Surface Modification of Carbonaceous Materials Toward Direct Air Capture of Carbon Dioxide

Author

Narges Mokhtarinori, University of Tennessee, KnoxvilleFollow

Date of Award

8-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Sheng Dai

Committee Members

Sheng Dai, Victor Nemykin, Konstantinos Vogiatzis, David Keffer

Abstract

Direct air capture (DAC) of CO₂ [carbon dioxide] is a promising solution for reducing the carbon footprint through "negative emission" technology. However, the low CO₂ concentration and the dynamic nature of DAC processes present challenges in designing effective sorbent systems. Recent advancements in material design and structural engineering have led to the development of high-performance solid sorbents, offering a more stable, safe, and energy-efficient alternative to traditional liquid CO₂ capture methods. This thesis covers design principles, synthesis methodologies, and their impact on CO₂ chemisorption, comparing the advantages and limitations of each approach. Characterization techniques, especially operando methods and computational tools to understand sorbent behavior during CO₂ integration and release. The reaction pathways and interaction mechanisms of these sorbents with CO₂ are analyzed to guide future design. Additionally, the CO₂ chemisorption behaviors, including capacity, sorption kinetics, recyclability, and durability in the presence of gaseous impurities and under humid conditions will be evaluated and compared. The superbase ionic liquids (ILs)-modified carbon substrates were developed towards DAC of CO₂ by harnessing the strong CO₂ binding capability of IL and the ordered porous channels provided by the carbon supports. Detailed porosity analysis revealed that the IL with aromatic cation and oxygenate anion preferred to fill the micropores, and a thin layer was created on the surface of the mesopores. Strong π-π interaction between the IL layer and the carbon surface was disclosed by wide-angle X-ray scattering (WAXS) analysis, leading to enhanced thermal stability of the IL phase. With the same lL coating amount, the DAC of CO₂ evaluation revealed that larger mesopore size and pore volume in the carbon/IL composite materials led to higher CO₂ uptake capacity by exposing more active sites to integrate CO₂ from diluted sources. The thermodynamic analysis confirmed the critical role of IL coating in providing strong chemisorption sites and significantly improved selectivity to enrich the diluted CO₂ from the air atmosphere.

Recommended Citation

Mokhtarinori, Narges, "Surface Modification of Carbonaceous Materials Toward Direct Air Capture of Carbon Dioxide. " Master's Thesis, University of Tennessee, 2025.
https://trace.tennessee.edu/utk_gradthes/14549