Enhancement in the sensitivity and selectivity of Cu functionalized MoS2 nanoworm thin films for nitrogen dioxide gas sensor

In this work, we report the controlled synthesis of Cu functionalized MoS2 nanoworm thin films based NO2 sensors using a reactive co-sputtering technique. Structural and surface morphological properties were studied using XRD and FESEM analysis, respectively. The surface chemistry and defects study of as-prepared samples were carried out using X-ray photoelectron spectroscopy and photoluminescence spectra, respectively. In addition, further insights into the absorbance and band gap studies were gained using UV-Visible spectroscopy. 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 developed 2D MoS2 thin-film-based sensor chip, due to its remarkable performance, might be used for low (2 ppm) detection of NO2 under a low working temperature regime.