A balance active sites and heteroatom content scheme on corn-derived brewing residue porous carbon for high-performance CO2 adsorption and energy storage

Biomass carbon is well-known for its abundant porous structure and heteroatom, indicating potential applications in gas adsorption and energy storage. However, striking a balance between specific surface area and heteroatom content in biomass carbon is challenging, potentially limiting active sites and adsorption kinetics. Here, the corn-derived brewing residue was initially treated at 400 °C in a nitrogen atmosphere, followed by activation at 750 °C using an 85 wt% KOH activator. The two-step process facilitates the production of corn-derived brewing residue porous carbon with a high specific surface area of 3019.7 m²·g^–1 and rich nitrogen/oxygen contents (12.52 %). These characteristics enable corn-derived brewing residue porous carbon to exhibit impressive CO₂ uptake (6.45 mmol·g^–1 at 0 °C and 3.64 mmol·g^–1 at 25 °C under 1.0 bar), along with a high CO₂/N₂ uptake ratio of 20:1. Density Functional Theory calculations indicate that pyridinic-N species and abundant micropores are crucial for improving CO₂ capture capacity. In addition, the supercapacitor performance of corn-derived brewing residue porous carbon was also investigated, displaying a remarkable area-specific capacity of 836 mF·cm^–2 and excellent electrochemical stability. In conclusion, this regulating strategy enhances the potential of corn-derived brewing residue porous carbon for reducing CO₂ emissions and energy storage applications.