Synergistic effect of Se doping and hierarchical pore structure on enhancing the energy storage of biomass-derived carbon in supercapacitors

In the face of increasingly severe energy shortages and environmental pollution, the development of energy storage materials that are both sustainable and cost-effective has become a key focus of current research. Due to their renewable nature and structural diversity, natural biomass and its derivatives demonstrate tremendous promise for supercapacitor electrode materials. However, traditional carbon materials are typically hindered by their low energy density. To address this challenge, researchers have undertaken a series of explorations. Among these, heteroatom doping technology has garnered widespread attention due to its process controllability and ability to effectively elevate material performance. In this study, a two-step activation process was employed to introduce selenium into honeydew peel-derived porous carbon (HPC/Se). The dose-effect relationship of Se doping in this biomass-derived carbon for supercapacitors, in terms of structural evolution, electronic modulation, and electrochemical performance, was systematically investigated by combining experimental characterizations with density functional theory (DFT) calculations. This approach significantly increased the specific surface area and improved the regularity of the pore structure in the resulting materials. The HPC/Se-0.5 exhibited an excellent specific surface area (3395.26 m 2 g −1 ) and rich porous structure, with a specific capacitance as high as 383 F g −1 at 1 A g −1 . Furthermore, the assembled symmetric supercapacitor demonstrated outstanding energy storage capabilities, achieving an energy density of 28.78 Wh kg −1 at a power density of 1177.36 W kg −1 . After 15,000 charge-discharge cycles, the energy density retention rate remained at 94.27%. Density functional theory (DFT) calculations revealed that moderate Se doping, preferentially stabilized at substitutional and edge/defect sites, facilitated ion adsorption and charge transfer. These results indicated that electrode materials prepared using biomass as a precursor, through Se-doping and activation, hold broad application prospects.