Carbon-supported platinum-based PEMFC

Due to slow kinetics, the conventional heterogeneous catalysis of the dehydrogenation of decalin in the solid-gas phase is performed at temperatures of more than 400 °C, which might result in the formation of by-products or carbonaceous deposit on the catalyst in addition to thermal energy loss. In a recent study, an attempt was made to apply the so-called liquid-film concept to hydrogen evolution from decalin with carbon-supported platinum-based catalysts under reactive distillation conditions in order to obtain high electric power suflficient for PEMFC vehicle operations in the temperature range 200-300°C [236]. 

The PE MFC has a solid ionomer membrane as the electrolyte, and a platinum, carbon-supported Pt or Pt-based alloy as the electrocatalyst. Within the cell, the fuel is oxidized at the anode and the oxidant reduced at the cathode. As the solid proton-exchange membrane (PEM) functions as both the cell electrolyte and separator, and the cell operates at a relatively low temperature, issues such as sealing, assembly, and handling are less complex than with other fuel cells. The P EM FC has also a number of other advantages, such as a high power density, a rapid low-temperature start-up, and zero emission. With highly promising prospects in both civil and military applications, PEMFCs represent an ideal future altemative power source for electric vehicles and submarines [6]. 

For polymer electrolyte membrane fuel cell (PEMFC) applications, platinum and platinum-based alloy materials have been the most extensively investigated as catalysts for the electrocatalytic reduction of oxygen. A number of factors can influence the performance of Pt-based cathodic electrocatalysts in fuel cell applications, including (i) the method of Pt/C electrocatalyst preparation, (ii) R particle size, (iii) activation process, (iv) wetting of electrode structure, (v) PTFE content in the electrode, and the (vi) surface properties of the carbon support, among others. ... 

Pekala RW, Mayer ST, Kaschmitter JL, Kong FM (1994) Carbon aerogels an update on structure, properties, and applications In Attia YA (ed) Sol-gel Process Appls, Plenum, New-York 369-377 Marie J, Berthon-Fabry S, Chatenet M, Chainet E, Pirard R, Comet N, Achard P (2007) Platinum supported on resorcinol-formaldehyde based carbon aerogels for PEMFC electrodes Influence of the carbon support on electrocatalytic properties. J Appl Electrochem 37 147-153... 

Carbon corrosion and platinum dissolution in the acidic electrolyte at elevated temperatures are well recognized from the early years of research on PAFCs and are definitely relevant to HT-PEMFCs based on the acid-doped FBI membranes. Both mechanisms are enhanced at higher temperatures and higher electrode potentials. This should be taken into account when platinum alloy catalysts are considered for the HT-PEMFC. More efforts are also needed to develop resistant support materials based on either structured carbons or non-carbon alternatives. 

Abstract To date, microcalorimetry of CO adsorption onto supported metal catalysts was mainly used to study the effects induced by the nature and the particle size of supported metallic clusters, the conditions of pretreatment and the support materials on the surface properties of the supported metallic particles. The present chapter focuses on the employ of adsorption microcalorimetry for studying the interaction of carbon monoxide with platinum-based catalyst aimed to be used in proton exchange membrane fuel cells (PEMFCs) applications. 

State-of-the-art catalyst in low and intermediate temperature polymer electrolyte membrane fuel cells (PEMFC) is a powdered material consisting of platinum nanoparticles between 1 and 5nm in size that are supported—preferably in high dispersion—on a carbon-based support. 

At present there are no alternative cathode electrocatalysts to platinum. Some platinum alloy electrocatalysts prepared on traditional carbon black supports offer a 25 mV performance gain compared with Pt electrocatalysts. However, only the more stable Pt-based metal alloys, such as PtCr, PtZr, or PtTi, can be used in PEMFC, due to dissolution of the base metal by the perfluorinated sulfonic acid in the electrocatalyst layer and membrane [26]. The focus of the continued search for the elusive electrocatalyst for oxygen reduction in acid environment should be on development of materials with required stability and greater activity than Pt. 

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