Pd-based catalysts: Influence of the second metal on their stability and oxygen reduction activity

PdM/C nanocatalysts (M = Ni, Fe and Co) were prepared by a polyol method varying nominal composition and reflux time. XRD studies revealed the presence of uniform strain as well as formation of an alloyed PdM phase and small crystallite size (around 2-3 nm). Accelerated stability tests showed that all catalysts prepared in this work are considerably more stable than Pd/C, at the time that demonstrated that stability depends on the second metal and follows the order PdNi > PdFe > PdCo. Studies of the oxygen reduction reaction showed that for each second metal the material with nominal composition Pd:M 70:30 prepared with reflux time of 30 min was the most active, following the order PdFe/C > PdCo > PdNi. The study of methanol tolerance showed that all the samples are inactive for methanol oxidation. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.