Application of anion-conducting lanthanum oxychloride for potentiometric chlorine gas sensors

► The influence of Na+ dopant on LaOCl crystallographic structure, phase composition and electrical properties was studied for the first time. ► Na+ does not incorporate into the LaOCl lattice; two‐phase LaOCl-NaCl system was formed. ► The presence of NaCl leads to the decrease of total electrical conductivity, especially at lover temperatures. ► The preliminary results concerning the sensing properties of the potentiometric chlorine gas sensor prototype prepared using LaOCl-NaCl as sensing electrode material and Nasicon as solid electrolyte are promising. However further studies are required in order to improve the performance of the device.