Mixed potential NH3 sensor based on Ag-Doped La2NiO4+δ sensing electrode

Abstract

Perovskite-type oxides have attracted extensive focus as sensing electrodes (SE) for NH3 sensors due to their excellent gas-sensing and tunability. The mixed-potential sensor was developed using yttrium stabilized zirconia (YSZ) as the solid electrolyte and non-stoichiometric perovskite oxides La2AgxNiO4+δ (x = 0, 0.025, 0.05, 0.1) as the SE. Due to the Ag doping in the SE, the electrochemical activity was enhanced, and the adsorption capacity of NH3 was further improved. Compared with the La2NiO4+δ-SE-based sensor, the Ag doping in SE significantly improved the response value and sensitivity of the sensor, and the sensor based on La2Ag0.05NiO4+δ-SE had the best capabilities. The response to 200 ppm NH3 was 61.2 mV, and the sensitivity was 8.12 mV/decade (5–25 ppm) and 73.77 mV/decade (50–200 ppm) at 500 ℃. The sensor had a strong anti-interference ability to H2, NO2, NO, CO2, CH4, and the O2 concentrations had little effect on the sensing performance.