Enhanced sensing performance of mixed potential ammonia gas sensor based on Bi0.95Ni0.05VO3.975 by silver

Bi0.95Ni0.05VO3.975 with flower-like structure was prepared by the hydrothermal method. Mixed potential type NH3 sensors were fabricated using Bi0.95Ni0.05VO3.975 as sensing electrode and La10Si5.5Al0.5O27 as electrolyte. The sensing performance of the sensors was tested in the temperature range of 500-650 °C. The test results show that the sensor exhibits excellent NH3 sensing performance. The response signals linearly depend on the logarithm of the NH3 concentrations. The sensor also shows a good stability and reproducibility. The sensor displays a good anti-interference ability to CO2, H2 and CH4. However, NO2 leads to a great influence on the response potential of the sensor. The effect of introduction of Ag into sensing electrode on sensor performances was investigated. Compared with the sensor based on Bi0.95Ni0.05VO3.975, the sensor with the Ag modified Bi0.95Ni0.05VO3.975 sensing electrode shows much higher sensitivities. More importantly, the interference from NO2 is completely eliminated and the selectivity of the sensor is significantly improved, which can be attributed to the NO2 adsorption ability of the sensing material being depressed by the introduction of Ag. This strategy provides a new idea to improve the selectivity of NH3 sensor besides sensitivity.