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.