Theories for Predicting Reversible Potentials of Reactions on Electrode Surfaces from Internal and Gibbs Energies: Applications to ORR

When I arrived at Case in January of 1979, Ernie Yeager introduced me to the oxygen cathode reaction, which was then, as now, the kinetic bottleneck for hydrogen fuel cells. Armed with a slow semiempirical quantum theory that lacked charge self-consistency, I soon found that even the dissociative adsorption of O2 on platinum surfaces could not be calculated accurately. My semiempirical band shift technique was good only for estimating electrode potential dependencies of vibrational frequencies and some dissociation processes involving adsorbed molecules. By the late 1990's, charge self-consistent calculations were at last feasible in my lab and I began using them to develop ways to calculate reversible potentials and potential dependencies of electron transfer reactions for adsorbed molecules. Sadly, Ernie passed away about the time I began making progress in understanding the oxygen reduction reaction. Here, emphasizing O2 reduction, is an overview of these quantum electrochemistry developments at Case.