Stretch-inactivated ion transport through subnanoporous two-dimensional membranes

Aqueous ions permeate subnanoscale pores in two-dimensional materials by leaping local energy barriers, not through simple diffusion. Depending on the local ion-pore and ion-solvent interactions, seemingly non-intuitive behaviors can arise. The authors combine molecular dynamics simulations, quantum-chemical calculations, and kinetic theory to demonstrate that electrostatically driven flow of aqueous alkali cations through subnanoscale pores can be $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}d$ by stretching the two-dimensional membrane hosting the pores. More specifically, they show that potassium transport significantly decreases in response to moderate membrane strain, while sodium transport increases. This behavior is attributed to a clearly observed strain-induced repulsive-to-attractive transition in the ion-pore electrostatic interactions.