Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

Abstract

Oxygen vacancy (OV) controlled TiO2 nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH4F and ethylene glycol with selective H2O content. The structural evolution of TiO2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively. This work was supported in part by CSIR, DST, AICTE, and INSA. A. Hazra, B. Bhowmik, and K. Dutta gratefully acknowledge the DST, Government of India and COE, TEQUIP-II, IIEST, Shibpur, respectively, for their fellowship for pursuing PhD program. The authors sincerely acknowledge Dr. Mallar Ray, School of Materials Science and Engineering, Indian Institute of Engineering Science and Technology (IIEST), Howrah 711 103, India for providing the facility of PL spectroscopy.