Nitrogen and Oxygen Co‐doped Hierarchical Porous Carbon by One‐Step Pyrolysis of PEG/Melamine/MgO Bulks for High‐Performance Supercapacitors

Abstract Simple and convenient protocols for fabricating heteroatom‐doped hierarchical porous carbon are highly imperative owing to their superior electrochemical performance. Here, nitrogen and oxygen co‐doped hierarchical porous carbon materials (NOPCs) are facilely prepared by the one‐step carbonization of PEG‐200/melamine/MgO bulks within ten minutes. The solid bulks enable the synthesis more conveniently, and make the NOPCs have a uniform structure and high electrochemical performance. The optimized products, NOPC‐900, has the largest specific surface area (the S BET of 1248 m 2 g −1 ), abundant mesopore structures (average pore diameter of 9.40 nm), with thin carbon walls (3–10 graphene layers), and the effective heteroatom doping (the content of N atom is 2.67 at.%, and O atom is 12.49 at.%). As a result, The NOPC‐900 displays the specific capacitance of 324 F g −1 at 0.5 A g −1 and a low IR drop of 0.018 V at 50 A g −1 . When assembling NOPC‐900 into a symmetric two‐electrode supercapacitor, it presents the cell capacitance of 54.18 F g −1 at 0.5 A g −1 and perseveres 84.6 % of initial capacitance at 10 A g −1 . Meanwhile, the energy density of 19.12 Wh kg −1 is achieved at the power density of 425 W kg −1 . The convenient preparation approach and excellent electrochemical performance render the NOPCs to be promising candidates for supercapacitor application.