TY  - JOUR
AU  - Gocyla, Martin
AU  - Kuehl, Stefanie
AU  - Shviro, Meital
AU  - Heyen, Henner
AU  - Selve, Soeren
AU  - Dunin-Borkowski, Rafal
AU  - Heggen, Marc
AU  - Strasser, Peter
TI  - Shape Stability of Octahedral PtNi Nanocatalysts for Electrochemical Oxygen Reduction Reaction Studied by in situ Transmission Electron Microscopy
JO  - ACS nano
VL  - 12
IS  - 6
SN  - 1936-086X
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2018-07637
SP  - 5306 - 5311
PY  - 2018
AB  - 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 PtNi1.5 octahedral nanoparticles inside a transmission electron microscope, in order to study their compositional and morphological changes. The starting PtNi1.5 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.
LB  - PUB:(DE-HGF)16
C6  - pmid:29799722
UR  - <Go to ISI:>//WOS:000436910200025
DO  - DOI:10.1021/acsnano.7b09202
UR  - https://juser.fz-juelich.de/record/858797
ER  -