Environmental Engineering Reference
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PVP
or
PVA
DR
SI
[AuCl
4
]
-
+
NaBH
4
[AuCl
4
]
-
NaBH
4
Au sol
[Au(en)
2
]
3+
GG
SG
DP-urea
urea
Support
cal.
[AuCl
4
]
-
AuN
2.2
O
1.2
C
0.9
H
4.2
CI
0.1
Au(OH)
3
[Au(en)
2
]
3+
cal.
NaOH
cal.
DP
cal.
PVD
CAPD
Au(PPh
3
)(NO
3
)
HAuCl
4
[Au
6
(PPh
3
)
6
](BF
4
)
2
Au(OAc)
2
M(NO
3
)
x
Na
2
CO
3
CP
IMP
Scheme 8.1
Illustration of various preparation methods for supported gold catalysts (cal.,
calcinations). Reproduced with permission from [30].
8.1.2
Charge Transfer between Gold and Metal Oxide Support
h e interaction between gold nanoparticles and the oxide support is an
important phenomenon because it modii es the electronic structure of
gold and these gold nanoparticles may play an important role in dif erent
types of chemical reaction [10, 31-36]. For example, Campbell [37] and
Goodman
et al.
[38, 39] found that metallic gold was indispensable for
the genesis of catalytic activity on Au/TiO
2
(110) model catalysts, whereas
Carrettin
et al.
[40], Schwartz
et al.
[41], Yang
et al.
[42] and Calla
et al.
[43] concluded that metallic gold nanoparticles are responsible for CO
oxidation reaction. h e cationic gold species in supported gold catalyst
are present in the form of AuO
x
or AuO(OH) [33, 36, 44, 45-48]. Bond
and h ompson [49] proposed that cationic gold naoparticles are respon-
sible for the activation of dioxygen in the catalytic process. h e positive
charge accumulated on the gold can promote adsorption of some reac-
tants, such as CO and hydrocarbons [48, 50]. In the case of negatively
charged gold nanoparticles, an extra electron from the gold readily trans-
fers to the antibonding 2π* orbital of the adsorbed O
2
, which weakens the
O-O bond and activates oxygen molecule for further catalytic reaction
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