Microcrystalline cellulose derived hierarchically porous nanocarbons via a template-free method for high performance supercapacitors

Abstract The efficient and low-cost method to produce sustainable energy materials for supercapacitor is highly sought after. Biomass offers great opportunities as green and low-cost raw materials; however, the extra activation and multi-step procedures to obtain desirable porosity are often required. Herein, a simple and economy way was developed to synthesized hierarchically porous nanocarbons with N-doping. Microcrystalline cellulose was chosen as the carbon precursor and thermally treated in N2, NH3, and CO2 atmospheres in tandem. This continuous gas treatment enables the formation of functional carbons with high surface area and abundant porosity. The optimized pyrolytic carbon HPNC-150 expresses a super high specific surface area reaching up to 3278 m2 g-1 with the pore volume of 1.6291 cm3 g−1. Electrochemical tests indicate the carbon HPNC-150 delivers a specific capacitance of 221 F g−1 at a current density of 1 A g−1 and remains 201 F g−1 at 5 A g−1, and thus show an excellent storage capacity for supercapacitor applications. Besides, it was found that the competition between the thermal graphitization and CO2 activation balances the hierarchical porosity and electrical conductivity, which is a good reference to synthesize the porous conductive substrates for further modifications.