Enhanced NO2 gas-sensing performance at room temperature using exfoliated MoS2 nanosheets

•Simple liquid-phase exfoliated method to fabricate few-layered MoS2 nanosheets.•Significant NO2 sensing performance of the sensor based on exfoliated MoS2 compared to that based on bulk MoS2.•The sensor based on the exfoliated MoS2 nanosheets indicates the highest response of about 8 times to 5 ppm at RT.•The exfoliated MoS2 nanosheet sensor shows good NO2 selectivity, ultra-low detection limit, good short- and long-term stability. [Display omitted] Gas sensors based on the bulk MoS2 and exfoliated MoS2 nanosheets, were fabricated by the probe ultrasonic vibration followed by the drop-casting method. The sensing performance of the sensor based on the exfoliated MoS2 was much higher than that based on the bulk MoS2. The exfoliated MoS2 sensor showed highest gas response of approximately eight times to 5 ppm NO2 at room temperature. This fabricated sensor showed a good NO2 selectivity, ultra-low detection limit, and good short- and long-term stability. Features such as surface-to-volume ratio, sensitive surface, and bandgap vary with the number of material layers of semiconductor two-dimensional transition metal dichalcogenides with superior responsivity at room temperature (RT) and their possible application as flexible electronic devices. Herein, a significant enhancement of NO2 gas sensing properties of few-layered MoS2 nanosheets exfoliated from bulk MoS2 through a simple sonication probe was reported. The gas responses of the sensor based on the exfoliated MoS2 nanosheets to 0.5–5 ppm NO2 at RT were as high as 5.3–8 times. At RT, the humidity effect to the performance of the exfoliated MoS2 sensor was insignificant. The exfoliated MoS2 sensor also exhibited an ultra-low detection limit of 27 ppb, excellent selectivity, and reliable long-term stability within 8 weeks, which are crucial for future application of the sensor in practical devices. The NO2 sensing mechanism of the exfoliated MoS2 nanosheets was discussed in detail.