Vertically Aligned MoS2/ZnO Heterostructure for Highly Selective NH3 Sensing at Room Temperature

The proliferation of the Internet of Things and Artificial Intelligence has fueled the demand for gas sensors operating at room temperature (RT), which can enable the development of ultralow power consumption devices for large-scale networking. Molybdenum disulfide (MoS2) shows great promise as a sensing layer material for near-RT chemiresistive sensors due to its larger specific surface area and high chemical-sensing capabilities over conventional metal oxide-based sensing materials. However, the horizontally aligned MoS2-based sensors have presented several challenges, such as poor response, low sensitivity, and incomplete recovery, for near-RT gas sensing. To address these limitations, we develop vertically aligned (VA) MoS2/ZnO heterostructure sensors for highly sensitive and selective detection of NH3 analyte. The fabricated VA-MoS2/ZnO heterostructure exhibits a high sensitivity value of 2.07%/ppm, excellent reproducibility, and stability with complete recovery at RT. Furthermore, the sensing performance of the heterostructure is investigated under the influence of temperature, humidity, and various ZnO concentrations. The sensor's superior performance is attributed to the enhancement in redox power of active sites in the vicinity of a 2D/0D heterointerface. This work offers a promising route to modulating the sensing behavior of VA-MoS2 that might be further exploited to expand its sensing capabilities.