Carbon nitrides: synthesis and characterization of a new class of functional materials

Pharaoh's Serpents: New Insights into a Classic Carbon Nitride Material

“…We assert that the dark color is due to the presence of HgS, which is removed from the outer part of the column by the heat of the combustion reaction, leaving the characteristic yellow color common to many carbon nitrides [Equation (2)]: [22] HgS + O 2 Ǟ Hg + SO 2 (2) Consistent with this interpretation, the reaction in a nitrogen atmosphere yielded a significantly grayer colored product.…”

“…[18][19][20][21] Most carbon nitride materials under current investigation are produced by thermolytic condensation reactions of organic molecular precursors such as dicyandiamide (DCDA, C 2 N 4 H 4 ) and melamine [C 3 N 3 (NH 2 ) 3 ], giving rise to a range of polymeric C x N y H z compounds. [22] However, Liebig's initial syntheses of "melon" formed part of a series of studies involving reactions of thiocyanate compounds, including NH 4 SCN and KSCN treated with Cl 2 . [23,24] Those investigations were initiated following Scheele's pioneering work of on prussic acid (HCN) and its salts, leading to studies of compounds containing the thiocyanate (SCN -) anion.…”

“…Nevertheless the equation implies that the reaction should result in a hydrogen-free carbon nitride, a product that is being actively sought among carbon nitride researchers. [22,28] Franklin carried out the only reported chemical analyses of the porous yellow product in 1922, with C and N contents recorded as ranging between 35.9-40.2 % and 58.0-60.7 % by weight, respectively, with 0.6-2.4 wt % H present in the samples examined. [29] 39.1 wt % C and 60.9 wt% N are expected for stoichiometric C 3 N 4 .…”

Reexamination of Solvothermal Synthesis of Layered Carbon Nitride

“…The bands at 1249 and 1316 cm −1 indicate the presence of C-N chain bonds between the heptazine rings and NH groups associated with C-NH-C units [14,40] ( Table 2), suggesting that the polymerization of aromatic rings has occurred during the reaction. A shoulder peak at 1647 cm −1 and the broad peaks in 3200-3400 cm −1 region are assigned to the deformation and stretching modes of bridging -NH-and terminal -NH 2 groups, respectively [34,35]. The origin of hydrogen is likely from NH 2 and/or OH molecules, which are derived from the NaNH 2 precursor and water (moisture) adsorbed on the surface.…”

“…Figure 2 shows the FT-IR spectrum of the sample synthesized by heating for 24 hours following the recipe of Guo et al [18], in which strong absorptions are observed in the range of 800-1800 and 2800-3600 cm −1 . Since inplane C-N stretching and bending vibration modes of the striazine-based g-C 3 N 4 show broad bands at 1150-1650 cm −1 region [8,35], the several bands observed in the 1400-1600 cm −1 region (two intense peaks at 1432 and 1568 cm −1 ) are likely attributed to the stretching vibration mode of CN as well as the deformation mode of NH 2 [14,35]. Although Larkin et al [37] pointed out that CN ring deformation mode generates the IR absorption peaks at 675 and 748 cm −1 , these peaks were not observed in this study.…”