Platinum/tin oxide/carbon cathode catalyst for high temperature PEM fuel cell

The performance of high temperature polymer electrolyte fuel cell (HT-PEMFC) using platinum supported over tin oxide and Vulcan carbon (Pt/SnOx/C) as cathode catalyst was evaluated at 160-200 degrees C and compared with Pt/C. This paper reports first time the Pt/SnOx/C preparation, fuel cell performance, and durability test up to 200 h. Pt/SnOx/C of varying SnO compositions were characterized using XRD, SEM, TEM, EDX and EIS. The face-centered cubic structure of nanosized Pt becomes evident from XRD data. TEM and EDX measurements established that the average size of the Pt nanoparticles were similar to 6nm. Low ionic resistances were derived from EIS, which ranged from 0.5 to 5 Omega-cm(2) for cathode and 0.05 to 0.1 Omega-cm(2) for phosphoric acid, doped PBI membrane. The addition of the SnOx to Pt/C significantly promoted the catalytic activity for the oxygen reduction reaction (ORR). The 7 wt.% SnO in Pt/SnO2/C catalyst showed the highest electro-oxidation activity for ORR. High temperature PEMFC measurements performed at 180 degrees C under dry gases (H-2 and O-2) showed 0.58V at a current density of 200 mA cm(-2), while only 0.40 V was obtained in the case of Pt/C catalyst. When the catalyst contained higher concentrations of till oxide, the performance decreased as a result of mass transport limitations within the electrode. Durability tests showed that Pt/SnOx/C catalysts prepared in this work were stable under fuel cell working conditions, during 200 h at 180 C demonstrate as potential cathode catalyst for HT-PEMFCs. (C) 2010 Elsevier By. All rights reserved.