Surface Modification Strategy for Enhanced NO₂ Capture in Metal-Organic Frameworks.

Area of Science:

• Materials Science
• Computational Chemistry
• Environmental Chemistry

Background:

• Nitrogen dioxide (NO2) is a harmful air pollutant.
• Metal-organic frameworks (MOFs) show promise for gas adsorption but require optimization for specific molecules like NO2.
• Functionalizing MOF linkers is a strategy to enhance gas uptake properties.

Purpose of the Study:

• To investigate the interaction strength of nitrogen dioxide (NO2) with functionalized benzene molecules.
• To identify functional groups that can enhance NO2 uptake in metal-organic frameworks (MOFs).
• To evaluate the NO2 adsorption capacity of modified MOFs using computational simulations.

Main Methods:

• Density Functional Theory (DFT) calculations were used to assess NO2 interaction energies with 43 functionalized benzene molecules.
• Grand Canonical Monte Carlo (GCMC) simulations were employed to predict NO2 uptake isotherms in functionalized IRMOF-8.
• RI-DSD-BLYP/def2-TZVPP level of theory was utilized for DFT calculations.

Main Results:

• Phenyl hydrogen sulfate (-OSO3H) exhibited the highest interaction energy with NO2 (5.4 kcal/mol), nearly triple that of non-functionalized benzene.
• Functional groups -OSO3H, -PO3H2, and -OPO3H2 demonstrated strong NO2 interactions.
• GCMC simulations predicted a significant enhancement in NO2 uptake for IRMOF-8 functionalized with these groups.

Conclusions:

• The introduction of strongly binding functional groups like phenyl hydrogen sulfate substantially improves NO2 adsorption in MOFs.
• Functionalized MOFs are promising candidates for enhanced NO2 capture applications.
• This approach can be applied to various porous materials for improved gas uptake performance.