Shown in Fig. 9(a) and (b) is the variations in the electrical
resistance of Pt on pSiC with pore diameters of 25 and
60 nm, respectively, at hydrogen concentrations in the range of
110–410 ppm. The sample with a pore diameter of 25 nm exhibited
a stable response and recovery transition with respect to the
hydrogen concentration. However, the sample composed of Pd on
60 nm pSiC still showed unstable sensing characteristics. With a
pore diameter of 25 nm, the response factor increased from 2.02 to
2.64 with an increase in the hydrogen concentration from 110 ppm
to 410 ppm.