The Research Of NH₃ Sensors Based On Oxygen Ion Conductive Solid Electrolytes

NH₃ sensor could be used for on-line monitoring of NH₃ in vehicle exhaust,thus the development of NH₃ sensor with high sensitivity and good stability has become a hot research.Solid electrolyte type NH₃ sensor has received wide attention due to its excellent stability under the high temperature.Mixed potential type NH₃ sensors were fabricated using LSAO as solid electrolyte and TiO₂ as the sensing electrode.The porous layer of LSAO electrolyte obviously enhanced sensor performance.?-TiO₂ based sensor exhibited better sensing property to NH₃ than ?-TiO₂ based sensor.The best calcining temperature for the sensor based on ?-TiO₂ was 900?,the potential values of the sensor response to NH₃ linearly depended on the logarithm of NH₃ concentrations at 450⁶00? and the sensitivity reached 169.7m V/decade at 500 ?.High temperature treatment and V₂O₅ additions caused ?-TiO₂ transformation into ?-TiO₂.As a result,the sensor sensitivity decreased.LSAO based mixed potential type NH₃ sensors were fabricated using 0.5 at% Ni doped BiVO₄ prepared by hydrothermal method as sensing electrode.The effect of loading Ag on sensor performances was investigated.The response values and sensitivities of BiVO₄+0.5 at% Ni were both enhanced significantly after loading Ag,what's more,the selectivity of the sensor to NO₂ was improved significantly.The TiO₂@WO₃ core-shell composite was prepared by a hydrothermal synthesis method.The sensor based on TiO₂@WO₃ sensing electrode possessed greatly better NH₃ sensing properties including higher and more stable response value and faster response rate compared to the sensor using TiO₂,WO₃ or TiO₂/WO₃ mixture sensing electrode at400⁵50 ?.The responding potential values of the sensor with TiO₂@WO₃ sensing electrode exhibited a linear dependence on the logarithm of the NH₃ concentrations.The highest NH₃ sensitivity of 74.8 m V/decade was achieved at 450?.In the meantime,the sensors also showed well anti-interference capability to CH₄,CO₂ and H₂,but a noticeable cross sensitivity toward NO₂ was observed.