Chemistry Reference
In-Depth Information
Fig. 33 Optimised structures of (
A
) bare Au
8
cluster (
yellow spheres
) adsorbed on an
F
centre of a
MgO(001) surface (O atoms are in red and Mg atoms in green); (
B
) a surface-supported gold
octamer with O
2
adsorbed at the interface between the Au
8
cluster and the magnesia surface and a
CO molecule adsorbed on the top triangular facet (the C atom is depicted in grey). The inset
between (
A
) and (
B
) shows a local-energy-minimum structure of the free Au
8
cluster in the three-
dimensional (3D) isomeric form with co-adsorbed O
2
and CO molecules. (
C
)Au
8
on the magnesia
surface [MgO(FC)] with three CO molecules adsorbed on the top facet of the cluster and an O
2
molecule preadsorbed at the interface between the cluster and the magnesia surface. Isosurfaces of
charge differences (
δρ
) are as follows: (
D
)Au
8
cluster adsorbed on defect-free MgO; (
E
)Au
8
cluster anchored to a surface
F
centre of MgO; (
F
) same as (
E
) but with O
2
and CO molecules
adsorbed on the gold cluster. Pink isosurfaces represent
δρ <
0 (depletion) and blue ones
correspond to
δρ >
0 (excess). Figure reproduced from reference [
352
]
5.2.2 Reactions of Surface Landed Gold Nanoclusters
Given Haruta's discovery that gold clusters can catalyse the oxidation of CO
(Eq. (
3
)), it is not surprising that several studies have examined how surface landed
gold nanoclusters react with mixtures of CO and O
2
as well as other substrates.
Table
11
highlighted key findings of these studies, while earlier work has been
previously reviewed [
348
]. Here we briefly discuss two important studies that use a
combination of experiments and theoretical calculations to shed light on how
surface defects and impurities can influence reactivity.
