Carbon dioxide (CO2) capture and storage including geological sequestration are essential for reducing greenhouse effect and mitigating climate change. Delineating the surface interactions, structure, and conversion of CO2 to carbonic acid (H2CO3) in nanoporous environments is one of the less explored approaches to ground advances in clay minerals for gas storage or predict the fate of stored gases in subsurface environments. To this end, the molecular scale interactions underlying the structure and reaction of carbon dioxide in clay nanopores need to be investigated. To probe the influence of hydrophobic and hydrophilic surfaces on the reaction, a series of ReaxFF [1] metadynamics [2] molecular simulations are performed to investigate the energy landscape of the CO2 conversion to H2CO3 in pyrophyllite and gibbsite nanopores at 300 K. The two minerals considered herein, pyrophyllite and gibbsite are hydrophobic and hydrophilic respectively. Our hypothesis is that the surface hydrophobicity will affect water structure and dynamics, and therefore will control the CO2 conversion into H2CO3. Our preliminary results indicate that within the hydrophobic pyrophyllite nanopores, CO2 conversion to H2CO3 is thermodynamically and kinetically favorable, compared to the same reaction in bulk water. We are currently investigating the CO2 conversion to H2CO3 in hydrophilic gibbsite nanopores and aim to provide an understanding of CO2 conversion to H2CO3 in two opposing environments.

Understanding the effect of surface hydrophobicity and nanoconfinement on the conversion of carbon dioxide to carbonic acid

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