Low O2 dissociation barrier on Pt(111) due to adsorbate-adsorbate interactions

• Published in: The Journal of chemical physics Vol. 133; no. 22; p. 224701
• Main Authors: Miller, D J, Öberg, H, Näslund, L-Å, Anniyev, T, Ogasawara, H, Pettersson, L G M, Nilsson, A
• Format: Journal Article
• Language: English
• Published: United States 14.12.2010
• ISSN: 1089-7690
• DOI: 10.1063/1.3512618

O(2) dissociation on Pt(111) has been followed at low and saturation coverage using temperature-programmed x-ray photoelectron spectroscopy and simulated with mean-field kinetic modeling, yielding dissociation (E(a)) and desorption (E(d)) barriers of 0.32 and 0.36 eV, respectively. Density functional theory calculations show that E(a) is strongly influenced by the O-O interatomic potential in the atomic final state: of the supercells considered, that which maximizes attractive third-nearest-neighbor interactions in the atomic final state yields both the lowest computed dissociation barrier (0.24 eV) and the best agreement with experiment. It is proposed that the effect of adsorbate-adsorbate interactions must be considered when modeling catalytic processes involving dissociative steps.