Porous biocarbon derived from rotten wood: Preparation, characterization, and applications for supercapacitors

Abstract

The development of nitrogen-doped porous carbon materials derived from naturally decayed rotten wood (RW) for high-performance supercapacitor electrodes applications was studied. By leveraging the natural porosity and surface chemistry introduced via microbial decay, RW is utilized as a renewable, low-cost carbon precursor.

First, a one-step carbonization method using a tube furnace was developed to fabricate nitrogen-doped biocarbon by introducing aqueous ethylenediamine (EDA) as an additional nitrogen source. The resulting material exhibited uniform nitrogen distribution, favorable graphitic domains, and excellent electrochemical properties. The optimized sample, RW-1000, achieved a high specific surface area of 1204 m²·g⁻¹ with a balanced pore structure. As a supercapacitor electrode, it delivered a high specific capacitance of 448 F·g⁻¹ and retained 95% of its capacitance after 10,000 charge-discharge cycles.

The second strategy employed a Borax-K₂CO₃ system to control combustion in an open-air environment, enabling the fabrication of porous biocarbon via a rapid flame-burning method for zinc-ion hybrid supercapacitor applications. This system preserved the inherent porous structure of wood while promoting additional pore formation through activation. The optimized sample, RW-15, reached a specific surface area of 2196 m²·g⁻¹. Integrated into a zinc-ion hybrid supercapacitor, RW-15 delivered a notable capacitance of 175 F·g⁻¹ at 0.5 A·g⁻¹, maintained 97% of its initial capacitance over 10,000 cycles, and achieved a high energy density of 79 Wh·kg⁻¹.

Lastly, a co-doping strategy introduced iron (Fe) via hydrothermal treatment with FeCl₃, followed by flame carbonization. The resulting material, RW-N-Fe-4, featured a hierarchical porous structure and a surface area of 1601 m²·g⁻¹. Fe acted as a catalytic dopant, enhancing graphitization and generating electrochemically active sites. The device fabricated with RW-N-Fe-4 achieved a specific capacitance of 448 F·g⁻¹ and an energy density of 11.8 Wh·kg⁻¹ with excellent cycle stability.

Overall, this work demonstrates the potential of rotten wood as a sustainable precursor for advanced supercapacitor electrodes and presents scalable, eco-friendly routes to produce high-performance porous carbon materials for next-generation energy storage.