Nanocrystalline Tin Oxide to be Applied in Gas Sensors

Abstract

The aim of this paper was to describe the methods of nanocrystalline SnO2 preparation and to show the improvement of the behavior of a hydrogen sensor built with the grown SnO2 nanoparticles since particular properties of the nanomaterial are related to the sensor response. Nanocrystalline SnO2 was synthesized by gel-combustion and by reactive oxidation methods. Characterization was performed by X-Ray Diffraction (XRD), Brunauer-Emmer-Teller isotherms (BET) absorption and by High Resolution Transmission Electron Microscopy (HRTEM). A careful characterization enabled to control the crystallites size and properties to improve the behaviour of a hydrogen sensor. It was proved that if nanocrystalline SnO2 was used to build the resistive sensor, replacing the conventional microcrystalline SnO2, the sensor sensitivity increased between 30% and 35% (according to the grown crystallites size of nanocrystalline SnO2) and the working temperature (Tw) decreased from 350-450ºC to 180-220ºC. The Tw decrease obliged to improve the heating and measuring system of sensor which is also described.