Research Interests:
Research Interests:
Research Interests:
Research Interests:
Segregation phenomena of group 10 (M = Ni, Pd, Pt) transition-metals substituted in Au (1 1 1) surface and sub-surface layers are investigated by DFT periodic calculations in presence of adsorbed atomic and molecular oxygen. In contrast... more
Segregation phenomena of group 10 (M = Ni, Pd, Pt) transition-metals substituted in Au (1 1 1) surface and sub-surface layers are investigated by DFT periodic calculations in presence of adsorbed atomic and molecular oxygen. In contrast with vacuum conditions, where the metal impurities M prefer to be in the bulk of gold, in the presence of adsorbed O or O2, the impurities mainly segregate to the surface. The analysis of oxygen adsorption trends and electronic surface structures explain the change in the local atomic arrangement which is expected to occur on the surface of alloys during reaction conditions.
Research Interests:
This paper reports a systematic study of the effect of CO gas on the chemical composition at the surface of gold-based alloys. Using DFT periodic calculations in presence of adsorbed CO the segregation behavior of group 9-10-11 transition... more
This paper reports a systematic study of the effect of CO gas on the chemical composition at the surface of gold-based alloys. Using DFT periodic calculations in presence of adsorbed CO the segregation behavior of group 9-10-11 transition metals (Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co) substituted in semi-infinite gold surfaces is investigated. Although, CO is found to be more strongly adsorbed on (100) than on the (111) surface, the segregation of M impurities is found to be more pronounced on the (111) surface. The results reveal two competitive effects: the effect of M on CO and the effect of CO on M. Thus, on one hand, if M exists on the (100) gold facet, CO would be strongly adsorbed on it. But if M is initially located in the bulk, it would segregate to the (111) facet instead of the (100) in order to bind to CO.