The variations in the electrical resistance of the Pd-deposited
pSiC for pore diameters of 25 and 60 nm are shown in Fig. 6(a)
and (b), respectively; the hydrogen concentration was varied in the
range of 110–410 ppm. For the 25 nm sample, the resistance recovered
directly when the hydrogen flow was turned off. However, for
the 60 nm sample, the resistance still changed with the hydrogen
off and recovered after 20 s. These results could indicate that hydrogen
atoms are captured in a large pore (although the hydrogen flow
is off), thereby generating a continuous reaction with the catalyst.