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

Abstract

Molybdenum disulfide (MoS 2 ), as a promising gas-sensing material, has gained intense interest because of its large surface-to-volume ratio, air stability, and various active sites for functionalization. However, MoS 2 -based gas sensors still suffer from low sensitivity, slow response, and weak recovery at room temperature, especially for NO 2 . Fabrication of heterostructures may be an effective way to modulate the intrinsic electronic properties of MoS 2 nanosheets (NSs), thereby achieving high sensitivity and excellent recovery properties. In this work, we design a novel p–n hetero-nanostructure on MoS 2 NSs using interface engineering via a simple wet chemical method. After surface modification with zinc oxide nanoparticles (ZnO NPs), the MoS 2 /ZnO hetero-nanostructure is endowed with an excellent response (5 ppm nitrogen dioxide, 3050%), which is 11 times greater than that of pure MoS 2 NSs. To the best of our knowledge, such a response value is much higher than the response values reported for MoS 2 gas sensors. Moreover, the fabricated hetero-nanostructure also improves recoverability to more than 90%, which is rare for room-temperature gas sensors. Our optimal sensor also possesses the characteristics of an ultrafast response time of 40 s, a reliable long-term stability within 10 weeks, an excellent selectivity, and a low detection concentration of 50 ppb. The enhanced sensing performances of the MoS 2 /ZnO hetero-nanostructure can be ascribed to unique 2D/0D hetero-nanostructures, synergistic effects, and p–n heterojunctions between ZnO NPs and MoS 2 NSs. Such achievements of MoS 2 /ZnO hetero-nanostructure sensors imply that it is possible to use this novel nanostructure in ultrasensitive sensor applications.