Pore Diameter and Chemistry Modulated Flexible Ion Selectivity through a Single-Layer MoS2 Nanopore

Abstract

Nanoporous membranes based on 2D materials are promising as the most efficient technologies for practical engineering applications such as seawater desalination, ion sieving, and gas separation. In this work, we utilize various nanopores in molybdenum disulfide (MoS2) membranes to enable flexible ion selectivity that is tuned efficiently by adjusting pore diameter and surface chemistry. We theoretically uncover the molecular mechanisms that lead to MoS2 nanopores with varied diameters and pore atom chemistry exhibiting distinctly different ion selectivity. MoS2 nanopores with S atoms at the nanopore boundary facilitate K+ ion translocation and rejection of Cl– ions. MoS2 nanopores with Mo atoms at the nanopore boundary permit Cl– ion translocation and reject K+ ions. The average flow velocity of K+ ions in the MoS2 nanopore with S atoms at the nanopore boundary is larger than that of Cl– ions in the MoS2 nanopore with Mo atoms at the nanopore boundary. This phenomenon is attributed to the totally different ion transport mechanisms modulated by the nanopore boundary atoms. This work provides new insights into designing multifunctional membranes on a single 2D material membrane with flexible and optimal ion selectivity toward broad applications.