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

A series of impedancemetric sensors for ammonia detection were fabricated using yttrium stabilized zirconia (YSZ) electrolyte and La n+1 Ni n O 3n+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 La n+1 Ni n O 3n+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 La 2 NiO 4+ δ sensing electrode exhibits the higher response values and sensitivity compared to the sensor using La 3 Ni 2 O 7- δ or La 4 Ni 3 O 10- δ sensing electrodes, which is attributed to the largest NH 3 adsorption capacity of La 2 NiO 4+ δ . The response signals |Z| or Θ of the La 2 NiO 4+ δ based sensor linearly depend on NH 3 concentrations. The sensor hardly is insensitive to co-existing gases such as CO 2 , CH 4 , H 2 and relative humidity, but NO or NO 2 causes a positive error.