Structure-Electronic Synergy in Bifunctionalized Zeolite Enables Fast CO₂ Capture at Indoor Levels.

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Elevated carbon dioxide (CO2) levels in indoor environments like conference rooms and vehicles degrade air quality and pose health risks.
• Developing effective solid adsorbents for CO2 capture at moderate concentrations (around 1000 ppm) is a significant challenge.

Purpose of the Study:

• To engineer ZSM-5 zeolites using a synergistic amine-bifunctionalization strategy for efficient CO2 capture under indoor-relevant conditions.
• To investigate the structure-electronic synergy influencing CO2 adsorption mechanisms.

Main Methods:

• Surface silanization of ZSM-5 with 3-aminopropyltriethoxysilane (APTES) to create stable anchoring sites and control pore accessibility.
• Impregnation of tetraethylenepentamine (TEPA) onto functionalized ZSM-5 to introduce a high density of active amine sites.
• Experimental characterization and density functional theory (DFT) calculations to analyze adsorption mechanisms and electronic properties.

Main Results:

• The bifunctionalized ZSM-5 exhibited a CO2 uptake of 7.82 mmol·g-1, a 2.1-fold increase compared to pristine ZSM-5 (3.78 mmol·g-1).
• The adsorbent demonstrated rapid adsorption kinetics and excellent regeneration stability over multiple cycles.
• DFT calculations revealed enhanced charge transfer and electronic coupling at the bifunctionalized interface, promoting chemisorption.

Conclusions:

• The synergistic amine-bifunctionalization strategy effectively enhances CO2 capture by ZSM-5 zeolites under moderate concentrations.
• The observed structure-electronic synergy provides mechanistic insights for designing advanced zeolite adsorbents for indoor air purification and carbon management.
• This approach offers a promising pathway for developing efficient materials for confined-space carbon capture applications.