The relationship between the catalyst size and pore diameter
is summarized in Table 1. Regardless of the catalyst, better performance
was observed with pore sizes of 25 nm. The Pd hydrogen
catalyst exhibits a fast response time (10 s) and a high change in
resistivity of 2.7%. However, the Pt catalyst shows a fast recovery
time. As inferred from the table, a 25 nm pore diameter is an optimal
process parameter for a reliable and stable hydrogen sensing
system over time.
For high temperature applications, the hydrogen sensing characteristics
were measured in the range of room temperature
∼300 ◦C. The sensing response and response factor (%) of Pd-doped
pSiC at different temperatures are shown in Fig. 12(a) and (b),