A novel sol-gel strategy for N, P dual-doped mesoporous carbon with high specific capacitance and energy density for advanced supercapacitors

In this work, a facile sol-gel strategy was developed to synthesize N/P co-doped ordered mesoporous carbons (NPMCs). By accelerating the volatilization of ethanol, a strong driving force promoted the self-assembly process among carbon precursor, surfactant and dopant at the interface of water and ethanol. The obtained NPMC showed stacked flake-like surface morphology and ordered 2D-hexagonal mesostructures with uniform pore size (4.3 nm) and high specific surface areas (938 m(2) g(-1)). Synergistic effects of improved surface wettability by N-doping and rich active sites by P-doping rendered the NPMC with excellent electrochemical performance. Computational analyses confirmed that N, P co-doping could enhance active sites and widen potential difference of carbon materials to improve their capacitance. An ultrahigh capacitance of 392 F g(-1) and an excellent rate capability were obtained. Furthermore, the assembled symmetric supercapacitor based on NPMC delivers a high energy density of 20.2 Wh kg(-1) at a power density of 225 W kg(-1) and exhibited an excellent long-term electrochemical stability (95% capacitance retention after 5000 cycles), which evidently reached the practical requirement for supercapacitors.