Chemistry Reference
In-Depth Information
modeled by Sutton-Chen 12-6 potentials.
50
The relative stability of the
metal nanoclusters embedded on graphene surface (i.e., graphene@M
40
)is
determined by the stabilization energies (E
stab
) or the so-called binding
energy, calculated using equation (1). As is well known, the larger the sta-
bilization energy, the stronger is the binding of the guest dopant cluster to
the graphene surface. The stabilization energy per deposited metal cluster
is calculated by subtracting the energy of the optimized isolated cluster of
nuclearity 40, E(M
40
) and the optimized equilibrium energy of the graphene
supercell, E(graphene), from the total energy of the optimized composite
systems, E(graphene@M
40
), :
∆
E
stab
=
E
graphene
@
M
40
− E
graphene
− E
M
40
(1)
A summary of the results for the optimized structures for all four com-
plexes is provided in Table 1.
Table 1. Summary of results for metal nanoclusters deposited on graphene. The +ve
(-ve) sign indicates the electron transfer from graphene (metal cluster) to metal clus-
ter (graphene). The R
eq
and C.T represent the equilibrium distances of separation and
amount of charge transfer, respectively. I.E
v
(I.E
a
)andE.A
v
(E.A
a
) represent the verti-
cal (adiabatic) ionization energy and electron anity, respectively (From reference 45a).
Nanocomposites
R
eq
∆E
stab
∆E
form
C.T
I.E
v
E.A
v
(A)
(∆E
form
c
)(eV)
(eV)
(e)
(I.E
a
)
(E.A
a
)
Graphene@Pd
40
2.33
-4.74
-3.70 (-3.58)
3.62
5.78 (5.76)
-3.54 (-3.55)
Graphene@Ag
40
2.45
-2.19
-2.45 (-2.40)
2.00
4.68 (4.68)
-2.48 (-2.51)
Graphene@Pt
40
2.35
-2.86
-6.14 (-6.07)
2.41
6.82 (6.60)
-4.10 (-4.03)
Graphene@Au
40
2.83
-1.91
-4.13 (-4.03)
-0.17
4.10 (4.10)
-1.49 (-1.54)
We too have calculated the formation energies (E
form
) per metal atom
defined by equation (2) and (3) of these metal nanoclusters in presence as
well as in absence of graphene to focus on the feasibility of spontaneous for-
mation of clustering from constitutional atomic metal moiety under suitable
experimental conditions. Our results indicate that the formation energy is
slightly increased in presence of graphene, acting as a catalyst, relative to
the free metal clustering.
∆
E
form
=[
E
graphene
@
M
40
− E
graphene
−
40
∗ E
M
40
]
/
40
(2)
E
form
=[
∆
E
M
40
−
40
∗ E
M
]
/
40
(3)
