Time-resolved spectroscopic studies of hematite photoelectrodes for photoelectrochemical water splitting

Forster, M
(2017) Time-resolved spectroscopic studies of hematite photoelectrodes for photoelectrochemical water splitting. PhD thesis, University of Liverpool.

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Harnessing the large quantities of energy delivered to the earth by the sun is one of the most promising routes to a clean, inexhaustible energy supply. However, the diurnal nature of sunlight and its variation in intensity around the globe necessitates an efficient means of storing (and transporting) solar energy on a large scale. The production of solar fuels provides a potential solution by capturing and storing solar energy in the form of chemical bonds to yield fuels which can then be stored, transported and used, as and when required. The majority of the work in this thesis focuses on the development of the metal oxide semiconductor, α-Fe2O3 (hematite), and its application as a photoelectrode in photoelectrochemical (PEC) water splitting systems. α-Fe2O3 is a promising photoelectrode material due to its suitable bandgap, low toxicity, stability, abundance and low cost. However, current α-Fe2O3 materials are well below the maximum theoretical efficiency due to limiting factors including: poor conductivity, short electron–hole lifetimes, slow oxygen evolution reaction kinetics and short hole diffusion length (2–4 nm). Modifications to α-Fe2O3 such as doping, nanostructuring and surface treatments are known to significantly improve activity and it is vitally important that the mechanisms of improvement are fully rationalised. The work presented here uses transient absorption spectroscopy (TAS) and electrochemical measurements to probe the charge carrier dynamics and address the activity of a range of recently developed α-Fe2O3 photoelectrodes, including oxygen deficient hematite and acid treated hematite. The presence of trap states in α-Fe2O3 photoelectrodes is also addressed, and the effect surface treatments have on such trap states are explored. Finally, shell isolated nanoparticles for enhanced Raman spectroscopy (SHINERS) is explored as an in situ technique for probing the mechanism of water oxidation on a metal oxide surface.

Item Type: Thesis (PhD)
Divisions: Fac of Science & Engineering > School of Chemistry
Depositing User: Symplectic Admin
Date Deposited: 13 Aug 2018 08:09
Last Modified: 29 Sep 2020 08:51
DOI: 10.17638/03009951
URI: http://livrepository.liverpool.ac.uk/id/eprint/3009951