Studies on PtNi alloys: AES and photoemission determination of the surface composition and interaction with oxygen and hydrogen

Elucidation of the active surface and origin of the weak metal–hydrogen bond on Ni/Pt(111) bimetallic surfaces: a surface science and density functional theory study

“…The surfaces of these alloys exhibit extremely rich, if not pathological, behavior, with varying degrees of surface segregation of one species or the other depending on the alloy composition and crystallographic surface [5,6]. Additionally, oxygen has been reported to induce segregation in Ni/Pt alloys [5,7] and carbon monoxide has been reported to reconstruct Ni films on Pt(1 1 1) [8]. The chemisorption properties of these surfaces is equally interesting; hydrogen is reported to desorb from the Pt-rich Pt 50 Ni 50 (1 1 1) alloy surface at a lower temperature than from either Pt(1 1 1) or Ni(1 1 1), while desorbing at an intermediate temperature on the Nirich Pt 10 Ni 90 (1 1 1) alloy surface [9].…”

Study of silica supported PtxNi1-x catalysts by ion scattering spectroscopy

“…Novacek et al [1,2] performed ISS experiments on polycrystals of PtxNi 1 -x after sputtering and annealing. They observed a lower Pt segregation to the surface than Sedlacek et al by XPS [8]. At low pressure (10-Tmbar), Novacek et al [1,2] showed that oxygen adsorption induced a Ni enrichment on the surface of Pt-Ni alloys, as also reported by Sedlacek et al [8] for higher oxygen pressures (0, 1 to 750 Torr).…”

“…They observed a lower Pt segregation to the surface than Sedlacek et al by XPS [8]. At low pressure (10-Tmbar), Novacek et al [1,2] showed that oxygen adsorption induced a Ni enrichment on the surface of Pt-Ni alloys, as also reported by Sedlacek et al [8] for higher oxygen pressures (0, 1 to 750 Torr). Adsorption of hydrogen on sputtered surfaces induced no significant segregation of Pt or Ni [1].…”

“…Adsorption of hydrogen on sputtered surfaces induced no significant segregation of Pt or Ni [1]. Moreover, the nickel surface segregation resulting from the oxidation treatments was only slightly offset after reduction [8]. The investigation of the PtloNi9o, Pt25Ni75 and PtsoNiso single crystals by ISS showed a dependence of the segregation on the surface orientation [3,9,10].…”

“…Surface characterisations of PtxNil_ x polycrystals and single crystals foils were previously done in vacuum and after adsorption of oxygen and hydrogen [1][2][3][8][9][10][11]. Novacek et al [1,2] performed ISS experiments on polycrystals of PtxNi 1 -x after sputtering and annealing.…”