Ab Initio Free Energy Surfaces for Coupled Ion-Electron Transfer
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866911740286992384 |
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| author | Abraham, Ethan Bazant, Martin Z. Van Voorhis, Troy |
| author_facet | Abraham, Ethan Bazant, Martin Z. Van Voorhis, Troy |
| contents | 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_19106 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Ab Initio Free Energy Surfaces for Coupled Ion-Electron Transfer Abraham, Ethan Bazant, Martin Z. Van Voorhis, Troy Chemical Physics Materials Science Quantum Physics 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. |
| title | Ab Initio Free Energy Surfaces for Coupled Ion-Electron Transfer |
| topic | Chemical Physics Materials Science Quantum Physics |
| url | https://arxiv.org/abs/2510.19106 |