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In view of possible use as cathode materials in polymer electrolyte membrane fuel cells, the electrocatalytic activity of palladium-cobalt catalysts for oxygen reduction has been investigated in acid medium. In this minireview, the effect of structural characteristics, such as degree of alloying, particle size and palladium segregation on the alloy surface to form a core-shell system, on the electrocatalytic activity of palladium-cobalt catalysts for oxygen reduction is discussed. Fine-tuning catalysts: The specific activity for the oxygen reduction reaction (ORR) of Pd-Co depends on the amount of cobalt alloyed and goes through a maximum (see picture). Because only part of cobalt present in the catalyst is alloyed with palladium, the amount of cobalt in the catalyst at the maximum ORR activity is higher than the amount of cobalt alloyed. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Antolini E.,Scuola di Science Dei Materiali
Applied Catalysis B: Environmental | Year: 2012

Highly dispersed catalysts on a conductive support, commonly platinum and platinum-based catalysts, are used as electrode materials in low-temperature fuel cells. Carbon blacks are commonly used as fuel cell catalysts supports, but their properties are not completely satisfactory. Thus, in the last years carbon black alternative materials such as nanostructured carbons, ceramic and polymer materials have been proposed as fuel cell catalyst supports. Very recently, in consideration of their high surface area, high conductivity, unique graphitized basal plane structure and potential low manufacturing cost, graphene nanosheets have been investigated as a support for low-temperature fuel cell catalysts. This paper presents an overview of graphene nanosheets used as supports for fuel cell catalysts. In particular, the catalytic activity and durability of catalysts supported on graphene are compared with those of catalysts supported on the commonly used carbon blacks and on carbon nanotubes, that is, on rolled graphene. © 2012 Elsevier B.V. Source

An empirical model is proposed to evaluate the contribution of alloyed and non-alloyed tin in Pt z-Sn/C catalysts to the performance of direct ethanol fuel cells (DEFCs). The model is based on the presence of SnO 2 and a Pt (1-x)S x solid solution in the bimetallic catalysts. The model predicts the dependence of the performance of a single DEFC on the total Sn content and the degree of alloying of Pt z-Sn/C catalysts used as the anode material. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Among noble metal electrocatalysts, only iridium presents high activity for both the oxygen reduction reaction (ORR) in acid medium, in the oxide form, and the oxygen evolution reaction (OER) in acid medium, alloyed with first row transition metals. Indeed, platinum, the best catalyst for the ORR, has poor activity for the OER in any form, and ruthenium, the best catalyst for the OER, in the oxide form, possess poor activity for the ORR in any form. In this work, an overview of the application of Ir and Ir-containing catalysts for the OER in proton-exchange membrane water electrolyzer anodes, for the ORR in proton exchange membrane fuel cell cathodes, and for both OER and ORR in unit regenerative fuel cell oxygen electrodes is presented. © 2014 American Chemical Society. Source

In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt-Ru and Pt-Ru-M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt-Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation. Packing a punch: The effect of structural parameters on the ethanol oxidation reaction (EOR) activity of Pt-Ru catalysts is discussed. The EOR activity versus Ru content plots of Pt-Ru catalysts prepared by using different methods go through a maximum, depending on the synthesis method (see image). Alloyed Ru supports ethanol dehydrogenation. Non-alloyed Ru, in the RuOxHy form, supports the oxidation of intermediates species in ethanol oxidation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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