Preparation and Characterization of TiO2 Nanotube Arrays in Ionic Liquid for Water Splitting

In the present work, it is described the fabrication and characterization of TiO2 nantotubes prepared potentiostatically using 1.0 or 5.0 vol.% ionic liquid electrolyte medium at 10 or 20 degrees C. These experimental conditions led to TiO2 nanotubes with 63-77 nm pore diameter, crystallite sizes between 27-33 nm, and band-gap values in the 3.1-3.2 eV range. Although the morphology and band-gap values were similar, the water splitting reaction showed differences in terms of photocurrent, up to 300%. Besides, we report also important changes in those parameters related with electronic defects, such as carrier density (N-D), width of depletion layer (w) and Debye length (lambda(D)). Then, the enhancement on photoelectrochemical properties could be related to a decrease in the rate of surface recombination processes. Finally, these proposition are in agreement with the open-circuit voltage-decay, where was observed a higher electron lifetime for TiO2NT obtained at higher vol.% of ionic liquid. (C) 2014 Elsevier Ltd. All rights reserved.