Hydrogen sensing ability of Pd-based amorphous alloys

Pd-based amorphous alloys have been investigated as materials for hydrogen sensor. We prepared thin films of Pd–Cu–Si alloys that are typical Pd-based amorphous alloys by RF magnetron sputtering method. And we examined their H2 response by measuring the change of electric resistance of thin films exposed in N2 and H2 under various conditions. The thin films of Pd–Cu–Si amorphous alloys showed H2 responses in wide H2 concentration range from 1% to 100%. They showed negative correlation between the H2 response and temperature. The 90% response time was under 1 s at 323 K and 373 K, and it is fast enough for the hydrogen sensor of fuel cell vehicles. We also examined the effect of O2, H2O and some impurity gases (CO, CH4 and CO2) on the H2 response. We found that O2 and H2O do not affect the H2 response of the alloys, but the impurity gases delayed the H2 response time of the alloys at 323 K. However, this effect was reduced by raising the experiment temperature from 323 K to 373 K. These results indicate that the Pd–Cu–Si amorphous alloys have excellent H2 sensing ability.