Energy security and climate change have brought on an increasing demand and urgency for the transition from fossil fuel dependency to more sustainable sources of renewable energy. Of the available renewable energy sources at our disposal, solar energy is by far the most abundant. However, the inherent variability of solar energy warrants the development of storage techniques for use during periods of low supply and high demand. Hydrogen fuel is a widely adaptable form of chemical fuel storage making it of great interest for the storage of solar energy. Semiconductor-based photoelectrochemical water splitting has the potential to be an elegant and efficient method of renewable hydrogen fuel production through the capture, conversion and storage of solar energy. Candidate materials must exhibit several exacting characteristics with low cost, and specific electronic properties being paramount. Silicon satisfies these requirements, however its susceptibility to photocorrosion and photopassivation in electrolyte solution hinders its performance. Consequently, Si is incapable of extended use for water splitting without the application of a protective layer such as to distance the harsh water splitting chemical reactions and electrolyte environment from the Si in order to enhance its stability. This work looks to protect the silicon photoelectrode and improve its performance and operational lifetime. Thin films (< 10 nm) of TiO2, NiO and CoN were deposited onto SiO2 via atomic layer deposition (ALD). This thesis details the nucleation, growth chemistry and photoelectrochemical performance of these transition metal -based thin films prepared via thermal and plasma enhanced ALD in addition to exploring the effect of post ALD film treatments by plasma and atmospheric annealing. Films were investigated using photoelectrochemical cell testing to evaluate photoelectrochemical performance, and in-situ cycle-by-cycle x-ray photoelectron spectroscopy was used as the primary characterisation technique.