Structural and Properties Study of Li3 PO4 Thin Film Electrolyte for Potentiometric Nox Sensing

Li₃ PO₄ solid-state electrolyte based mixed potential NO_x gas sensors were fabricated with Ba(NO₃)₂-Li₃ PO₄ sensing electrodes and three different reference electrodes: Li₂ TiO₃-Ti0₂, sputtered Au and porous Pt electrodes. For each prototype, the sensing properties for NO₂, NO and O₂ were tested, respectively. The NO_x sensors could hardly respond to low concentration NO₂ because of electrochemical junctions. The sensor with a Li₂ TiO₃-TiO₂ reference electrode showed an outstanding sensing performance for NO₂ with smooth but sluggish response and recovery, and good selectivity to NO and O₂. The results revealed that the reference electrode materials may influence the sensing mechanism, and affect the properties of the NO_x sensors further.