Natural cotton is a widely available and low-cost biomass resource with a high carbon content, making it an ideal precursor for carbon materials. In this work, H₃PO₄ was employed as a chemical activating agent to pretreat cellulose-rich natural cotton, and the effects of the H₃PO₄-to-cotton impregnation mass ratio and pyrolysis temperature on the pore structure and CO₂ adsorption performance of the resulting carbon materials were systematically investigated. The results show that the optimal sample, CP1-900, exhibits the highest specific surface area of 1119.0 m²/g and a substantial micropore volume of 0.463 cm³/g, achieving a CO₂ adsorption uptake of 2.715 mmol/g at 25 °C and 1 bar. In addition, the material can maintain an integrated structure without additional binders, offering practical advantages over conventional powdered adsorbents in shaping, handling, and potential applications.
Building on this material platform, the prepared carbon aerogel was further explored as an electrode for electrochemical charging treatment. This strategy enables control of the surface chemical environment and promotes the enrichment of active functional groups on the carbon surface, thereby strengthening interactions between the adsorbent and CO₂ molecules. As a result, the material exhibits enhanced CO₂ adsorption capacity under low-concentration conditions, together with improved CO₂/N₂ adsorption selectivity, leading to the development of a novel functionalized carbon aerogel suitable for direct air capture (DAC). More importantly, owing to its intrinsic electrical conductivity, the carbon aerogel can be rapidly and directly heated through the Joule heating effect, enabling efficient in situ regeneration of the adsorbent while reducing heat-transfer losses associated with conventional external heating approaches. The integration of electrochemical surface regulation, selective low-concentration CO₂ capture, and electrically driven Joule-heating regeneration provides a promising material and process platform for developing a new generation of low-carbon and energy-efficient DAC technologies powered by renewable electricity.

CO2 adsorption,carbon aerogel,natural cotton,direct air capture,Joule heating