MnO2 Nanoparticle‐Loaded Self‐Doped (N/O) Porous Carbon Derived from Orychophragmus Violaceus for Application as a High‐Performance Supercapacitor.

Waste orychophragmus violaceus was used to prepare a novel 3D self‐doped (N/O) porous carbon (OPC). The aim was to expand the application and increase the value of waste orychophragmus violaceus. In order to improve its specific capacitance, composites OPC@MnO2x of OPC and MnO2 were prepared by simple hydrothermal method. In 6 M KOH, specific capacitance obtained by OPC at 1 A g−1 is 268 F g−1, surprisingly, specific capacitance of OPC@MnO232 can be up to 419 F g−1 at 1 A g−1 and its capacitance retention rate is as high as 83.62 % after 10000 cycles (20 A g−1). The energy density of OPC@MnO232//OPC asymmetric supercapacitor in 1 M Na2SO4 can even reach 14.22 Wh kg−1 at 400 W kg−1, besides, it showed good cycling stability after 10000 cycles (20 A g−1), with capacitance retention rate of up to 86.64 %. Finally, the device is tested in an application. Connecting two identical asymmetric supercapacitors in series enables red LED to emit greater than 90 s. Overall, this study confirms that the waste orychophragmus violaceus derived porous carbon can reduce the wastage of waste resource, additionally, the composite material prepared is an electrode material for high‐performance supercapacitors with broad prospects. [ABSTRACT FROM AUTHOR]