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URL:https://murmitoyen.com/events/vanille/udem/detail/739254-model-systems-
 in-electrocatalysis
LOCATION:Université de Montréal - Pavillon J.-Armand-Bombardier\, 5155\, 
 chemin de la rampe \, Montréal\, QC\, Canada\, H3T 2B2
SUMMARY:Model systems in electrocatalysis
DESCRIPTION:Cette conférence sera prononcée par le professeur Daniel G
 uay du Centre Énergie Matériaux Télécommunications de l'Institut nati
 onal de la recherche scientifique-INRS.
\nRésumé : The intrinsic electro
 catalytic activity of materials is critically dependent on their compositi
 on and surface orientations. It is well known that the addition of a secon
 d element (bimetallic catalysts) to a metal has a profound effect on the a
 ctivity and stability of the resulting materials through ensemble\, ligand
 \, and strain effects. Likewise\, it has been known for a long time that a
 n element’s electrocatalytic activity is critically dependent upon surfa
 ce orientation and atomic surface arrangement. For example\, the following
  electrocatalytic reactions occur more easily at metals that exhibit perfe
 ct two-dimensional (100) terraces: (i) reduction of CO on copper [[1]\,[2]
 \,[3]]\; and (ii) ammonia oxidation on platinum [[4]]. Other examples abou
 nd in the literature. Accordingly\, it is of the utmost importance to cont
 rol both the composition and surface orientation of electrodes to determin
 e as precisely as possible the intrinsic electrocatalytic activity of mate
 rials.
\nPulsed laser deposition (PLD) was used to prepare epitaxial thin 
 films with well-defined composition and surface orientation. PLD is a part
 icularly attractive deposition method for the formation of epitaxial layer
 s\, since it has an unmatched ability to vary the kinetic energies of the 
 species impinging on the substrate\, along with the nature and the pressur
 e of the gas in the deposition chamber. Most importantly\, almost all elem
 ents can be deposited by PLD. Moreover\, PLD is considered a non-equilibri
 um deposition technique and several metastable alloys have been prepared s
 o far\, allowing the investigation of bimetallic compounds that are kineti
 cally stable but would be difficult to obtain by following a heat-treatmen
 t step\, as the elements are not miscible\, or only partially so.
\nIn thi
 s presentation\, we will focus on Pt alloys thin films with (100) orientat
 ion and investigate the effect of the alloying element (Ir\, Ru\, Rh and P
 d) on the electrocatalytic activity for the oxidation of ammonia (NH3). We
  first undertook a detailed investigation of the growth and the surface ar
 rangement of Pt thin films deposited on (001)-oriented MgO substrates as a
  function of the deposition conditions. It will be shown that the width of
  the (100) terraces vary with the deposition temperature and shows a maxim
 um value corresponding to 9 atoms at 325° C. Then\, we will look at the e
 ffect of the alloying element on both the growth mode and the electrocatal
 ytic activity. We will show that all Pt alloys thin films investigated her
 e exhibit only one diffraction peak (the (001) peak) and a 4-fold in-plane
  symmetry\, indicating epitaxial growth is achieved independently of the d
 eposition temperature. The pole figure indicates that all films exhibit a 
 Pt(001)[010]//[010](001)MgO cube-on-cube epitaxial relationship\, consiste
 nt with the AFM images. The effect of the alloying element (Ir\, Ru\, Rh a
 nd Pd) on the electrocatalytic activity for the oxidation of NH3 will be d
 iscussed.
\nHôte : Professeur Jean-François Masson
\nReferences
\n[[1]]
             F. Calle-Vallejo and M. T. M. Koper\, ²Theoretical 
 Considerations on the Electroreduction of CO to C2 Species on Cu(100) Elec
 trodes² Angew. Chem. 52\, 7282 (2013).
\n[[2]]            K. J.
  P. Schouten\, Z. S. Qin\, E. P. Gallent and M. T. M. Koper\, ²Two Pathwa
 ys for the Formation of Ethylene in CO Reduction on Single-Crystal Copper 
 Electrodes² J. Am. Chem. Soc. 134\, 9864 (2012).
\n[[3]]         
    K. J. P. Schouten\, E. P. Gallent\, and M. T. M. Koper\, ²Structure 
 Sensitivity of the Electrochemical Reduction of Carbon
\nMonoxide on Coppe
 r Single Crystals² ACS Catal. 3\, 1292 (2013).
\n[[4]]          
   F. J. Vidal-Iglesias\, J. Solla-Gullón\, V. Montiel\, J. M. Feliu and
  A. Aldaz\, ²Ammonia Selective Oxidation on Pt(100) Sites in an Alkaline 
 Medium² J. Phys. Chem. B 109 12914 (2005).
\nInformation supplémentaireA
 ffiche de la conférence
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