Sierpinski gasket-like Pt-Ag octahedral alloy nanocrystals with enhanced electrocatalytic activity and stability

Architectural engineering of noble metal nanocrystals can result in structural diversity and complexity, thereby providing catalysts with multifunctional properties. Herein, a unique Sierpinski gasket-like Pt-Ag octahedral alloy nanostructure with a three-dimensional hyperbranched architecture containing abundant well-defined Pt-rich {111} stable facets and dense low-coordinated active sites is reported. Unlike the well-accepted long-range limiting diffusion govened growth model for fractal structures, our success relies on creating local depletion layer near the crystal surface by surfactant. The as-prepared Sierpinski gasket-like Pt-Ag octahedral nanocrystals allows us to achieve three milestones for electrocatalysts, i.e. high catalytic activity, great durability, and stability towards the methanol oxidation reaction in acidic media. Specifically, the catalyst shows a high specific activity (6.61 mA cm(-2), is superior than most of reported Pt-based catalysts), outstanding COads-poisoning tolerance and stability (the morphology and composition of the catalyst are preserved after 2000 cycles). This study points to a new approach to develop highly efficient catalysts in the form of fractal nanostructures with structural diversity and complexity to balance the delicate trade-off between activity and stability of catalysts.