Oxidation of methanol at an electrocatalytic film containing platinum and polynuclear oxocyanoruthenium microcenters dispersed within tungsten oxide matrix

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 512; no. 1; pp. 110 - 118
• Main Authors: Kulesza, Pawel J, Grzybowska, Bozena, Malik, Marcin A, Chojak, Malgorzata, Miecznikowski, Krzysztof
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2001; Elsevier Science
• Subjects: Activation; Chemistry; Composite film; Dispersed platinum; Electrocatalysis; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics and mechanism of reactions; Methanol oxidation; Oxocyanoruthenium species; Tungsten oxide matrix; Composite film; Electrocatalysis; Methanol oxidation; Dispersed platinum; Activation; Tungsten oxide matrix; Oxocyanoruthenium species; Alcohol; Acidic solution; Surface structure; Sulfuric acid; Electrodes; Platinum; Noble metal; Oxidation; Electrochemical reaction; Organic compounds; Modified material; Methanol; Scanning electron microscopy; Transition metal; Transition metal Complexes; Experimental study; Metal particle; Carbon; Cyano complex; Oxo complex; Morphology; Tungsten VI Oxides; Polynuclear complex; Ruthenium Complexes; Glassy state
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/S0022-0728(01)00596-4

We propose a composite bifunctional electrocatalytic film that contains platinum microparticles and oxocyanoruthenium microstructures dispersed in the reactive matrix of non-stochiometric tungsten(VI,V) oxides. Polynuclear oxocyanoruthenium can be viewed as a ruthenium analogue of Prussian blue or, more precisely, ruthenium(II,III,IV) hexacyanoruthenate(II,III), that features ruthenium oxo species within the cyanide bridged network. The composite film was fabricated by sequential electrodeposition starting from the preparation of tungsten oxide film into which oxocyanoruthenium and metallic platinum (from chloroplatinate) centers were introduced. To evaluate the reactivity of such a hybrid system toward the oxidation of methanol at fairly low potentials (0.1–0.3 V vs. SCE), cyclic voltammetric and chronoamperometric measurements have been performed at 22 and 60
°C. With approximately the same platinum loading and under analogous conditions, the composite film shows higher catalytic activity than a simple platinized tungsten oxide. It is possible that ruthenium hydroxo species generated within polynuclear oxocyanoruthenium microstructures exhibit an activating effect on neighboring dispersed platinum microparticles. An alternative explanation may involve the possibility of different morphologies of the catalytic films in the presence and absence of oxocyanoruthenium species. At higher potentials, ruthenium(IV)-oxo centers participate directly in the oxidation of methanol. The protonically/electronically conducting and physicochemically stable tungsten oxide/hydrogen bronze matrix is expected to support the activity of platinum and ruthenium centers.