XPS studies of active elements surface of gas sensors based on WO3-x nanoparticles

Nanodisperse WO3-x oxides (x >= 0) were synthesized by method of electrical explosion of wires. The structure of core levels W4f and 0 Is was explored by XPS-method. Exposure of oxides to air at 293 K leads to the formation of WO3.(OH2)(n)-phase on the surface of nanoparticles. A correlation between value x of nonstoichiometric WO3-x oxide matrix and contents of OH-groups in it was revealed. It was noticed, that the increase of number of W5+-states at nanoparticles synthesis leads to rise of the sensor response to molecular hydrogen at room temperature. (c) 2007 Elsevier B.V. All rights reserved.