Mixed potential type ammonia sensor using Fe-substituted LaCoO3 sensing electrode prepared by flame spray pyrolysis

NH 3 detection is of great significance for precise control of the SCR system. In this paper, mixed potential type ammonia sensor using LaCo 1-x Fe x O 3 sensing electrode, YSZ electrolyte, and Pt reference electrode was developed. LaCo 1-x Fe x O 3 sensing materials were made by flame spray pyrolysis technique, and Fe B-site substitution was implemented to enhance the sensing performance. It was observed that in the concentration range of 20–70 ppm at 475 °C, the sensor using LaCo 0.9 Fe 0.1 O 3 as sensing electrode exhibited the highest sensing signal and sensitivity to ammonia among the LaCo 1-x Fe x O 3 -SE sensors (x = 0, 0.05, 0.1, 0.2, 0.3). A sectional linear relationship between the response value change( Δ V ) of that sensor and the logarithm of ammonia concentration within the range of 2–15 ppm and 15–70 ppm was noticed, and the sensitivities were 17.52 and 87.22 mV/decade, respectively. Its lower detection limit reached 2 ppm at 475 °C. Its excellent sensing properties are ascribed to enriched oxygen vacancies and high electrocatalytic performance of the perovskite electrode. Moreover, the sensor exhibited good selectivity against CH 4 , CO, NO, NO 2 , and good stability against oxygen and water vapor concentration fluctuation. Besides, the sensing response to 50 ppm ammonia has been tested for 22 days and only a slight fluctuation within 7 % was observed. Furthermore, the mixed potential sensing mechanism of the sensor was discussed.