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

Abstract

SO2 gas is toxic for humans, and extended exposure to low concentration SO2 gas can trigger bronchitis and other respiratory impairments, thus leading to an increased mortality. However, high-efficiency gas sensors for detecting SO2 have not been widely developed and applied. Here, an Au nanoparticle-modified SnO2 (AuNPs-SnO2) sensor has been successfully prepared to detect SO2 gas. The gas sensor functioned at a low temperature of 200 °C can detect SO2 concentrations as low as 500 ppb, has an excellent selectivity of SO2 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 SO2 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 SO2 sensing which depends on the in situ Fourier transform infrared spectra and other catalysis results have been proposed.