Abstract

This work presents the research of myself, my advising professor, and our collaborators in first-principles studies of several catalytic materials for improving the efficiency and economics of hydrogen fuel cells, focusing on the oxygen reduction reaction (ORR) at the cathode, CO removal and the hydrogen oxidation reaction (HOR) at the anode, and the redox reactions used for water splitting through photocatalysis. We use a computational design approach to analyze the reaction thermodynamics, applying density functional theory (DFT) for most calculations. We find that, through a subversion of the linear scaling approximation for surface reactivity, an Au monolayer deposited on the early transition metals Nb and Ta is both stable under fuel cell operating conditions and reaches a higher onset potential for the ORR than the current expensive Pt-based cathodes. In a similar light, we find that Pd/Mo(110) and Pd/W(110) are both active toward the CO removal reaction and the HOR at the fuel cell anode through their interesting binding energy relations, in comparison to the Pt catalyst anode which suffers the problem of CO poisoning of active sites. We study the reaction thermodynamics of the two-dimensional structures C2N and C2N doped with P, whose band gaps are favorable with regards to solar light photocatalysis, but find that the redox reactions through several routes do not seem energetically favorable. We also study another candidate for photocatalytic water splitting, the wide-band gap semiconductor ß-phase Ga2O3, assessing the effects of H- and Si-doping on the material's band structure through the GW method. We find, using DFT, that Si prefers to replace the Ga (I) atom and H prefers to bind to the O (2) atom. We find through GW analysis of the band gap that Si and H act as n-type dopants of ß-phase Ga2O3.

Notes

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Graduation Date

2021

Semester

Spring

Advisor

Stolbov, Sergey

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Degree Program

Physics

Format

application/pdf

Identifier

CFE0008451; DP0024126

URL

https://purls.library.ucf.edu/go/DP0024126

Language

English

Release Date

May 2021

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Included in

Physics Commons

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