Molecular Self‐Assembly Enables Tuning of Nanopores in Atomically Thin Graphene Membranes for Highly Selective Transport. Issue 11 (3rd February 2022)

• Record Type: Journal Article
• Authors: Jang, Doojoon; Bakli, Chirodeep; Chakraborty, Suman; Karnik, Rohit
• Is Part Of: Advanced materials. Volume 34:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-03
• Subjects: atomically thin membranes -- graphene nanopores -- polyelectrolytes -- selective mass transport -- self‐assembly -- water purification; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202108940
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Atomically thin membranes comprising nanopores in a 2D material promise to surpass the performance of polymeric membranes in several critical applications, including water purification, chemical and gas separations, and energy harvesting. However, fabrication of membranes with precise pore size distributions that provide exceptionally high selectivity and permeance in a scalable framework remains an outstanding challenge. Circumventing these constraints, here, a platform technology is developed that harnesses the ability of oppositely charged polyelectrolytes to self‐assemble preferentially across larger, relatively leaky atomically thin nanopores by exploiting the lower steric hindrance of such larger pores to molecular interactions across the pores. By selectively tightening the pore size distribution in this manner, self‐assembly of oppositely charged polyelectrolytes simultaneously introduced on opposite sides of nanoporous graphene membranes is demonstrated to discriminate between nanopores to seal non‐selective transport channels, while minimally compromising smaller, water‐selective pores, thereby remarkably attenuating solute leakage. This improved membrane selectivity enables desalination across centimeter‐scale nanoporous graphene with 99.7% and >90% rejection of MgSO4 and NaCl, respectively, under forward osmosis. These findings provide a versatile strategy to augment the performance of nanoporous atomically thin membranes and present intriguing possibilities of controlling reactions across 2D materials via exclusive exploitation of pore size‐dependent intermolecular interactions. Abstract : Membranes with precise pore size distributions are needed for efficient and selective separations for a sustainable future. Self‐assembly of oppositely charged polyelectrolytes across nanopores in atomically thin graphene membranes is shown to enable controllable size‐dependent sealing of nanopores to tighten their size distribution and attenuate leakage. The enhanced membrane selectivity, without compromising water permeance, allows for desalination under forward osmosis.