%0 Journal Article
%A Gocyla, Martin
%A Kuehl, Stefanie
%A Shviro, Meital
%A Heyen, Henner
%A Selve, Soeren
%A Dunin-Borkowski, Rafal
%A Heggen, Marc
%A Strasser, Peter
%T Shape Stability of Octahedral PtNi Nanocatalysts for Electrochemical Oxygen Reduction Reaction Studied by in situ Transmission Electron Microscopy
%J ACS nano
%V 12
%N 6
%@ 1936-086X
%C Washington, DC
%I Soc.
%M FZJ-2018-07637
%P 5306 - 5311
%D 2018
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:29799722
%U <Go to ISI:>//WOS:000436910200025
%R 10.1021/acsnano.7b09202
%U https://juser.fz-juelich.de/record/858797