Comparison of the gas sensing properties of tin, indium and tungsten oxides nanopowders: carbon monoxide and oxygen detection

It is now well established that the use of nanosized powders in the fabrication of gas sensors by screen-printing technology significantly enhances the sensor sensitivity. However, further improvements of nanosized powder-based sensors require a careful study of the surface reactions at the origin of the gas detection mechanisms. This is a necessary step toward a rigorous industrial fabrication protocol, In this work, chemical reactions occurring at the surface of semiconductor (tin, indium, and tungsten oxides) nanopowders are analyzed by Fourier transform infrared (FTIR) spectrometry simultaneously with their effects on the electrical conductivity of the materials. These surface reactions are compared for the different materials and their relation with the metal oxide sensitivity toward CO and O-2 at different temperatures is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.