High-sensitivity SO2 Gas Sensor Based on YSZ Electrolyte and SrTiO3 Sensing Electrode

In this paper, SrTiO3 nano-powder was successfully prepared by the sol-gel method and used as the sensing electrode (SE) of the mixed potential SO2 sensor based on yttria-stabilized zirconia (YSZ) electrolyte. The composition and structure of the sensor were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM). The sensing properties of the sensor were tested. The morphology of the SrTiO3 particles changes with the variation of sintering temperatures from 900 to 1100°C. The size of SrTiO3 particles rises progressively as the sintering temperature increases, and the porosity of SE layer increases firstly and then decreases. The experimental results of the sensor show that the sensor with SrTiO3 SE sintered at 950°C has the best performance at the working temperature of 400°C. Under the conditions, the relationship between response values (ΔV) and the logarithm of SO2 concentrations was piecewise linear in the 0.3-0.5 ppm and 0.5-2.5 ppm ranges, with a sensitivity of 48.5 and 91.8 mV/decade, respectively. In addition, the sensor has outstanding anti-interference capability, repeatability, and long-term stability, demonstrating its utility in in-situ SO2 monitoring applications.