An Atomic Scale Simulation Framework to Decipher the Complex, High-Temperature Solid Oxide Electrolysis Cell Electro-Chemistries

Abstract

Solid oxide electrolysis cells (SOECs) have received a significant attention due to their highhydrogen (H2) generation efficiency. However, the major scientific challenges such as lowfaradaic efficiency of SOECs affects the costs per kilogram of H2 and the large-scale adoption ofH2 as a fuel. Therefore, it is imperative to address the fundamental issues surrounding the lowfaradaic efficiency bottleneck and pave the way for a better SOEC design with a relatively higherfaradaic efficiency. In the present research, we present eReaxFF atomic scale simulationsworkflow that can reproduce quantum mechanical (QM) calculations on relevant condensedphase and cluster systems of solid oxide materials describing oxygen vacancies, vacancymigrations, water adsorption, water splitting and hydrogen generation on the solid oxide materialsurfaces in a typical electrocatalysis process. We used barium zirconate doped with 20 mol% ofyttrium (BZY20) solid oxide as model system. Using the developed eReaxFF force field, weperformed zero-voltage molecular dynamics simulations to observe water adsorption and thesteps leading to the eventual hydrogen production. In addition, the introduction of explicitelectron concept to the force field led to the understanding of the non-zero-voltage effects onhydrogen generation. Based on our simulation results, we conclude that this force field opens anavenue to simulate electron conductivity, electron leakage and provide us a far-reachingmolecular understanding of improving the faradaic efficiency of SOECs.