(244b) Mechanistic Role of Cations in the Electric Double Layer during Electrocatalysis

Electrocatalysis, whose reaction venue locates at the catalyst–electrolyte interface, is controlled by the electron transfer across the electric double layer, envisaging a mechanistic link between the electron transfer (ET) rate and the electric double layer structure. A fine example is so-called a “cation effect”, which stands for a strong dependence of electrocatalytic activity on the alkali metal cation (M⁺) identity. Although the cation effect has been observed in a variety of electrochemical reactions, there is yet to be a unified molecular picture for that. To address this issue, our group has been developing a quantum-mechanics-based multiscale simulation method, which can elucidate the M⁺-coupling capability to possible intermediates. In this talk, I will discuss our atomic and electronic level understandings on the cation effect based on our new computational capability. Particularly, we theoretically establish H⁺- and M⁺-associated ET mechanisms; the former is often termed as a proton-coupled ET (PCET), and the latter can be analogically termed to be a cation-coupled ET (CCET). I further suggest an experimental route to prove the CCET-based mechanisms, and how to utilize the CCET pathways to tailor the electrocatalytic activity.