Activity and Durability of PEFCs Alloy Core-Shell Catalysts: Role of Surface Oxidation

Low temperature fuel cells are one of the most promising systems for the transformation of fuels into electricity in an efficient, silent, and environmentally friendly manner. In this paper we show the advances accomplished in the synthesis and a theoretical-experimental analysis of the changes induced by the Ni@Pt structure and the presence of the almost unavoidable NiO species. The synthesis of core-shell nanoparticles is described and then physical and electrochemical characterizations confirm the presence of core-shell nanoparticles with a high electrochemical activity towards the Oxygen Reduction Reaction. Periodic density functional theory calculations are used to analyze the shift in the oxidation potential for Pt, Ni@Pt and NiO@Pt with different number of layers in the shell. The changes in the electrochemical activity towards oxygen reduction are evaluated by allowing oxygen to adsorb on the surface of the nanoparticle and alloys. It is found that only the first and second layers of Pt are being affected by the presence of the Ni or NiO core.