Biomass nanoarchitectonics of hierarchical porous carbon with ultrahigh surface area for direct air carbon capture and supercapacitor

High specific surface area carbon materials have attracted significant attention due to their important roles in energy and environmental applications. However, it remains a major challenge to enhance their performance by incorporating effective hierarchical pore structures while maintaining the ultrahigh specific surface area. A low-cost and versatile N-doped carbon material with hierarchical nanopores and ultrahigh specific surface area was prepared via supercritical CO₂-assisted urea pretreatment followed by simple activation. The prepared carbon materials were fabricated into supercapacitor electrodes and amine-loaded solid adsorbents to evaluate its electrochemical performance and carbon dioxide adsorption capacity. The results showed that, due to its remarkable specific surface (3784.23 m2/g), excellent pore volume (2.21 cm3/g), hierarchical pore structure, and considerable N-loading rate (5.69 wt%), the carbon material achieved a specific capacitance of up to 321.48 F/g at a current density of 0.5 A/g in a 1 mol/L electrolyte, with a capacitance retention rate of 91.08% after 1000 cycles at 5 A/g. Additionally, the corresponding amine-loaded solid adsorbent achieved a maximum CO₂ adsorption capacity of 109.58 mg/g in simulated air containing 400 ppm CO₂ under ambient conditions. These results demonstrate that the synergistic combination of ultrahigh surface area, hierarchical porosity, and nitrogen doping endows the biomass-derived carbon material with strong potential for integrated energy storage and carbon capture applications.