Thermal Conversion of Guanylurea Dicyanamide into Graphitic
Carbon Nitride via Prototype CN<i><sub>x</sub></i> Precursors
Bettina V. Lotsch
Wolfgang Schnick
10.1021/cm050350q.s002
https://acs.figshare.com/articles/dataset/Thermal_Conversion_of_Guanylurea_Dicyanamide_into_Graphitic_Carbon_Nitride_via_Prototype_CN_i_sub_x_sub_i_Precursors/3275695
Guanylurea dicyanamide, [(H<sub>2</sub>N)C(O)NHC(NH<sub>2</sub>)<sub>2</sub>][N(C⋮N)<sub>2</sub>], has been synthesized by ion exchange
reaction in aqueous solution and structurally characterized by single-crystal X-ray diffraction (<i>C</i>2/<i>c</i>, <i>a </i>=
2249.0(5) pm, <i>b </i>= 483.9(1) pm, <i>c </i>= 1382.4(3) pm, β = 99.49(3)°, <i>V </i>= 1483.8(5) × 10<sup>6</sup> pm<sup>3</sup>, <i>T </i>= 130
K). The thermal behavior of the molecular salt has been studied by thermal analysis, temperature-programmed X-ray powder diffraction, FTIR spectroscopy, and mass spectrometry between room
temperature and 823 K. The results were interpreted on a molecular level in terms of a sequence of
thermally induced addition, cyclization, and elimination reactions. As a consequence, melamine (2,4,6-triamino-1,3,5-triazine) is formed with concomitant loss of HNCO. Further condensation of melamine
yields the prototypic CN<i><sub>x</sub></i> precursor melem (2,6,10-triamino-<i>s</i>-heptazine, C<sub>6</sub>N<sub>7</sub>(NH<sub>2</sub>)<sub>3</sub>), which alongside
varying amounts of directly formed CN<i><sub>x</sub></i>H<i><sub>y</sub></i> material transforms into layered CN<i><sub>x</sub></i>H<i><sub>y</sub></i> phases without
significant integration of oxygen into the core framework owing to the evaporation of HNCO. Thus,
further evidence can be added to melamine and its condensation product melem acting as “key
intermediates” in the synthetic pathway toward graphitic CN<i><sub>x</sub></i>H<i><sub>y</sub></i> materials, whose exact constitution is
still a point at issue. Due to the characteristic formation process and hydrogen content a close relationship
with the polymer melon is evident. In particular, the thermal transformation of guanylurea dicyanamide
clearly demonstrates that the formation of volatile compounds such as HNCO during thermal decomposition
may render a large variety of previously not considered molecular compounds suitable CN<i><sub>x</sub></i> precursors
despite the presence of oxygen in the starting material.
2005-07-26 00:00:00
CN x H y material
Graphitic Carbon Nitride
melamine yields
FTIR spectroscopy
guanylurea dicyanamide
mass spectrometry
CN x H y phases
NH 2
HNCO
condensation product melem
C 6 N 7
Thermal Conversion
polymer melon
pm
graphitic CN x H y materials
CN x precursors
Guanylurea Dicyanamide
Prototype CN x Precursors Guanylurea dicyanamide
130 K
ion exchange reaction
hydrogen content
823 K
formation process
elimination reactions
core framework
room temperature