A quantitative analysis of surface segregation and in-depth profile of copper-nickel alloys

Surface segregation of the metal impurity to the (100) surface of fcc metals

“…On the contrary, a positive value of a surface segregation energy E on an atomic layer implies that the impurity or solute cannot exist in that layer. Excepting Ni in Pt host, our calculated −0.40 [41] 0.11 [41] −0.13 [41] 0.15 [41] −0.37 [44] 0.233 [48] −0.49 [45] Y [42,43] Y [46,47] N [49] −0.28 [67] −0.14 [67] 0.12 [67] −0.03 [67] 0.21 [67] −0.01 [41] −0.03 [41] 0.04 [41] 0.01 [41] −0.147 [48] 0.11 [41] 0.11 [41] 0.24 [41] 0.42 [41] N [45] N [50] 0.15 [67] 0.07 [67] 0.35 [67] 0.28 [68] 0.27 [67] −0.07 [41] 0.15 [41] 0.21 [41] 0.38 [41] 0.56 [44] N [46,47] Y [43,51] N [52] N [53] 0.34 [68] −0.04 [67] 0.56 [68] 0.28 …”

Hydrogen Transfer on Metal Surfaces

“…In all three cases both the electronic structure of the alloy surface (density of electronic states) and its topography can, and often will, be greatly modified by the mutual concentrations of the constituents. In addition, surface enrichment may occur, whereby the more volatile constituent usually segregates at the surface [73]. Taking an example from sub-category (i), we consider an alloy between Ni and Cu, where Ni is the active' and Cu the inactive' component.…”

“…On heterogeneous catalyst materials consisting of small Ni, Ru, Pd, Ir or Pt clusters dispersed on a silica, alumina, titania, zirconia or carbon support, H spillover has frequently been reported [72,[100][101][102][103]. It should be noted here that the literature available for the issue "spill-over of hydrogen" certainly fills several book shelves [100], and there are very important novel aspects of energy technology where the transfer of hydrogen, e.g., from transition metal nanoparticles to carbon nanotubes is considered in order to develop new materials (carbon-metal composites) for hydrogen storage and fuel cell applications [72,73,103]. For alloys or bimetallic systems, fewer reports exist in favor of H spill-over.…”

Hydrogenation of Propyne Verifying the Harmony in Surface and Bulk Compositions for Fe-Ni Alloy Nanoparticles

“…In alloys, large differences in the surface energies of the constituents causes surface segregation, such as in Ni-Cu. 16) Besides the surface energy, the surface composition depends on the conditions used in liquidphase synthesis owing to the different reduction processes of the constituents. For example, in noble-metal core-shell nanoparticles, the tendency to form shells follows the trend Rh > Pd > Pt > Au, 17) but the surface energies follow the trend Rh > Pt > Pd > Au.…”