Low Pt content on the Pd45Pt5Sn50 cathode catalyst for PEM fuel cells

Pd45Pt5Sn50 electrocatalyst was prepared by a NaBH4 reduction of PdCl2, H2PtCl6 and SnCl2 in THF at 0 degrees C. This catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) microanalysis and hydrodynamic electrochemical technique. XRD, SEM and TEM results demonstrate that the borohydrate reduction methodology enable the synthesis of conglomerated particles nanometric in size ranging from I to 6 nm. Oxygen reduction reaction (ORR) activity was investigated on carbon dispersed catalyst by rotating disk electrode (RDE) technique in H2SO4 0.5 M. The effect of temperature on the kinetics was analyzing resulting in an apparent activation energy of 42.54 +/- 1 kJ mol(-1), value which is less than the obtained for the nanostructured bimetallic PdSn electrocatalyst under the same experimental condition. The Pd45Pt5Sn50 electrocatalyst dispersed on a carbon powder was tested as cathode electrocatalyst in a membrane-electrode assembly (MEA) arriving to a power density of 210 mW cm(-2) at 0.35 V and 80 degrees C. (C) 2009 Elsevier B.V. All rights reserved.