Mixed potential NH3 sensor based on La9.95K0.05Si5Al1O26.45 electrolyte and Ag doped BiVO4 sensing electrode

Mixed potential NH 3 sensors with La 9.95 K 0.05 Si 5 AlO 26.45 (LKSAO) as the solid electrolyte and Bi 1-x Ag x VO 4- δ as the sensing electrode (SE) were developed. Bi 1-x Ag x VO 4- δ was produced by solid state reaction and then characterized by XRD, XPS, SEM and EDS. As revealed from the results, The BiVO 4 samples exhibit an unchanged crystalline structure after Ag doping molar amount x≤0.2, accompanied by the growth of the particle. The sensor based on Bi 1-x Ag x VO 4 - δ exhibit the noticeably enhanced sensing performance to NH 3 in contrast to the sensor using BiVO 4 , including its larger response potential (Δ V ) and higher sensitivity. For instance, the sensors based on BiVO 4 and Bi 0.8 Ag 0.2 VO 4 - δ at 400 °C exhibit the sensitivities of -28.1 and -77.3 mV/decade, respectively. Nevertheless, by Ag doping, there is no effective improvement of the anti-interference ability of the sensor against NO and NO 2 . To address the mentioned problem, CuO, NiO and La 0.8 Sr 0.2 MnO 3 (LSM) were used as reference electrodes (RE). As suggested from the results, using CuO and NiO as the reference electrodes can obviously reduce the cross-sensitivity of the sensor to NO and NO 2 , whereas the sensitivity slightly decrease.