• Sasaki, K.
• Smith, B. H.
• Kaneko, K.
• Su, D.
• Darling, R. M.
• Odell, J. H.
• Humbert, M. P.
• Protsailo, L.
• Marzullo, J.
• Guerrero, S.

Abstract

A comprehensive experimental study was conducted on the dealloying of PdNi6 nanoparticles under various conditions. A two-stage dealloying protocol was developed to leach >95% of Ni while minimizing the dissolution of Pd. The final structure of the dealloyed particle was strongly dependent on the acid used and temperature. When H2SO4 and HNO 3 solutions were used in the first stage of dealloying, solid and porous particles were generated, respectively. The porous particles have a 3-fold higher electrochemical surface area per Pd mass than the solid ones. The dealloyed PdNi6 nanoparticles were then used as a core material for the synthesis of core-shell catalysts. These catalysts were synthesized in gram-size batches and involved Pt displacement of an underpotentially deposited (UPD) Cu monolayer. The resulting materials were characterized by scanning transmission electron microscopy (STEM) and in situ X-ray diffraction (XRD). The oxygen reduction reaction (ORR) activity of the core-shell catalysts is 7-fold higher than the state-of-the-art Pt/C. The high activity was confirmed by a more than 40 mV improvement in fuel cell performance with a Pt loading of 0.1 mg cm-2 by using the core-shell catalysts. © the Owner Societies 2013.

Topics

• nanoparticle
• porous
• impedance spectroscopy
• surface
• x-ray diffraction
• Oxygen
• transmission electron microscopy