Highly Sensitive Room-temperature NO2 Sensing based on SnO2/WS2 Heterojunctions

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered attention due to their rich active sites, layered structures, and suitable electronic structures for gas sensing at room temperature. However, the sensitivity, response, recovery, stability, and selectivity of TMDs-based gas sensors remain significant challenges. Therefore, it is necessary to functionalize them to improve their gas-sensing performance at room temperature. In this work, a novel gas sensor based on 0D/2D tin oxide (SnO2)/tungsten disulfide (WS2) heterojunctions was rationally designed via a sol-gel process, enabling high-performance detection of nitrogen dioxide (NO2) at room temperature. The ratio of SnO2 in the hybrid was optimized by modulating the amount of SnO2 nanoparticles. Specifically, compared with other composites with SnO2 nanoparticles, the SnO2/WS2 hybrid shows the best gas-sensitive performance when the SnO2 content is 30 mol%, with a response of 17.4 to 10 ppm NO2, which is 4.12 times higher than that of the bare WS2 gas sensor, and full recovery can be achieved. The gas sensor displays good response performance, ultra-high repeatability, and long-term stability, with excellent selectivity to NO2 against other interfering gases, including CO2, NH3, H2S, and H2. Furthermore, it is demonstrated that the greatly enhanced gas sensing performance of 0D/2D SnO2/WS2 heterojunctions can be ascribed to the unique structure and the synergistic effects between WS2 nanosheets and SnO2 nanoparticles in terms of geometry, charge transfer, and chemical aspects. This work presents a promising methodology for the rational design of high-performance gas sensing materials for room-temperature environmental monitoring.