Gas Sensing Studies of an n-n Hetero-Junction Array Based on SnO2 and ZnO Composites

Abstract

Abstract:A composite metal oxide semiconductor (MOS) sensor array based on tin dioxide (SNO 2 ) and zinc oxide (ZnO) has been fabricated using a straight forward mechanical mixing method. The array was characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The array was evaluated against a number of environmentally important reducing and oxidizing gases across a range of operating temperatures (300-500˝C). The highest response achieved was against 100 ppm ethanol by the 50 wt% ZnO-50 wt% SnO 2 device, which exhibited a response of 109.1, a 4.5-fold increase with respect to the pure SnO 2 counterpart (which displayed a response of 24.4) and a 12.3-fold enhancement with respect to the pure ZnO counterpart (which was associated with a response of 8.9), towards the same concentration of the analyte. Cross sensitivity studies were also carried out against a variety of reducing gases at an operating temperature of 300˝C. The sensors array showed selectivity towards ethanol. The enhanced behaviour of the mixed oxide materials was influenced by junction effects, composition, the packing structure and the device microstructure. The results show that it is possible to tune the sensitivity and selectivity of a composite sensor, through a simple change in the composition of the composite.

ZnO Coated Anodic 1D TiO2 Nanotube Layers: Efficient Photo‐Electrochemical and Gas Sensing Heterojunction

“…Enhanced response toward ethanol has been achieved through integrating two metal oxides, for example, for SnO 2 –ZnO, SnO 2 –TiO 2 , CuO–ZnO, and WO 3 –ZnO structures . Similarly, for the ZnO and TiO 2 heterostructure, adsorption of rich oxygen species and synergistic catalytic breakdown of ethanol occurred, specifically when sufficiently thick ZnO coatings were added to TiO 2 nanotube layers, that is, 7.6 and 19 nm in thickness. Even these thickest coatings in this work did not inhibit the TiO 2 nanotubes layer underneath from adsorbing ethanol and participating in the sensing reaction.…”

“…This implies that the sensors offer more active reaction sites and adsorbed oxygen species to capture more electrons from ethanol. Due to the unsaturated reaction sites, shorter response and recovery time are registered for the ZnO coated TiO 2 nanotube layers, compared to the blank nanotube layers …”

Path Way For Electrical Conduction In ZnO Basedternary Nanocomposite Room Temperature Ethanol Sensors

“…Continued attention on metal oxide semiconductors (MOS) such as; ZnO [1], In2O3 [2], SnO2 [3], MoO3 [4], V2O5 [5] and WO3 [6] nanostructures of different shapes and sizes reveals optimistic properties for application in short wavelength optoelectronic devices and sensors [7].…”

Structural, textural, surface chemistry and sensing properties of mesoporous Pr, Zn modified SnO 2 –TiO 2 powder composites

“…The materials based on semi-conducting metallic oxides such as SnO 2 , ZnO, and TiO 2 have been reported in the literature as sensitive for various gases detection [8][9][10] in a different range of working temperatures [11,12]. The idea behind the metal oxide nanocomposites is to take advantage over the electronic interactions between their own constituents which play a significant role in the conductivity and sensing properties [4; 13].…”