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.

► Stability and oxygen reduction activity studies of PdM/C catalysts. ► Time of reflux during preparation influences second metal incorporation. ► Stability depends on the second metal and follows the order PdNi > PdFe > PdCo > Pd/C. ► Oxygen reduction activity depends on composition and Pd:M 70:30 are the most active. ► PdM/C catalysts are more stable and more active than Pd/C and tolerate methanol.