INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
artículos
Título:
PM IRRAS spectroelectrochemistry of layer-by-layer self-assembled polyelectrolyte multilayers
Autor/es:
M. TAGLIAZUCCHI; L.P. MENDEZ DE LEO; A. CADRANEL; L.M. BARALDO; E. VOLKER; C. BONAZZOLA; E.J. CALVO; V. ZAMLYNNY
Revista:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY - (Print)
Editorial:
ELSEVIER SCIENCE SA
Referencias:
Lugar: Amsterdam; Año: 2010 p. 1 - 9
ISSN:
1572-6657
Resumen:
In situ polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) has been used to
study layer-by-layer self-assembled films made of a novel redox polymer bearing an osmium pentacyano
pyridine complex (PAH-OsCN) and polyacrylic acid at different electrode potentials and solution compositions.
PM IRRAS provides information on the oxidation state of the osmium complex, the fraction of protonated
carboxylates and the content of IR-active counterions (such as nitrate) as well as water content
(hydratation of the multilayer). It has an advantage over SNIFTIRS because it measures the absolute IRsignal
arising from the molecular species at the interface rather than its variation with respect to a reference
state. For instance, we show that only a fraction of the total number of redox sites responds to
changes in the electrode potential as expected from the Nernst equation. The remaining sites are trapped
in the Os(II) or Os(III) states and can only be oxidized/reduced by chemical agents in solution. We also
present spectroscopic evidence that nitrate ions enter into the film during oxidation and leave during
reduction. The number of these anions involved in the first process is larger than that participating in
the latter and hence nitrate accumulates within the film. This finding is analyzed in terms of two possible
mechanisms.