Advanced nitrogen-doped wood-derived biocarbon for supercapacitor electrode applications

This study presents a sustainable and scalable strategy for synthesizing N-doped porous carbon from rotten wood through a one-step green process. The natural fungal decay of wood forms a porous structure, which is crucial for the synthesis of porous carbon. Additionally, the decay process generates some nitrogen, which is further enhanced by introducing ethylenediamine (EDA) as an additional nitrogen source during carbonization. The resulting material exhibits a high specific surface area (1204 m 2 · g −1 ), excellent specific capacitance (448F · g −1 ), and remarkable cycle stability (95% retention after 10,000 cycles). These exceptional electrochemical properties highlight the potential of biomass-derived carbon materials for next-generation energy storage applications, offering an eco-friendly solution for converting waste into high-performance supercapacitor electrodes. • Taking advantage of the fungi on rotten wood, which produces a porous structure, we developed a scalable, green approach to convert it into N-doped porous carbon. • Nitrogen-doped carbon derived from rotten wood exhibited excellent supercapacitor performance. • The optimized sample, RW-1000, achieved a high specific surface area of 1204 m 2 · g −1 . • RW-1000-based electrode delivered a specific capacitance of 448F · g −1 at 0.2 A · g −1 . • Exceptional cycling stability was demonstrated, with 95% capacitance retention after 10,000 cycles. Biomass-derived carbon materials are receiving much attention for supercapacitor applications due to their well-developed porous structures, large specific surface areas, good conductivity, and environmental sustainability. In this study, we present a simple and scalable green strategy to prepare nitrogen (N)-doped biocarbon materials from naturally decayed wood (rotten wood, RW), which is to take advantage of the intrinsic porous nature of wood and the structural modifications induced by microbial activation (e.g., surface oxidation and nitrogen incorporation). To further increase the doped nitrogen content, we used aqueous ethylenediamine (EDA) solution for activating and immersing pre-treated RW. The N-doped biocarbon samples show uniform nitrogen distribution and favorable graphitization, resulting in outstanding supercapacitor performance. The optimized sample- RW-1000 exhibits a high specific surface area of 1204 m 2 · g −1 with a hierarchical porous structure. When applied as a supercapacitor electrode, RW-1000 demonstrates excellent electrochemical properties, including a specific capacitance of 448F · g −1 at 0.2 A · g −1 . The device assembled using this biocarbon delivers an energy density of up to 10.2 Wh · kg −1 at a power density of 100 W · kg −1 , while exhibiting excellent cycling stability with 95 % capacitance retention after 10,000 charge–discharge cycles. This exceptional energy storage performance is attributed to the RW-1000-derived electrode’s high specific surface area, optimal pore size distribution, and well-dispersed nitrogen content. Thus, our work offers a sustainable, scalable and facile strategy for transforming biomass waste into valuable biocarbon materials for high performance supercapacitors.