Abstract:Carbon nitride is synthesized in the form of g -C 3 N 4 and β -C 3 N 4 with the use of two methods: (i) thermal decomposition of a mixture of sodium and potassium thiocyanates and (ii) interaction of carbon tetrachloride CCl 4 with ammonia NH 3 . The carbon-nitrogen phases thus synthesized are investigated using electron microscopy, X-ray powder diffraction, IR spectroscopy, and mass spectrometry.
“…By analogy, we speculate that the structure of triazole-LiCl/KCl-derived carbon nitrides is built of partially deprotonated 1D-polymer chains intercalated with K + and Li + . Solid state 13 C{ 1 H} CP/MAS NMR investigations of II-LiK-CN showed the presence of signals at 161 and 154 ppm, as in the bulk product (Supporting Information Figure S5). However, the ratio of intensities of the 13 C signal at 161 ppm to the one at 154 ppm is higher in the salt-melt-derived material, indicating that in this case more carbon nuclei have closer contact to hydrogen atoms, i.e., there are more NH/NH 2 groups, which is in agreement with EA and FTIR data.…”
Section: Chemistry Of Materialsmentioning
confidence: 99%
“…Solid state 13 C{ 1 H} CP/MAS NMR investigations of II-LiK-CN showed the presence of signals at 161 and 154 ppm, as in the bulk product (Supporting Information Figure S5). However, the ratio of intensities of the 13 C signal at 161 ppm to the one at 154 ppm is higher in the salt-melt-derived material, indicating that in this case more carbon nuclei have closer contact to hydrogen atoms, i.e., there are more NH/NH 2 groups, which is in agreement with EA and FTIR data. The absence of any low field signal at 168 ppm excludes the presence of triazine rings in the polymer.…”
Section: Chemistry Of Materialsmentioning
confidence: 99%
“…Carbon nitrides can be obtained by the thermal condensation of nitrogen-rich precursors. The common monomers for such syntheses are cyanamide, dicyandiamide, melamine, and urea, but also different thiocyanates are classically used (e.g., Hg, Na, K, NH 4 ). , The structure of the polymeric CN materials is typically built of tri- s -triazine rings, also called heptazine (in case of various carbon nitrides based on condensed melon), but also triazine units (in case of poly(triazine imides), PTI , ).…”
Carbon nitride polymers were prepared for the first time by the pyrolysis of 3,5-disubstituted-1,2,4-triazole derivatives, namely 3,5-diamino-1,2,4-triazole [1] and 3-amino-1,2,4-triazole-5-thiol [2], in bulk as well as in LiCl/KCl salt melts. The reaction of [1] and [2] in bulk yields condensed heptazine-based polymers, while in LiCl/KCl eutectics it leads to the formation of well-defined potassium poly(heptazine imides), according to the results of 13 C NMR and XPS investigations, whose formation resembles that of emeraldine salts of polyaniline. The density functional calculations supported the structural model suggested for potassium poly(heptazine imide) polymer. Owing to the specific reaction path, the products obtained from triazoles therefore show electronic properties rather different to known carbon nitrides, such as band gap and conduction and valence bands positions. With the degree of crystallinity of the reference materials, triazole-derived carbon nitrides are characterized by almost complete absence of steady photoluminescence, charge separation and localization upon excitation seems to be improved. As a consequence, photocatalysts prepared from [2] outperform classical carbon nitrides in a model dye degradation reaction and mesoporous graphitic carbon nitride in hydrogen evolution reaction under visible light irradiation. On its turn, [1] can be conveniently used as a co-monomer in order to prepare carbon nitrides with improved visible light absorption.
“…By analogy, we speculate that the structure of triazole-LiCl/KCl-derived carbon nitrides is built of partially deprotonated 1D-polymer chains intercalated with K + and Li + . Solid state 13 C{ 1 H} CP/MAS NMR investigations of II-LiK-CN showed the presence of signals at 161 and 154 ppm, as in the bulk product (Supporting Information Figure S5). However, the ratio of intensities of the 13 C signal at 161 ppm to the one at 154 ppm is higher in the salt-melt-derived material, indicating that in this case more carbon nuclei have closer contact to hydrogen atoms, i.e., there are more NH/NH 2 groups, which is in agreement with EA and FTIR data.…”
Section: Chemistry Of Materialsmentioning
confidence: 99%
“…Solid state 13 C{ 1 H} CP/MAS NMR investigations of II-LiK-CN showed the presence of signals at 161 and 154 ppm, as in the bulk product (Supporting Information Figure S5). However, the ratio of intensities of the 13 C signal at 161 ppm to the one at 154 ppm is higher in the salt-melt-derived material, indicating that in this case more carbon nuclei have closer contact to hydrogen atoms, i.e., there are more NH/NH 2 groups, which is in agreement with EA and FTIR data. The absence of any low field signal at 168 ppm excludes the presence of triazine rings in the polymer.…”
Section: Chemistry Of Materialsmentioning
confidence: 99%
“…Carbon nitrides can be obtained by the thermal condensation of nitrogen-rich precursors. The common monomers for such syntheses are cyanamide, dicyandiamide, melamine, and urea, but also different thiocyanates are classically used (e.g., Hg, Na, K, NH 4 ). , The structure of the polymeric CN materials is typically built of tri- s -triazine rings, also called heptazine (in case of various carbon nitrides based on condensed melon), but also triazine units (in case of poly(triazine imides), PTI , ).…”
Carbon nitride polymers were prepared for the first time by the pyrolysis of 3,5-disubstituted-1,2,4-triazole derivatives, namely 3,5-diamino-1,2,4-triazole [1] and 3-amino-1,2,4-triazole-5-thiol [2], in bulk as well as in LiCl/KCl salt melts. The reaction of [1] and [2] in bulk yields condensed heptazine-based polymers, while in LiCl/KCl eutectics it leads to the formation of well-defined potassium poly(heptazine imides), according to the results of 13 C NMR and XPS investigations, whose formation resembles that of emeraldine salts of polyaniline. The density functional calculations supported the structural model suggested for potassium poly(heptazine imide) polymer. Owing to the specific reaction path, the products obtained from triazoles therefore show electronic properties rather different to known carbon nitrides, such as band gap and conduction and valence bands positions. With the degree of crystallinity of the reference materials, triazole-derived carbon nitrides are characterized by almost complete absence of steady photoluminescence, charge separation and localization upon excitation seems to be improved. As a consequence, photocatalysts prepared from [2] outperform classical carbon nitrides in a model dye degradation reaction and mesoporous graphitic carbon nitride in hydrogen evolution reaction under visible light irradiation. On its turn, [1] can be conveniently used as a co-monomer in order to prepare carbon nitrides with improved visible light absorption.
“…In order to understand the different performances of these 12 nitrogen sources, their difference on the decomposition products should be considered. The thermal decomposition products of 12 inorganic compounds under conventional heating conditions are available in the literature, − and summarized in Scheme (see also Table ). 1 Decomposition Reactions of 12 Inorganic Nitrogen Sources under Conventional Heating Conditions a These are presumed to be the possible decomposition processes during discharging as well. In eq 18, the generated melamine condenses into “melem” with the further release of NH 3 . , …”
A series of nitrogen-containing inorganic solid compounds with variable oxidation states of nitrogen and counter ions have been successfully applied as new inorganic solid nitrogen sources toward the synthesis of Sc-based metal nitride clusterfullerenes (Sc-NCFs), including ammonium salts [(NH4)xH(3-x)PO4 (x = 0-2), (NH4)2SO4, (NH4)2CO3, NH4X (X = F, Cl), NH4SCN], thiocyanate (KSCN), nitrates (Cu(NO3)2, NaNO3), and nitrite (NaNO2). Among them, ammonium phosphates ((NH4)xH(3-x)PO4, x = 1-3) and ammonium thiocyanate (NH4SCN) are revealed to behave as better nitrogen sources than others, and the highest yield of Sc-NCFs is achieved when NH4SCN was used as a nitrogen source. The optimum molar ratio of Sc2O3:(NH4)3PO4·3H2O:C and Sc2O3:NH4SCN:C has been determined to be 1:2:15 and 1:3:15, respectively. The thermal decomposition products of these 12 inorganic compounds have been discussed in order to understand their different performances toward the synthesis of Sc-NCFs, and accordingly the dependence of the production yield of Sc-NCFs on the oxidation state of nitrogen and counter ion is interpreted. The yield of Sc3N@C80 (I(h) + D(5h)) per gram Sc2O3 by using the N2-based group of nitrogen sources (thiocyanate, nitrates, and nitrite) is overall much lower than those by using gaseous N2 and NH4SCN, indicating the strong dependence of the yield of Sc-NCFs on the oxidation state of nitrogen, which is attributed to the "in-situ" redox reaction taking place for the N2-based group of nitrogen sources during discharging. For NH3-based group of nitrogen sources (ammonium salts) which exhibits a (-3) oxidation states of nitrogen, their performance as nitrogen sources is found to be sensitively dependent on the anion, and this is understood by considering their difference on the thermal stability and/or decomposition rate. Contrarily, for the N2-based group of nitrogen sources, the formation of Sc-NCFs is independent to both the oxidation state of nitrogen (+3 or +5) and the cation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
