High-temperature NO2 sensor based on aluminum/indium co-doped lanthanum silicate oxyapatite electrolyte and cobalt-free perovskite oxide sensing electrode

Al3+ and In3+ are co-doped in Si4+ site of lanthanum silicate oxyapatite (LSAIO) and the influences of Al3+/In3+ molar ratio on the properties of LSAIO are investigated. The co-doped materials achieve about 97% of the theoretical density at 1873 K. The total ionic conductivity of the Al3+/In3+ co-doped samples are much higher than those of single Al3+ or In3+ doped samples. A LSAIO electrolyte with dense/porous bilayer structure is fabricated for a solid electrolyte type NO2 sensor. The cobalt-free perovskite oxide La0.8Sr0.2Fe0.8Cu0.2O3-δ (LSFC) with the particle size of <50 nm as the sensing electrode is in-situ prepared in the porous LSAIO layer by impregnation method. The sensor exhibits excellent amperometric response characteristics to 10-200 ppm NO2 at 873-1073 K and good anti-interference ability to various coexistence gases.