Toluene sensor combining NASICON with ZnTiO_3 electrode

摘要

A compact tubular sensor based on NASICON (sodium super ionic conductor) and ZnTiO_3 sensing electrode was designed for detection of C_7H_8. The NASICON and ZnTiO_3 material were prepared by sol-gel method, respectively. ZnTiO_3 thick film was prepared to investigate characteristics to aromatic hydrocarbon gas-toluene at various operating temperatures. The sensor using ZnTiO_3 gave excellent sensing properties to 5-50ppm C_7H_8 in air at 300-400℃. The EMF value of the sensor was almost proportional to the logarithm of C_7H_8 concentration, the sensitivity (slope) was -90 mV/decade at 350 ℃ It was also seen that the sensor showed a good selectivity to C_7H_8 against H_2S, HCHO, NH3, CH_4, C_6H_5CH_2CH_3, C_6H_6 and C_6H_4(CH_3)2. The sensor had speedy response kinetics to C_7H_8, the 90% response time to 5,10, 20, 50 ppm C_7H_8 was 15,10, 8, 5 s, respectively, and the recovery time was 25, 39, 50, 90s, respectively. Finally, a sensing mechanism was proposed.