Template-free synthesis of N-doped porous carbons and their gas sorption properties

Nitrogen-rich carbon precursors are prepared and subsequently used for the preparation of N-doped porous carbons (NPCs). Two carbon precursors (CPs), CP-60 and CP-40, are prepared at different temperatures, 60 °C and 40 °C, respectively. The obtained CP materials are almost nonporous based on the N2 adsorption/desorption analysis. These nonporous CP materials are converted into NPC materials through a carbonization at 800 °C. Porous NPC-60-800 and NPC-40-800 are prepared from CP-60 and CP-40, respectively. In contrast to the CP materials, the NPC materials exhibit higher surface areas. The surface areas of NPC-60-800 and NPC-40-800 are 422.9 m2 g−1 and 520.8 m2 g−1, respectively. The respective N-contents of NPC-60-800 and NPC-40-800 materials are 4.30 and 3.54 wt.% based on the elemental analysis. The types of N-containing groups of NPC materials are investigated by X-ray photoelectron spectroscopy (XPS) analysis. The NPC materials are good sorbents for CO2 storage. The heats of CO2 adsorption (Qst) are 48.4 kJ mol−1 for NPC-60-800 and 47.0 kJ mol−1 for NPC-40-800. Both materials are also good H2 sorbents at 77 K: 1.23 wt.% (NPC-60-800) and 1.22 wt.% (NPC-40-800).