Nanocrystalline composites in TiO2 and SnO2 system for ammonia resistance sensors

Abstract

This work describes the production of nanocrystalline TiO 2 and SnO 2 oxides, as well as their nanocomposites (containing 26.9, 58.7 and 79.0 wt.% of SnO 2) with two-stage sol-gel method combined with high temperature treatment. The phase composition and medium size crystallites were determined using X-ray diffraction analysis (XRD) and revealed that the nanocomposites crystallize in tetragonal structures of TiO 2-anatase and SnO 2-cassiterite. Specific surface area of the nanopowders, measured using sorption method (BET), changed from 42.1 to 160.8 m 2 /g. The morphology of the nanopowders was observed using transmission electron microscope (TEM). As indicated by TEM images, the manufactured nanopowders were well crystallized and consisted of small, spherical grains. The obtained nanopowders were also tested for NH 3 gas detection application. The presented method of nanopowders synthesis enables to obtain nanocrystalline TiO 2 and SnO 2 oxides, as well as composites from TiO 2-SnO 2 of known and controlled chemical and phase composition. It also enables to obtain composites used for gas sensors. The sensor made of composite containing 58.7 wt.% of SnO 2 exhibited the best NH 3 sensing features.

Mechanistic understanding of the sensing process by analyzing response curves of TiO2 based humidity sensors

“…TiO 2 has been used in crystalline forms of both anatase and rutile phases [24,25]. It has been used as sensor for detecting various gases like hydrogen [24,26,27], nitrogen dioxide [28,29], ammonia [30,31], acetone [32], propanol [33], methane [34], humidity [35] and many others. It has also been tested in various forms like TiO 2 nanoparticles [12,36], thick films [37,38], thin films [29,39], nanomaterials [27,40,41], films [25,34], etc.…”

Crystalline WO3 nanoparticles for No2 sensing

“…A great deal of attention is currently paid to the design of sensor materials with good sensor properties by engineering various composites [46,47]. The enhance-B.…”