Improved Oxygen Reduction Activity on Pt 3 Ni(111) via Increased Surface Site Availability
Vojislav R. Stamenkovic, Ben Fowler, Bongjin Simon Mun, Guofeng Wang, Philip N. Ross, Christopher A. Lucas, Nenad M. Marković- Multidisciplinary
The slow rate of the oxygen reduction reaction (ORR) in the polymer electrolyte membrane fuel cell (PEMFC) is the main limitation for automotive applications. We demonstrated that the Pt 3 Ni(111) surface is 10-fold more active for the ORR than the corresponding Pt(111) surface and 90-fold more active than the current state-of-the-art Pt/C catalysts for PEMFC. The Pt 3 Ni(111) surface has an unusual electronic structure ( d -band center position) and arrangement of surface atoms in the near-surface region. Under operating conditions relevant to fuel cells, its near-surface layer exhibits a highly structured compositional oscillation in the outermost and third layers, which are Pt-rich, and in the second atomic layer, which is Ni-rich. The weak interaction between the Pt surface atoms and nonreactive oxygenated species increases the number of active sites for O 2 adsorption.