Who Should be Credited for the Gouy-Chapman Model?

Abstract

The Gouy-Chapman theory is well known to all electrochemists. However, examining the works of Gouy and Chapman, one can find that the current mathematical basis of this theory notably differs from the original concept. The Poisson-Boltzmann equation is at the heart of this model in its present form. However, not only did neither Gouy nor Chapman solve this equation, they did not even formulate it. Concerning the diffuse double layer, this equation was solved for the first time by Karl Herzfeld Phys. Z. 21, 28, (1920). Please note that this exact solution of the Poisson-Boltzmann equation predates the Debye-Hückel approximation. Unfortunately, the scientific community is currently ignoring Karl Herzfeld’s contributions to this theory. This paper is an analysis of the mathematical apparatus of the Gouy, Chapman, and Herzfeld versions of the double layer theory. The author presented the equations they derived as close as possible to the original.