Self-Assembly: A Facile Way of Forming Ultrathin, High-Performance Graphene Oxide Membranes for Water Purification

Abstract

Single-layer graphene oxide (SLGO) is emerging as a new-generation membrane material for high-flux, high-selectivity water purification, owing to its favorable two-dimensional morphology that allows facile fabrication of ultrathin membranes with subnanometer interlayer channels. However, reliable and precise molecular sieving performance still necessarily depends on thick graphene oxide (GO) deposition that usually leads to low water flux. This trade-off between selectivity and flux significantly impedes the development of ultrathin GO membranes. In this work, we demonstrate that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control. We find GO membranes, prepared by slow deposition of SLGO flakes, exhibit considerably improved salt rejection, while counterintuitively having 2.5-4 times higher water flux than that of membranes prepared by fast deposition. This finding has extensive implications of designing/tuning interlayer nanostructure of ultrathin GO membranes by simply controlling SLGO deposition rate and thus may greatly facilitate their development for high flux, high selectivity water purification.

2D Laminar Membranes for Selective Water and Ion Transport

“…Therefore, these groups are first able to lock adjacent water by strong hydrogen bonds, which further limits the movement of unlocked water molecules in the same plane, causing a “side‐pinning effect” to drag down overall water mobility . To experimentally verify this effect, Yu and co‐workers studied the water permeation in GO channels with different chemical structure (Figure b) . By simply controlling the deposition speed of GO suspension, interlayer channels can be tuned to have symmetrical (slow‐deposited) or asymmetrical (fast‐deposited) surface chemistry.…”

Electric‐Field‐Induced Ionic Sieving at Planar Graphene Oxide Heterojunctions for Miniaturized Water Desalination

“…[ 44 ] The salt rejection rate obtained with homogeneous GOM is merely 32.9%, in accord with previous reports. [ 45–47 ]…”

Antibiotics Separation with MXene Membranes Based on Regularly Stacked High‐Aspect‐Ratio Nanosheets

“…The excellent antifouling property is ascribed to the homogeneous distributed hydrophilic terminations on the Ti 3 C 2 T x nanosheets . These functional terminations also make it easier to form better stacking structure during vacuum filtration, resulting in better separation performance. In order to proof the stability of the used Ti 3 C 2 T x membranes after filtration, series of characterizations were carried out as shown in Figures S20–S24, including the contact angle analysis, XRD, AFM, SEM, and XPS analysis.…”