Hydrogen-bonding supramolecular protic salt as an “all-in-one” precursor for nitrogen-doped mesoporous carbons for CO2 adsorption

Abstract

Traditional methods for preparation of nitrogen-doped mesoporous carbons (NMCs), especially NMCs with high nitrogen content and narrow pore size distribution, typically require tedious, time-consuming procedures involving polymer precursors (or monomers for pre-polymerization), specific templates, and/or nitrogen-containing agents, as well as additional template-removal step by etching. Herein we reported a facile, template-free, and easily scalable route to NMCs by direct carbonization of an easily prepared, low cost, small-molecule protic salt [pPDA][2HSO4], which was obtained by simple neutralization of p-phenylenediamine with two equivalents of sulfuric acid. NMCs with high relative yield, high nitrogen content, large surface area, large mesopore, and narrow pore size distribution were obtained in one step. Intensive analysis revealed that the key to the success of this strategy was the hydrogen-bond-assisted self-assembled structure, as well as the ingenious “all-in-one” role of the precursor during carbonization, wherein both the cationic [pPDA] and anionic [HSO4] played indispensable and synergetic roles. Further KOH activation of the obtained NMCs resulted in not only ultrahigh surface areas of up to 3573m2/g, but also significant increases in selective CO2 uptake over N2. Especially, one of the activated carbons, NMC-7-6, exhibited a high CO2 uptake of 3.69mmol/g at 25°C and 1atm, comparable to the best results by N-doped carbons and higher than those of all known zeolitic imidazolate frameworks.