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Main Title: Controlling Near-Surface Ni Composition in Octahedral PtNi(Mo) Nanoparticles by Mo Doping for a Highly Active Oxygen Reduction Reaction Catalyst
Author(s): Dionigi, Fabio
Weber, C. Cesar
Primbs, Mathias
Gocyla, M.
Bonastre, A. Martinez
Spöri, Camillo
Schmies, Henrike
Hornberger, Elisabeth
Kühl, Stefanie
Drnec, J.
Heggen, M.
Sharman, J.
Dunin-Borkowski, R. Edward
Strasser, Peter
Type: Article
Abstract: We report and study the translation of exceptionally high catalytic oxygen electroreduction activities of molybdenum-doped octahedrally shaped PtNi(Mo) nanoparticles from conventional thin-film rotating disk electrode screenings (3.43 +/- 0.35 A mg(pt)(-1) at 0.9 V-RHE) to membrane electrode assembly (MEA)-based single fuel cell tests with sustained Pt mass activities of 0.45 A mg(pt)(-1) at 0.9 V-cell, one of the highest ever reported performances for advanced shaped Pt alloys in real devices. Scanning transmission electron microscopy with energy dispersive X-ray analysis (STEM-EDX) reveals that Mo preferentially occupies the Pt-rich edges and vertices of the element-anisotropic octahedral PtNi particles. Furthermore, by combining in situ wide-angle X-ray spectroscopy, X-ray fluorescence, and STEM-EDX elemental mapping with electrochemical measurements, we finally succeeded to realize high Ni retention in activated PtNiMo nanoparticles even after prolonged potential-cycling stability tests. Stability losses at the anodic potential limits were mainly attributed to the loss of the octahedral particle shape. Extending the anodic potential limits of the tests to the Pt oxidation region induced detectable Ni losses and structural changes. Our study shows on an atomic level how Mo adatoms on the surface impact the Ni surface composition, which, in turn, gives rise to the exceptionally high experimental catalytic ORR reactivity and calls for strategies on how to preserve this particular surface composition to arrive at performance stabilities comparable with state-of-the-art spherical dealloyed Pt core-shell catalysts.
Subject(s): oxygen reduction reaction
surface doping
octahedral nanoparticles
PtNi alloy
membrane electrode assembly
Issue Date: 11-Sep-2019
Date Available: 4-Jan-2022
Language Code: en
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: EC/H2020/700127/EU/Integration of Novel Stack Components for Performance, Improved Durability and Lower Cost/INSPIRE
Journal Title: Nano Letters
Publisher: American Chemical Society (ACS)
Volume: 19
Issue: 10
Publisher DOI: 10.1021/acs.nanolett.9b02116
Page Start: 6876
Page End: 6885
EISSN: 1530-6992
ISSN: 1530-6984
TU Affiliation(s): Fak. 2 Mathematik und Naturwissenschaften » Inst. Chemie » FG Technische Chemie / Elektrokatalyse - Materialien
Appears in Collections:Technische Universität Berlin » Publications

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