A novel method, based upon potential-pH response measurements, was used to determine the proton chemical diffusion of titanium oxide thin films. The technique, which was based upon a model for diffusion-controlled proton transport at the oxide surface, measured the potential-pH response drift as a step-wise increase and decrease in the pH during thermostatic measurements. The proton chemical diffusion coefficient for titanium oxide films, as obtained by using this method, was 10-17cm2/s. This value was about 2 orders of magnitude smaller than the H chemical diffusion coefficient (10-15cm2/s) obtained by using conventional electrochemical permeation techniques.

A Comparison between Proton and Hydrogen Chemical Diffusion Coefficients of Titanium Oxide Films. Yu, G.C.: Physica Status Solidi A, 2003, 198[2], 302-11