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

Abstract

Mixed potential NH3 sensors with La9.95K0.05Si5AlO26.45 (LKSAO) as the solid electrolyte and Bi1-xAgxVO4-δ as the sensing electrode (SE) were developed. Bi1-xAgxVO4-δ was produced by solid state reaction and then characterized by XRD, XPS, SEM and EDS. As revealed from the results, The BiVO4 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 Bi1-xAgxVO4-δ exhibit the noticeably enhanced sensing performance to NH3 in contrast to the sensor using BiVO4, including its larger response potential (ΔV) and higher sensitivity. For instance, the sensors based on BiVO4 and Bi0.8Ag0.2VO4-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 NO2. To address the mentioned problem, CuO, NiO and La0.8Sr0.2MnO3 (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 NO2, whereas the sensitivity slightly decrease.