F. J. Rodríguez Varela

Real-Time Mass Spectrometric Analysis of the Anode Exhaust Gases of a Direct Propane Fuel Cell

The exhaust gases composition of a direct propane fuel cell DPFC operating at 80°C was studied by mass spectrometric methods. Blank propane was introduced in the anode chamber without external reforming. The effect of the anode catalysts on the composition of the exhaust gases was investigated. It was found that the mass spectra of the electro-oxidized propane presented significant differences compared to the mass spectra of the blank propane introduced directly into the mass spectrometer. It was found that the operation of the DPFC at 80°C involves several processes, i.e., adsorption, dehydrogenation, and C-C bond cleavage of the molecule. It was shown that the intensity of the peaks associated with species like CH4, CO, and C2H4 increases with the polarization potential of the fuel cell. The opposite effect was found for the relative intensity of the molecular ion at m/z = 44, which decreased with the cell polarization potential. These spectrometric characteristics indicate that the composition of the anode exhaust gases is related to the polarization conditions. These results confirm that the direct propane electro-oxidation was responsible for the operation of the DPFC.

Catalytic Activity of Carbon-Supported Electrocatalysts for Direct Ethanol Fuel Cell Applications

The catalytic activity of some carbon-supported electrocatalysts toward the ethanol oxidation reaction EOR and the oxygen reduction reaction ORR in the presence of ethanol was investigated. It was found that anodes based on PtSn alloys possess a higher catalytic activity for the EOR, compared to other anode catalysts such as Pt, PtRu, and Pt oxide. For example, when tested in a direct ethanol fuel cell, a twofold increase was observed in the current density obtained from a PtSn–Pt membrane electrode assembly MEA configuration at 0.4 V, compared to the current density obtained from a PtRu–Pt MEA. Furthermore, it was found that cathode catalysts based on Ru/C exhibit a good catalytic activity for the ORR and a high selectivity for this reaction in the presence of ethanol. The results showed that in the presence of 0.125, 0.25, or 0.5 M ethanol concentrations, a decrease in the onset potential of about 60, 62, and 68 mV emerged, respectively. These values were about ten times lower than those measured for some Pt-based cathode catalysts tested in this study in the presence of 0.125 M EtOH. Accordingly, an ethanol fuel cell based on a PtSn/C anode and a Ru/C cathode showed important current density vs cell voltage characteristics.

Performance of Pd/C Cathode Electro-Catalysts for the ORR in Sulfuric Acid Containing Small Organic Molecules

Besides the high activity for the ORR, another interesting property of Pd-based electrocatalysts is their high degree of tolerance to the presence of organic molecules in a medium saturated with oxygen. It has been demonstrated that Pd or Pd-alloys possess surface properties that make them promising cathode materials for DAFCs applications. The tolerance of this family of catalytic materials to organic substances such as methanol or ethanol is remarkable and it has been shown that a negligible variation in onset potential of the ORR from the value in the absence to the value in the presence of organic molecules is observed for Pd and Pd-Co. This behavior contrast with that of Pt-alone electrocatalysts, which are greatly affected by organic molecules in terms of onset potential of the ORR and ORR overpotential.

EDITORIAL - IX Congress of the Mexican Hydrogen Society

In recent years, fundamental and applied scientific research on alternative energy sources has received more attention from the Mexican Government, through the National Council for Science and Technology (CONACYT). This shift in strategy seeks for alternatives for an oil-dependent economy, and is related to the negative trend in oil production at the main oil fields in the Gulf of Mexico. Thus, the opportunities for technology development, transfer or adaptation, are becoming increasingly attractive for sun, wind, hydrogen and fuel cells systems. In this scenario, the Mexican Hydrogen Society (SMH, Sociedad Mexicana del Hidrogeno), has played a key role in promoting the collaborative work among researchers, government officials and industry representatives through innovative projects and the dissemination of knowledge in novel H2 and fuel cell technologies. Founded ten years ago, the SMH celebrates an annual meeting and short course on hydrogen technologies, as well as multiple academic events around the calendar. Held in Saltillo, capital City of the northern state of Coahuila, September 21-22, 2009, the IX Congress of the SMH brought together over 140 delegates from Mexico, USA, Canada, France, Cuba, Spain, Brazil and Venezuela. The latest advances in hydrogen production and storage, fuel cells (PEMFCs, DAFCs, Microbial Fuel Cells, SOFCs and Integrated Fuel Cell systems), government poli- cies, novel energetic materials, climate change and environment were discussed during the meeting. The plenary lectures were delivered by Prof. John Turner, from the National Renewable Energy Laboratory (USA); Prof. Oumarou Savadogo, from the Ecole Polytechnique de Montreal (Canada); Prof. Teko Napporn, from the Universite de Poitiers (France); Prof. Omar Solorza Feria, from the Centro de Investigacion y de Estudios Avanzados –Cinvestav- at Zacatenco and Prof. Antonio Fernandez Fuentes, from Cinvestav at Saltillo, (Mexico). The Congress included 91 oral presentations, short communications and poster session. This issue of the Journal of New Materials for Electrochemical Systems is the third from the series of special issues of selected papers presented at SMH Congresses. The SMH wishes to extend its gratitude to all that have given their time and effort. We also extend special thanks to Prof. O. Sava- dogo for his support in publishing it. The X Congress of the SMH will be held September 27 to October 1, 2010, at Toluca, Mexico State, Mexico (more information at www.smh.org.mx). We look forward to seeing you there. Special Issue Selected Papers of the IX International Congress of the Mexican Hydrogen Society September 21-25, 2009 Saltillo, Coahuila, Mexico