Introduction Electrocatalysts for fuel cell applications are based on Pt or Pt-alloys particles dispersed on a porous carbon support [1]. Ordered mesoporous carbons (OMC) have attracted much interest due to their use as catalytic supports for fuel cell applications both for oxygen reduction and methanol oxidation. High surface area, good electrical conductivity, mesoporosity enhancing the diffusion of reactants and, finally, the possibility of an easy metal particles dispersion are some of their promising characteristics. In the present work ordered mesoporous carbon has been synthesized and has been used as platinum nanoparticles support with high specific surface area (> 1000 m 2 g -1 ). Synthesis & Characterization Mesoporous carbons (CMK type) were synthesized as inverse replicas of silica templates (SBA-15) [2]. Calcined SBA-15 was impregnated with an acidic solution of sucrose and heat-treated at 373K for six hours and subsequent at 433K for six hours. In order to perform the carbonization, a pyrolysis step is needed: typically the sample was heated at 1173K under nitrogen flow. Finally the sample was washed with a solution 3% wt of HF (Aldrich) and ethanol in order to remove the silica template from the silica- carbon composite. Platinization of the carbon support was obtained by wet impregnation. A certain amount of Chloroplatinic acid hexahydrate (H 2 PtCl 6 Aldrich) was dissolved in 20 ml of acetone. The impregnated carbon was treated under H 2 flow at 573K for 3 hours, under vacuum, to reduce the Pt. The characterization of two catalysts: namely CMK3Pt10 (around Pt 10%wt) and CMK3Pt20 (Pt 20%wt) will be presented. BET, BJH, ICP of the catalysts & their precursors:SAMPLEBETBJHICP (Pt wt.-%) SBA m 2 /g6,243 nm CMK-3961 m 2 /g3,504 nm CMK3-Pt10853 m 2 /g3,280 nm8,74% SBA m 2 /g6,081 nm CMK m 2 /g3,120 nm CMK3-Pt20754 m 2 /g3,062 nm20,07% As expected, mesoporous carbons (CMK3), obtained as inverse replicas of SBA-15 materials, have larger BET surface areas and narrow pore size distributions with respect to the silica template. The last column of the table reports the platinum weight percentage of the catalysts determined by ICP-AES analysis. Surface areas of 2 commercial carbons are reported as comparison:SAMPLE SURFACE AREA SHAWININGAM82 m 2 /g VULCAN XTC72R254 m 2 /g CMK3Pt20 catalyst Polarization curves & Impedance on a gas diffusion electrode (GDE) Test cell for LSV measurements on the GDE 0.2 mV/s, H 2 SO 4 1 M, 25°C; O 2 flow 5 ml/min; Pt load on the electrode:0.5mgcm -2 SAMPLE RTRTRTRT Pt/C 20% 0.34  cm 2 Pt/C 10% 0.58  cm 2 CMK3-Pt  cm 2 CMK3-Pt  cm 2 Evaluation of R T obtained by impedance measurements Tests in a 5cm 2 PEMFC SAMPLE RTRTRTRT CMK3-Pt m  cm 2 CMK3-Pt m  cm 2 Pt/C 10% & 20% ~96.0 m  cm 2 Evaluation of the MEA resistance with the current interruption technique PEMFC: 5cm 2 purchaised by Electrochem; fed by pure Hydrogen & Oxygen Cell temperature: 70°C The catalyst ink (catalyst+Nafion 5%) was painted on a hydrophilic layer which consisted of a commercial LT 1200-W ELAT GDL ETEK. Pt load on the gas diffusion electrode: 0.5mg/cm 2 for all the tested catalysts. The geometrical area of the electrode was 1cm 2 A three electrode cell is employed to test the electrocatalytic activity of the samples towards the oxygen reduction reaction (ORR). Oxygen (5ml/min) is continuously put into feed the electrode during operation, on the electrode backside. Tests are performed in 1M H 2 SO 4 at 25°C. Electrochemical Results Membrane: Nafion 155 DuPont purchased by Ion Power Inc. Ink deposited by painting on a gas diffusion layer: LT 1200-W ELAT GDL E-TEK The electrodes were hot pressed to the Nafion 115 membrane at 35kg/cm 2, 120°C, 2 min. Catalyst at the cathode: Pt/OMC (Pt load: 0.5mg/cm 2 ) Catalyst at the anode: Pt/C 20% Etek (Pt load: 0.5mg/cm 2 ) 5 cm 2 single cell purchaised by Electrochem Polarization curves of MEAS containing Pt/OMC catalysts at the cathode; Pt load: 0.5mgcm -2 Polarization curves on GDE in 1M H 2 SO 4 can be related to the behavior of the cathode in the MEA of a fuel cell. The best performing sample is the commercial Pt/C 20%. The performances of CMK3-Pt10 and the commercial Pt/C 10% are almost equal, which is in agreement with the charge transfer resistance values R T for the oxygen reduction reaction, obtained by the analyses of the impedence spectra In the fuel cell, the best performances observed were associated to the sample with the lower Pt content (namely CMK3Pt-10), but a lower conductivity of the mesoporous carbon support, that is related to higher values of the cell resistance (R T ), causes a loss of performances in the polarization curves of the mesoporous catalysts compared to that of commercial ones. References [1] S. H. Joo, C. Pak, D. J. You, S. Lee, H. Lee, J. Kim, H. Chang, D. Seung, Electrochim. Acta, 52 (2006) [2] J. Ding, K. Chan, J. Ren, F. Xiao, Electrochim. Acta, 50 (2005) Platinum supported on mesoporous carbon as electrocatalysts for PEM fuel cells M. Manzoli a, G. Ghiotti a, A. Chiorino a, F. Frola a, E. P. Ambrosio b, C. Francia b, S. Bodoardo b, P. Spinelli b, N. Penazzi b a Dip. di Chimica I.F.M. and NIS Centre of Excellence, Torino, 10125, Italy. b Politecnico di Torino, Dip. di Scienze dei Materiali e Ingegneria Chimica, Torino, 10125, Italy. Purpose Synthesis of the silica template (SBA-15) and of the carbon replica (CMK3) Platinum dispersion into the carbon support Investigations of the influence of the carbon and Nafion ionomer contents in the catalytic ink Comparison of the electrocatalytic performances between Pt/OMC and commercial catalysts High Resolution Transmission Microscopy (HRTEM) Analysis CMK3Pt10 catalyst 10 nm 20 nm d a =1.7nm 10 nm Pt-Vulcan 20% Electrochem TEM images of the catalysts show an homogeneous morphology and a good platinum particles dispersion. Carbon nanorods of the CMK3 structure are recognizable. The Pt particles dimensions do not vary when the platinum weight percentage increases from 10% to 20%. d a =2.0nm Commercial Pt/C catalyst 10 nm