Calcium-decorated carbon nanostructures for the selective capture of carbon dioxide

The development of advanced materials for CO₂ capture is of great importance for mitigating climate change. In this paper, we outline our discovery that calcium-decorated carbon nanostructures, i.e., zigzag graphene nanoribbons (ZGNRs), carbyne, and graphyne, have great potential for selective CO₂ capture, as demonstrated via first-principles calculations. Our findings show that Ca-decorated ZGNRs can bind up to three CO₂ molecules at each Ca atom site with an adsorption energy of ∼-0.8 eV per CO₂, making them suitable for reversible CO₂ capture. They adsorb CO₂ molecules preferentially, compared with other gas molecules such as H₂, N₂, and CH₄. Moreover, based on equilibrium thermodynamical simulations, we confirm that Ca-decorated ZGNRs can capture CO₂ selectively from a gas mixture with a capacity of ∼4.5 mmol g^-1 under ambient conditions. Similar results have been found in other carbon nanomaterials, indicating the generality of carbon based nanostructures for selective CO₂ capture under ambient conditions.