Pt-based multimetallic nanoparticles (NPs) are active catalysts for various heterogeneous reactions and have particularly promising performance in catalyzing oxygen reduction reaction (ORR), but still suffer from the relatively low ORR activity and very limited ORR stability in particular. To well address these challenging issues, herein we report a robust wet-chemical approach for a new class of high-index faceted PtNi nanowires with extremely high catalytic activity and durability, in which a large density of surface steps and dangling bonds provide an additional yet very important factor for promoting the catalysis of 1D Pt alloy nanostructure. Time-dependent morphology and composition changes reveal that the formation of unique 1D PtNi nanowires includes three distinct steps: (1) the initial formation of ultrathin Pt nanowires, (2) the quick reduction of Ni species onto the preformed nanowires, and (3) the diffusion of Pt into the Ni-rich 1D nanostructures. The newly-developed approach is quite general that can be extended to produce other various 1D Pt-based bimetallic and trimetallic nanostructures, such as PtCo, PtFe, PtRh and PtNiFe, <i>etc</i>. Significantly, this synthetic advancement finally results in a new thermally and electrochemically stable 1D PtNi electrocatalyst with multiple catalysis enhancements (alloy effect, shape and high-index facet) for ORR. The specific and mass activities of 1D PtNi catalyst exhibits the impressive improvement factor of 51.1 and 34.6 over commercial Pt/C catalyst, respectively, making it among the most active electrocatalyst for ORR reported to date. More importantly, the obtained 1D PtNi nanostructures are highly stable in the ORR condition with negligible activity decay over the course of 10000 cycles and also thermally stable with no morphology change after annealing at 600 <sup>o</sup>C. This study represents an important step towards high-level control of high-performance 1D Pt alloy nanostructures with new horizons for important fundamental and technological applications.

Beyond multimetallic nanoparticles for catalysis: A general approach to stable high-index faceted multimetallic nanowires

253rd National Meeting (2017)

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