Nitrogen-doped carbon nanoparticles (NCNPs) were synthesized by a solution plasma process followed by a thermal annealing at 900°C. Cyano-aromatic molecules, including cyanobenzene (C7H5N), 2-cyanopyridine (C6H4N2), and cyanopyrazine (C5H3N3), were used as single source precursors for the synthesis. The morphological features of NCNPs were governed by the aggregates and agglomerates of uniform nanosized particles (20-40nm). The structural analyses confirmed that NCNPs mainly exhibited a disordered amorphous carbon structure. The nitrogen doping contents determined from an X-ray photoelectron spectroscopy were found to be 0.58, 1.36, and 1.29 at% for NCNPs synthesized from cyanobenzene, 2-cyanopyridine, and cyanopyrazine, respectively. The improvements of oxygen reduction reaction activity and selectivity toward a four-electron pathway in an alkaline solution of NCNPs were correlated with the nitrogen doping content and nitrogen bonding state. The NCNPs also possessed excellent long-term durability and strong methanol tolerance in an alkaline solution compared to those of a commercial Pt/carbon catalyst.
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