CO₂ capture on h -BN sheet with high selectivity controlled by external electric field

Developing highly efficient sorbent materials for CO₂ separation and capture from gas mixture is most important for reducing impact of CO₂ on the environment. On the basis of density functional theory calculations with dispersion correction, we show that hexagonal boron nitride sheet (h-BN), when under an external electric field, can become an effective sorbent for CO₂ capture. In the absent of the electric field, CO₂ molecules are physisorbed on the h-BN sheet. Under the external electric field, the adsorption of CO₂ molecules on h-BN monolayer can be strongly strengthened. Compared to CO₂, the adsorption of H₂, N₂, CH₄, CO, or H₂O on h-BN sheet is notably weaker, indicating that the capture of CO₂ on h-BN sheet under the electric field is highly preferred over other gas molecules. The calculated ratio of adsorption rate constant of CO₂ to other gas molecule can be as high as 10⁵. Moreover, the capture of CO₂ molecule on h-BN sheet is reversible; that is, the adsorbed CO₂ can be released by shutting down the applied electric field. This study suggests potential application of h-BN sheet not only for CO₂ capture but also as a gas-storage material with high selectivity. The degree of selectivity can be controlled by an applied external electric field.