Scuola di Science Dei Materiali

Cogoleto, Italy

Scuola di Science Dei Materiali

Cogoleto, Italy
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Combinatorial chemistry and high-throughput screening represent an innovative and rapid tool to prepare and evaluate a large number of new materials, saving time and expense for research and development. Considering that the activity and selectivity of catalysts depend on complex kinetic phenomena, making their development largely empirical in practice, they are prime candidates for combinatorial discovery and optimization. This review presents an overview of recent results of combinatorial screening of low-temperature fuel cell electrocatalysts for methanol oxidation. Optimum catalyst compositions obtained by combinatorial screening were compared with those of bulk catalysts, and the effect of the library geometry on the screening of catalyst composition is highlighted. © 2016 American Chemical Society.

The application of intermetallic compounds in heterogeneous catalysis had a significant boost during the last decade. Notwithstanding the advantages related to the use of intermetallics in catalysis, random alloys, more easy to prepare, are commonly used as catalysts in low temperature polymer electrolyte membrane fuel cells (LT-PEMFC). In various papers, however, the use of Pt- and Pd-based intermetallics in LT-PEMFCs is reported. In this work an overview of the effect of the crystal structure ordering on the activity for oxygen reduction and stability of fuel cell catalysts is discussed, by comparing ordered and disordered structures with the same A/M (A = Pt, Pd; M = first row transition metal) atomic ratio and ordered structures with different A content. © 2017 Elsevier B.V.

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.

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.

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.

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.

Antolini E.,Scuola di Science dei Materiali | Antolini E.,University of Sao Paulo
Applied Catalysis B: Environmental | Year: 2010

Highly dispersed platinum or platinum-based catalysts on a conductive support are commonly used as electrode materials in low-temperature fuel cells. The performance and, in particular, the stability of these catalysts strongly depend on the characteristics of the support. Being the use of plain carbon, ceramic or polymer materials not completely satisfactory, in the last years hybrid polymer-carbon, ceramic-carbon and polymer-ceramic materials have been proposed as fuel cell catalyst supports. These hybrid materials, possessing the properties of each component, or even with a synergistic effect, would present improved characteristics with respect to the bare components.In this paper we present an overview of these hybrid materials as low-temperature fuel cell catalyst supports. The improved characteristics of the mixed supports with respect to the individual component and their effect on the electrochemical activity are highlighted. © 2010 Elsevier B.V.

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.

Antolini E.,Scuola di Science dei Materiali
Applied Energy | Year: 2011

The electrode stability is a key issue for the development of conventional hydrogen fuelled and direct internal reforming (DIR) molten carbonate fuel cells (MCFCs). While for conventional MCFC anodes the stability problem has been addressed by the addition of Al or Cr to Ni, the problems of the dissolution of the NiO cathode and of the deactivation of DIR-MCFC anodes have not been fully resolved too. This review reports recent improvements in the chemical and physicochemical stability of cathode and anode materials in MCFCs and DIR-MCFCs, respectively. © 2011 Elsevier Ltd.

Antolini E.,Scuola di Science dei Materiali | Antolini E.,University of Sao Paulo | Gonzalez E.R.,University of Sao Paulo
Journal of Power Sources | Year: 2010

The faster kinetics of the alcohol oxidation and oxygen reduction reactions in alkaline direct alcohol fuel cells (ADAFCs), opening up the possibility of using less expensive metal catalysts, as silver, nickel and palladium, makes the alkaline direct alcohol fuel cell a potentially low cost technology compared to acid direct alcohol fuel cell technology, which employs platinum catalysts. A boost in the research regarding alkaline fuel cells, fuelled with hydrogen or alcohols, was due to the development of alkaline anion-exchange membranes, which allows the overcoming of the problem of the progressive carbonation of the alkaline electrolyte. This paper presents an overview of catalysts and membranes for ADAFCs, and of testing of ADAFCs, fuelled with methanol, ethanol and ethylene glycol, formed by these materials. © 2009 Elsevier B.V. All rights reserved.

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