Evidence for a film theory of hydrogen overpotential from surface tension measurements

Abstract

Whenever hydrogen overpotential occurs at a cathode there must be some transition layer between the electrode surface and the electrolyte, where hydrogen exists in a condition whose free energy is greater than that of the gaseous hydrogen into which it passes. Even if the overpotential is believed to be the result of a resistant film this point of view is still applicable, the additional free energy in this case being the electrical energy between the plates of a condenser. The experiments described below seem to show that this layer has many of the properties of a skin or film, and it will be referred to in the future as a film, without any significance being attached to the term besides that deduced in the course of the discussion.