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Electrooxidation of Ammonia at Tuned (100)Pt Surfaces by using Epitaxial Thin Films
Author(s) -
Galipaud Jules,
Roy Claudie,
Martin Manuel H.,
Garbarino Sébastien,
Roué Lionel,
Guay Daniel
Publication year - 2015
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201500045
Subject(s) - epitaxy , underpotential deposition , materials science , crystallite , x ray photoelectron spectroscopy , analytical chemistry (journal) , thin film , pulsed laser deposition , electrochemistry , layer (electronics) , crystallography , electrode , chemical engineering , metallurgy , chemistry , cyclic voltammetry , nanotechnology , chromatography , engineering
Pt x Ni 100− x thin films (72≤ x ≤100, 10–25 nm thick) were deposited on MgO (100) substrates by using pulsed laser deposition. As shown from X‐ray diffraction analysis, the formation of a Pt(Ni) solid solution was observed over the Ni range investigated. All PtNi‐based films showed epitaxial growth in the (100) direction at 350 °C, which is in contrast to pure Pt films, where a Ni seeding layer was required to obtain epitaxial deposits at this temperature. X‐ray photoelectron spectroscopy depth‐profile analyses showed a Ni enrichment at the PtNi/MgO interface, which may be at the origin of the epitaxial growth in the alloys. After immersion in acidic media, Ni atoms are totally dissolved from the first ten atomic layers of the PtNi films, forming pure Pt electrodes. On the basis of underpotential‐deposited hydrogen electrochemical analyses, a (100) preferential surface orientation of the crystallites originating from epitaxial growth was confirmed on both Pt seeded and Pt x Ni 100− x films. It was shown that the fraction of (100) terraces and terrace edge sites are a determining factor in the electrooxidation of NH 3 . The highest electrocatalytic activity was observed with the Pt seeded film.