A novel CO sensor based on the point contact between Pd decorated TiO2 nanotubes array.

To obtain a high sensitive CO sensor, a new nanostructure based on the point contact between Pd decorated TiO2 nanotubes was proposed in this paper. TiO2 nanotubes array was fabricated on titanium wire by electrochemical anodic oxidation, and Pd catalytic nanoparticles were modified by the micro-emulsion electrochemical deposition. The surface morphology was characterized by field emission scanning electron microscopy (FE-SEM), and CO sensitivity of the point contact between TiO2 nanotubes was investigated through the current-voltage (I-V) characteristic measurement. It was found that Pd epitaxially grew along the tube walls, and they were distributed on the surface of the nanotubes. The point contact based sensor between Pd decorated TiO2 nanotubes exhibited a strong temperature dependent sensitivity towards CO. From the I-V curves, we found the Schottky barrier was formed on the contact and the barrier height was also calculated.