科研之友
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摘要
Aniline, pyrrole and phenanthroline, which have different nitrogen compositions, are used as carbon precursors to synthesize nitrogen-doped ordered mesoporous carbons (NOMCs) by the nano casting method. The effect of the precursor on the resultant NOMC is extensively investigated by nitrogen adsorption-desorption measurements, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and rotating ring-disk electrode measurements. Salient findings are as follows. First, the precursor has a significant influence on the specific surface area and textural properties. The NOMC materials derived from pyrrole (C-PY-900: 765 m(2)/g) and phenanthroline (C-Phen-900: 746 m(2)/g) exhibit higher specific surface areas than the aniline analog (C-PA-900: 569 m(2)/g). Second, the XPS results indicate that the total nitrogen content (ca. 3.1-3.3 at%) is similar for the three carbon sources, except for a slight difference in the nitrogen configuration. Furthermore, the content of the nitrogen-activated carbon atoms is found to closely depend on the precursor, which is the highest for the phenanthroline-derived carbon. Third, the electrochemical results reveal that the electrocatalytic activity follows in the order C-PA-900 < C-PY-900 < C-Phen-900, confirming that the nitrogen-activated carbon atoms are the active sites for the oxygen reduction reaction (ORR). In summary, the precursor has considerable influence on the composition and textural properties of the NOMC materials, of which the ORR electrocatalytic activity can be enhanced through optimization of the NOMCs.
