Mesoporous carbon sheets embedded with vesicles for enhanced supercapacitor performance

Carbon composite materials with diverse structures show enhanced electrochemical performance as electrodes in energy storage devices than single component structures. Herein, rich mesoporous carbon nanosheets embedded with vesicle structures (CS-v) were prepared by a simple synergetic assembly strategy using 1-octadecyl-3-methylimidazolium bromide ([C(18)Mim]Br) as the surfactant, phenolic resin as the carbon precursor, silica precursor as an additive and iron(iii) nitrate as the catalytic active center. [C(18)Mim]Br played an important role in the formation of flake morphology and nitrogen doping. The silica created a rich mesoporous structure on the CS-v, which improved the surface area. The addition of iron(iii) nitrate not only creates vesicle structures but also leads to thinner sheets for CS-v, which accelerates the transfer and storage of charge, and improves the electrochemical performance. When used as the electrode in a supercapacitor, CS-v showed a high specific capacity of 341 F g(-1) at the current density of 1 A g(-1) in a three-electrode system, which is more than ca. 2.5 times enhancement compared with that of pure mesoporous carbon nanosheets, and an excellent long cycling ability with 99.5% of the initial capacity was retained after 10 000 cyclic tests, demonstrating its potential in energy storage devices.