Nanocomposites of Quasicrystal Nanosheets and MoS₂ Nanoflakes for NO₂ Gas Sensors

Abstract

Nitrogen dioxide (NO2) is one of the air pollutant gases that harms the environment, human health, and the world ecosystem. The main source of NO2 emission is the combustion engine, and therefore, it requires a gas-sensing device to monitor the emission. Herein, we report a highly sensitive and selective NO2 sensor by low-cost and scalable fabrication methods using a hybrid nanocomposite of two-dimensional (2D) Al70Co10Fe5Ni10Cu5 quasicrystal (QC) nanosheets and MoS2 nanoflakes. The 2D-QC nanosheets combined with MoS2 nanoflakes form a heterostructure, which improves the gas sensor's performance. The Al70Co10Fe5Ni10Cu5/MoS2 heterostructure showed an excellent gas-sensing response (ΔR/Ra %) of ∼66%, which is about 2.27 times higher than that of the pristine MoS2 nanoflakes-based sensor for 100 ppm NO2 at 100 °C. In addition, the hybrid nanocomposite gas sensor device also exhibited high selectivity and good sensitivity. The improvement in the gas sensor performance is explained using the density functional theory analysis, which illustrates that the 2D-QC provides a lot of active sites for the adsorption of NO2 molecules, explained using the adsorption energy, charge difference density, and Bader charges analysis. These gas-sensing results emphasize the significance of the integration of the 2D Al70Co10Fe5Ni10Cu5 QC with MoS2 nanoflakes, being useful to the design and development of NO2-based gas-sensing technology and holding great promise in environmental protection.