Coal tar pitch derived N-doped porous carbon nanosheets by the in-situ formed g-C3N4 as a template for supercapacitor electrodes

N-doped porous carbon nanosheets (N-CNS) were prepared from coal tar pitch with the addition of urea and KOH activation. In the synthesis route, urea plays an important role in constructing the 2D sheet-like structure, which serves as a nitrogen source, chemical blowing agent and the in-situ formation of g-C3N4 self-degraded template. At a low activation temperature (600 °C), the as-prepared N-doped porous carbon nanosheets possess high nitrogen content (7.06 at. %) and high specific surface area (1181 m2 g−1), which offers remarkable capacitive performances due to the unique architecture and pseudocapacitance contribution of the N doping. The N-CNS exhibits high capacitive performance (210 F g−1 at 0.1 A g−1), and an excellent cycling stability. Additionally, the assembled symmetric supercapacitor displays an energy density of 7.15 Wh kg−1, and the capacitance retention remains 91.2% after 5000 cycles at 1 A g−1. The facile and low-cost route to massively prepare N-doped porous carbon nanosheets from coal tar pitch would be favorable to the applications of carbon materials for high performance supercapacitors.