The Promoting Role of Tungsten Oxides in the Anodic Oxidation of Methanol on Platinum-Based Catalysts

• Published in: Electrocatalysis 2017-05, Vol.8 (3), p.261-269
• Main Authors: Cíntora-Juárez, D., Ocampo-Flores, A. L., Ordóñez, L. C., Roquero, P.
• Format: Article
• Language: English
• Subjects: Carbon content; Catalysis; Catalysts; Chemistry; Chemistry and Materials Science; Electrochemistry; Energy Systems; Methanol; Original Research; Particle size; Physical Chemistry; Thermal decomposition; X-ray diffraction
• ISSN: 1868-2529; 1868-5994
• DOI: 10.1007/s12678-017-0361-2

Carbon-supported Pt-WO 3 catalysts formulated with different proportions of platinum and tungsten were synthesized by thermal decomposition of metal carbonyl precursors. The activity of the PtWO 3 /C catalysts towards the methanol electrooxidation reaction (MOR) was evaluated in half-cell configuration and as anode catalyst in a direct methanol fuel cell device (DMFC) with a homemade membrane electrode assembly (MEA). The presence of WO 3 increases significantly the catalyst activity, expressed by higher oxidation currents at lower potential values than those obtained with Pt/C. DMFC power output is comparable to that obtained by using a commercial MEA containing twice of the Pt loading at the anode. Electron microscopy and X-ray diffraction analysis (XRD) revealed that monoclinic WO 2.92 and hexagonal WO 3 phases coexist in the PtWO 3 /C catalysts. In samples with equal Pt loadings, the Pt particle size increases and its active area decreased as tungsten is added to the catalyst formulation. As the tungsten loading is increased and carbon content is diminished, hexagonal WO 3 appears as the predominant crystalline phase. Graphical Abstract