Facets, junctions and functions – TiO2 a highly tuneable catalytic material

Abstract

As the energy demand increases, it becomes imperative to create more efficient, accessible, and sustainable ways to harness energy. Accordingly, the role of titanium dioxide (TiO2) has been expanded from the development of environmental treatment technologies to the production of devices for solar energy conversion and storage devices. In the quest for optimal TiO2 structures, several synthetic modifications have been attempted. However, since 2018, the tailored synthesis of TiO2 crystals with facets of different surface energies has received much attention with special attention on their application in sustainable processes. In this thesis, the hydrothermal synthesis of faceted rutile TiO2 rods on FTO substrate is reported. By adjusting the concentration of HF, the co-growth of [100] oriented rutile TiO2 nanorod arrays and their heterojunction with {001} faceted anatase TiO2 crystals can be achieved, resulting in improved photoelectrochemical water splitting activity. Moreover, the plasmonic interactions between silver nanoparticles and various rutile TiO2 facets are studied to help design a route towards materials with better visible light activity. Additionally, the heterojunction of TiO2 with other metal oxides such as SiO2 and SnO2 introduces new interfacial reactive sites that, promote an improved performance in lithium ion batteries and perovskite-based photovoltaics respectively. The methodology developed in this work also showcases the reliability of using different microscopic techniques in the detailed characterisation of surface defects, which provides new insights for the creation of new and improved materials for energy conversion. Cumulatively, this thesis details new insights into, and a greater understanding of, the application of different facets and junctions across different functional devices for energy conversion and storage.