Ethanol and methanol sensing characteristics of Nb‐doped TiO₂ porous thin films

Abstract

Undoped and Nb-doped TiO 2 porous thin films have been obtained through a sol-gel method using analytical grades Ti(O i C 3 H 7 ) 4 and Nb(OC 2 H 5 ) 5 as precursors. The morphology, crystalline microstructure, and the sensing properties towards ethanol and methanol of the obtained thin films have been investigated. The effects of the dopant on the film morphology and on alcohol sensing properties are discussed. Both direct current (DC) and alternating current (AC) measurements were performed at different temperatures in methanol and ethanol ambients to better understand the mechanisms of the alcohol detection. In the presence of a small amount of Nb, the activation energy for electrical conduction decreased. Nb doping improves the selectivity for methanol in the temperature range of 300-400 8C. The Nyquist diagrams showed complex phenomena during alcohol detection.

XPS and STM Study of Nb-Doped TiO2(110)-(1 × 1) Surfaces

“…Niobium doping improves the performance of titanium dioxide (TiO 2 ) nanocrystalline films as high-temperature gas sensors − and photocatalysts. − A rise of the anatase-to-rutile phase transition temperature and a suppression of the coalescence of the grains are induced by the doping, which makes it possible to maintain gas-sensing abilities of the film at high temperatures. Increase in the conduction band electrons by substituting the pentavalent Nb cation for the tetravalent Ti cation reduces the lattice O vacancies that act as nucleation sites of the rutile structure .…”

Homogeneously niobium-doped MoS2 for rapid and high-sensitive detection of typical chemical warfare agents

“…The electron density of Nb-MoS 2 NSs surface is higher than that of pure MoS 2 NSs. CWAs molecules are more likely to capture electrons on the surface of Nb-MoS 2 NSs and form physical adsorption, thus causing resistance changes in Nb-MoS 2 NSs ( Nechita et al, 2011 ). During the response process, the donor impurity Nb indirectly reacts with the CWAs and makes its molecules adsorbed on the active spot on the surface of Nb-MoS 2 NSs.…”

CVD Deposited Titania Thin Films for Gas Sensors with Improved Operating Characteristics

“…Titanium dioxide (TiO 2 ), as an n‐type, wide band gap, oxide semiconductor synthesized in various nanostructured forms, has been considered to be a promising material for the use as an active sensing layer in various gas sensors for the detection of formaldehyde, hydrogen, ethanol, ammonia, carbon monoxide, etc . Various types of sol‐gel technology are the most widely used methods for manufacturing sensing layers on the basis of titania because of their simplicity and low cost.…”