Disassembly, Reassembly, and Photoelectrochemistry of Etched TiO2 Nanotubes

Etched TiO2 nanotubes are removed from the titanium foil substrate by sonication and are reassembled onto new electrodes for photovoltaic applications. CdS nanocrystallites were deposited on the restructured electrodes to compare their performance as quantum dot-sensitized solar cells to aligned nanotube electrodes. The sensitized photoresponses of the photoelectrochemical cell created from reassembled TiO2) nanotubes are very similar to aligned TiO2 nanotube arrays. Transient absorption spectroscopy of dispersed tubes indicates that electron transfer from excited CdS nanocrystallites into TiO2 nanotubes occurs at a rate of 2.0 x 10(10) s(-1). BET surface area analysis is investigated on etched nanotube powder without the need for weight approximation and was found to be 77.0 +/- 2.9 m(2)/g. The importance of nanotube orientation and porosity on the electrode surface in stabilizing accumulated electrons in TiO2 nanotubes is elucidated from the open circuit voltage decay. Nanotube orientation was also seen to affect electron transport in photocurrent experiments.