Abstract
We demonstrate that TiO 2 -SnO x -Sn composite nanowires (NWs) can be obtained by the reduction/oxidation of Sn and Ti ions. First, SnO 2 nanowires were synthesized on TiO 2 /alumina substrate by a thermal evaporation through the vapor-liquid-solid (VLS) mechanism. Afterwards, SnO 2 NWs/TiO 2 /alumina was thermally annealed in Ti powder at 1050°C in a controlled mixture of gaseous argon and hydrogen (H 2 ). The SnO 2 nanowires were then decomposed to SnO and H 2 O vapors, which were together with Ti vapor species to form the TiO 2 -SnO x -Sn composite nanowires. High-resolution X-ray photoelectron spectroscopy (XPS) evaluated that the as-synthesized TiO 2 nanowires mainly consisted of TiO 2 with the dopants SnO x and Sn. Through the evaluation of the change in Gibbs free energy, it was found that a spontaneous reaction resulted in the formation of TiO 2 -SnO x -Sn composite nanowires. The characterization and formation of TiO 2 -SnO x -Sn composite nanowires are discussed. © 2008 The Japan Society of Applied Physics.