N-doped ordered mesoporous carbon spheres derived by confined pyrolysis for high supercapacitor performance

Herein, we report a confined pyrolysis strategy to prepare mesoporous carbon nanospheres by which surface area of carbon spheres is increased, pore size is enlarged and effective N-doping is achieved. In this method, the mesoporous polymer sphere as carbon precursor and 2-methylimidazole as nitrogen precursor are encapsulated in a compact silica shell which provides a confined nano-space for the pyrolysis treatment. The in situ generated gases from mesoporous polymer sphere and 2-methylimidazole under pyrolysis diffuse into the pores of mesoporous polymer sphere in the confined compact silica shell, resulting in increased surface area, larger pore size and N-doping due to self-activation effect. As electrodes in supercapacitor, the N-doped mesoporous carbon nanospheres exhibit a significantly enhanced specific capacitance of 326F g(-1) at 0.5 A g(-1), which is 2 times higher than that of mesoporous carbon spheres under unconfined pyrolysis condition, exhibiting its potential for electrode materials with high performance. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.