IR study of gas-sensor materials: NO interaction on ZnO and TiO2, pure or modified by metals

The interaction with NO of differently pretreated ZnO and TiO 2 pressed powders, pure or modified by noble metal addition (Pt and Ru, respectively) is studied, mainly by FT-IR spectroscopy; the analysis of the IR spectra concerns both the vibrational modes of the absorbed species and the variations of the IR transparency related to changes in the electrical properties. The data presented indicate that the NO molecules are dissociated and that electron transfer from the solid to the produced oxygen atoms occurs on prereduced samples, both pure and metal modified; the metal modifiers also adsorb NO in molecular form.