Highly Sensitive NO 2 Gas Sensors Based on MoS 2 @MoO 3 Magnetic Heterostructure.

Recently, two-dimensional (2D) materials and their heterostructures have attracted considerable attention in gas sensing applications. In this work, we synthesized 2D MoS 2 @MoO 3 heterostructures through post-sulfurization of α-MoO 3 nanoribbons grown via vapor phase transport (VPT) and demonstrated highly sensitive NO 2 gas sensors based on the hybrid heterostructures. The morphological, structural, and compositional properties of the MoS 2 @MoO 3 hybrids were studied by a combination of advanced characterization techniques revealing a core-shell structure with the coexistence of 2H-MoS 2 multilayers and intermediate molybdenum oxysulfides on the surface of α-MoO 3 . The MoS 2 @MoO 3 hybrids also exhibit room-temperature ferromagnetism, revealed by vibrating sample magnetometry (VSM), as a result of the sulfurization process. The MoS 2 @MoO 3 gas sensors display a p -type-like response towards NO 2 with a detection limit of 0.15 ppm at a working temperature of 125 °C, as well as superb selectivity and reversibility. This p -type-like sensing behavior is attributed to the heterointerface of MoS 2 -MoO 3 where interfacial charge transfer leads to a p -type inversion layer in MoS 2 , and is enhanced by magnetic dipole interactions between the paramagnetic NO 2 and the ferromagnetic sensing layer. Our study demonstrates the promising application of 2D molybdenum hybrid compounds in gas sensing applications with a unique combination of electronic and magnetic properties.