title: Europium phosphomolybdate and osmium metallopolymer multi-functional LbL films: redox and electrocatalytic properties.
abstract: Hybrid multilayer films composed by osmium metallopolymer [Os(bpy)2(PVP)10Cl]Cl (Os-poly) and europium phosphomolybdate, K₁₁[Eu(III)(PMo₁₁O₃₉)₂] (Eu(PMo11)2), were prepared using the electrostatic layer-by-layer (LbL) self-assembly method. The film build-up, monitored by electronic spectroscopy, showed a regular stepwise growth indicating a strong interaction between layers. The XPS measurements corroborated the successful fabrication of the hybrid films with the Os-poly/Eu(PMo11)2 composition. SEM images revealed a completely covered surface with a highly roughened texture. Electrochemical characterisation of films by cyclic voltammetry revealed three Mo-based reduction processes (Mo(VI)→Mo(V)) in the potential range between -0.4 and 0.1 V and one Os reduction process (Os(III)→Os(II)) at ≈0.270 V. The cyclic voltammograms of two electroactive probes, [Fe(CN)₆](3-/4-) and [Ru(NH₃)₆](3+/2+) on {Os-poly/Eu(PMo11)2}n modified electrodes revealed redox mediation between film and the probes. Furthermore, the {Os-poly/Eu(PMo11)2}n multilayer films also showed excellent Mo-based electrocatalytic activity towards reduction of nitrite and iodate, confirming the multi-functional properties of the hybrid europium phosphomolybdate - osmium metallopolymer LbL films.
authors.affiliation: REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Fernandes
authors.affiliation: School Chemistry Science, Dublin City University, Dublin 9, Ireland.
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Vos
authors.affiliation: REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal. Electronic address: acfreire@fc.up.pt.
authors.forename: Cristina
authors.initials: C
authors.lastname: Freire
keywords: Electrocatalysis; Layer-by-layer self-assembly; Metallopolymer; Osmium; Phosphomolybdates