This outstanding thesis provides a wide-ranging overview of the growth of titanium dioxide thin films and its use in photo-electrochemicals such as water splitting. The context for water splitting is introduced with the theory of semiconductor-liquid junctions, which are dealt with in detail. In particular plasmonic enhancement of TiO₂ by the addition of gold nanoparticles is considered in depth, including a thorough and critical review of the literature, which discusses the possible mechanisms that may be at work. Plasmonic enhancement is demonstrated with gold nanoparticles on Nb-doped TiO2. Finally, the use of temperature and pressure to control the phase and morphology of thin films grown by pulsed laser deposition is presented.