Multi-element co-doped biomass porous carbon with uniform cellular pores as a supercapacitor electrode material to realise high value-added utilisation of agricultural waste

Biomass-based porous carbon materials have attracted considerable attention because of their simple, low-cost, green, and pollution-free preparation process. Owing to their unique tubular structure and subsequent activation process, they often have a well-developed pore structure. Biomass-based carbon materials with three-dimensional hierarchical pores and polyatomic doping are regarded as promising electrode materials in the field of energy storage. In this study, cornstalk was used as the biomass and a pioneering approach was used to prepare porous carbon co-doped with N, B, and P. The B,N,P-codoped porous carbon has a three-dimensional honeycomb-like network structure with uniformly distributed and interwoven macro-, meso-, and micropores. Furthermore, it has an ultra-high specific surface area of 3123.5 m² g⁻¹, a high specific capacitance of 342.5 F g⁻¹ at a current density of 0.5 A g⁻¹, and an energy density of up to 26.18 W h kg⁻¹. This study demonstrates a multi-element co-doping strategy that enhances the performance of cornstalk as a precursor of a supercapacitor electrode material and has important implications in the high-value-added utilisation of waste straw.