Bottom-Up Synthesis of Pyridinic Nitrogen-Containing Carbon Materials with Reactive C-H from Two-Ring Aromatics
50 Pages Posted: 8 Nov 2022
Abstract
Carbon materials containing pyridinic nitrogen are expected to be effective for electrodes and catalysts, but it is challenging to selectively introduce pyridinic nitrogen at a high content in the absence of catalysts. Carbon materials with high percentages of pyridinic nitrogen have been recently prepared from aromatic compounds with three or more aromatic rings, whereas the precursors have low pyridinic-nitrogen contents. It is possible to utilize precursors with more pyridinic nitrogen and fewer aromatic rings instead, but these precursors are generally thermally unstable, generating various nitrogen-containing functional groups, although these precursors tend to be inexpensive. In this work, among six precursors with pyridinic N and two aromatic rings, 1,5-naphthyridine showed the highest percentage (80%) and the highest pyridinic-nitrogen content (12.4 at. %) after carbonization at 873 K. Reactive C-H groups next to pyridinic nitrogen, which have been reported to work as an active site for oxygen reduction reaction, also remained. The highest percentage and the highest pyridinic-nitrogen content were attained using 1,5-naphthyridine because of the high thermal stability of C-N bonds without being hydrogenated and the low thermal stability of C-N bonds after being hydrogenated, which were quite different tendencies compared to other precursors with three or more aromatic rings.
Keywords: Pyridinic nitrogen, X-ray photoelectron spectroscopy, Raman spectroscopy, Infrared spectroscopy, ReaxFF, Density functional theory calculation
Suggested Citation: Suggested Citation