CO₂ Capture on <i>h</i>-BN Sheet with High Selectivity Controlled by External Electric Field

Abstract

Developing highly efficient sorbent materials for CO 2 separation and capture from gas mixture is most important for reducing impact of CO 2 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 CO 2 capture. In the absent of the electric field, CO 2 molecules are physisorbed on the h -BN sheet. Under the external electric field, the adsorption of CO 2 molecules on h -BN monolayer can be strongly strengthened. Compared to CO 2, the adsorption of H 2, N 2, CH 4, CO, or H 2 O on h -BN sheet is notably weaker, indicating that the capture of CO 2 on h -BN sheet under the electric field is highly preferred over other gas molecules. The calculated ratio of adsorption rate constant of CO 2 to other gas molecule can be as high as 10 5 . Moreover, the capture of CO 2 molecule on h -BN sheet is reversible; that is, the adsorbed CO 2 can be released by shutting down the applied electric field. This study suggests potential application of h -BN sheet not only for CO 2 capture but also as a gas-storage material with high selectivity. The degree of selectivity can be controlled by an applied external electric field.