Highly efficient charge inversion in dense periodic nanoporous framework membranes

Abstract

Charge inversion (overscreening), a counterintuitive electrokinetic phenomenon, provides a pivotal pathway for manipulating ion selectivity in nanofluidic systems. Here, we show that this effect can be realized in a covalent organic framework (COF) membrane modulated solely by monovalent cations, enabling a reversible switch from cation to anion selectivity. Our findings indicate that the inversion behavior stems from a notably high saturated ion adsorption capacity that may be facilitated by synergistic pore-pore interactions at ultrahigh pore density, along with nanoconfined steric hindrance within the COF pores.