Oxygen reduction reaction activity of Pd-based bimetallic electrocatalysts in alkaline medium

摘要

A series of 10 wt.% Pd-M (M: Ag, Ca, Co, Cu, Fe, Ni, Sn, Zn) / C electrocatalysts, with Pd to M mass ratio equal to 3:1, were prepared via the wet impregnation method, physicochemically characterized employing various techniques (BET, XRD, TEM, XPS) and electrochemically characterized towards their ORR activity in 0.1M KOH solution using the RDE technique. Presence of alloy formations was revealed in the bulk of the Pd-Zn and Pd-Sn electrocatalysts. The highest ORR activity was exhibited by the Pd-Cu electrocatalyst, surpassing the activity of the 10 wt.% Pt/C reference. Specific ORR activity higher than that of 10 wt.% Pt/C was also exhibited, in descending order, by the Pd-Zn, Pd-Sn and Pd-Ni electrocatalysts. 10 wt.% Pd/C reference electrocatalyst exhibited the lowest ORR activity among all the tested samples. The superior ORR activity of the Pd-Cu electrocatalyst was mainly associated with an optimum Pd lattice strain.