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Direct methanol fuel cells (DMFC), as environmentally friendly energy devices, are being intensively studied due to their numerous advantages with respect to other energy storing systems, including low environmental impact, high-energy density, high-efficiency and low noise, portable applications. One of the main problems of these fuel cells is the cost of the MEA due to the platinum content as catalyst. The Pt-Rub binary alloy electrocatalyst appears as the most promising formulation to oxidize the methanol at DMFC anodes. Pt sites in Pt-Ru alloys are especially involved in both the methanol dehydrogenation step and strong chemisorption of methanol residues. The aim of this work is to investigate the electron beam evaporation for preparing Pt/Ru layers deposited on the un-catalysed gas diffussion layers for DMFC, Freudenberg H2215 T10A. Pt/Ruf films in atomic ratio 1:1(50.4µg Pt cm2, 26.1 µg Ru cm2) were evaporated in a vacuum chamber using an e-beam evaporator QUAD-EV-C, Mantis. Electrochemical measurements were carried out in a three electrode cell with a Pt wire used as auxiliary electrode connected to a Schlumbeger 1286 potentiostast/galvanostat connected to a frequency analyser Solarton 1255B. The prepared e-beam PtRu electrode and a commercial of 3 mg PtRu cm2, BC-M100-30F T10A were measured using membrane electrode assemblies (MEAs) in a single DMFC of 3.8 cm2 of active area. A commercial cathode: Quintech H2315 IX91CX320 containing 1mgPt cm2 has been used to fabricate the MEAs. Polarization curves were registered at different temperatures and methanol concentrations with each DMFC. The electrochemical behaviour of the catalyst support and the electrodes has been studied by cyclicvoltammetry in 0.5M H2SO4 and O.5M H2SO4+1M MeOH medium. The electrochemical active surfaces were determined and their morphological characteristics were examined by SEM. Low Pt/Ru electrodes shows more electroactivity than carbon paper without e-beam evaporation and they are also comparable with commercial ones. The e-beam MEA maximum power density (Wm, mW per mg of PtRu at the anode) is higher than that of the commercial MEA. At 80ºC and 1M of methanol the ratio between Wm of e-beam and commercial MEAs is 3.5. This ratio decreases when the temperature decreases, but it is always greater than 1. Thus, PtRu e-beam electrode makes better use of the catalyst. Therefore, at low Pt-Ru loadings, the e-beam evaporation technique seems to be an easily scalable preparation method for fuel cell electrodes.

(SPA) Con el objetivo de disminuir el coste de los electrodos utilizados en las pilas de combustible de membrana polimérica se ha llevado a cabo un estudio de la influencia sobre la respuesta electroquímica y en ensayos en monocelda de pila de combustible de alcohol directo, de la deposición por evaporación electrónica de platino sobre tela de carbón. Se han estudiado en las mismas condiciones dos electrodos comerciales con distinta carga de catalizador y dos electrodos preparados por evaporación electrónica de platino. Se encuentra que la evaporación electrónica de platino sobre tela de carbón ahorra carga de catalizador, aumenta la superficie electroactiva y permite alcanzar rendimientos comparables a los de los electrodos comerciales, mejorando mucho la potencia obtenida por unidad de masa de material catalítico. (ENG) In order to diminish the cost of the electrodes used in polymer membrane fuel cells a study of the influence on the electrochemical response and essays in a single direct methanol fuel cell of the deposition by electronic evaporation of Platinum on carbon cloth has been carried out. Two commercial electrodes with different catalyst loading and two electrodes prepared by electronic evaporation of Platinum have been studied in the same conditions. It can be concluded that electronic evaporation of Platinum on carbon cloth saves catalyst load, increases the electroactive surface area and reaches fuel cell performances comparable with those obtained using commercial electrodes, improving clearly the power obtained per unit mass of catalytic material.