Synthetic Routes to Shaped AuPt Core–Shell Particles with Smooth Surfaces Based on Design Rules for Au Nanoparticle Growth

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Widespread implementation of polymer electrolyte fuel cells is limited by the performance of Pt catalysts because of the high cost of Pt and the propensity for catalyst surfaces to lose activity as a result of surface poisoning. AuPt core–shell particles show potential to address these issues, but offer new challenges because of the immiscibility of Au and Pt during particle growth. In this work, AuPt core–shell particles with distinct shapes are made using a one‐pot synthesis under mild reaction conditions by exploiting the difference in reduction rate between Au and Pt ions. Employing this approach results in smooth, well‐defined surfaces, rather than the more commonly observed dendritic or island‐like Pt shells that generally form when presynthesized Au cores are used to template Au‐core/Pt‐shell particle growth. By using the established mechanisms of Au nanoparticle growth, facile modification of particle shape and size is achieved with no significant change to the Pt surface. Consequently, this approach also offers a synthetic route to the preparation of more complex AuPt nanostructures, such as those with exotic shapes and high‐energy surface facets.