Nitrogen and Oxygen Codoped Hierarchically Porous Carbon Derived from Tannic Acid and Reed Straw for High-Performance Supercapacitors

The effective utilization of abundant natural biomass-derived materials as sustainable precursors for developing high-performance electrodes is of great significance for advancing practical applications of supercapacitors. In this study, we propose an effective strategy to convert biomass reed straw and tannic acid (TA) as dual carbon sources into N, O codoped hierarchically porous carbon electrode materials with a rich micro/mesoporous interconnected layered structure, denoted as N-RTC-1.5, through cochemical activation of KOH and melamine (MA) and precarbonization. N-RTC-1.5 exhibits a unique honeycomb-like porous structure with a high specific surface area of up to 2545 m²/g. As a supercapacitor electrode, N-RTC-1.5 demonstrates an excellent specific capacitance of 366.0 F/g at 1 A/g in a three-electrode system. Furthermore, the energy density of an N-RTC-1.5//N-RTC-1.5 symmetric supercapacitor reaches 18.32 Wh/kg, and after 10000 cycles at 3 A/g, the capacitance retention is approximately 96%. This research provides a simple, sustainable, and environmentally friendly approach to convert biomass into novel carbon materials required for high-performance supercapacitor electrodes.