Fabrication and investigation of gas sensing properties of Nb-doped TiO2 nanotubular arrays

Synthesis of Nb-containing titania nanotubular arrays at room temperature by electrochemical anodization is reported. Crystallization of pure and Nb-doped TiO2 nanotubes was carried out by post-growth annealing at 400 °C. The morphology of the tubes obtained was characterized by scanning electron microscopy (SEM). Crystal structure and composition of tubes were investigated by glancing incidence x-ray diffraction (GIXRD) and total reflection x-ray fluorescence (TXRF). For the first time gas sensing characteristics of Nb-doped TiO2 nanotubes were investigated and compared to those of undoped nanotubes. The functional properties of nanotubular arrays towards CO, H2, NO2, ethanol and acetone were tested in a wide range of operating temperature. The introduction of Nb largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes.