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Computational Investigation of the Interplay Between Activity and Stability of Noble Metal Oxide Electrocatalysts
The heterogeneous catalysis of oxygen evolution reaction (OER) has received enormous attention as an environmentally benign way of storing energy from renewable sources in the form of pure hydrogen. While a lot of emphasis has been placed on developing new highly active OER catalysts, our atomistic understanding of their electrochemical stability falls behind. In this work, we focus on RuO2 and IrO2 as two representative metal-oxide catalysts to investigate how their activity and corrosion are intertwined mechanistically under OER conditions. We employ a combination of ab initio molecular dynamics (AIMD) based free-energy simulations to examine the kinetics of metal dissolution along with the computational hydrogen electrode (CHE) approach to study the OER thermodynamics. In addition to revealing the atomistic mechanisms of material corrosion, we also demonstrate that i) OER and metal dissolution indeed share common reaction intermediates, and ii) the presence of metastable dissolution intermediates at the catalyst surface can significantly reduce the theoretical overpotential of OER. Over the past years, our understanding of OER mechanisms have been expanded to include a variety of reaction pathways. The lattice oxygen participation mechanism (LOM) has received specific attention as it is believed to be directly related to degradation mechanism due to structural oxygen involvement. We demonstrate that lattice oxygen participation mechanism (LOM) can be compatible with conventional adsorbate evolving mechanism (AEM) in the presence of both intrinsic and extrinsic defects (metal vacancies, transition metal dopants) from both thermodynamic and kinetic perspectives. In this work, we have also examined the mechanism of cathodic corrosion. Unlike anodic process, the investigation of materials degradation under cathodic polarization is particularly challenging both experimentally and computationally. Here, we have applied constant-potential ab initio molecular dynamics simulations to determine the reaction intermediates of platinum cathodic corrosion in the presence of alkali metal cations in aqueous solutions.
Zagalskaya, Alexandra, "Computational Investigation of the Interplay Between Activity and Stability of Noble Metal Oxide Electrocatalysts" (2022). ETD collection for University of Nebraska - Lincoln. AAI29322045.