Correlative ex-situ analysis and operando ellipsometric investigation during oxygen evolution reaction of mesoporous iridium oxide model catalysts
type: CreativeWork
description: In the face of rising energy demand and the impending climate change, the development of sustainable, fossil-free fuel and chemical production is of global importance. One way to achieve these goals is the development of electrochemical conversion processes using catalysts. Key to the development of improved catalysts is a better understanding of the relations between their performance, stability, and physicochemical properties. However, the complex morphology of such catalysts constitutes a challenge even for modern analytical techniques. For example, standard rotating disc electrode experiments are performed to study the impact of the catalysts structure on electrochemical processes, but do not provide any information about changing material properties during the experiment. Ellipsometry is a very versatile spectroscopic method, often used to study film thickness and refractive index, but also providing access to electrical and electronic properties. Spectroscopic ellipsometry (SE) further offers the possibility to study materials under different environments. However, since material properties cannot be taken directly from the measured spectra, suitable models have to be developed and validated. In this thesis, a model for ellipsometric fit studies of a calcination series of mesoporous iridium oxide films (300 °C – 600 °C) was developed and validated in terms of film thickness and porosity as well as electrical and electronic properties using various ex-situ characterization methods such as scanning electron microscopy (SEM), X-ray reflectometry (XRR), conductivity measurements, and UV-VIS-NIR absorption spectroscopy. SE data also offer the possibility to derive valence electron energy loss spectra (VEELS), which provide further information about the electronic structure of the materials. Comparison of the data from the VEEL spectra with activity measurements of the oxygen evolution reaction (OER) suggests that the intrinsic activity (surface charge normalized ac…
abstract: In the face of rising energy demand and the impending climate change, the development of sustainable, fossil-free fuel and chemical production is of global importance. One way to achieve these goals is the development of electrochemical conversion processes using catalysts. Key to the development of improved catalysts is a better understanding of the relations between their performance, stability, and physicochemical properties. However, the complex morphology of such catalysts constitutes a challenge even for modern analytical techniques. For example, standard rotating disc electrode experiments are performed to study the impact of the catalysts structure on electrochemical processes, but do not provide any information about changing material properties during the experiment. Ellipsometry is a very versatile spectroscopic method, often used to study film thickness and refractive index, but also providing access to electrical and electronic properties. Spectroscopic ellipsometry (SE) further offers the possibility to study materials under different environments. However, since material properties cannot be taken directly from the measured spectra, suitable models have to be developed and validated. In this thesis, a model for ellipsometric fit studies of a calcination series of mesoporous iridium oxide films (300 °C – 600 °C) was developed and validated in terms of film thickness and porosity as well as electrical and electronic properties using various ex-situ characterization methods such as scanning electron microscopy (SEM), X-ray reflectometry (XRR), conductivity measurements, and UV-VIS-NIR absorption spectroscopy. SE data also offer the possibility to derive valence electron energy loss spectra (VEELS), which provide further information about the electronic structure of the materials. Comparison of the data from the VEEL spectra with activity measurements of the oxygen evolution reaction (OER) suggests that the intrinsic activity (surface charge normalized ac…
author: Sachse, René
language: en
license: https://creativecommons.org/licenses/by-nc-nd/4.0/
date published: 2022
date modified: 2026-07-27T21:28:35Z
provider: Technische Universität Berlin
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Technische Universität Berlin

PropertyValue
property ID: DOI
value: 10.14279/depositonce-14820