Li Selectivity of Carboxylate Graphene Nanopores Inspired by Electric Field and Nanoconfinement.

The regulation of the ion selectivity by electric field and ion association on the Li selectivity of carboxyl functionalized graphene nanopores are investigated by molecular dynamics simulation. Carboxylate graphene nanopores of sub-2 nm exhibit excellent Li selectivity under the electric field of 1.0 V nm . The results show that ion association inspired by electric field may be a key factor affecting ion selectivity of sub-2 nm nanopores. The ion association of Mg and Cl can be promoted obviously near the nanopores under the electric field of 1.0 V nm . The migrating of Mg can be retarded by stable clusters of Mg and Cl formed near nanopores. The degree of association of Li with Cl is relatively low and the disassociation of the Li cluster is easier so that Li can more easily pass through the nanopores. These results gain insight into the effect of ion association inspired by electric field and nanoconfinement of graphene nanopore on Mg /Li separation, and provide helpful information for the application of nanoporous materials in extraction of Li ion from salt-lake brine.