Free-Standing Pt-Au Hollow Nanourchins with Enhanced Activity and Stability for Catalytic Methanol Oxidation

Controlling the morphology of Pt-Au bimetal nanostructures can provide a great opportunity to increase their catalytic activity on a Pt mass basis and improve their durability at the same time. In this study, we synthesized Pt-on-Au hollow urchinlike nanoparticles (NPs), which present a structure consisting of a monolayer of small Pt NPs uniformly overgrown on an Au hollow nanourchin (HNU). The Pt-Au HNUs demonstrated an ultrahigh density of sharp tips and uniform coating of 2 nm Pt NPs. This well-controlled bimetal nanostructure exhibited a large electrochemical surface area, more than 2 times higher than that of Pt black, and a relatively high electrocatalytic activity toward the methanol oxidation reaction, more than 3 times greater than the Pt black and Pt/C commercial reference catalysts. Simultaneously, the Pt-Au HNUs showed greatly improved durability because of the small Pt NPs on the surface of Pt-Au HNUs which were effectively stabilized by the Au metal support.