Titania Nanotubes: Study of Properties as a Function of Synthesis Conditions and Implementation into Useful Applications
Elizabeth Ranney and Johannes Schwank

SEM Micrograph of Titania Nanotubes
The increasing use of laptops, cell phones, PDA's, digital cameras, and other portable electronic devices, as well as electric and hybrid vehicles, has created a demand for low-cost, rechargeable batteries. Lithium ion batteries are preferable for these applications due to their higher energy densities. However, lithium ion batteries can suffer from low discharge rates, which can cause problems in applications where high power is required. For example, some electronic devices require short bursts of energy; likewise, hybrid vehicles need enough energy to accelerate quickly. When discharged too quickly these batteries can heat up and even explode. As a result, there is a clear need for improved lithium ion battery technology.
A solution to the shortcomings of lithium ion batteries could be the replacement of the anode with titania nanotubes. Nanotubes are desirable due to their high surface area to volume ratio, which allows for increased capacity because more lithium ions can be stored in a smaller volume. Nanotubes would also provide pathways for ion travel, allowing the discharge rate to be controlled. In particular, titania nanotubes would allow for rapid discharge rates because lithium ions can be easily stored and released from its lattice structure.
As a semiconducting and photosensitive material, titania can also be incorporated into gas sensing and photocatalytic water-splitting technologies. The high surface area to volume ratio provided by a nanotube structure is beneficial in these applications, as well. In gas sensing, the large titania area would allow for greater sensitivity to target gases. The increased surface area would also offer higher rates of hydrogen production in photocatalytic water-splitting.
An understanding of how to tailor the properties of titania nanotubes by varying synthesis conditions would better improve gas sensing, hydrogen production, and energy storage systems. The goal of this project is to study the fundamental physical and chemical properties of titania nanotubes as a function of synthesis conditions.