Activation-induced bowl-shaped nitrogen and oxygen dual-doped carbon material and its excellent supercapacitance

Abstract

Porous heteroatom-doped carbon materials exhibit promising electrochemical applications because of tunable porous structure and doping heteroatom-induced charge redistribution. Nevertheless, it is still a great challenge to develop porous heteroatom-doped carbon materials with both high-content active heteroatom species and facilitated diffusion route. Herein, we report a bowl-shaped nitrogen and oxygen dual-doping carbon (N, O-doped carbon) material based on low-temperature defluorination pyrolysis and alkali-etched activation of 3-fluorophenol-3-amino-4-hydroxypyridine-formaldehyde co-condensed resin and its excellent supercapacitance. This low-temperature thermal treatment strategy ensures high-content pyrrolic nitrogen (4.6 at.%) and oxygen species (15.9 at.%) to avoid high-temperature treatment-induced heteroatom loss and undesired configuration conversion. In these processes, the defluorination pyrolysis promotes the transformation from the resin to carbon material to some extent, and KOH activation also promotes the ordered arrangement of 002 planes, which together assure the appropriate conductivity of the final microporous carbon material. More importantly, KOH-etched activation partially removes an unstable nano/microscale domain of the intermediate carbon microspheres to form a unique bowl-shaped structure extremely facilitating the diffusion of the substitutes and/or electrolyte ions. As expected, N, O-doped carbon material displays a remarkable specific capacitance of 486.4 F g−1 at 1 A g−1 with nitrogen/oxygen species-dependant pseudocapacitance and good electrochemical durability.