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

• Simple liquid-phase exfoliated method to fabricate few-layered MoS 2 nanosheets. • Significant NO 2 sensing performance of the sensor based on exfoliated MoS 2 compared to that based on bulk MoS 2 . • The sensor based on the exfoliated MoS 2 nanosheets indicates the highest response of about 8 times to 5 ppm at RT. • The exfoliated MoS 2 nanosheet sensor shows good NO 2 selectivity, ultra-low detection limit, good short- and long-term stability. Gas sensors based on the bulk MoS 2 and exfoliated MoS 2 nanosheets, were fabricated by the probe ultrasonic vibration followed by the drop-casting method. The sensing performance of the sensor based on the exfoliated MoS 2 was much higher than that based on the bulk MoS 2 . The exfoliated MoS 2 sensor showed highest gas response of approximately eight times to 5 ppm NO 2 at room temperature. This fabricated sensor showed a good NO 2 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 NO 2 gas sensing properties of few-layered MoS 2 nanosheets exfoliated from bulk MoS 2 through a simple sonication probe was reported. The gas responses of the sensor based on the exfoliated MoS 2 nanosheets to 0.5–5 ppm NO 2 at RT were as high as 5.3–8 times. At RT, the humidity effect to the performance of the exfoliated MoS 2 sensor was insignificant. The exfoliated MoS 2 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 NO 2 sensing mechanism of the exfoliated MoS 2 nanosheets was discussed in detail.