Atomistic Simulations: Atomistic level investigation of the dissolution, precipitation, and surface diffusion dynamics at the aqueous metal interface for renewable energy applications and the oxidation of silicon carbide for aero-propulsion

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Author:
Slapikas, Robert
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
March 19, 2023
Committee Members:
Kristen Fichthorn, Outside Unit & Field Member
Ismaila Dabo, Major Field Member
Wesley Reinhart, Major Field Member
Susan Sinnott, Co-Chair & Dissertation Advisor
Douglas Wolfe, Co-Chair & Dissertation Advisor
Zuleima T Karpyn, Special Signatory
Keywords:
Molecular Dnamics
Pt
Platinum nanoparticles
ultra-high temperature ceramics
Abstract:
In this work classical molecular dynamics (MD) simulations were used to study scientific problems at the atomic level. The two areas of research are platinum nanoparticle stability for renewable energy resources, where in the past few decades it has become more pressing to find clean energy storage. This need had cause for the generation of large-scale electrochemical models at the atomic level to improve the performance of Pt catalysts in fuel cell applications. With this desire to produce large scale simulations, MD simulations were optimized with the third-generation charge-optimized many-body (COMB3) reactive interatomic potential to allow for reduced computational cost to study these electrochemical systems. From these optimized models, the stability of Pt NPs in oxygen gas corrosion environment has been studied, to understand the NP durability with respect to the size, morphology, temperature, and concentration of adsorbed oxygen atoms on NP surfaces. The Pt NPs were then studied in an explicit water electrolyte environment to understand the kinetic effects of oxygen coverage on the dissolution of Pt atoms from the NPs. It is determined that the rate of Pt atom dissolution is affected by oxide film present and the ion concentration around the NPs. The second study focused on improving the efficiency of passive oxidation in UHTC, so to increase the lifetime of aero-propulsion vehicles. This study employed the ReaxFF reactive interatomic potential to use classical MD simulations to understand the oxidation behavior of SiC in unique environments. These predictions are then compared to the oxide film growth on different SiC samples through static oxidation testing at 1100 oC and 1300 oC. This work helps to develop new age aero-propulsion vehicles to withstand higher operating temperatures and extreme environments, to increase the power efficiency of the engines and the thermomechanical properties of vehicle structures.

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