Bottom-up Synthesis of Pyridinic-Nitrogen Doped Carbon Materials from Brominated Two-fused-ring Aromatics at Low Carbonization Temperatures

抄録

Pyridinic nitrogen-containing carbon materials are expected to show high performance as electrodes and catalysts. Carbon materials introducing only pyridinic nitrogen have been synthesized in recent years, and the use of two-fused-ring aromatic compounds as precursors enabled the synthesis of relatively inexpensive pyridinic nitrogen-containing carbon materials. However, a two-fused-ring aromatic compound such as isoquinoline required a relatively high temperature (973 K) for carbonization, causing C-N bond cleavage, and the percentage of pyridinic nitrogen was relatively low (52%). In this study, pyridinic nitrogen-containing carbon materials were synthesized from six brominated isoquinolines. Bromination of isoquinolines lowered the carbonization temperatures to 673-873 K, which help avoid the decomposition of pyridinic nitrogen. The precursor with two bromine substitutions (1,4-dibromoisoquinoline) showed the highest percentage of pyridinic nitrogen (65%) at 773 K among six precursors in this work. The factors to enhance the percentage of pyridinic nitrogen are 1) avoiding the formation of a 1,10-phenanthroline-like structure during dimerization, 2) avoiding the formation of N-H and the scission of the formed C-N in dimers formed after C=C coupling at bromine substituted positions between precursors, and 3) the formation of a more ordered six-membered-ring structure due to the introduction of two or more highly reactive bromines.