Solid electrolyte-type gas sensors applied trivalent cation conducting solid electrolytes

Gas sensors with trivalent cation-conducting solids have been reviewed. In general, because ionic conductivity in solids is strongly influenced by the valence state of migrating ion species, multivalent cation conducting solids are not considered to be suitable candidates for electrochemical devices, including gas sensors. However, the discovery of highly trivalent cation conducting solids in two- or three-dimensional network structures has resulted in gas sensors with high sensing performances for CO 2 , NO x , and NH 3 even at moderate temperatures. These sensors provide a strategy for developing novel solid electrolyte-type gas sensors with enhanced selectivity, sensitivity, and long-term stability. • This article reviews the sensing property of the sensors with trivalent cation conducting solid electrolytes. • The high sensing performances were successfully obtained by applying trivalent cation conducting solid electrolyte. • Trivalent cation conductor can be a promising candidate for the key material of the solid electrolyte-type sensor.