Effects of sintering temperature on the NH3 sensing properties of Mg2Cu0.25Fe1O3.75 electrode for YSZ-based potentiometric NH3 sensor

Abstract Mg 2 Cu 0.25 Fe 1 O 3.75 mixed metal oxides have been synthesized by a co-precipitation method for fabricating NH 3 sensors electrodes. The sensor electrodes were sintered at 1000 °C, 1100 °C, 1200 °C, and 1300 °C to obtain different electrode microstructures. The electrodes were characterized by X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method and Environmental Scanning Electron Microscope (ESEM). NH 3 response performances of the NH 3 sensors to different concentrations of test gases (20–400 ppm NH 3 ) were evaluated at 400 °C. The influences of sintering temperature on the microstructures, NH 3 sensing performances, and electrochemically catalytic activity of Mg 2 Cu 0.25 Fe 1 O 3.75 electrodes were investigated. The electrode sintered at 1200 °C exhibited the biggest response (about 110 mV for 400 ppm NH 3 ) and the highest NH 3 sensitivity (72 mV/decade NH 3 ) of all the electrodes. Moreover, the response time and recovery time were within 8–4 s and 8–14 s, respectively. The enhanced NH 3 sensing performances of the Mg 2 Cu 0.25 Fe 1 O 3.75 electrodes may be attributed to electrodes׳ larger electrochemically catalytic activity and more quantity of triple-phase boundary (TPB) of the sintered three-dimensional network electrode structure.