Formation and characterization of TiO2-SnOx-Sn composite nanowires fabricated by reduction/oxidation of Sn and Ti ions

We demonstrate that TiO2-SnOx-Sn composite nanowires (NWs) can be obtained by the reduction/oxidation of Sn and Ti ions. First, SnO2 nanowires were synthesized on TiO2/alumina substrate by a thermal evaporation through the vapor-liquid-solid (VLS) mechanism. Afterwards, SnO2 NWs/TiO2/alumina was thermally annealed in Ti powder at 1050 degrees C in a controlled mixture of gaseous argon and hydrogen (H-2). The SnO2 nanowires were then decomposed to SnO and H2O vapors, which were together with Ti vapor species to form the TiO2-SnOx-Sn composite nanowires. High-resolution X-ray photoelectron spectroscopy (XPS) evaluated that the as-synthesized TiO2 nanowires mainly consisted of TiO2 with the dopants SnO, and Sn. Through the evaluation of the change in Gibbs free energy, it was found that a spontaneous reaction resulted in the formation of TiO2-SnOx-Sn composite nanowires. The characterization and formation of TiO2-SnOx-Sn composite nanowires are discussed.