Synergistic effect of charge transfer and interlayer swelling in V2CTx/SnS2 driving ultrafast and highly sensitive NO2 detection at room temperature

Transition metal carbides/nitrides (MXenes) have shown great potential in room temperature (RT) gas sensors, but the self-stacking of MXene sheets limits their sensitivity and response/recovery speed. In addition, the poor selectivity of MXenes sensors caused by the conventional single sensing mechanism remains a challenge. Herein, a synergistic effect of charge transfer and interlayer swelling is proposed to comprehensively improve the gas sensing performance of the MXenes toward oxidizing NO2. To this end, a resistive gas sensor is prepared by combining the accordion-like V2CTx MXene and n-type SnS2 nanoplates. The results reveal that the NO2 sensitivity of the V2CTx/SnS2 sensor is enhanced by 581.6 times compared to the pristine V2CTx sensor, while achieving ultrafast response and recovery speeds (4.8/4.7 s) at 25 °C under 51.9 % relative humidity. Furthermore, the V2CTx/SnS2 sensor exhibits excellent selectivity (response ratio > 5) to NO2. The outstanding gas sensing performances can be attributed to the synergistic sensing of charge transfer and interlayer swelling, unique structure and more active sites. This work expands the gas sensing application of the V2CTx MXene and promotes the in-depth combination of multiple sensing mechanisms, opening an effective avenue for developing high-performance RT NO2 sensors.