Single Step, Direct Pyrolysis Assisted Synthesis of Nitrogen-Doped Porous Carbon Nanosheets Derived from Bamboo wood for High Energy Density Asymmetric Supercapacitor

Herein, we report a scalable, large-area synthesis of nitrogen-doped carbon nanosheets (N-AC) from bamboo biomass using KOH and urea as the activating and doping agent, respectively, for high performance asymmetric supercapacitor applications. The carbonization of the biomass bamboo at 300 degrees C for 2 h yields N-AC0 (char) while activation at 900 degrees C for 2 h under inert atmosphere yields N-AC. The detailed characterization of N-AC revealed the significance of heteroatom doping for the supercapacitor application. The N-AC electrode delivered the half-cell specific capacitance of 475 Fg(-1) at 1 Ag-1. The assembled asymmetric N-AC parallel to N-AC0 supercapacitor device delivered the highest specific capacitance of 296 Fg(-1) at 1 Ag-1 with specific energy of 42 Whkg(-1) at specific power of 4500 Wkg(-1), which are very high compared to other reported nitrogen-doped carbon materials. This enhanced performance can be attributed to the synergistic effect of larger specific surface area (of 769.714 m(2)g(-1)) and hetero-atom (N) doping, which helped in rapid charge-transfer, improved electrical conductivity and efficient electrode-electrolyte interactions. Furthermore, the N-AC asymmetric supercapacitor device works until 1.2 V with 6 M KOH as with 150% capacitance retention over 10,000 charge-discharge cycles. Thus, the strategy presented here provides new directions to synthesize low cost, green, sustainable electrodes for high energy supercapacitor applications.