SnS<sub>2</sub>/In<sub>2</sub>O<sub>3</sub> based gas sensors and its high performance of detecting NO<sub>2</sub> at room temperature

Abstract

NO<sub>2</sub> is a toxic gas that can react with other organic compounds in the air, causing air pollution and posing a significant harm to human health. Therefore, a gas sensor that can detect NO<sub>2</sub> is needed. However, conventional NO<sub>2</sub> gas sensors are difficult to operate at room temperature (25 ℃). In this work, NO<sub>2</sub> gas sensing based on SnS<sub>2</sub>/In<sub>2</sub>O<sub>3</sub>, which can operate at room temperature (25 ℃), is reported. In<sub>2</sub>O<sub>3</sub> quantum dots and SnS<sub>2</sub> nanosheets are prepared by the hot-injection method and hydrothermal method. By using the unique two-dimensional structure of SnS<sub>2</sub>, In<sub>2</sub>O<sub>3</sub> is decorated on it, and the composite enhances its sensing performance. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the composites prepared by 52% In<sub>2</sub>O<sub>3</sub> exhibit the best sensing response. The fabricated sensor shows a response range from 26.6 to NO<sub>2</sub> of 1×10<sup>–6</sup> in volume fraction, fast response and short recovery time at room temperature (25 ℃). Moreover, this sensor demonstrates excellent reproducibility and selectivity. The heterojunction structure increases the number of active sites and accelerates the gas transport, which promotes charge transfer and gas desorption to improve NO<sub>2</sub> gas sensing performance. This excellent sensing performance has a great application prospect in NO<sub>2</sub> detection.