The electrical properties of NOx-storing carbonates during NOx exposure

► In-situ investigation of carbonate lean NOx traps via impedance spectroscopy. ► Conductivity and activation energy of BaCO3 and Ba(NO3)2 in the range of 300-550 °C. ► Conductivity increases reversible sorbing NO2 on BaCO3 or K2CO3. ► Stepwise NOx accumulation detected electrically. ► K2CO3 dominates in mixture due to 5 orders of lower conductivity.