A Novel Highly Sensitive NO(2) Sensor Based on Perovskite Na(0.5+x)Bi(0.5)TiO(3−δ) Electrolyte

NO(x) is one of dangerous air pollutants, and the demands for reliable sensors to detect NO(x) are extremely urgent recently. Conventional fluorite-phase YSZ used for NO(x) sensor requires higher operating temperature to obtain desirable oxygen ion conductivity. In this work, perovskite-phase Na(0.5)Bi(0.5)TiO(3) (NBT) oxygen conductor was chosen as the solid electrolyte to fabricate a novel highly sensitive NO(2) sensor with CuO as the sensing electrode and Pt as reference electrode. Na dopped Na(0.5)Bi(0.5)TiO(3) greatly improved the sensing performance of this sensor. The optimal sensor based on Na(0.51)Bi(0.50)TiO(3−δ) exhibited good response-recovery characteristics to NO(2) and the response current values were almost linear to NO(2) concentrations in the range of 50–500 ppm at 400–600 °C. The response current value towards NO(2) reached maximum 11.23 μA at 575 °C and the value on NO(2) is much higher than other gases (CH(4), C(2)H(4), C(3)H(6), C(3)H(8), CO), indicating good selectivity for detecting NO(2). The response signals of the sensor were slightly affected by coexistent O(2) varying from 2 to 21 vol% at 575 °C. The response current value decreased only 4.9% over 2 months, exhibiting the potential application in motor vehicles.