A novel NO2 sensor based on TiO2 nanotubes array with in-situ Au decoration.

Au decorated TiO2 nanotubes array was successfully fabricated on a Ti-Au alloy via an electrochemical anodization process. The crystal phase and microstructure of the TiO2 nanotubes array were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. Au particles were well distributed among TiO2 nanotubes and acted as the catalyst. It was found that the sensor based on Ti-Au alloy anodization can be a promising sensor which was highly sensitive to low concentrations of nitrogen dioxide (NO2), and response at room temperature. The sensitivity of Au-decorated TiO2 nanotubes sensor was 36.11 to 8 ppm NO2 at room temperature. Meanwhile, the resistance signal of Au-decorated TiO2 sensor changes quickly within 80 s upon exposure to 8 ppm NO2 at 35 degrees C, the undecorated TiO2 however takes much more time (>110 s) to respond and the resistance signal remains unstable.