Journal
NANO RESEARCH
Volume 9, Issue 1, Pages 149-157Publisher
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-015-0927-3
Keywords
PtNi alloy; concave; oxygen reduction reaction
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Funding
- National Science Foundation (NSF) [DMR-1437263]
- Office of Naval Research (ONR) [N00014-15-1-2146]
- U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering [DE-SC0008055]
- China Scholarship Council (CSC)
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Controlled syntheses of PtNi metal nanocrystals with unique structures for catalyzing oxygen reduction reactions (ORRs) have attracted great interest. Here, we report the one-step synthesis of single-crystal PtNi octahedra with in situ-developed highly concave features and self-confined composition that are optimal for ORR. Detailed studies revealed that the Pt-rich seeding, subsequent Pt/Ni co-reduction, and Pt-Ni interfusion resulted in uniform single-crystal PtNi octahedra, and that the combination of Ni facet segregation and oxygen etching of a Ni-rich surface led to the concavity and confined Ni content. The concave PtNi nanocrystals exhibited much higher ORR performance than the commercially available Pt/C catalyst in terms of both specific activity (29.1 times higher) and mass activity (12.9 times higher) at 0.9 V (vs. reversible hydrogen electrode (RHE)). The performance was also higher than that of PtNi octahedra without concavity, confirming that the higher activity was closely related to its morphology. Moreover, the concave octahedra also exhibited remarkable stability in ORR (93% mass activity remained after 10,000 cycles between 0.6 and 1.1 V vs. RHE) owing to the passivation of the unstable sites.
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