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Shape Stability of Octahedral PtNi Nanocatalysts for Electrochemical Oxygen Reduction Reaction Studied by in situ Transmission Electron Microscopy.
- Source :
-
ACS nano [ACS Nano] 2018 Jun 26; Vol. 12 (6), pp. 5306-5311. Date of Electronic Publication: 2018 Jun 05. - Publication Year :
- 2018
-
Abstract
- Octahedral faceted nanoparticles are highly attractive fuel cell catalysts as a result of their activity for the oxygen reduction reaction (ORR). However, their surface compositional and morphological stability currently limits their long-term performance in real membrane electrode assemblies. Here, we perform in situ heating of compositionally segregated PtNi <subscript>1.5</subscript> octahedral nanoparticles inside a transmission electron microscope, in order to study their compositional and morphological changes. The starting PtNi <subscript>1.5</subscript> octahedra have Pt-rich edges and concave Ni-rich {111} facets. We reveal a morphological evolution sequence, which involves transformation from concave octahedra to particles with atomically flat {100} and {111} facets, ideally representing truncated octahedra or cuboctahedra. The flat {100} and {111} facets are thought to comprise a thin Pt layer with a Ni-rich subsurface, which may boost catalytic activity. However, the transformation to truncated octahedra/cuboctahedra also decreases the area of the highly active {111} facets. The morphological and surface compositional evolution, therefore, results in a compromise between catalytic activity and morphological stability. Our findings are important for the design of more stable faceted PtNi nanoparticles with high activities for the ORR.
Details
- Language :
- English
- ISSN :
- 1936-086X
- Volume :
- 12
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- ACS nano
- Publication Type :
- Academic Journal
- Accession number :
- 29799722
- Full Text :
- https://doi.org/10.1021/acsnano.7b09202