Edge‐Enriched Mo2TiC2Tx/MoS2 Heterostructure with Coupling Interface for Selective NO2 Monitoring

Abstract Endowed with rich terminal groups, good electrical conductivity, and controllable structure, transition metal carbides/nitrides (MXenes) have attracted extensive attention for potential application in gas sensor, but long‐standing challenges of the MXenes (titanium carbide as the representative) are their limited selectivity and sensitivity. Herein, a high‐active double transition‐metal titanium molybdenum carbide (Mo 2 TiC 2 T x ) with superstrong surface adsorption (−3.12 eV) for NO 2 gas molecule is proposed, and it is further coupled with molybdenum disulfide (MoS 2 ) by interface modulation to construct an edge‐enriched heterostructure. Due to the synergistic effect of strong adsorption, rich adsorption sites, and coupling interface of Mo 2 TiC 2 T x /MoS 2 composite, the as‐fabricated Mo 2 TiC 2 T x /MoS 2 gas sensor exhibits an outstanding response toward NO 2 with high selectivity against various interference gases, which is well supported by density functional theory calculations. Meanwhile, the sensor exhibits a sensitivity of 7.36% ppm −1 , detection limit of 2.5 ppb, and reversibility at room temperature. A portable, wireless NO 2 monitoring system is demonstrated for gas leakage searching and dangerous warning based on Mo 2 TiC 2 T x /MoS 2 gas sensor. This work facilitates the gas sensing application of MXenes, and provides an avenue for the development of wireless sensing system in environmental monitoring and safety assurance.