Journal of Power Sources, Vol.196, No.15, 6092-6098, 2011
Evaluation of the catalytic activity of Pd-Ag alloys on ethanol oxidation and oxygen reduction reactions in alkaline medium
Pd-Ag alloys containing different amounts of Ag (8, 21 and 34 at.%) 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 degrees C under Ar stream, was used as the alloy electrode deposition process. From half-cell measurements in a 1.0 M NaOH electrolyte at congruent to 20 degrees 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 21 at.% Ag content alloy presents the highest catalytic activity for the EOR and the lowest Ag content alloy (8 at.% 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. (C) 2011 Elsevier B.V. All rights reserved.
Keywords:Ethanol oxidation reaction (EOR);Pd-Ag;Pd alloy;Oxygen reduction reaction (ORR);Direct ethanol fuel cell (DEFC);Alkaline medium