Structural transformations and adsorption properties of PtNi nanoalloy thin film electrocatalysts prepared by magnetron co-sputtering
Brummel O, Waidhas F, Khalakhan I, Vorokhta M, Dubau M, Kovacs G, Aleksandrov HA, Neyman KM, Matolin V, Libuda J (2017)
Publication Status: Published
Publication Type: Journal article
Publication year: 2017
Journal
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Book Volume: 251
Pages Range: 427-441
DOI: 10.1016/j.electacta.2017.08.062
Abstract
PtNi thin film catalysts provide higher activity and enhanced Pt efficiency in the oxygen reduction reaction (ORR) in comparison to pure Pt catalysts. We explored the structural transformations and degradation mechanisms in such films by cyclic voltammetry (CV), electrochemical atomic force microscopy (EC-AFM), and electrochemical infrared reflection absorption spectroscopy (EC-IRRAS) using CO as a probe. The model catalysts were prepared by magnetron sputtering, and the results were compared to reference experiments on Pt(111). Freshly prepared catalysts show two characteristic IR bands in the on-top CO region. The signal at lower wavenumbers is assigned to isolated CO on Pt sites. Based on density functional theory (DFT) calculations, we suggest that another blue-shifted CO band can be attributed to dicarbonyls on low-coordinated Pt centers, generated by the leaching of surface Ni. This band vanishes upon cycling to 1.1 V versus the reversible hydrogen electrode (V-RHE) and the catalyst shows a weak decrease in grain size in AFM. A dramatic change of the film structure is observed upon potential cycling to 1.2 V-RHE. CV indicates the formation of [110] and [100] steps and AFM points to a strong decrease in particle size. Simultaneously, EC-IRRAS shows the appearance of a new, strongly red-shifted CO band. Based on DFT, we assign these changes to a transient enrichment of Ni in the (sub) surface region. Upon cycling to higher potential, Ni is completely leached from the surface region, and large Pt particles are formed. (C) 2017 Elsevier Ltd. All rights reserved.
Authors with CRIS profile
Olaf Brummel
Lehrstuhl für Physikalische Chemie II
Fabian Waidhas
Lehrstuhl für Physikalische Chemie II
Jörg Libuda
Professur für Physikalische Chemie
Involved external institutions
Univerzita Karlova v Praze / Charles University in Prague
Czech Republic (CZ)
Universitat de Barcelona (UB) / University of Barcelona
Spain (ES)
Czech Republic (CZ)
Universitat de Barcelona (UB) / University of Barcelona
Spain (ES)
How to cite
APA:
Brummel, O., Waidhas, F., Khalakhan, I., Vorokhta, M., Dubau, M., Kovacs, G.,... Libuda, J. (2017). Structural transformations and adsorption properties of PtNi nanoalloy thin film electrocatalysts prepared by magnetron co-sputtering. Electrochimica Acta, 251, 427-441. https://dx.doi.org/10.1016/j.electacta.2017.08.062
MLA:
Brummel, Olaf, et al. "Structural transformations and adsorption properties of PtNi nanoalloy thin film electrocatalysts prepared by magnetron co-sputtering." Electrochimica Acta 251 (2017): 427-441.
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