Photo-activated MoS2 based ultrafast and reversible NO2 Sensors

Prof. Mahesh Kumar, Department of Electrical Engineering, Indian Institute of Technology Jodhpur, Jodhpur-342037, India

Continued growth of industrialization has led to the emission of various toxic and combustible gases. Among them, NO2 is one of the most poisonous gases which are mainly produced by the exhaust of automobiles and power plants. Exposure to even low concentration of NO2 results in several skin and respiratory diseases, so highly selective and sensitive gas sensors are required to detect the presence of ppm level of NO2. The emerged two-dimensional (2D) materials have gained considerable attention in chemical sensing owing to its naturally high surface–to-volume ratio. However, the poor response time and incomplete recovery at room temperature remain a challenge to develop high-performance practical gas sensor. Herein, we demonstrated ultrafast detection and reversible MoS2 gas sensor at room temperature. The sensor’s performance was investigated to NO2 at room temperature and under thermal as well as photo energy. Incomplete recovery and high response time ~250 sec of sensor were observed at room temperature. Thermal energy was enough to complete recovery but it was at the expense of sensitivity. Further, under photo excitation, MoS2 exhibited an increment in response with ultrafast response time of ~30 sec and excellent recovery to NO2 (100ppm) at room temperature. Moreover, sensor showed reliable selectivity toward NO2 against various other gases. These unprecedented results are discussed based on the degree of charge perturbation on the surface of sensing layer in the context of NO2 /MoS2 interaction under optical-illumination