Simple and scalable synthesis of phosphorus and nitrogen enriched porous carbons with high volumetric capacitance

Phosphorus and nitrogen enriched porous carbons were fabricated by direct heat treatments of the honeycomb-patterned H3PO4/polyacrylonitrile composite precursors obtained through solvent evaporation. Surface chemistry analysis showed that high surface concentrations of phosphorus and nitrogen as well as the desirable chemical structures can be achieved by controlling the carbonization temperature. Electrochemical measurements in 1 M H2SO4 aqueous electrolyte showed that the gravimetric capacitance and the volumetric capacitance reached as high as 205.7 F g−1 and 261 F cm−3 at 0.5 A g−1, respectively. In particular, the capacitance showed no degradation even after 8000 charge/discharge cycles, clearly demonstrating a robust long-term stability. The excellent electrochemical performance makes the electrode material a promising candidate for supercapacitors.