Selective Carbon Dioxide Binding on Carbon Quantum Dots

Mitigating the most extreme potential effects of climatechangedue to fossil fuel burning requires unprecedented global carbon sequestration.The materials used for carbon capture must be renewable, economicallyfeasible, abundant, and recyclable with the ability to recover theadsorbed gas. Carbon quantum dots (CQD) are evaluated as materialsto decorate the interior pore space of model carbon surfaces to achieveselective carbon dioxide adsorption from gas mixtures. We used classicalmolecular dynamics (MD) simulation to evaluate the effect of CQD sizeand composition on the selectivity of CO2 relative to N-2 and O-2. The CQDs are modified either through nitrogendoping of the interior aromatic structure or functionalization ofthe edges with amine groups. CQDs show selective adsorption for CO2 relative to N-2 and O-2 in all cases.The magnitude of the selectivity is a function of CQD size and theamount of doping and functionalization. In this exploratory study,a maximum CO2:N-2 selectivity of 4.3 and CO2:O-2 selectivity of 3.1 were obtained on isolatedCQDs at 300 K without structural optimization. This preliminary computationalstudy sets the framework for optimizing the CQD atomic architectureon a CQD/AC adsorbent.