Catalysts for oxygen reduction reaction based on nanocrystals of a Pt or Pt-Pd alloy shell supported on a Au core

Nanocrystals (NCs) of a Pt or Pd or Pt-Pd alloy shell supported on a Au core were synthesized and dripped onto a glassy carbon (GC) surface to generate thin films. Their electrocatalytic activity towards the oxygen reduction reaction (ORR) was studied employing hydrodynamic cyclic voltammetry. Of the Pt or Pt-Pd alloy electrocatalysts synthesized over a Au core (including Au cores produced from redox-transmetalation of Ni cores), Pt-Pd@Au, Pt@Au, and Pt@Au' NCs-which contained heterogeneous NCs with spherical, triangular, squared, pentagonal, hexagonal, heptagonal, and rod-like shapes, with large (about 80 nm in several cases), well-defined crystalline structures, and evidenced a nanodendritic Pt or Pt-Pd alloy covering pattern at the NC surface-exhibited high electrocatalytic activity towards ORR and high stability (without dissolution of inner metallic nanoparticles such as Au) after 10,000 potential scans-features that suggest their utility for use in acid fuel cells.