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 H-2, N-2, 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 10(5). 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.