Evaluation of the catalytic activity of Pd–Ag alloys on ethanol oxidation and oxygen reduction reactions in alkaline medium

Abstract: Pd–Ag alloys containing different amounts of Ag (8, 21 and 34at.%) were prepared in order to evaluate their catalytic activity towards the ethanol oxidation (EOR) and oxygen reduction (ORR) reactions. A sequential electroless deposition of Ag and Pd on a stainless steel disc, followed by annealing at 650°C under Ar stream, was used as the alloy electrode deposition process. From half-cell measurements in a 1.0M NaOH electrolyte at ≅20°C, it was found that alloying Pd with Ag leads to an increases of the ORR and EOR kinetics, relative to Pd. Among the alloys under study, the 21at.% Ag content alloy presents the highest catalytic activity for the EOR and the lowest Ag content alloy (8at.% Ag) shows the highest ORR activity. Moreover, it was found that the selectivity of Pd–Ag alloys towards ORR is sustained when ethanol is present in the electrolyte. [Copyright &y& Elsevier]