Methanol-tolerant heterogeneous PdCo@PdPt/C electrocatalyst for the oxygen reduction reaction

Abstract

We have prepared carbon-supported nanoparticles with the heterogeneous structure of a PdPt shell on a PdCo core which are effective for the oxygen reduction reaction (ORR) in the presence of methanol. The preparation was based on the galvanic replacement reaction between PdCo/C nanoparticles and PtCl 4 2-, a method of general utility which can be extended to the preparation of other core-shell electrocatalysts. The heterogeneous PdCo-core and PtPd-shell architecture was confirmed by multiple techniques including high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy. The activity of the PdCo@PdPt/C catalyst in ORR was evaluated in acidic solutions both with and without methanol (0.1 M). The results showed four to sixfold increases in activity over a standard Pt/C catalyst with no apparent loss of catalyst stability. It is inferred that the strain effect from the lattice mismatch between the shell and core components is the major contributor for the enhancement of ORR activity and selectivity. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.