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

• TiO2NT arrays photoelectrodes prepared in ionic liquid media
• Morphology, crystallite size and band-gap data were similar
• Mott-Schottky parameters revealed significant differences among the electrodes
• Increase in the peak photocurrent near 130% for water splitting reaction

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 °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 (ND), width of depletion layer (w) and Debye length (λD). 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.

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