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Electronic structure of oxide materials for photoelectrochemistry

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Title: Electronic structure of oxide materials for photoelectrochemistry
Authors: Blumenthal, Lars
Item Type: Thesis or dissertation
Abstract: To achieve climate protection goals set out by national governments and the United Nations, it is paramount to reduce society’s dependence on fossil fuels and to introduce more sustainable energy solutions. Furthermore, to not only protect our climate but the natural environment in general, it is necessary to reduce humanity’s waste production and to turn waste into a resource wherever possible. The solutions to both of these ambitions will heavily rely on new chemical processes being discovered and upscaled. Thus, with catalysis and photochemistry at its heart, the challenge to build a greener and more sustainable future is largely a materials discovery and design problem. In this work, I introduce a new way of aligning the electronic energy levels of semiconductors with respect to redox potentials which might facilitate in silico screening studies of materials suitable for photoelectrochemistry. In particular, I demonstrate how continuum solvation models can be used to replace computationally expensive atomistic descriptions of water when describing an electrode-electrolyte interface. I tested this approach on rutile (TiO2) showing that, when combined with a description of rutile’s electronic structure within many-body perturbation theory, the proposed alignment procedure yields the correct positioning of rutile’s band edges on the standard hydrogen electrode scale. My investigation surfaced and explained important differences between atomistic and continuum solvation models when describing the electric potential across interfaces. Furthermore, I present a detailed study of the electronic structure of osmium dioxide (OsO2) near its Fermi level. OsO2 is closely related to important catalysts such as IrO2 and RuO2, which also crystallise in the rutile structure. Specifically, by collaborating with colleagues specialised in experimental photoelectron spectroscopy (PES), we highlight the importance of computational insights for the correct interpretation of PES spectra. By going beyond a simple comparison between the experimentally measured PES spectrum and the computed single-particle electronic density of states, we reveal that the spectrum of OsO2 features a rare low-energy bulk plasmon satellite.
Content Version: Open Access
Issue Date: Dec-2019
Date Awarded: Apr-2020
URI: http://hdl.handle.net/10044/1/80385
DOI: https://doi.org/10.25560/80385
Copyright Statement: Creative Commons Attribution ShareAlike Licence
Supervisor: Lischner, Johannes
Tangney, Paul
Sponsor/Funder: Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/L015579/1
EP/L000202
Department: Physics
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Physics PhD theses