Porous carbon derived from rice husks as sustainable bioresources: Insights into the role of micro/mesoporous hierarchy in Co3O4/C composite for asymmetric supercapacitors

The natural biological waste, grain husk, was pre-treated by high temperature-activated carbonization with KOH, and the derived multi-pore carbon materials were obtained. Porous carbon-supported cobalt oxide composite materials were generated by anchoring flower-like cobalt oxide nanocrystals on porous carbon-derived materials via subsequent hydrothermal reactions. The maximum specific capacitance of the composites is 671 F g(-1) (0.5 A g(-1)), and 94.01% of specific capacitance is retained after 5000 cycles. The energy density of the asymmetric electrodes assembled is 35.08 Wh.kg(-1) at a power density of 0.63 kW kg(-1), indicating their potential application value in energy storage devices.