Enhanced electrochemical capacitance of nitrogen-doped carbon gels synthesized by microwave-assisted polymerization of resorcinol and formaldehyde

Nitrogen-doped carbon gels were synthesized by ammonia-assisted carbonization of resorcinol-formaldehyde (RF) polymers obtained under microwave irradiation without any basic catalyst. Compared with the RF polymer synthesized by the conventional hydrothermal method, microwave polymerization produced spherical beads with a higher surface area (1710 m(2)/g vs. 1080 m(2)/g), and smaller (similar to 700 nm vs. similar to 5 mu m) but more uniform bead sizes. The majority of their pores were micropores. As a result, the electrochemical capacitance of microwave-assisted nitrogen-doped carbons was significantly higher than that of materials prepared by the conventional hydrothermal method. Thus microwave-assisted polymerization followed by ammonia-assisted carbonization is a useful method to synthesize nitrogen-doped carbon gels for electrochemical double layer capacitors. (C) 2008 Elsevier B.V. All rights reserved.