Study of ionic transport through metalized nanoporous membranes functionalized with self-assembled monolayers

• Charge selectivity can be improved with the presence of an alkane-terminated SAM.
• Permselectivity of gold-coated nano-capillary-array-membranes (NCAMs) was studied.
• Surface charge at the NCAM has a large influence on the transport of analytes.
• Surface charge at the nanopore wall effects transport properties of analytes.
• Selectivity increased up to 200% with the presence of a SAM at the NCAM surface.

Ionic transport through synthetic nanoporous membranes has received great attention in applications related to biosensing, fuel cell, and desalination. Past work has demonstrated that charge selectivity can be achieved by applying a potential across a metallized conductive membrane. However, challenges arise for improving charge selectivity as a result of irreversibility of the system from the anion adsorption at the membrane surface. This study demonstrates how charge selectivity can be improved with the presence of a well grown self-assembled monolayer (SAM), which can aid in applications that use chemical separation processes based on the surface charge of the nanopore.In this work, the transport and selectivity properties of gold-coated conductive nano-capillary-array-membranes (NCAMs) are studied using charged species methyl viologen paraquat, (MV2+) and napathalenedisulfonate disodium salt (NDS2−). The selectivity coefficients for MV2+ and NDS2− increased with the functionalization of undecanethiol on the gold-coated NCAM surface. With the presence of a SAM, the selectivity coefficients increased by 44% for MV2+ and 200% for NDS2−. The influence of ionic transport from the diffuse layer potential at the walls and surface of the nanopore is also discussed.