Potentiometric NO2 gas sensor using LiRESiO4 (RE=Nd and Sm)

The properties of two kinds of lithium ionic conductors, LiNdSiO4 and LiSmSiO4 as solid electrolytes were investigated by designing the solid electrochemical cells such as (−) air, Pt|lithium ionic conductor|Au, LiNO3, NO2, O2 (+), for the NO2 gas sensor. The electromotive force, EMF, of these sensors increased linearly with an increase in the logarithmic value of nitrogen dioxide partial pressure, in accordance with Nernstʹs law. It was suggested from the slope of Nernstʹs equation that the one-electron reaction associated with the nitrogen dioxide molecule takes place at the detection electrode around 150°C. The 90% response time of EMF for an increase in NO2 concentration were within 12 min at 150°C.