Quantum Mechanical Theory of Electrochemical Kinetics: Analysis by Electron Transfer Distance and Transition Probability

Abstract Quantum mechanical theory of electrochemical kinetics based on Fermi’s golden rule was formulated by introducing the concept of electron-transfer distance. The expressions for the exchange current density and standard rate constant in electrochemistry were derived in analytical form, as well as exponential current overpotential dependence. The theory corresponds well to the electrode kinetics based on the transition state theory that is familiar at present with many electrochemists. It was applied to various kinds of electrode reactions to analyze the standard rate constants and the exchange current densities reported in past literature. The evaluated magnitudes of the electron exchange energy were very small, being in the order of 10−3–10−5 eV. This theory supports the ordinary electron-transfer mechanism due to the overlap of wave functions between the electrode and redox species, denying tunneling mechanism.