Selective capture of CO₂ over N₂ and CH₄: B clusters and their size effects
Using density-functional theory (DFT), we investigate the selectivity of adsorption of CO₂ over N₂ and CH₄ on planar-type B clusters, based on our previous finding of strong chemisorption of CO₂ on the B₁₀₋₁₃ planar and quasiplanar clusters. We consider the prototype B₈ and B₁₂ planar-type clusters and perform a comparative study of the adsorption of the three molecules on these clusters. We find that, at room temperature, CO₂ can be separated from N₂ by selective binding to the B₁₂ cluster and not to the B₈ cluster. Selective adsorption of CO₂ over CH₄ at room temperature is possible for both clusters. Based on our DFT-adsorption data (including also a semi-infinite Boron sheet) and the available literature-adsorption value for N₂ on the planar-type B₃₆ cluster, we discuss the selectivity trend of CO₂ adsorption over N₂ and CH₄ with planar-cluster size, showing that it extends over sizes including B₁₀₋₁₃ clusters and significantly larger.