Preparation and characterization of antimony-doped tin dioxide electrodes. 3. XPS and SIMS characterization.

Several antimony- and antimony-platinum-doped tin dioxide electrodes supported on titanium have been
characterized by X-ray photoelectron spectroscopy (XPS) for surface analysis and secondary-ion mass
spectrometry (SIMS) for in-depth profile analysis. The surface analysis of the freshly prepared electrodes
indicates that the Sb/Sn ratio in the electrode surface is similar to the nominal composition in the precursor
solution, but the amount of Pt is higher than this nominal composition. The presence of platinum also produces
the segregation of Sb near the electrode surface. The anodic polarization treatment of the electrode produces
changes in its chemical state. The growth of a passivating hydroxide in the outer layer is the main cause of
the deactivation of Ti/SnO2-Sb electrodes. The introduction of platinum in the layer prevents the hydroxide
formation and modifies the deactivation mechanism of the electrode. The growth of an isolating TiO2 between
the support and the active oxide produces the deactivation of Ti/SnO2-Sb-Pt electrodes