Structure and Dynamics of Carbon Dioxide inside ”Hot” Ice with Cylindrical Channels

Inclusion compound based on crystalline water is increasingly recognized as a promising solution for carbon dioxide (CO 2 ) capture, either for carbon sequestration from greenhouse gas emissions or for gas mixture separation. Molecular dynamics simulations revealed that water crystallizes into a novel porous structure in a carbon nanobrush environment even at room temperature, thus termed ”hot” ice whose structure code is dtc. This study employs a hybrid Grand Canonical/isothermal-isobaric Monte Carlo (GCMC) simulations to investigate CO 2 confinement inside the cylindrical channels of ice dtc structure. The results show that CO 2 occupancy, here expressed as CO 2 -to-water mole ratio, is approximately 2:5 at maximum. The simulations also demonstrate the mechanical stability of ice dtc structure under positive pressures when its voids are filled with CO 2 . Furthermore, molecular dynamics simulations are performed to provide molecular insights into the structures and dynamics of CO 2 inside the porous channels framework. The results show that CO 2 molecules form a bilayer structure inside the cylindrical channels, where certain molecule orientation angles are favored. Dynamics analysis shows that CO 2 molecules are relatively immobile in all directions at maximum occupancy.