Designing advanced 2D/2D heterojunctions of MoS2 nanosheets/Ti3C2Tx MXene in gas-sensing applications

In this work, two dimensional (2D) MoS2 nanosheets were functionalized on Ti3C2Tx MXene nanosheets via a surface modification strategy, leading to significant enhancement in the gas-sensing performance of Ti3C2Tx MXene. Specifically, the MoS2 nanosheets were grown on the Ti3C2TX MXene surface, thus forming a unique microstructure. The unique structure of Ti3C2TX MXene provides abundant growth sites, allowing MoS2 nanosheets to uniformly and largely grow on the surface of the multilayered Ti3C2TX MXene. Based on the electron depletion layer theory with the formation of 2D/2D heterojunctions, the sensor based on MoS2/Ti3C2TX MXene composites has high response towards ethanol with fast response and recovery speed (5/12 s) at low temperature of 140 °C. Furthermore, we also verified the heterojunctions between MoS2 nanosheets/Ti3C2Tx MXene and the selectivity for different gases through first-principles density functional theory (DFT) calculations, including adsorption energy and the most stable configuration. This study provides a certain reference for the gas-sensing research of 2D/2D composite materials, as well as the future development of low temperature gas sensors.