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

Abstract

Molybdenum disulfide (MoS₂), 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, MoS₂-based gas sensors still suffer from low sensitivity, slow response, and weak recovery at room temperature, especially for NO₂. Fabrication of heterostructures may be an effective way to modulate the intrinsic electronic properties of MoS₂ nanosheets (NSs), thereby achieving high sensitivity and excellent recovery properties. In this work, we design a novel p-n hetero-nanostructure on MoS₂ NSs using interface engineering via a simple wet chemical method. After surface modification with zinc oxide nanoparticles (ZnO NPs), the MoS₂/ZnO hetero-nanostructure is endowed with an excellent response (5 ppm nitrogen dioxide, 3050%), which is 11 times greater than that of pure MoS₂ NSs. To the best of our knowledge, such a response value is much higher than the response values reported for MoS₂ 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 MoS₂/ZnO hetero-nanostructure can be ascribed to unique 2D/0D hetero-nanostructures, synergistic effects, and p-n heterojunctions between ZnO NPs and MoS₂ NSs. Such achievements of MoS₂/ZnO hetero-nanostructure sensors imply that it is possible to use this novel nanostructure in ultrasensitive sensor applications.