A SnTe/In2S3 heterojunction gas sensor with ppb-level detection of NO2 at room temperature

NO 2 is an important component of air pollution and can have a significant impact on the environment and human respiratory health. Therefore, the requirement for real-time detection of low-concentration NO 2 from various emission sources drives the development of a specialized gas sensor. In this work, a heterojunction material based on bulk SnTe and In 2 S 3 nanosheets was developed, which can reach the ppb-level detection of NO 2 at room temperature. The sensor based on SnTe/In 2 S 3 exhibits better response (5.56) and a faster response time (58 s) for 1 ppm of NO 2 compared to the original SnTe-based sensor with the response of 1.11 and the response time of 204 s and reaches the detection limit of 75 ppb. The heterojunction sensor exhibits not only enhanced response and low detection limit but also performs improved selectivity, repeatability and long-term stability. The comprehensive performance enhancements result from both the promoted charge transfer due to the SnTe/In 2 S 3 heterojunction and abundant surface-adsorbed oxygen. The sensing mechanisms were studied through the use of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and electrochemical impedance spectroscopy.