A study of the effect of morphology on the optical and electrical properties of TiO₂ nanotubes for gas sensing applications

Abstract

In this paper, we report the results of the optical and electrical properties of TiO 2 nanotubes with different morphologies for gas sensing applications. Four nanomaterials of TiO 2 were prepared by electrochemical anodization using four different electrolyte solutions: 0.255 wt% NH 4 F with 1 wt%, 3 wt%, 6 wt% and 9 wt% of deionized water in ethylene glycol. Micrographs by scanning electron microscopy (SEM) showed different morphologies caused by the variation in the water content of the solutions. Consequently, as an effect of morphology, the photoluminescence intensity in the visible spectrum was modified. By a change of the crystalline phase of TiO 2 nanotubes, the oxygen vacancies increased and affected to the optical and electrical properties of TiO 2 films. These films were used for detecting gas at room temperature. Hence, we studied and analyzed the relationship of the morphology, elemental composition, phase composition, band gap energy and defect states as a function of the electrical resistance change of TiO 2 nanotubes to understand and improve the sensor response.