Mixed-Potential-Type Gas Sensors Based on Pt/YSZ Film/LaFeO3 for Detecting NO2

LaFeO3 nanoparticles were synthesized by a citrate sol–gel method and characterized by x-ray diffraction, field-emission scanning electron microscopy and x-ray photoelectron spectroscopy. A mixed-potential-type gas sensor was fabricated using LaFeO3 nanoparticles as sensing electrode, 8 mol.% Y2O3-stabilized ZrO2 (YSZ) film as electrolyte and platinum (Pt) as reference electrode. The gas-sensing properties of the gas sensor were investigated by exposing the gas sensor to the test chamber at different operating temperatures and NO2 concentrations. The results showed that the maximum response value was 164 mV to 100 ppm NO2 at 300°C, and the response and recovery times were about 73 s and 94 s to 100 ppm NO2. The gas sensor exhibited a nearly linear response at 50–400 ppm NO2, and the slope coefficient reached up to 353 mV/decade. We expect that YSZ film electrolyte can be used to fabricate high-performance mixed-potential-type gas sensors for detecting NO2.