We will present mechanisms underlying the alloying effect of Pd-based alloy catalysts on their oxygen reduction reaction (ORR) activity based on density functional theory calculations. We first look at the Pd/Pd3Co system with Pd overlayer; the results clearly highlight the synergetic interplay between the surface electronic structure modification due to the underlying Co atoms and the compressive strain caused by the Pd3Co substrate. We find that the Co atoms present in the subsurface have a profound effect on the ORR activity due to the enhanced surface-subsurface interlayer interaction via surface and subsurface dxz+yzhybridization, but the Co atoms lying below the subsurface have no significant contribution in altering the surface reactivity. We will also discuss the alloying effects of a series of Pd/Pd3X (X=Sc, Ti, V, Fe, Ni) systems and selected Pd-based ternary systems, and provide some suggestions for the design of new ORR catalysts.

ORR activity enhancement in Pd-based alloy catalysts and its underlying mechanisms: A first principles study

245th National Meeting (2013)

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