Impedancemetric zirconia-based sensor attached with laminated-oxide sensing-electrode aiming at highly sensitive and selective detection of propene in atmospheric air

摘要

Aiming at a sensitive and selective detection of very low concentrations of propene (C3H6) in an atmospheric air, the impedancemetric yttria-stabilized zirconia (YSZ)-based sensor was fabricated and examined. Among the different oxide sensing-electrodes (SEs) studied, SnO2-SE was found to give the highest sensitivity to C3H6 at 600 degrees C even in the presence of 1.35 vol.% H2O and 400 ppm CO2. Then, the selective response to C3H6 was achieved by coating of the additional oxide layer (ZnO) onto SnO2-SE, giving the laminated-type ZnO/SnO2-SE. Moreover, to improve further the sensing performances of the present sensor, ZnO powder (0-30 wt.%) was subsequently added to the SnO2 layer of the laminated ZnO/SnO2-SE. As a result, the sensor using ZnO/SnO2 (+ 20 wt% ZnO)-SE exhibited highly selective and sensitive response to C3H6 at 500 degrees C with minor cross sensitivities to other co-existing gases, such as NOx, H-2, CO and CH4. The sensitivity of the present sensor varied linearly with the logarithm of C3H6 concentration in the range of 20-100 ppb and was found to be hardly affected by the change in water vapor concentration.