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.