Synthesis and Gas Sensing Porperties of SnO2 Nanostructures

Introduction Metal oxides are considered to be the most attractive functional materials in the past decade and research on metal oxide nanostructured materials has attracted a great deal of attention as it has been widely used in various technical applications. For example, they are used as gas sensors, biosensors, nanoelectronics, nanogenerators, electrochromic devices, light emitting diodes, field emitters, supercapacitors and photodetectors. Nanomaterials have different mechanical, chemical, thermal, electrical and optical properties than their bulk counterparts due to an increase in surface to volume ratio and possible quantum confinement effects (Dulce N. et al.

Among nanostructured semiconductor oxides, ZnO nanostructures have been extensively studied for their interesting physical and electronic properties such as wide bandgap (3.4 eV at room temperature), strong piezoelectric properties, and thermoelectric properties. In gas sensing applications, ZnO nanostructure-based sensors have been widely noted due to their good sensitivity to important industrial gases such as NH 3, CO, NO 2 and H 2 S. The main focus of this paper is to study the effectiveness and detection performance of ZnO nanostructured gas sensor for detecting NO 2 gas in practical application under natural environmental conditions.

Semiconductor metal oxide based gas sensors are widely used to detect gases and vapors. The first motivation is Seiyama et al. It was derived from the discovery of. The metal-oxide gas reaction effect of 1962 showed that the presence of active gas in the air changed the electrical conductivity of ZnO. Advantages of these sensors include reliability, low cost, ease of implementation, and so on. Nanostructures of metal oxides proved to be most effective as gas sensing materials at high temperatures. Very common sensing materials are metal oxide semiconductors such as ZnO, SnO 2, TiO 2 and WO 3.

A high speed gas switching system can be used to improve the response of the gas sensor. Yamazoe et al. Response and recovery characteristics of SnO 2 porous membrane gas sensor using high speed gas switching system were investigated. The developed system allows a rapid change in the gas atmosphere within the chamber between the air and H 2 (or CO). According to reports, the response speed of the sensor is very fast and the response time is less than 0.5 seconds at 350 ° C. The diffusion rate and surface reaction of these gases (H 2 and CO) in the porous sensing membrane are high enough to allow the sensor to reach steady state in a short time. However, by repeating switching, the resistance in the air does not reach the original value. This incomplete recovery is due to the slow desorption of H 2 O and CO 2 formed by SnO 2 by the surface reaction of H 2 and CO, respectively.