84
5 Adatoms, Defects, and Kink Edges
Fig. 5.2 Thickness dependence of the a Pt 4f, b In 4d, and c Se 3d XPS spectra of InSe/Pt interfaces
formed by Pt deposition. C1 and C2 indicate spin-resolved core level shift. All the Pt 4f, In 4d and
Se 3d core levels undergo redshift when the Pt adlayer thickness increases. Reprinted with copy
right permission from [30]
process. This observation suggests the presence of various iso-energetic Au isomers
on the surface and points to a relatively weak metal–oxide interaction. At higher Au
exposures, tall 3D particles develop on the ceria surface. Conductance spectroscopy
on these deposits reveals a set of unoccupied states localized in the energy region
of the Au 6p levels. Neither the topographic nor the spectroscopic data indicate a
charging of Au species on the defect-poor CeO 2 (111) surface, suggesting that Au
mainly binds in the neutral charge state [33]. However, scanning TEM revealed that
Pt (radius = 1.290–1.385 Å; 5d
9 6s
1 or 5d
10 6s
0 ) adatoms prefer sites of bridging
subsurface oxygen vacancies.
Both the real and Laplace filtered TEM images [35] in Fig. 5.3d show clearly the
Ni polarization as bright spot at graphene edges. This TEM observation and force
field MD and DFT calculations captured the catalytic action of individual Ni atoms
at the edges of a growing graphene flake at the millisecond time scale, which unveil
the mechanism governing the activity of a single-atom catalyst at work—Ni adatoms
at graphene edge lowers substantially the corresponding reaction barriers.
In contrast, XPS measurements revealed that Pt atoms equally incorporate into two
trigonal-prismatic intralayer positions existing within the InSe layer, although, at low
Pt coverage, Pt atoms prefer one of these sites, where they have a lower interaction
with Se atoms. At initial stages of Pt diffusion, isolated Pt atoms act as a surface
5 Adatoms, Defects, and Kink Edges
Fig. 5.2 Thickness dependence of the a Pt 4f, b In 4d, and c Se 3d XPS spectra of InSe/Pt interfaces
formed by Pt deposition. C1 and C2 indicate spin-resolved core level shift. All the Pt 4f, In 4d and
Se 3d core levels undergo redshift when the Pt adlayer thickness increases. Reprinted with copy
right permission from [30]
process. This observation suggests the presence of various iso-energetic Au isomers
on the surface and points to a relatively weak metal–oxide interaction. At higher Au
exposures, tall 3D particles develop on the ceria surface. Conductance spectroscopy
on these deposits reveals a set of unoccupied states localized in the energy region
of the Au 6p levels. Neither the topographic nor the spectroscopic data indicate a
charging of Au species on the defect-poor CeO 2 (111) surface, suggesting that Au
mainly binds in the neutral charge state [33]. However, scanning TEM revealed that
Pt (radius = 1.290–1.385 Å; 5d
9 6s
1 or 5d
10 6s
0 ) adatoms prefer sites of bridging
subsurface oxygen vacancies.
Both the real and Laplace filtered TEM images [35] in Fig. 5.3d show clearly the
Ni polarization as bright spot at graphene edges. This TEM observation and force
field MD and DFT calculations captured the catalytic action of individual Ni atoms
at the edges of a growing graphene flake at the millisecond time scale, which unveil
the mechanism governing the activity of a single-atom catalyst at work—Ni adatoms
at graphene edge lowers substantially the corresponding reaction barriers.
In contrast, XPS measurements revealed that Pt atoms equally incorporate into two
trigonal-prismatic intralayer positions existing within the InSe layer, although, at low
Pt coverage, Pt atoms prefer one of these sites, where they have a lower interaction
with Se atoms. At initial stages of Pt diffusion, isolated Pt atoms act as a surface