Precise ångström controlling the interlayer channel of MoS2 membranes by cation intercalation

Abstract

MoS2 nanosheets have been used as building block candidates for assembling two dimensional (2D) laminates. However, the use of MoS2 membranes remains to be severely imposed by the narrow interlayer width of ~3 Å. In this work, we proposed a feasible and efficient approach to enlarge the interlayer distance of MoS2 membranes using cations (K+, Na+, Li+ or Mg2+) intercalation. The resulting membranes show significant increases in interlayer widths, which attain 6.25, 6.63, 7.25, and 8.48 Å for K+, Na+, Li+ and Mg2+ regulation respectively. Moreover, the 2D galleries’ regularity in cations inserting MoS2 membranes is well inherited from that of the original MoS2 membrane. The water purification performances further validate the cations intercalation manipulation. In the nanofiltration mode, cations interlacation enables the water permeances of MoS2 membranes to improve 2–3 times without sacrificing dye rejections. In the forward osmosis mode, the water permeances of cations intercalating MoS2 membranes almost improve an order of magnitude (24.4× 10−3 - 36.4 × 10−3 L m−2 h−1 bar−1) in comparison with the pristine MoS2 membrane (3.4 × 10−3 L m−2 h−1 bar−1), while retaining the comparable NaCl rejections. This approach of broadening 2D channels paves a way to the design and regulation of 2D membranes for achieving extending applications.