# Ab Initio Free Energy Surfaces for Coupled Ion-Electron Transfer

Source: [Ab Initio Free Energy Surfaces for Coupled Ion-Electron Transfer](<https://www.sota2.com/research/paper/68fa4c641e209131ce94cbe6>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2026-07-02T05:00:05.659Z

Authors: Ethan Abraham, Martin Z. Bazant, Troy Van Voorhis

Published: 2025-10-21T21:59:44.000Z

## Abstract

Although coupled ion-electron transfer (CIET) has emerged as a powerful framework to rationalize the kinetics of Faradaic reactions, its mechanism has lacked a fully microscopic, first-principles description. Here we show that the coupling of electron-transfer to ion-transfer can be understood as an extension of Marcus theory in which the ensemble of diabatic nuclear configurations is conditioned on a classical collective variable describing the interfacial anisotropy. This formalism enables direct construction of the CIET free-energy surface from constrained ab initio trajectories, providing a first-principles route to electrochemical current-overpotential relations. We demonstrate this method for CO2 redox on a gold electrode and find that the resulting two-dimensional saddle-point barriers differ substantially from one-dimensional treatments that consider only electron- or ion-transfer coordinates individually.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2510.19106>)

[PDF](<https://arxiv.org/pdf/2510.19106.pdf>)