Highly sensitive and low detection limit of resistive NO2 gas sensor based on a MoS2/graphene two-dimensional heterostructures

The atomic-layer thickness of two-dimensional (2D) materials allows efficient interaction with gas molecules, promotes charge transfer inside these materials, and allows fast absorption/desorption of gas molecules on their surface. 2D materials such as graphene, transition metal dichalcogenides (e.g., MoS₂), and phosphorene are promising gas sensor components, exhibiting the advantages of high surface-to-volume ratio, low noise levels, and sensitivity of electronic properties to changes in the surrounding environment. Herein, we performed large-scale thermal chemical vapor deposition (CVD) of MoS₂ on graphene and used the prepared hybrid to construct a resistive NO₂ gas sensor, which showed high sensitivity, good selectivity and a low detection limit (0.2 ppm), exhibiting the additional advantages of broad detection (0.2–100 ppm) and working temperature (25–200 °C) ranges. The excellent performance of the above sensor was ascribed to the synergistic effects of MoS₂ and graphene, with the high active surface of MoS₂ leading to the exposure of a large fraction of edge sites and thus achieving excellent activity.