Synthesis of Pt−Mo−N Thin Film and Catalytic Activity for Fuel Cells

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• 作者：Akira Miura ; Michele E. Tague ; John M. Gregoire ; Xiao-Dong Wen ; R. Bruce van Dover ; Hctor D. Abrua ; Francis J. DiSalvo
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：June 8, 2010
• 年：2010
• 卷：22
• 期：11
• 页码：3451-3456
• 全文大小：819K
• 年卷期：v.22,no.11(June 8, 2010)
• ISSN：1520-5002

文摘

Although platinum and platinum-based intermetallic alloys have been extensively studied as catalysts for proton exchange membrane fuel cells, platinum-based nitride catalysts have been relatively unexplored. We report the synthesis and characterization of a platinum-based nitride, Pt₂Mo₃N, using a composition spread thin-film deposition technique. The Pt₂Mo₃N thin film was generated by codeposition of platinum and molybdenum and subsequent heat treatment in an ammonia flow at 800 °C for 6 h. The thin film was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical tests, including the assessment of catalytic activity toward the oxidation of methanol and formic acid and the reduction of oxygen. The nitride film was smooth and contained single-phase, nearly stoichiometric Pt₂Mo₃N. Cyclic voltammograms of Pt₂Mo₃N in 0.1 M H₂SO₄ demonstrated electrochemical stability far greater than that of a PtMo alloy with the same Pt:Mo ratio, indicating that the formation of the nitride phase enhances electrochemical stability. The ternary nitride exhibited oxidation currents in formic acid and methanol solutions above approximately 0.0 and 0.4 V vs an Ag/AgCl reference electrode, respectively. These are above the expected equilibrium oxidation potentials of approximately −0.2 V. The onset potential for oxygen reduction was estimated to be 0.2 V vs Ag/AgCl, well below the equilibrium value of 1.0 V.