Ab Initio Free-Energy Surfaces for Coupled Ion-Electron Transfer
Ethan Abraham1, Martin Z Bazant2, Troy Van Voorhis1
1Massachusetts Institute of Technology, Department of Chemistry, Cambridge, Massachusetts 02139, USA.
Physical Review Letters
|July 23, 2026
Summary
Coupled ion-electron transfer (CIET) mechanisms were described using an extended Marcus theory. This first-principles approach models interfacial anisotropy, enabling accurate prediction of electrochemical reactions like CO2 reduction.
Area of Science:
- Physical Chemistry
- Electrochemistry
- Computational Chemistry
Background:
- Coupled ion-electron transfer (CIET) is crucial for understanding Faradaic reaction kinetics.
- A fully microscopic, first-principles description of CIET mechanisms has been lacking.
- Existing models often simplify the complex interplay between charge and mass transport.
Purpose of the Study:
- To develop a first-principles theoretical framework for CIET.
- To provide a microscopic understanding of how ion and electron transfer are coupled.
- To enable direct calculation of electrochemical current-overpotential relationships.
Main Methods:
- Extension of Marcus theory incorporating interfacial anisotropy.
- Utilizing constrained ab initio molecular dynamics (AIMD) to map free-energy surfaces.
- Applying the formalism to the CO2 reduction reaction on a gold electrode.
Main Results:
- Developed a novel formalism to construct CIET free-energy surfaces from first principles.
- Demonstrated the method’s applicability to CO2 redox on Au(111).
- Identified significant differences between 2D saddle-point barriers and 1D models.
Conclusions:
- The extended Marcus theory provides a robust first-principles description of CIET.
- Interfacial anisotropy plays a critical role in determining reaction kinetics.
- This approach offers a more accurate route to predicting electrochemical reaction rates and mechanisms.
More Related Videos
11:04Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides
Published on: September 7, 2019
05:51Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Related Concept Videos
01:17Coupled Reactions
Cellular processes such as building and breaking down complex molecules occur through stepwise chemical reactions. Some of these chemical reactions are spontaneous and release energy, whereas others require energy to proceed. Cells often couple the energy-releasing reaction with the energy-requiring one to carry out important cell functions.
Energy in adenosine triphosphate or ATP molecules is easily accessible to do work. ATP powers the majority of energy-requiring cellular reactions. Cells...
Energy in adenosine triphosphate or ATP molecules is easily accessible to do work. ATP powers the majority of energy-requiring cellular reactions. Cells...
03:45Formation of Complex Ions
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
01:06Interfacial Electrochemical Methods: Overview
Interfacial electrochemical methods focus on the phenomena occurring at the boundary between an electrode and a solution, as opposed to bulk methods that concentrate on the solution's overall properties. These interfacial methods are classified as either static or dynamic based on the presence of a nonzero current in the electrochemical cell and the consistency of analyte concentrations. Static methods, such as potentiometry, measure the cell's potential without any significant current passing...
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
01:28Electron Transport Chains
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
The ETC is comprised of...
The ETC is comprised of...
01:32Chemiosmosis
Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives many cellular processes. Oxidative phosphorylation involves two processes— the electron transport chain and chemiosmosis.
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...