Nanochannel-confined charge repulsion of ions in a reduced graphene oxide membrane

Abstract

Confined mass transfer through the interlayered nanochannels of graphene oxide (GO) laminates has attracted considerable research interest. The distinct properties of GO enable selective transport of water over ions, which is an intriguing outcome for membrane desalination applications. However, the limited stability of the laminated structure in water impairs the maintenance of nanochannels, leading to difficulty in feasible control of ion transport behavior. This study explores the charge repulsion of ions within well-confined nanochannels of chemically reduced graphene oxide (rGO) laminates. Based on the ionic transport behavior, effectively setting energy barriers at the nanochannel entrance and inside the nanochannel enables the resulting membrane to highly retard the transport of salt solutes, achieving a NaCl rejection ratio as high as 95% in pressurized desalination. The presented strategy in controlling the ion transport via constituting energy barrier for nanochannel-confined charge repulsion could prompt the development of GO-based desalination membranes in the future.