function of the hydrogen flow was observed with a response time
of 12 s for the Pt on pSiC with a pore diameter of 25 nm.
The hydrogen enhancement could be attributed to the spillover
of H atoms from hydrogen molecules that dissociative chemisorbs
on the surface of the Pt nano-catalyst. The increase in the resistance
is also circumstantial evidence of the formation of H bonds on the
pSiC surface [20,21]. The resistance increased with hydrogen flow
and directly recovered to its initial value after the flow of hydrogen
was turned off. While this result is similar to that observed for the
Pd-pSiC sample, the recovery time of 12 s was slightly faster than
that seen with the Pd. However, the 60 nm pore diameter sample
deposited with Pt demonstrated unstable recovery properties. In
particular, the sample did not recover its initial resistance.