Preparation of nitrogen-doped macro-/mesoporous carbon foams as electrode material for supercapacitors

An oil-in-water (O/W) emulsion system of Span 80–Tween 80/1iquid paraffin/aqueous resorcinol–formaldehyde was manufactured. Nitrogen-doped macro-/mesoporous carbon foams (N-MMCFs) were prepared by the polymerization of this O/W emulsion, followed by carbonization and activation process. As-prepared N-MMCFs were characterized by scanning electron microscopy, infrared (IR) spectra, N2 adsorption and desorption analysis, and electrochemical workstation. The results indicate that the N-MMCFs have main macropore of 0.2 μm, mesopore of 2.6–4.0 nm and specific surface areas of 1205–1808 m2 g−1. The contact angle of N-MMCFs for water is about 37.5°, obviously lower than that of MMCFs (72.9°), which suggests that the surface wettability of N-MMCFs is greatly improved due to the incorporation of nitrogen into the carbon framework. Electrochemical measurements show that specific capacitance of a typical N-MMCF as electrode material in 6 M KOH aqueous solution is as high as 198 F g−1 at a current density of 1.0 A g−1. Its specific capacitance can still remain 159 F g−1 at a high loading current density of 20.0 A g−1 with the retention of 80.3%, which indicates that the typical N-MMCF as electrode material has a good rate capability. The high current charge and discharge capability offers the promising prospects for the application of N-MMCFs as electrode materials in supercapacitors which could meet the need of high power density.