Structure-Activity-Stability Relationships for Space-Confined PtxNiy Nanoparticles in the Oxygen Reduction Reaction
Mezzavilla S, Baldizzonev C, Swertz AC, Hodnik N, Pizzutilo E, Polymeros G, Keeley GP, Knossalla J, Heggen M, Mayrhofer K, Schuth F (2016)
Publication Status: Published
Publication Type: Journal article
Publication year: 2016
Journal
Publisher: AMER CHEMICAL SOC
Book Volume: 6
Pages Range: 8058-8068
Journal Issue: 12
Abstract
This study focuses on the synthesis and electrochemical performance (i.e, activity and stability) of advanced electrocatalysts for the oxygen reduction reaction (ORR), made of Pt-Ni nanoparticles embedded in hollow graphitic spheres (HGS). The mechanism of the confined space alloying, that is, the controlled alloying of bimetallic precursors with different compositions (i.e., Pt3Ni, PtNi, and PtNi3) within the HGS mesoporous shell, was examined in detail. It was found that the presence of platinum during the reduction step, as well as the application of high annealing temperatures (at least 850 degrees C for 3.Sh in Ar), are necessary conditions to achieve the complete encapsulation and the full stability of the catalysts. The evolution of the activity, the electrochemical surface area, and the residual alloy composition of the Pt-Ni@HGS catalysts was thoroughly monitored (at the macro- and nanoscale level) under different degradation conditions. After the initial activation, the embedded Pt-Ni nanoparticles (3-4 nm in size) yield mass activities that are 2- to 3.5-fold higher than that of pure Pt@HGS (depending on the alloy composition). Most importantly, it is demonstrated that under the normal operation range of an ORR catalyst in PEM-FCs (potential excursions between 0.4 and 1.0 V-RHE) both the nanoparticle-related degradation pathways (particle agglomeration) and dealloying phenomena are effectively suppressed, irrespectively of the alloy composition. Thus, the initial enhanced activity is completely maintained over an extended degradation protocol. In addition, owing to the peculiar configuration of the catalysts consisting of space-confined nanoparticles, it was possible to elucidate the impact of the dealloying process (as a function of alloy composition and severity of the degradation protocols) separately from other parallel phenomena, providing valuable insight into this elusive degradation mechanism.
Authors with CRIS profile
Involved external institutions
Max-Planck-Institut für Kohlenforschung (MPI KoFo) / Max Planck Institute for Coal Research
Germany (DE)
Max-Planck-Institut für Eisenforschung GmbH (MPIE) / Max Planck Institute for Iron Research
Germany (DE)
Forschungszentrum Jülich / Research Centre Jülich (FZJ)
Germany (DE)
Germany (DE)
Max-Planck-Institut für Eisenforschung GmbH (MPIE) / Max Planck Institute for Iron Research
Germany (DE)
Forschungszentrum Jülich / Research Centre Jülich (FZJ)
Germany (DE)
How to cite
APA:
Mezzavilla, S., Baldizzonev, C., Swertz, A.-C., Hodnik, N., Pizzutilo, E., Polymeros, G.,... Schuth, F. (2016). Structure-Activity-Stability Relationships for Space-Confined PtxNiy Nanoparticles in the Oxygen Reduction Reaction. ACS Catalysis, 6(12), 8058-8068. https://doi.org/10.1021/acscatal.6b02221
MLA:
Mezzavilla, Stefano, et al. "Structure-Activity-Stability Relationships for Space-Confined PtxNiy Nanoparticles in the Oxygen Reduction Reaction." ACS Catalysis 6.12 (2016): 8058-8068.
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