Highly Crystalline Multimetallic Nanoframes with Three-Dimensional Electrocatalytic Surfaces
Chen Chen, Yijin Kang, Ziyang Huo, Zhongwei Zhu, Wenyu Huang, Huolin L. Xin, Joshua Snyder, Dongguo Li, Jeffrey A. Herron, Manos Mavrikakis, Miaofang Chi, Karren L. More, Yadong Li, Nenad M. Marković, Gábor A. Somorjai, Peidong Yang, Vojislav R. Stamenković
Abstract
Control of structure at the atomic level can precisely and effectively tune catalytic properties of materials, enabling enhancement in both activity and durability. We synthesized a highly active and durable class of electrocatalysts by exploiting the structural evolution of platinum-nickel (Pt-Ni) bimetallic nanocrystals. The starting material, crystalline PtNi3 polyhedra, transforms in solution by interior erosion into Pt3Ni nanoframes with surfaces that offer three-dimensional molecular accessibility. The edges of the Pt-rich PtNi3 polyhedra are maintained in the final Pt3Ni nanoframes. Both the interior and exterior catalytic surfaces of this open-framework structure are composed of the nanosegregated Pt-skin structure, which exhibits enhanced oxygen reduction reaction (ORR) activity. The Pt3Ni nanoframe catalysts achieved a factor of 36 enhancement in mass activity and a factor of 22 enhancement in specific activity, respectively, for this reaction (relative to state-of-the-art platinum-carbon catalysts) during prolonged exposure to reaction conditions.