Manufacturing and Characterization of a Potentiometric Sensor Highly Sensitive to NO2 Gas, based on K2CO3/Al2O3 Composite Material

NO2 is known as one of the most dangerous air pollutants. Even extremely low concentrations of this gas could cause life-threatening diseases such as cancer. Ppb-level detection and measurement of this gas are still serious challenges for researchers. In current work, for the first time, K2CO3/Al2O3 composite material, was employed as solid electrolyte to fabricate a potentiometric sensor for the detection of extremely low NO2 concentrations (in the ppb range) at room temperature (RT). This material was chemically synthesized through a low-cost and facile process and then loaded into appropriate templates, forming rectangular-cube shaped ceramics. A thin layer of gold nano particles was sputtered on the both sides of ceramics’ top surface to provide external electrical connections. The sensor’s dynamic responses were recorded in the concentrations ranging from 15 to 1500 ppb at RT, and it was observed that its response variations corresponds the Nernst equation. This sensor’s limit of detection (LOD) was recorded as 15 ppb which is much lower than that of the standard threshold for safe industrial environments (200 ppb). Tipically, the sensor’s response (ΔV = Vgas – Vair, where Vgas and Vair are its voltages in NO2 contaminated air and clean air, respectively) toward 60 ppb NO2 at RT is equal to 14 mV. In the entire evaluated concentration range the rise and recovery times did not exceed 80 s. Therefore, this sensor could be considered as a promising candidate for air quality control applications at RT.