Selective Carbon Dioxide Binding on Carbon Quantum Dots
Michael T. Broud, Mohsen Samandari, Lu Yu, David P. Harper, David J. Keffer
Abstract
Mitigating the most extreme potential effects of climate change due to fossil fuel burning requires unprecedented global carbon sequestration. The materials used for carbon capture must be renewable, economically feasible, abundant, and recyclable with the ability to recover the adsorbed gas. Carbon quantum dots (CQD) are evaluated as materials to decorate the interior pore space of model carbon surfaces to achieve selective carbon dioxide adsorption from gas mixtures. We used classical molecular dynamics (MD) simulation to evaluate the effect of CQD size and composition on the selectivity of CO 2 relative to N 2 and O 2 . The CQDs are modified either through nitrogen doping of the interior aromatic structure or functionalization of the edges with amine groups. CQDs show selective adsorption for CO 2 relative to N 2 and O 2 in all cases. The magnitude of the selectivity is a function of CQD size and the amount of doping and functionalization. In this exploratory study, a maximum CO 2:N 2 selectivity of 4.3 and CO 2:O 2 selectivity of 3.1 were obtained on isolated CQDs at 300 K without structural optimization. This preliminary computational study sets the framework for optimizing the CQD atomic architecture on a CQD/AC adsorbent.