Fig. 1.

Artificial angstrom-scale 2D ion channels. (A) Schematic of the competitive permeation test of mixed ions through MoS₂-based angstrom-scale 2D channels. The anions (either pure nitrate or mixed chloride/nitrate) are omitted for clarity. The hydrated ions go through dehydration processes when going through the confined 2D channels. (B) The selected seventeen cations in the mixture and their corresponding hydrated diameters (23) (see details in SI Appendix, Table S1). (C) Cross-section STEM image of MoS₂-COOH membrane showing the 2D channels in the dry state. (D) XRD spectra of bulk MoS₂ and MoS₂-COOH membranes in both the air-dry state without any ion and the wet state in the mixture solution.