Ammonia sensors based on stabilized zirconia and CoWO4 sensing electrode
Abstract A series of tungstate MWO 4 (M = Co, Zn and Ni) has been prepared by the polymeric precursor method. Meanwhile, yttria stabilized-zirconia (YSZ) based sensors using these oxides as sensing electrodes were investigated, and among the oxides tested, CoWO 4 was found to be the most suitable for the sensing electrode (SE) of the ammonia sensor. The sensor attached with CoWO 4 shows the fast response and recovery characteristics (not more than 5 s respectively) and large sensitivity (− 51 mV/decade) at elevated temperature. The electric potential difference (∆V) of the sensor varies almost linearly with the NH 3 concentrations in the examined range of 50–1000 ppm. The SEM observation reveals that the special microstructure of CoWO 4 -SE, bulky rod-like crystals coated by tiny particles, plays a significant role in sensing performance.