sc9b07161_si_001.pdf (5.65 MB)
Tunable Synthesis of Nitrogen Doped Graphene from Fluorographene under Mild Conditions
journal contribution
posted on 2020-02-25, 15:48 authored by Dagmar Zaoralová, Vítĕzslav Hrubý, Veronika Šedajová, Radim Mach, Vojtĕch Kupka, Juri Ugolotti, Aristides Bakandritsos, Miroslav Medved’, Michal OtyepkaThe
nitrogen doping of graphene via mild and low energy processes
to afford homogeneous product composition and topology with high nitrogen
content (>10 at. %) remains a challenge of contemporary 2D materials
chemistry. Here, we report a previously unexplored route to synthesize
N-doped graphene (NG) with exceptionally high N content (up to 18.2
at. %) by reaction of fluorographene (FG) with NaNH2 in N,N-dimethylformamide (at 130 °C) or acetonitrile (at
70 °C). The N content can be tuned by changing the reaction time,
temperature, and/or solvent, ranging from 6.6 to 18.2 at. %, mainly
in the form of pyridinic and pyrrolic configurations. With thermal
annealing, the N content remained constant up to 400 °C but then
decreased by ∼50% upon being further annealed to 1000 °C.
Density functional theory (DFT) calculations showed that nitrogen
incorporation into the carbon lattice mostly occurred at vacancies
present in the starting material. We also conducted a thorough rationalization
of side-reaction pathways leading to byproducts, which were confirmed
by GC-MS analysis. This is the highest yet recorded N content for
a wet chemical doping procedure and at such a low temperature of 70
°C. The reported synthetic approach thus offers a sustainable
and cost-effective way to prepare NG with a broad tunability window
of N content for potential applications related to energy storage
and catalysis.