Abstracts Category : Other

Plasma-enhanced chemical vapor deposition of cobalt-based catalysts for the oxygen evolution reaction

by Natascha Weidler

In this thesis a plasma-enhanced chemical vapor deposition system has been installed to synthesize transition metal oxide/hydroxide flms as catalysts for the oxygen evolution reaction (OER). First, the infuence of various deposition parameters like the substrate temperature, the operation mode (thermal vs. plasma) and the type of reactive gas(oxygen vs. air) on the electrochemical activity has been investigated in detail for single metal oxide/hydroxide flms. It turned out, that especially the choice of reactive gas has a great impact on the resulting oxidation state and surface composition. WhileCoOx(OH)y flms were deposited when air was used as a reactive gas, the use of oxygen as a reactive gas lead to the deposition of CoOx. By measuring XPS from before and after the electrochemical characterization, a correlation between the change of oxidationstate and the resulting electrochemical activity has been identifed. Finally, Co-based bimetallic catalysts, CoMOx and CoMOx(OH)y (M=Ni, Fe, Cu), were deposited and the effect of the admixture of the second metal on the electronic structure and activity was studied.Advisors/Committee Members: Jaegermann, Wolfram (advisor), Kramm, Ulrike (advisor).