Understanding ion-transfer reactions in silver electrodissolution and electrodeposition from first-principles calculations and experiments

Richard Kang; Yang Zhao; Diptarka Hait; Joseph A Gauthier; Paul A Kempler; Kira A Thurman; Shannon W Boettcher; Martin Head-Gordon

doi:10.1039/d3sc05791g

Understanding ion-transfer reactions in silver electrodissolution and electrodeposition from first-principles calculations and experiments

Chem Sci. 2024 Feb 28;15(13):4996-5008. doi: 10.1039/d3sc05791g. eCollection 2024 Mar 27.

Authors

Richard Kang^{1

2}, Yang Zhao³, Diptarka Hait^{1

2}, Joseph A Gauthier⁴, Paul A Kempler³, Kira A Thurman³, Shannon W Boettcher^{3

5

6}, Martin Head-Gordon^{1

2}

Affiliations

¹ Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California Berkeley California 94720 USA mhg@cchem.berkeley.edu richard.kang@berkeley.edu.
² Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA.
³ Department of Chemistry and Biochemistry, the Oregon Center for Electrochemistry, University of Oregon Eugene Oregon 97403 USA.
⁴ Department of Chemical Engineering, Texas Tech University Lubbock TX 79409 USA.
⁵ Department of Chemical & Biomolecular Engineering, Department of Chemistry, University of California Berkeley California 94720 USA, boettcher@berkeley.edu.
⁶ Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory Berkeley California 94720 USA.

Abstract

The electrified aqueous/metal interface is critical in controlling the performance of energy conversion and storage devices, but an atomistic understanding of even basic interfacial electrochemical reactions challenges both experiment and computation. We report a combined simulation and experimental study of (reversible) ion-transfer reactions involved in anodic Ag corrosion/deposition, a model system for interfacial electrochemical processes generating or consuming ions. With the explicit modeling of the electrode potential and a hybrid implicit-explicit solvation model, the density functional theory calculations produce free energy curves predicting thermodynamics, kinetics, partial charge profiles, and reaction trajectories. The calculated (equilibrium) free energy barriers (0.2 eV), and their asymmetries, agree with experimental activation energies (0.4 eV) and transfer coefficients, which were extracted from temperature-dependent voltage-step experiments on Au-supported, Ag-nanocluster substrates. The use of Ag nanoclusters eliminates the convolution of the kinetics of Ag⁺_(aq.) generation and transfer with those of nucleation or etch-pit formation. The results indicate that the barrier is controlled by the bias-dependent competition between partial solvation of the incipient ion, metal-metal bonding, and electrostatic stabilization by image charge, with the latter two factors weakened by stronger positive biases. We also report simulations of the bias-dependence of defect generation relevant to nucleating corrosion by removing an atom from a perfect Ag(100) surface, which is predicted to occur via a vacancy-adatom intermediate. Together, these experiments and calculations provide the first validated, accurate, molecular model of the central steps that govern the rates of important dissolution/deposition reactions broadly relevant across the energy sciences.