In this thesis, the charge carrier dynamics that underpin the impressive performance of SrTiO3-
based photocatalysts for overall water splitting are investigated. This is primarily achieved using
time-resolved transient and steady-state spectroscopic techniques. An in depth introduction
into the motivation and background of this work is included in Chapter 1, whilst a detailed
description of the methods employed is included in Chapter 2.
In Chapter 3, the charge carrier dynamics of SrTiO3 on ps-ns timescales are characterised. In the
first 10 ps after photoexcitation, charge trapping into shallow localised states is observed. This
results in two distinct components, that are extracted by global analysis, and result in a slow
rise and fast decay in distinct spectral regions. The bimolecular recombination that follows in
SrTiO3 is remarkably slow, and is quantified to reveal a bimolecular rate constant that is two
magnitudes slower than that of alternative metal oxides.
In Chapters 4 and 5, the effects of flux mediated Al3+ doping and RhCrOx deposition on SrTiO3
are explored, to identify their role in enabling high photocatalytic activities. Here, there is
a focus on the steady-state charge carrier dynamics under water splitting conditions, where
the performance enhancements resulting from these material modifications are observed. Al3+
doping suppresses recombination to enhance charge lifetimes and steady-state charge densities.
RhCrOx amplifies these effects, with the influence of its deposition method on determining
the balance between reactive and unreactive hole species highlighted. The optimum balance
is achieved by facet selective photodeposition of RhCrOx, whereby hole accumulation can be
tolerated, but reactive hole species dominate and a near-unity AQY can be achieved.
Finally, SrTiO3 is investigated under applied bias in Chapter 6, to gain further insights into the
charge carrier dynamics of SrTiO3, in addition to enabling calculation of the hole extinction
coefficient and kinetics of water oxidation.