Electrical double layer: revisit based on boundary conditions

TL;DR

This paper reevaluates the electrical double layer at flat surfaces within the triple layer model, focusing on boundary conditions and charge density assumptions at the outer Helmholtz plane.

Contribution

It introduces a new calculation of charge density and discusses the implications of assuming negligible charge density at the outer Helmholtz plane.

Findings

Charge density at the outer Helmholtz plane can be non-zero.

The assumption of zero charge density affects the position of the outer Helmholtz plane.

Conditions for negligible charge density are analyzed.

Abstract

The electrical double layer at infinite flat solid surface was discussed with respect to the triple layer model. Charge density at the outer Helmholtz plane is assumed to be zero usually. However, the assumption causes the position of the outer Helmholtz plane to be obscure. The charge density was calculated and the condition that the charge density is negligible was discussed.