no. 23; pp. 7373 - 7379 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
11.06.2008
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Online Access | Get full text |
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Summary: | Nitrogen-rich carbon nitride (CN x , x ≥ 1) network materials have been produced as disordered structures by a variety of precursor-based methods, many that involve solid-state thermolysis at or above 500 °C. One popular precursor building block is the triazine unit (C3N3), and most postulated amorphous CN x network structures are based on cross-linked triazine units. Since hydrogen is most often observed in the product, these materials are usually more appropriately described as CN x H y materials. Results from recent carbon nitride studies using larger conjugated heptazine (C6N7) precursors and from rigorous structural investigations of triazine to heptazine thermal conversion processes have prompted a reexamination of likely local structures present in amorphous carbon nitride networks formed by triazine thermolysis reactions. In the present study, the formation and local structure of a CN x H y material formed via the rapid and exothermic decomposition of a reactive triazine precursor, C3N3(NHCl)3, was examined by byproduct gas mass spectrometry, NMR and IR spectroscopy, base hydrolysis, and crystallographic analysis. The combined results clearly indicate that the moderate-temperature (∼400 °C) self-sustaining decomposition of trichloromelamine results in ring fragmentation and reorganization into a CN x H y product that contains predominantly larger heptazine-like structural building blocks. These results may have applicability to many other disordered carbon nitride materials that are formed via triazine thermolysis. It also provides clearer and more accurate structural guidance in the use of these carbon nitrides as photoactive materials or coordination supports for metal and nonmetal species. |
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Bibliography: | TGA of TCM-CNxHy and K3C6N7O3·3H2O, CP-MAS NMR spectrum of TCM-CNxHy, and powder XRD of triazine KOH hydrolysis products. This material is available free of charge via the Internet at http://pubs.acs.org. istex:D19D8F682E4DFE7DBA97A34E8D546FE9AE03A204 ark:/67375/TPS-V1C5DHG5-2 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/ja709992s |