Impedance behavior of n-type TiO2 nanotubes porous layer in reducing vapor ambient

Abstract

Impedance behavior of n-type TiO2 nanotubes array based vapor sensor is presented in this work with focus on the behavior of resistive and capacitive changes separately in presence of reducing organic vapors like methanol and acetone. The sensing layer of TiO2 nanotubes array was synthesized by anodizing Ti substrate by electrochemical route. The surface morphology, crystallinity and chemical composition of TiO2 nanotubes array were characterized with field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) spectroscopy and X-ray photoelectron spectroscopy (XPS) respectively. Gold (Au) contact was deposited on film surface by thermal evaporation technique for developing Au/TiO2 nanotubes/Ti sensor. Cole-Cole plots of the sensor (operating at room temperature) in methanol and acetone ambient were drawn and an equivalent circuit of device was modelled to explain the sensing mechanism of the sensor.