sensor. H2 Sensing Properties of Diode-type Sensors Fabricated with Anodized TiO2 Films Equipped with Polymer Coated Pd-Pt Electrodes

Diode-type gas sensors have been fabricated by employing anodized TiO2 films equipped with the Pd-Pt electrodes (Pd-Pt/TiO2) coated with a polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA) or polyimide (PI) film (P-n/Pd-Pt/TiO2 (P: PTFE, PVA or PI, n: polymer concentration of coating solution (wt%))), and their H2 sensing properties have been investigated under dry and wet air as well as N2 atmospheres. The coating of a relatively-thin polymer film, except for PTFE, on the electrodes likely enhanced the H2 response, in comparison with that of a Pd-Pt/TiO2 sensor. However, the H2 response tended to decrease with an increase in the thickness of these polymer films under both dry and wet air atmospheres. In addition, the H2 responses of almost all sensors in wet air were much larger than those in dry air. On the other hand, the H2 response of PI-n/Pd-Pt/TiO2 was always larger than that of Pd-Pt/TiO2 in both dry and wet air as well as N2atmospheres. The coating of PTFE on the Pd-Pt electrodes was effective in reducing the interference from humidity on the H2 response of the Pd-Pt/TiO2 sensor