Cage-bell structured Au-Pt nanomaterials with enhanced electrocatalytic activity toward oxygen reduction

Mastery over the structure of nanomaterials enables control of their properties and enhancement of their usefulness for a given application. Herein we report a template-based approach for the synthesis of Au-Pt nanomaterials with cage-bell structures. Typically, Au nanoparticles with narrow size distributions are prepared first, followed by the Ag coating. Then Pt-II ions are reduced using citrate in the presence of core-shell Au-Ag nanoparticles, resulting in the formation of core-shell-shell Au-Ag-Pt nanoparticles with discontinuous Pt shells. Finally, Ag is removed using bis(p-sulfonatophenyl) phenylphosphane, leaving behind the hydrosol containing the Au-Pt nanomaterials with cage-bell structures. The cage-bell structured Au-Pt nanomaterials have displayed superior catalytic activity toward oxygen reduction in proton-exchange membrane fuel cells because of their relatively higher surface areas than their solid counterparts (the nano-channels on the Pt shell permit the access of the inner surface areas), and the electronic coupling effect between the inner-placed Au core and the Pt shell. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.