A novel method for the synthesis of titania nanotubes using sonoelectrochemical method and its application for photoelectrochemical splitting of water

This new method describes the application of sonoelectrochemistry to quickly synthesize well-ordered and robust titanium dioxide (TiO2) nanotubular arrays. Self-ordered arrays of TiO2 nanotubes of 30-100 m in diameter and 300-1000 nm in length can be rapidly synthesized under an applied potential of 5-20 V. The rate of formation of the TiO2 nanotubes by the sonoelectrochemical method is found to be almost twice as fast as the magnetic stirring method. It also demonstrates that high-quality nanotubes can be prepared using high viscous solvents like ethylene glycol under ultrasonic treatment. The TiO2 nanotubes prepared in the organic electrolytes (ethylene glycol) are then annealed under H-2 atmosphere to give TiO2-xCx types material having a band gap of around 2.0 eV. This process is found to be highly efficient for incorporating carbon into TiO2 nanotubes. Various characterization techniques (viz., FESEM, GXRD, XPS, and DRUV-vis) are used to study the morphology, phase, band gap, and doping of the nanotubes. The photoelectrocatalytic activity of these materials to generate H-2 by water splitting is found to be promising at 0.2 V vs Ag/AgCl. (c) 2007 Elsevier Inc. All rights reserved.