In Situ Spectroscopy of Metal Oxides Reveal Electrocatalyst Structure-Property Relationships
Eom, Chuhyon John
The structure-property relationship is a foundational concept of materials science and engineering. Tuning the catalytic properties of materials by varying their structural properties like stoichiometry and crystal facets have been integral to advances in electrocatalysis. Traditionally, these studies rely on ex situ, bulk structural characterizations to describe catalytic properties. Catalysis, however, occurs on a dynamic catalytic surface sensitive to its local environment. This dissertation uses in situ spectroscopy of metal oxide electrocatalysts to better capture the intricacies of such catalyst structure-property relationships. La2/3S1/3rMnO3 films are grown using molecular beam epitaxy for a controlled study on the effects of surface and sub-surface structure of metal oxides on the oxygen reduction reaction (ORR) catalysis. Ambient pressure X-ray photoelectron spectroscopy of the films show that the surface and sub-surface structures control the balance between electronic benefits vs. parasitic surface reactions for the ORR. The low atomic number group of an amorphous cobalt oxide catalyst in a phosphate network (CoPi) is studied using home-built stimulated Raman spectroscopy (SRS). In situ SRS reveals previously unreported phosphate motifs in CoPi under oxygen evolution reaction conditions. Isotopic studies show that the phosphate structure is intimately linked to the aqueous environment with implications for the catalyst microstructure and deposition. Extensions of the dissertation on the in situ spectroscopy of a quinone electrochemical systems is discussed in the end.
Electrochemistry; Metal Oxide; Spectroscopy
Schlom, Darrell; Marohn, John A.
Materials Science and Engineering
Ph. D., Materials Science and Engineering
Doctor of Philosophy
Attribution 4.0 International
dissertation or thesis
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