Publication
Potential dependent ionic sieving through functionalized laminar MoS2 membranes
Publisher:
IOP Publishing
Date:
11-12-2019
DOI:
10.1088/2053-1583/AB5AD9
Abstract: Laminar MoS 2 membranes show outstanding potential for practical applications in energy conversion/storage, sensing, and as nanofluidic devices. The re-stacking of exfoliated MoS 2 creates nanocapillaries between the layers of MoS 2 nanosheets. These MoS 2 membranes have been shown to possess a unique combination of ionic rejection properties, high water permeation rates, and long-term solvent stability, with no significant swelling when exposed to aqueous or organic solvents. Chemical modification of MoS 2 membranes has been shown to improve their ionic rejection properties, however the mechanism behind this improvement is not well understood. In this work, we elucidate the ion-sieving mechanism by the study of potential-dependent ion transport through functionalized MoS 2 membranes. The ionic permeability of the MoS 2 membrane is transformed by chemical functionalization with a simple naphthalene sulfonate dye (sunset yellow) and with a resultant attenuation of permeability by at least an order of magnitude, compared to the pristine MoS 2 membranes and permeability reported for graphene oxide and Ti 3 C 2 T x (MXene) membranes. The effects of pH, solute concentration, and ionic size/charge on the ionic selectivity of the functionalized MoS 2 membranes are also reported. Understanding the mechanism of ionic sieving within functionalized MoS 2 membranes will enable future applications in electro-dialysis and ion exchange for water treatment technologies.