Detection mechanism of TiO2-based ceramic H2 sensors

This work reports an H-2-sensing mechanism of TiO2 thick-films, deposited on alumina substrates by screen-printing. The role of the catalytic activity of the electrode material on the sensor response was tested with platinum and gold electrodes. An impedance analyser (20 Hz-1 MHz) was used to monitor the film impedance before and after exposure to H-2. Continuous monitoring of the film resistance was performed with a simple dc measurement. The film resistance was measured as a function of temperature (500-650 degrees C), time, and gas phase composition (air and 0-10% H-2 in a N-2-based gas stream). The equilibrium gas phase PO2 (monitored with a zirconia-based oxygen sensor) was also used to identify the hydrogen detection mechanism of the films. (C) 1999 Elsevier Science Limited. All rights reserved.