Design\nof Hetero-Nanostructures on MoS₂ Nanosheets To Boost NO₂ Room-Temperature Sensing

Abstract

Molybdenum\ndisulfide (MoS₂), as a promising gas-sensing material,\nhas gained intense interest because of its large surface-to-volume\nratio, air stability, and various active sites for functionalization.\nHowever, MoS₂-based gas sensors still suffer from low sensitivity,\nslow response, and weak recovery at room temperature, especially for\nNO₂. Fabrication of heterostructures may be an effective\nway to modulate the intrinsic electronic properties of MoS₂ nanosheets (NSs), thereby achieving high sensitivity and excellent\nrecovery properties. In this work, we design a novel p–n hetero-nanostructure\non MoS₂ NSs using interface engineering via a simple wet\nchemical method. After surface modification with zinc oxide nanoparticles\n(ZnO NPs), the MoS₂/ZnO hetero-nanostructure is endowed\nwith an excellent response (5 ppm nitrogen dioxide, 3050%), which\nis 11 times greater than that of pure MoS₂ NSs. To the\nbest of our knowledge, such a response value is much higher than the\nresponse values reported for MoS₂ gas sensors. Moreover,\nthe fabricated hetero-nanostructure also improves recoverability to\nmore than 90%, which is rare for room-temperature gas sensors. Our\noptimal sensor also possesses the characteristics of an ultrafast\nresponse time of 40 s, a reliable long-term stability within 10 weeks,\nan excellent selectivity, and a low detection concentration of 50\nppb. The enhanced sensing performances of the MoS₂/ZnO\nhetero-nanostructure can be ascribed to unique 2D/0D hetero-nanostructures,\nsynergistic effects, and p–n heterojunctions between ZnO NPs\nand MoS₂ NSs. Such achievements of MoS₂/ZnO\nhetero-nanostructure sensors imply that it is possible to use this\nnovel nanostructure in ultrasensitive sensor applications.