Vertically aligned MoSe2-WS2 nanoworms heterojunction towards room temperature NO2 gas sensors

Gas sensing devices have gained substantial attention by using semiconducting heterojunctions composed of two-dimensional (2D) transition metal dichalcogenide (TMDs) materials, offering increased sensitivity, stability, selectivity, and full recoverability. However, a deeper understanding of the sensing behavior of these heterojunctions is necessary. In this investigation, the focus centers on the fabrication of p-n heterojunction consisting of hexagonal molybdenum diselenide-tungsten disulfide (MoSe2-WS2) for room-temperature (RT, 27˚C) NO2 (Nitrogen dioxide) gas detection. A catalyst-free magnetron sputtering technique has been employed to fabricate the composite thin film of vertically aligned hydrophobic MoSe2-WS2 nanoworms on the n-type silicon substrate. The resulting sensor exhibited exceptional sensitivity (59.63%), quick response (68.90 s), and full recovery (65.68 s) towards 50 ppb NO2 even at RT, highlighting its strong affinity for NO2 molecules. The reliability of the as-fabricated MoSe2-WS2 composite thin film sensor has been confirmed by its high selectivity (59.63%) and long-term stability (> 60 days) towards 50 ppb NO2 at RT. The remarkable sensing capabilities of this innovative TMDs composite hold promising potential for future low-power and room-temperature NO2 gas sensors.