Visible light photoelectrochemical and water-photoelectrolysis properties of titania nanotube arrays

We examine the visible light water-photoelectrolysis and photoelectrochernical properties of highly ordered titania nanotube arrays as a function of nanotube crystallinity, length (up to 6.4 mu m), and pore size. Most noteworthy of our results, under visible light AM 1.5 illumination (100 mW/cm(2)) the titania nanotube array photoanodes (1 cm(2) area), pore size 110 nm, wall thickness 20 nm, and length 6 mu m, generate hydrogen by water photoelectrolysis at a rate of 175 mu L/h, with a photoconversion efficiency of 0.6%. The energy-time normalized hydrogen evolution rate is 1.75 mL/h W. The oxygen bubbles evolving from the nanotube array photoanode do not remain on the sample, hence the output remains stable with time irrespective of the duration of hydrogen production. (c) 2005 Elsevier B.V. All rights reserved.