Unraveling surface oxygen functionality in ordered mesoporous carbon for enhanced CO₂ capture behavior

Surface oxygen functionalization enhances CO₂ affinity in porous carbons, but the molecular-level roles of distinct oxygen species remain ambiguous. Here, we controllably grafted oxygen groups on ordered mesoporous carbon while preserving its mesostructure by using a mild H₂O₂ oxidation. Experimental and theoretical analyses reveal that hydroxyl groups work as the dominant sites to enhance low-pressure CO₂ uptake, CO₂/N₂ selectivity, and adsorption kinetics through optimized bidirectional charge transfer and hydrogen-bonding networks. An optimal hydroxyl density maximizes CO₂ affinity without inducing steric hindrance or pore collapse. This work provides molecular-level insights and design principles for efficient post-combustion carbonaceous adsorbents.