Engineering grain boundaries in monolayer molybdenum disulfide for efficient water-ion separation

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Two-dimensional (2D) materials are promising for separation membranes.
• Achieving uniform subnanometer pores over large areas on 2D materials remains a challenge.

Purpose of the Study:

• To investigate the use of eight-membered ring (8-MR) pores in monolayer molybdenum disulfide (MoS2) as molecular sieves for water-ion separation.
• To demonstrate tunable pore density through grain boundary engineering.

Main Methods:

• Utilized grain boundary engineering in monolayer MoS2 to form well-defined 8-MR pores.
• Controlled the density of 8-MR pores by regulating the grain size of MoS2.
• Tested optimized MoS2 membranes in forward osmosis.

Main Results:

• Identified 8-MR pores at antiparallel grain boundaries of MoS2 as effective molecular sieves.
• Demonstrated tunability of pore density by controlling MoS2 grain size.
• Achieved ultrahigh water/sodium chloride selectivity and exceptional water permeance, surpassing state-of-the-art membranes.

Conclusions:

• Grain boundary engineering in 2D materials offers a viable method for creating precise pore structures.
• Optimized MoS2 membranes show significant potential for efficient water-ion separation applications.
• This approach provides a promising route for developing advanced separation membranes.