This title appears in the Scientific Report :
2017
Please use the identifier:
http://dx.doi.org/10.1021/jacs.7b06846 in citations.
Tuning the Electrocatalytic Oxygen Reduction Reaction Activity and Stability of Shape-Controlled Pt–Ni Nanoparticles by Thermal Annealing − Elucidating the Surface Atomic Structural and Compositional Changes
Tuning the Electrocatalytic Oxygen Reduction Reaction Activity and Stability of Shape-Controlled Pt–Ni Nanoparticles by Thermal Annealing − Elucidating the Surface Atomic Structural and Compositional Changes
Shape-controlled octahedral Pt–Ni alloy nanoparticles exhibit remarkably high activities for the electroreduction of molecular oxygen (oxygen reduction reaction, ORR), which makes them fuel-cell cathode catalysts with exceptional potential. To unfold their full and optimized catalytic activity and s...
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Personal Name(s): | Beermann, Vera |
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Gocyla, Martin / Kühl, Stefanie / Padgett, Elliot / Schmies, Henrike / Goerlin, Mikaela / Erini, Nina / Shviro, Meital / Heggen, Marc / Dunin-Borkowski, Rafal / Muller, David A. / Strasser, Peter (Corresponding author) | |
Contributing Institute: |
Technoökonomische Systemanalyse; IEK-3 Mikrostrukturforschung; PGI-5 Physik Nanoskaliger Systeme; ER-C-1 |
Published in: | Journal of the American Chemical Society, 139 (2017) 46, S. 16536 - 16547 |
Imprint: |
Washington, DC
American Chemical Society
2017
|
DOI: |
10.1021/jacs.7b06846 |
PubMed ID: |
29019692 |
Document Type: |
Journal Article |
Research Program: |
Controlling Configuration-Based Phenomena |
Publikationsportal JuSER |
Shape-controlled octahedral Pt–Ni alloy nanoparticles exhibit remarkably high activities for the electroreduction of molecular oxygen (oxygen reduction reaction, ORR), which makes them fuel-cell cathode catalysts with exceptional potential. To unfold their full and optimized catalytic activity and stability, however, the nano-octahedra require post-synthesis thermal treatments, which alter the surface atomic structure and composition of the crystal facets. Here, we address and strive to elucidate the underlying surface chemical processes using a combination of ex situ analytical techniques with in situ transmission electron microscopy (TEM), in situ X-ray diffraction (XRD), and in situ electrochemical Fourier transformed infrared (FTIR) experiments. We present a robust fundamental correlation between annealing temperature and catalytic activity, where a ∼25 times higher ORR activity than for commercial Pt/C (2.7 A mgPt–1 at 0.9 VRHE) was reproducibly observed upon annealing at 300 °C. The electrochemical stability, however, peaked out at the most severe heat treatments at 500 °C. Aberration-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy (EDX) in combination with in situ electrochemical CO stripping/FTIR data revealed subtle, but important, differences in the formation and chemical nature of Pt-rich and Ni-rich surface domains in the octahedral (111) facets. Estimating trends in surface chemisorption energies from in situ electrochemical CO/FTIR investigations suggested that balanced annealing generates an optimal degree of Pt surface enrichment, while the others exhibited mostly Ni-rich facets. The insights from our study are quite generally valid and aid in developing suitable post-synthesis thermal treatments for other alloy nanocatalysts as well. |