Bimetallic Supported Catalysts from Single-source Precursors - Atomically-Precise Methods for Synthesis of Solid Catalysts - page 81

compares very advantageously for the oxidation of methanol with other
state-of-the-art PtRu electrocatalysts prepared via traditional routes.
Many other groups have of course exploited this idea. A nice example
concerns the preparation of TiO 2 -supported PdAu bimetallic catalysts from
dendrimer-encapsulated nanoparticles. 93 The nanoparticles were syn-
thesized by co-complexation of the two corresponding metal salts within
fourth generation PAMAM dendrimers followed by chemical reduction with
NaBH 4 . The PdAu/TiO 2 composite was prepared by the sol-gel method, from
Ti(O i Pr) 4 , to contain 1 wt% of the metals after thermal treatment in flowing
O 2 and then H 2 . Thermogravimetric and elemental analyses indicated
that the dendrimer was removed during calcination. The dendrimer-
encapsulated PdAu alloy nanoparticles presented an average particle size of
1.8 nm, which increased to 3.2 nm during thermal treatment (Figure 3.13).

d n 9 r 4 n g | 5

.

Figure 3.13 TEM images and particle-size distributions for dendrimer-encapsulated
nanoparticles prepared by co-complexation of metal salts followed by
reduction: (a) and (b) as synthesized, (c) and (d) after incorporation into
the titania matrix and activation.
Reprinted with permission from R. W. J. Scott et al., J. Am. Chem. Soc.,
2005, 127, 1380. Copyright 2005 American Chemical Society.