Fabrication of Reactive Sputtered Deposited Cu-MoS₂ nanoworm thin film for NO₂ gas sensor

NO₂ is one of the most common atmospheric air pollutants causing lung, respiratory, and cardiovascular disease even at low concentrations. It originates mainly from vehicle emissions, burning of fossil fuels, and industrial production of nitric acids, and is a major threat to the human as well as the ecosystem. Therefore, the development of a highly sensitive and selective sensor for efficient detection of NO₂ is necessary for the well-being of human health and the environment. In the present work, we report the controlled synthesis of Cu-functionalized MoS₂ nanoworm thin films based on NO₂ sensors using a reactive co-sputtering technique. Structural and surface morphological properties were studied using XRD and FESEM analysis, respectively. The study of surface chemistry and defects of as-prepared samples was carried out using X-ray photoelectron spectroscopy and photoluminescence spectroscopy, respectively. The sensing performance of pure MoS₂ and Cu-MoS₂ thin films was studied towards nitrogen dioxide (NO₂) gas concentrations (2-200 ppm) at the optimum working temperature of 100°C. The Cu-MoS₂ sensor provides a high sensing response as compared to the pure MoS₂ thin-film sensor towards 20 ppm of NO₂ gas with a fast response and recovery time. The Cu-MoS₂ thin-film sensor is highly sensitive, stable, and selective towards NO₂ against NH₃, CO, and H₂ gases. The as-prepared 2D MoS₂ thin-film-based sensor, owing to its remarkable performance, might be used for low detection of NO₂ under a low working temperature regime.