Layered perovskite oxides Lan+1NinO3n+1 (n = 1, 2, and 3) for detecting ammonia under high temperature

Abstract A series of impedancemetric sensors for ammonia detection were fabricated using yttrium stabilized zirconia (YSZ) electrolyte and Lan+1NinO3n+1 (n = 1, 2, and 3) sensing electrodes. The sensing materials with layered perovskite structure were prepared using in-situ impregnation method and well-dispersed in YSZ porous skeleton after calcination at 900 °C. The sensing performances of the sensors with Lan+1NinO3n+1 sensing electrodes were investigated using the impedancemetric modulus |Z| and phase angle Θ as response signals, respectively. The results show that the sensor with La2NiO4+δ sensing electrode exhibits the higher response values and sensitivity compared to the sensor using La3Ni2O7-δ or La4Ni3O10-δ sensing electrodes, which is attributed to the largest NH3 adsorption capacity of La2NiO4+δ. The response signals |Z| or Θ of the La2NiO4+δ based sensor linearly depend on NH3 concentrations. The sensor hardly is insensitive to co-existing gases such as CO2, CH4, H2 and relative humidity, but NO or NO2 causes a positive error.