Detection mechanism of TiO2-based ceramic H2 sensors

The H2-sensing mechanism of TiO2 thick-films, deposited on Al2O3 substrates by screen-printing, is described. The role of the catalytic activity of the electrode material on the sensor response was tested using Pt and Au electrodes. An impedance analyser (20 Hz-1 MHz) was used to monitor the film impedance before and after exposure to H2. Continuous monitoring of the film resistance was performed by dc measurements. The film resistance was measured as a function of temperature (500-650 C), time, and gas phase composition (air and 0-10% H2 in a N2-based gas stream). The equilibrium gas phase pO2 (monitored with a ZrO2-based oxygen sensor) was also used to identify the H2 detection mechanism of the films. 8 refs.