The nature of chemisorbates formed from ammonia on gold and palladium electrodes as discerned from surface-enhanced Raman spectroscopy
2001; Elsevier BV; Volume: 3; Issue: 6 Linguagem: Inglês
10.1016/s1388-2481(01)00156-4
ISSN1873-1902
AutoresA.C.A. de Vooys, M.F. Mrozek, Marc T. M. Koper, Rutger A. van Santen, J.A.R. van Veen, M. J. Weaver,
Tópico(s)Catalytic Processes in Materials Science
ResumoThe chemisorbates formed from ammonia-containing alkaline electrolyte on gold and palladium electrodes have been identified using surface-enhanced Raman spectroscopy (SERS). On gold, a potential-dependent band at ca. 365–385cm−1 is observed, consistent with the metal–nitrogen stretch for molecular adsorbed ammonia on the basis of the frequency redshift observed upon deuteration. A similar feature is also observed on palladium, at 440–455cm−1, again consistent with chemisorbed ammonia on the basis of the H/D shift. On palladium, but not on gold, however, transfer of the electrode to ammonia-free electrolyte yielded a vibrational band at 455–465cm−1. The near-zero H/D frequency shift obtained for this irreversibly adsorbed component indicates the formation of chemisorbed atomic nitrogen on palladium. This finding is discussed in terms of the mechanism for ammonia electro-oxidation.
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