Design of highly sensitive and selective diode-type H_2 sensors

摘要

Diode-type gas sensors employing an anodized TiO_2 film and Pt electrodes modified with and without a small amount of Au (Au/Pt/TiO_2 and Pt/TiO_2, respectively) have been fabricated, and their H_2-sensing properties have been investigated in detail. The Pt/TiO_2 sensor showed much larger H_2 response in N_2 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 H_2 response and enhancing the H_2 selectivity against hydrocarbons such as C_3H_8 and C_3H_6 in both wet air and wet N_2, at a forward bias of +100 mV at 250°C. In addition, the Au/Pt/TiO_2 sensor showed relatively good H_2-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 N_2.