Sensing properties of amperometric ppb-level NO₂ sensor based on sodium ion conductor with sensing electrodes comprising different WO₃ nanostructures

In this study, amperometric NO₂ sensors based on Na⁺ superionic conductor electrolyte and sensing electrodes with different WO₃ nanostructures (WO₃ nanoparticles, WO₃ nanosheets, and mesoporous WO₃) have been fabricated and compared. Sensing properties, such as optimum test temperature, sensitivity, repeatability, and selectivity have been determined and compared. Compared with the literatures, the sensors, prepared using three different WO₃ nanostructures, all showed improved sensing properties to 100–1000 ppb NO₂ at low work temperatures of 100–150 °C. Among above sensors, the sensor equipped with mesoporous WO₃ sensing electrode exhibited the best amperometric sensitivity characteristics and the minimum test temperature. The relationship between the sensing properties and the mesoporous structure has also been discussed. What’s more, the sensor can test ppb-level NO₂ in low temperature, which makes it possible to monitor low concentrations of NO₂ in the air.