Ordered Mesoporous Carbons as Catalyst Support for PEM Fuel Cells E. P. Ambrosio 1 , M. A. Dumitrescu 1 , C. Francia 1 , C. Gerbaldi 1 and P. Spinelli 1 * 1 Department of Materials Science and Chemical Engineering, Politecnico di Torino, Italy Received August 28, 2008; accepted October 21, 2008 1 Introduction The increasing interest in proton exchange membrane fuel cells (PEMFC) as possible devices to face some of the strin- gent energetic problems gave rise, in recent years, to a vast amount of scientific and technological work aiming at improving the performance of such systems. Among various areas of potential improvement, the kinetics of the oxygen reduction reaction (ORR) is one of the most important and it has been addressed taking into account the need for a good catalyst activity, commonly Pt or Pt-based alloys, at a reduced load of the costly metal catalyst. If the total performance of the catalytic layer is considered, not only the true electrocata- lytic effect but also the effectiveness of the carbon support of the catalyst is another interesting possibility of improvement of the electrode performance without increase in the Pt load. To this aim, new materials for the carbon support of the catalyst were investigated in recent years. Particularly, ordered mesoporous carbons (OMC), because of their high surface area and regular structure, were proposed to improve the homogeneous highly dispersed distribution of the catalyst particles. The interesting feature of OMC structure is the pres- ence of uniform mesopores originated by periodic arrays of carbon nanorods [1]. Literature data indicate for these materi- als very high values of specific surface area of up to 2,000 m 2 g –1 , uniform pore diameters of 2–10 nm and very good thermal, chemical and mechanical stability. The effec- tiveness of a Pt-based FC catalyst strongly depends on the size and distribution of metal particles [2–3]; this is particu- larly true in the case of the ORR, for which the good disper- sion of the catalyst particles was proved to markedly enhance the electrode kinetics. It is also very important to achieve a good electric contact between the electronic conductors (car- bon support and metal catalyst) and the ionic conductor (polymeric electrolyte); this requirement, frequently referred to as the three-phase-boundary (TPB) condition, is necessary for the electrode sites where the reactant gases undergo the electrochemical reaction. When investigating new electrodes as possible substitute to the commonly used Pt/C Vulcan electrodes, the whole preparation of the membrane electrode assembly (MEA) must be carefully considered to account for all the aspects previously outlined. The scope of the present communication is to present pre- liminary results with Pt/OMC electrocatalysts for the O 2 elec- trode to be used in PEM FCs. We took into consideration a mesoporous catalyst support based on CMK3 type of carbon, which is obtained from a SBA-15 silica template. Structural and morphological characterisation of this carbon support has been recently reported [4], together with electrochemical – [ * ] Corresponding author, paolo.spinelli@polito.it Abstract Preliminary results on Pt-based electrocatalysts prepared with CMK3 mesoporous carbons are presented. The electro- catalytic performance towards the oxygen reduction reaction (ORR) was compared to that of commercial Pt/C-Vulcan catalysts with the same Pt content. Polarisation tests were carried out with a single PEM fuel cell containing the Pt/ OMC cathodes. The analysis of these tests, based on a semi- empirical determination of the various polarisation terms, showed an interesting catalytic activity for ORR for the cath- odes prepared with mesoporous carbon supports. The preli- minary results indicate some critical aspects which need further investigation to improve the ohmic resistance limita- tion of these materials. Particularly, the variation of the grain size distribution with the Pt content and the effective distri- bution of Nafion ® on the OMC surface should be consid- ered. Keywords: Oxygen Reduction Reaction, Pt-Based Electroca- talysts, PEM Fuel Cells, PEMFC Model FUEL CELLS 09, 2009, No. 3, 197–200 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 197 COMMUNICATION DOI: 10.1002/fuce.200800082