Enhanced Electric Double-Layer Capacitance of 1,10-Phenanthroline-Derived Mesoporous Carbon CMK-1 Electrodes via Selective Elimination of Pyridinic Nitrogen during Carbonization

1,10-Phenanthroline was carbonized in the wide pores of ordered mesoporous silica (MCM-48; hard template) at different temperatures to yield nitrogen-doped ordered mesoporous carbon CMK-1. Carbonization at 550 °C resulted in inadequate carbon network formation, whereas nitrogen-doped carbons with ordered mesoporous structures and low and high electrical conductivities were obtained at 750 and 900 °C, respectively. When used as an electrode in an electric double-layer capacitor, the high-conductivity carbon delivered a gravimetric capacitance of ∼100 F g–1 and a specific areal capacitance (Cs) of 9.2 μF cm–2, thus breaking the limit of 6.0 μF cm–2 established for conventional activated-carbon electrodes. Advanced temperature-programmed desorption and X-ray photoelectron spectroscopy analyses revealed that heating at 750–900 °C caused the selective elimination of pyridinic nitrogen and initiated recombination reactions within the carbon network to generate a carbon surface with highly adsorptive sites for electrolyte ions, which resulted in a high electric double-layer capacitance.