Development of 2D and 3D MoS2 Nanostructure based Efficient Alcohol and Humidity Sensor Devices Employing Noble Metal as Electrodes and Surface Modifiers

Abstract

A sensor is a device that detects and converts physical or chemical stimuli into measurable outputs, mimicking human sensory systems but with far greater sensitivity. Sensors are essential for alcohol vapor and humidity detection in industrial, environmental, and healthcare sectors. Accurate sensing of methanol, ethanol, and isopropanol is crucial due to their widespread use and health hazards. Humidity control is also vital for health and product longevity. Conventional metal oxide sensors suffer from high-temperature operation and poor sensitivity. Nanostructures like nanosheets and nanoflowers, offer improved surface area, sensitivity, though challenges in selectivity and trace detection remain. Hybrid materials, combining metal oxides with graphene or noble metals, have advanced performance, with 2D materials like molybdenum disulfide (MoS2) and graphene offering superior properties. However, cost-effective, room-temperature, selective, and low-power sensing still requires further research. In this research work, 2D and 3D morphologies of MoS2 were investigated for their applicability as alcohol and humidity sensors. 2D MoS2 nanosheets sensor synthesized via electrodeposition exhibited 191.3% methanol response at 700 ppm (LoD 10 ppm) and retained performance under humidity, but was insensitive as a humidity sensor. In contrast, 3D MoS2 nanoflowers synthesized hydrothermally showed faster alcohol sensing (79.8% at 700 ppm; LoD 5 ppm) and better humidity response, though alcohol detection declined in humid conditions. Pd-functionalization improved both sensors. Pd-modified 2D MoS2 achieved 218.3% dry and 203.5% humid methanol response with 1 ppm LoD, while Pd-modified 3D MoS2 showed 91.1% methanol response and 54.4% RH response with fast kinetics. Thus, Pd-modified 2D MoS2 was found suitable for high-response alcohol sensing in humid environments, while Pd-modified 3D MoS2 was demonstrated to be effective for rapid alcohol detection and humidity sensing. newline