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

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Surface oxygen functionalization in porous carbons improves carbon dioxide (CO2) affinity.
• The precise molecular roles of different oxygen species in this process are not fully understood.

Purpose of the Study:

• To controllably graft oxygen groups onto ordered mesoporous carbon using mild hydrogen peroxide (H2O2) oxidation.
• To elucidate the molecular-level mechanisms by which oxygen species influence CO2 adsorption.

Main Methods:

• Mild H2O2 oxidation to functionalize ordered mesoporous carbon.
• Experimental characterization of functionalized materials.
• Theoretical analysis to understand adsorption mechanisms.

Main Results:

• Hydroxyl groups were identified as the primary sites enhancing CO2 uptake, CO2/N2 selectivity, and adsorption kinetics.
• Optimized bidirectional charge transfer and hydrogen-bonding networks involving hydroxyl groups were key.
• An optimal hydroxyl density was found to maximize CO2 affinity without negative structural impacts.

Conclusions:

• Hydroxyl groups play a dominant role in enhancing CO2 adsorption in functionalized porous carbons.
• This study provides molecular-level insights for designing advanced carbonaceous adsorbents for CO2 capture.
• The findings offer design principles for efficient post-combustion carbon capture materials.