Doctor of Philosophy (PhD)


Mechanical Engineering

Document Type



With the consumption of energy continually increasing around the world and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. Demand for solar energy has experienced exponential increase over the last decade. Nanostructured TiO2 has attracted significant attention due to its nontoxicity, low cost and wide applications in photovoltaics and photocatalysis. This research is focused on novel synthesis and surface modification of TiO2 nanotube arrays for applications in advanced dye-sensitized solar cells (DSSCs) and efficient photocatalysis. The first part of this work entails fast synthesis of bamboo-type TiO2 nanotube arrays with large surface area via anodization of Ti substrates for applications as photo-anodes in high-efficiency DSSCs. In addition, titania nanotubes are modified with other nanomaterials for further increased efficiency of DSSCs. For example, uniformly-sized Ag nanoparticles are deposited onto TiO2 nanotube array via pulse electrodeposition for plasmon effect, leading to enhanced light absorption in DSSCs. Also, reduced graphene oxide nanosheets are deposited onto a TiO2 nanotube array using electrophoretic deposition, for increased electronic conductivity and improved electron transport in DSSCs. Additionally, ultra-thin two dimensional TiO2 nanosheets are synthesized via exfoliation of layered protonated titanate into separate layers using bulky organic ions, for application as photo-anodes with enhanced light scattering and dye loading in high-efficiency DSSCs. The second part of the work concentrates on synthesis of Ag-modified bamboo-type TiO2 nanotube arrays for efficient photocatalysis. Such novel titania-based nanocomposite structure provides large surface area for organic pollutant absorption and subsequent degradation; the ordered structure of nanotube array also offers direct pathway for fast electron transport. Moreover, Ag nanoparticles deposited onto TiO2 nanotubes function as reservoirs for photogenerated electrons to improve charge separation and facilitate catalytic reactions.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Wang, Ying