Local Electroneutrality Violation as a Universal Constraint in Confined Electrolytes

TL;DR

This paper demonstrates that topology governs finite-size violations of local electroneutrality in confined electrolytes, revealing a universal hierarchy of deviations across different geometries within Poisson-Boltzmann theory.

Contribution

It introduces an electroneutrality deviation ratio and establishes topology as the key factor influencing charge redistribution in confined electrolytes.

Findings

Finite-size deviations strongest in spherical cavities

Deviations weaker in cylindrical confinement

Weakest in planar slits

Abstract

We show that finite-size violations of local electroneutrality in confined electrolytes are governed by the topology of the confining domain, yielding a universal hierarchy of deviations across spherical, cylindrical, and planar geometries. Within Poisson-Boltzmann theory, we introduce an electroneutrality deviation ratio that quantifies how global electrostatic constrains associated with compacness and boundary multiplicity modify charge balance inside confined domains. Although electroneutrality is asymptotically restored in all geometries, finite-size deviations are strongest in compact spherical cavities, weaker in cylindrical confinement, and weakest in planar slits. These results identify topology as the structural origin of confinement-induced charge redistribution and stablish the violation of local electroneutrality as global constraint underlying phenomena such as overcharging anf charge reversal, demostrating that confinement-not local-not local geometric details-controls the emergence of these effects.