3D hierarchical porous N, O co‐doped carbon derived from the waste walnut shell via one‐step carbonization for high‐performance supercapacitor

Abstract Porous carbon derived from biomass is considered a promising material for supercapacitors. However, improving the wettability and electrical conductivity of porous carbon materials remains a great challenge. Herein, a bidirectional pore‐creating strategy is proposed to construct N/O‐doped Walnut‐shells‐based hierarchical porous carbon materials (WSC‐N/O‐900). The high specific surface area (981 m 2 g −1 ) and heteroatom content of WSC‐N/O‐900 enhance the wettability and electrical conductivity. Thus, WSC‐N/O‐900 shows a high capacitance of 431 F g −1 at 1.0 A g −1 . Additionally, the capacitance retention rate of WSC‐N/O‐900//WSC‐N/O‐900 (SSC) remains 88.4 % after 9000 cycles and achieves an energy density of 14.8 Wh kg −1 with a power density of 300 W kg −1 . Overall, this work can provide an effective strategy to prepare advanced biomass derived porous carbon for electrochemical energy storage.