La. Da Silva et al., XPS study of the state of iridium, platinum, titanium and oxygen in thermally formed IrO2+TiO2+PtOx films, COLL SURF A, 170(2-3), 2000, pp. 119-126
Citations number
28
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Electrodes of nominal composition Ir0.3Ti(0.7-x)PtxO2 (x = 0; 0.4 and 0.7)
have been prepared by thermal decomposition of mixtures of the chloride pre
cursors. H2PtCl6 was used as Pt-precursor. A systematic study of the chemic
al composition and oxidation states of the elements of these electrodes was
performed by XPS. XPS analysis showed that the surface of the PtOx-contain
ing coatings are Pt enriched. Additionally, XPS revealed that the Ir signal
s are almost absent from the spectra of PtOx-containing electrodes, while t
he Ti signal is completely absent. On the basis of the XPS results it is po
ssible to propose a model of the surface structure of these electrodes: the
grains, composed almost exclusively of Ir Jr Pt, are Pt enriched and distr
ibuted in a matrix, which although having Ti in its composition, besides Ir
and Pt, is also Pt enriched. This finding corroborates the electrochemical
behaviour of these electrodes, which is characteristic of polycrystalline
Pt. (C) 2000 Elsevier Science B.V. All rights reserved.