N, P co-doped cellulose-based carbon aerogel: A dual-functional porous material for CO2 capture and supercapacitor

Biomass-derived carbon aerogels have attracted considerable attention for applications in CO₂ capture and supercapacitors (SCs). However, these carbon aerogel materials often suffer from an insufficient number of active sites. In this study, a novel N, P co-doped porous carbon aerogel with a hierarchical structure was synthesized using cellulose biomass as the raw material, a NaOH/urea system as the solvent and activator, and urea and urea phosphate as heteroatom dopants. Owing to the synergistic effects of heteroatom co-doping and the hierarchical pore structure, the optimal sample, NPCA-600–0.5, exhibited a large specific surface area of 582.9 m²/g and a high pore volume of 0.187 cm³/g. It demonstrated a CO₂ adsorption capacity of 2.89 mmol/g (25 ℃, 1 bar), along with high CO₂/N₂ selectivity and excellent recyclability, retaining 91 % efficiency after 10 cycles. As a SC electrode, NPCA-600–0.5 achieved a high specific capacitance of 238 F/g at 1 A/g, maintaining 80 % of its initial capacitance after 5000 cycles at 10 A/g. This work not only provides a promising adsorbent and electrode material for CO₂ capture and supercapacitors, but also offers valuable insights for the design of advanced carbon-based materials.