Fig. 3(a) shows a typical FE-SEM image of the bimetallic Pd/Pt
nanoparticles synthesized on a Si (1 0 0) wafer via the two-step -
ray radiolysis. Pd nanoparticles were first synthesized at 10 kGy h−1
-ray exposition for 1 h. Subsequently, Pt nanoparticles were
synthesized using the same radiolysis conditions. The FE-SEM
image shows round nanoparticles with diameters of approximately
35 nm. The inset in Fig. 3(a) is a low-magnification image showing
the overall features of the bimetallic Pd/Pt nanoparticles. The
high-resolution TEM image in Fig. 3(b) shows the coexistence of Pd
and Pt nanoparticles. The interplanar distances of 0.22 and 0.23 nm
match well with the d spacings of the (1 1 1) planes of Pd and Pt
nanoparticles, respectively. Because the Pd-Pt sequential radiolysis
was conducted, core (Pd)-shell (Pt)-structured nanoparticles might
be created. In spite of thorough TEM observations, no core-shell