Molybdenum disulfide (MoS2), a just three atoms thick semiconductor has opened up new avenues in gas sensing because of its high surface-to-volume ratio. However, the low sensitivity, incomplete recovery and poor selectivity at room temperature restricts its uses for practical gas sensors. Here, we report a facile strategy to develop highly sensitive, extremely selective and fully recoverable gas sensor at room temperature through photo excitation. Although, pristine MoS2 gas sensor showed a considerable response and incomplete recovery to NO2 at room temperature. Though after photo excitation, the MoS2 sensor exhibited an improved response along with the complete recovery upon NO2 exposure. © 2018 Author(s).