Electrochemical Kinetics and Dimensional Considerations at the Nanoscale

Abstract

A critical understanding of thermodynamics inherent to charge transfer is necessary for scientific insights, as well as for applications ranging from biochemical reactions, electrocatalysis, and charge storage in capacitors and batteries. In this letter, we first examine issues related to conventional classical reaction rate theories, such as the Marcus-Hush models for homogeneous electron transfer, and the extensions by Chidsey to heterogeneous electron kinetics. While the foundational attributes have almost always been reckoned in terms of one-electron based charge transfer, much of the theoretical and experimental analysis has only obliquely referred to dimensionality considerations. We have found a major role of the dimensionality dependent density of states (DOS) in mesoscale and nanoscale materials in modulating electron kinetics. We have then discovered several novel characteristics that have never been reported before, such as, (i) the observation of DOS dependent reaction rate constant and electrical current oscillations, coupled with (ii) the prediction of tests of dimensionality/quasi-dimensionality. We posit a chirality dependent electron transfer rate constant in nanotubes and graphene-like structures, considering the coupling of the energy level spacing in the nanostructured electrode with that in the ambient, e.g., electrolyte. The manifestation of novel features in electron transfer kinetics as a function of dimensionality probes new frontiers in the tunability of electrochemical characteristics. We expect our work to generate very wide interest in the scientific community due to the importance of heterogeneous charge transfer across a variety of disciplines.