Structure-Property Relationships in Mixed-Metal Oxides and (Oxy)Hydroxides for Energy Applications

• Main Author: Enman, Lisa
• Other Authors: Page, Catherine
• Language: en_US
• Published: University of Oregon 2019
• Subjects: Electrocatalysis; Electrochemistry; Oxygen evolution; Thin films; Water electrolysis; X-ray absorption spectroscopy
• Online Access: http://hdl.handle.net/1794/24227

Metal oxides and (oxy)hydroxides, particularly those containing two or more metals have many uses as electronic materials and catalyst, especially in energy applications. In this dissertation, the structure-property relationships of these mixed-metal materials are explored in order to understand how these materials work and to guide design of materials with even higher efficiency for a given application. Chapter I introduces the materials and studies undertaken. Chapter II presents a fundamental analysis of the electronic and local atomic properties of mixed-transition-metal aluminum oxide thin films. The final three chapters focus on water electrolysis for hydrogen production, which is limited in part by the slow kinetics of the oxygen evolution reaction (OER). Nickel-iron and cobalt-iron (oxy)hydroxides have been shown to be the most active in alkaline conditions. Although it is evident that Fe is essential for high activity, its role is still unclear. Chapter III investigates the role of Fe in NiOOH by comparing the effects of Ti, Mn, La, and Ce incorporation on the OER activity of NiOOH in base. Chapter IV evaluates the OER activity and Tafel behavior of Fe3+ impurities on different noble metal substrates. Chapter V describes the results of in situ and in operando X-ray spectroscopy experiments, which shows that the local structure around Fe atoms in Co(Fe)OOH changes during OER while that of Co stays the same. This work adds to the growing body of literature that suggests Fe is essential to the catalytic active site for the OER on transition-metal (oxy)hydroxides. This dissertation contains previously published and un-published coauthored material. === 2020-01-11