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

Abstract

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 NO 2 . To this end, a resistive gas sensor is prepared by combining the accordion-like V 2 CT x MXene and n-type SnS 2 nanoplates . The results reveal that the NO 2 sensitivity of the V 2 CT x /SnS 2 sensor is enhanced by 581.6 times compared to the pristine V 2 CT x sensor, while achieving ultrafast response and recovery speeds (4.8/4.7 s) at 25 °C under 51.9 % relative humidity. Furthermore, the V 2 CT x /SnS 2 sensor exhibits excellent selectivity (response ratio > 5) to NO 2 . 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 V 2 CT x MXene and promotes the in-depth combination of multiple sensing mechanisms, opening an effective avenue for developing high-performance RT NO 2 sensors.