Spherical
mesoporous carbon (with a particle size in the range
of 40–75 μm) was synthesized by nanoreplication of a
hard silica template using sucrose as the carbon precursor. The mesoporous
carbon with BET surface areas higher than 1200 m2/g was
doped with N by a treatment in an aqueous solution of nitric acid
and/or in a flow of gaseous ammonia. The highest N content (3.2 wt
% of N in bulk) was obtained when both modification methods were combined.
Complementary physicochemical characterization techniques, including
scanning electron microscopy (SEM), low-temperature N2 adsorption,
powder X-ray diffraction (XRD), and Raman spectroscopy revealed the
morphology, structure, and textural properties of the synthesized
N-loaded carbon materials. For the identification of the detailed
chemical structure on the surface of the carbons, 1H, 13C, and 15N solid-state nuclear magnetic resonance
(NMR) measurements were performed, and the data were supported by
chemical shift calculations with accurate quantum chemistry methods
and X-ray photoelectron spectroscopic (XPS) analyses. All NMR experiments
were performed at natural isotope abundance. The verified experimental
data clearly showed that after the introduction of the N-containing
moieties by the combined methods of treatment, a high concentration
of pyridinic N at the edge, and pyrrolic N being external to the edge,
was achieved for the mesoporous carbon. The distributed N surface
species promoted the catalytic activity in the oxidative dehydrogenation
of ethylbenzene to styrene but did not significantly influence the
efficiency of the carbon materials in the electrochemical reduction
of nitrate ions.