Improved water-splitting behaviour of flame annealed TiO2 nanotubes

In the present work we investigate the effect of flame annealing on the water-splitting properties of anodic TiO2 nanotubes. It is shown that flame annealed (FA) nanotubes can yield a two-fold increase in the maximum water-splitting efficiency under standard AM 1.5 conditions compared to classic annealing treatments. The improved efficiency is mainly the result of the fact that using FA, a higher rutile content can be established in the tube walls without a thermal degradation of the tube morphology. A minor, secondary effect is carbon doping which is caused mainly by organic remnants from the tube formation electrolyte. (C) 2011 Elsevier B.V. All rights reserved.