Analysis of the high-temperature methanol oxidation behaviour at carbon-supported Pt–Ru catalysts

Abstract Methanol oxidation behaviour at three Pt–Ru catalysts varying by the concentration of active phase on the carbon support has been investigated in a wide temperature range (80–130 °C). An increase of the adsorbed methanolic residue stripping charge is observed with the increase of catalyst dispersion. As the temperature is increased, the stripping peak potential shifts more negatively accounting for a lower activation barrier for the reaction. An increase of temperature above 90 °C also produces a strong decrease in the coverage of adsorbed methanolic residues. The fuel cell performance is significantly enhanced by catalysts with intrinsically high catalytic activity, whereas the methanol reaction rate appears to be less influenced by an increase in coverage of active species. Catalysts characterized by a higher degree of alloying and metallic behaviour on the surface appear to be more active towards methanol oxidation. However, the physico-chemical properties of the catalysts have less influence on the anode electrochemical behaviour at high temperature since CO poisoning is alleviated under such conditions. The decrease of CO-like species coverage with temperature and the methanol tolerance characteristics of a Pt/C cathode are also discussed in relation to the crossover drawback of direct methanol fuel cells.

[1]  Shimshon Gottesfeld,et al.  Electrocatalysis in direct methanol fuel cells: in-situ probing of PtRu anode catalyst surfaces , 2000 .

[2]  T. Iwasita.  Electrocatalysis of methanol oxidation , 2002 .

[3]  P. Ross,et al.  Methanol electrooxidation on supported Pt and PtRu catalysts in acid and alkaline solutions , 2002 .

[4]  Antonino S. Aricò,et al.  Comparison of Ethanol and Methanol Oxidation in a Liquid‐Feed Solid Polymer Electrolyte Fuel Cell at High Temperature , 1999 .

[5]  C. Pu,et al.  Carbon supported and unsupported Pt–Ru anodes for liquid feed direct methanol fuel cells , 1998 .

[6]  Masahiro Watanabe,et al.  Electrocatalysis by ad-atoms: Part II. Enhancement of the oxidation of methanol on platinum by ruthenium ad-atoms , 1975 .

[7]  V. Antonucci,et al.  Carbon monoxide electrooxidation on porous Pt–Ru electrodes in sulphuric acid , 1997 .

[8]  A. Shukla,et al.  Effect of carbon-supported and unsupported Pt–Ru anodes on the performance of solid-polymer-electrolyte direct methanol fuel cells , 1999 .

[9]  Antonino S. Aricò,et al.  Analysis of the Electrochemical Characteristics of a Direct Methanol Fuel Cell Based on a Pt‐Ru/C Anode Catalyst , 1996 .

[10]  Shimshon Gottesfeld,et al.  High performance direct methanol polymer electrolyte fuel cells , 1996 .

[11]  Karen E. Swider-Lyons,et al.  Local Atomic Structure and Conduction Mechanism of Nanocrystalline Hydrous RuO2 from X-ray Scattering , 2002 .

[12]  S. Gottesfeld,et al.  Adsorption of CO poison on fuel cell nanoparticle electrodes from methanol solutions: a radioactive labeling study , 2001 .

[13]  Antonino S. Aricò,et al.  DMFCs: From Fundamental Aspects to Technology Development , 2001 .

[14]  V. Antonucci,et al.  Effect of PtRu alloy composition on high-temperature methanol electro-oxidation , 2002 .

[15]  L. Cornaglia,et al.  Characterization of platinum-rutheniun electrodeposits using XRD, AES and XPS analysis 1 Dedicated t , 1999 .

[16]  R. Behm,et al.  Composition and activity of high surface area PtRu catalysts towards adsorbed CO and methanol electrooxidation: A DEMS study , 2002 .

[17]  T. Mallouk,et al.  Structural and Electrochemical Characterization of Binary, Ternary, and Quaternary Platinum Alloy Catalysts for Methanol Electro-oxidation1 , 1998 .

[18]  U. Stimming,et al.  Catalysts for Direct Methanol Fuel Cells , 2002 .

[19]  Musuwathi Krishnamoorthy Ravikumar,et al.  Effect of Methanol Crossover in a Liquid‐Feed Polymer‐Electrolyte Direct Methanol Fuel Cell , 1996 .

[20]  V. Antonucci,et al.  Investigation of unsupported Pt-Ru catalysts for high temperature methanol electro-oxidation , 2000 .

[21]  D. Rolison,et al.  Role of hydrous ruthenium oxide in Pt-Ru direct methanol fuel cell anode electrocatalysts: The importance of mixed electron/proton conductivity , 1999 .

[22]  Andrzej Wieckowski,et al.  Catalysis and Electrocatalysis at Nanoparticle Surfaces , 2003 .

[23]  Robert F. Savinell,et al.  Evaluation of Ethanol, 1‐Propanol, and 2‐Propanol in a Direct Oxidation Polymer‐Electrolyte Fuel Cell A Real‐Time Mass Spectrometry Study , 1995 .

[24]  Andrew B. Bocarsly,et al.  Silicon Oxide Nafion Composite Membranes for Proton-Exchange Membrane Fuel Cell Operation at 80-140°C , 2002 .

[25]  G. Mickelson,et al.  In-Situ XANES of Carbon-Supported Pt−Ru Anode Electrocatalyst for Reformate-Air Polymer Electrolyte Fuel Cells , 2002 .