eZacros: Kinetic Monte Carlo Simulations for Electrochemical Catalysis
- 1Department of Chemistry
- 2University of Utah
Abstract
Free energy diagrams rank electrocatalysts thermodynamically but do not resolve which elementary step limits the rate under operating conditions, or how the surface coverage that governs that competition is established. Lattice kinetic Monte Carlo (kMC) recovers both by treating elementary steps as stochastic events on an explicit lattice, but electrochemical kMC workflows remain far less standardized than the free-energy approaches common in computational electrocatalysis. Here we present eZacros, a framework that implements potential-dependent reaction energetics within the computational hydrogen electrode formalism, electrochemical Brønsted-Evans-Polanyi relations for activation barriers, and effective rate prefactors for charge-transfer steps. It is built on Zacros, a widely used kMC engine, and takes a compact Python input that specifies the lattice, the mechanism, and the energetics. We validate the implementation against an established microkinetic model of the oxygen reduction reaction on Pt(111), recovering its polarization curve and steady-state coverages. For hydrogen evolution, we sweep a single model definition over electrode potential and hydrogen adsorption free energy to generate activity, Tafel slope, and coverage maps. These resolve into a kinetic phase diagram in which no single rate-determining step characterizes the reaction across the full space: the boundaries between Volmer-, Heyrovsky-, and Tafel-controlled regimes are set by the steady-state coverage, which departs from equilibrium adsorption expectations under reaction conditions. eZacros makes potential-resolved kinetics accessible to anyone who can supply adsorption free energies and reference barriers, complementing free-energy screening in catalyst modeling and discovery.
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BibTeX
@misc{gadea2026ezacros,
title = {{eZacros: Kinetic Monte Carlo Simulations for Electrochemical Catalysis}},
author = {Esteban D. Gadea and Valeria Molinero},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009375/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009375/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - eZacros: Kinetic Monte Carlo Simulations for Electrochemical Catalysis
AU - Esteban D. Gadea
AU - Valeria Molinero
PY - 2026
DA - 2026/09/23
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009375/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009375/v1
AB - Free energy diagrams rank electrocatalysts thermodynamically but do not resolve which elementary step limits the rate under operating conditions, or how the surface coverage that governs that competition is established. Lattice kinetic Monte Carlo (kMC) recovers both by treating elementary steps as stochastic events on an explicit lattice, but electrochemical kMC workflows remain far less standardized than the free-energy approaches common in computational electrocatalysis. Here we present eZacros, a framework that implements potential-dependent reaction energetics within the computational hydrogen electrode formalism, electrochemical Brønsted-Evans-Polanyi relations for activation barriers, and effective rate prefactors for charge-transfer steps. It is built on Zacros, a widely used kMC engine, and takes a compact Python input that specifies the lattice, the mechanism, and the energetics. We validate the implementation against an established microkinetic model of the oxygen reduction reaction on Pt(111), recovering its polarization curve and steady-state coverages. For hydrogen evolution, we sweep a single model definition over electrode potential and hydrogen adsorption free energy to generate activity, Tafel slope, and coverage maps. These resolve into a kinetic phase diagram in which no single rate-determining step characterizes the reaction across the full space: the boundaries between Volmer-, Heyrovsky-, and Tafel-controlled regimes are set by the steady-state coverage, which departs from equilibrium adsorption expectations under reaction conditions. eZacros makes potential-resolved kinetics accessible to anyone who can supply adsorption free energies and reference barriers, complementing free-energy screening in catalyst modeling and discovery.
ER -