Chemistry Reference
In-Depth Information
Figure 6.3 shows the effect of different metal deposits (as islands equivalent to a few
monolayers with about 90% surface coverage) on the photocurrent of
p
-Si.
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The shift
of the
i-V
curve from that of bare material is due to the catalytic effect of the metal on
exchange
hydrogen evolution. For a metal deposit the photocurrent is parallel to the
current density for the dark evolution of Pt, as a catalyst, has the highest exchange
current whereas Pb, as an inhibitor, has a very low exchange current.
Hydrogen evolution on
p-
Si can also be catalyzed by adding a redox species
to the solution as shown in Fig. 6.4.
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The reactions involved are postulated by
Bookbinder
et al
.
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as
