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

Abstract

Aiming at a sensitive and selective detection of very low concentrations of propene (C 3H 6) in an atmospheric air, the impedancemetric yttria-stabilized zirconia (YSZ)-based sensor was fabricated and examined. Among the different oxide sensing-electrodes (SEs) studied, SnO 2-SE was found to give the highest sensitivity to C 3H 6 at 600 °C even in the presence of 1.35 vol.% H 2O and 400 ppm CO 2. Then, the selective response to C 3H 6 was achieved by coating of the additional oxide layer (ZnO) onto SnO 2-SE, giving the laminated-type ZnO/SnO 2-SE. Moreover, to improve further the sensing performances of the present sensor, ZnO powder (0–30 wt.%) was subsequently added to the SnO 2 layer of the laminated ZnO/SnO 2-SE. As a result, the sensor using ZnO/SnO 2 (+ 20 wt.% ZnO)-SE exhibited highly selective and sensitive response to C 3H 6 at 500 °C with minor cross sensitivities to other co-existing gases, such as NO x , H 2, CO and CH 4. The sensitivity of the present sensor varied linearly with the logarithm of C 3H 6 concentration in the range of 20–100 ppb and was found to be hardly affected by the change in water vapor concentration.