Oxygen Vacancies as an Efficient Strategy for Promotion of Low Concentration SO2 Gas Sensing: The Case of Au-Modified SnO2

SO 2 gas is toxic for humans, and extended exposure to low concentration SO 2 gas can trigger bronchitis and other respiratory impairments, thus leading to an increased mortality. However, high-efficiency gas sensors for detecting SO 2 have not been widely developed and applied. Here, an Au nanoparticle-modified SnO 2 (AuNPs-SnO 2 ) sensor has been successfully prepared to detect SO 2 gas. The gas sensor functioned at a low temperature of 200 °C can detect SO 2 concentrations as low as 500 ppb, has an excellent selectivity of SO 2 gas, and shows good repeatability and stability through the regulation of oxygen vacancies. Meanwhile, the sensor has a response sensitivity of 10.4 for 20 ppm of SO 2 and a response/recovery time of 34 and 14 s at 200 °C, which is twice less than those of the products with the absence of oxygen vacancies. Additionally, a possible mechanism of SO 2 sensing which depends on the in situ Fourier transform infrared spectra and other catalysis results have been proposed.