High nitrogen-oxygen dual-doped three-dimensional hierarchical porous carbon network derived from Eriocheir sinensis for advanced supercapacitors

In this study, we report a unique, facile process for the preparation of a high-nitrogen-oxygen dual-doped threedimensional (3D) hierarchical porous carbon network by one-step pyrolysis and in situ activation under a CO2 atmosphere combined with acid treatment using Eriocheir sinensis as the precursor. The evolution of the physicochemical structure of carbon at different pyrolysis temperatures was investigated. Removing inorganics from the shell carbon of Eriocheir sinensis enabled the formation of a unique 3D network structure. In addition, a high doping concentration of nitrogen and oxygen can be formed in the porous carbon skeleton. The increase in the pyrolysis temperature was beneficial to the pore development and graphitisation of carbon. Because of the interconnected 3D hierarchical porous structure and high heteroatom doping content, which provides fast channels for electron and ion transport, the obtained carbon materials exhibit excellent capacitive performance as supercapacitor electrodes. Quantum chemical calculations further confirmed that the heteroatom-doped carbon plane has a larger negative charge and stronger interaction with K+ than that of the pure carbon surface. This inexpensive green carbon material based on food waste is expected to be a candidate material for highperformance electrode precursors.