(Invited) Design of Highly Sensitive and Selective Diode-Type H2 Sensors

Abstract

Diode-type gas sensors employing an anodized TiO2 film and Pt electrodes modified with and without a small amount of Au (Au/Pt/TiO2 and Pt/TiO2, respectively) have been fabricated, and their H2-sensing properties have been investigated in detail. The Pt/TiO2 sensor showed much larger H2 response in N2 than that in air, but the surface modification of the Pt electrode with Au was quite effective in reducing the oxygen concentration dependence of the H2 response and enhancing the H2 selectivity against hydrocarbons such as C3H8 and C3H6 in both wet air and wet N2, at a forward bias of +100 mV at 250°C. In addition, the Au/Pt/TiO2 sensor showed relatively good H2-sensing properties at a low forward bias (+ 1 mV) at 250°C as well as at a forward bias of +100 mV at a low temperature (50°C) in both wet air and wet N2.