YSZ-based mixed potential H2S sensor using La2NiO4 sensing electrode

In this paper, mixed potential electrochemical sensors based on YSZ and La2NiO4 sensing electrode were fabricated for the sub-ppm H2S detection. The sensing materials La2NiO4 was prepared by a sol-gel method. The different moles citric acid (CA) were used as complex agent to change the micro-structure of the La2NiO4. In comparison with other mole proportions, the sensor based on La2NiO4-SE with n(CA):n(La3+ + Ni2+) = 1:1 performed the highest response of −55 mV to 500 ppb H2S at 500 °C. Moreover, a short temperature pulse of 700 °C was used to decrease the recovery time and the result shows a significance decrease for the sensor to 500 ppb H2S, which is changed from 20 min to about 150s. In addition, the sensor displayed good stability for H2S during the testing period and excellent selectivity toward H2S in comparison to the other interference gases, such as SO2, NO2, NO, CO, CH4 and NH3. The sensing mechanism related to the mixed potential ws proposed for the sensor based on YSZ and oxide electrodes.