Fast response speed of mechanically exfoliated MoS2 modified by PbS in detecting NO2

Abstract

MoS2, acting as a promising gas sensing material, has shown huge potential in monitoring of toxic and harmful gases at room temperature. However, MoS2-based gas sensors still suffer from poor gas sensing performance such as poor sensitivity, long response time. Constructing the heterostructure is an effective approach to improve gas-sensing performance of MoS2. Herein, PbS@MoS2 composites synthesized by mechanical exfoliation combining with wet-chemical precipitation are used to investigate its performance in detecting NO2 at room temperature. The response value of PbS@MoS2 gas sensor against NO2 is significantly improved compared with the pure MoS2 gas sensor. At the same time, the modification with PbS also accelerates the response speed of MoS2, and the response time is almost reduced by two orders of magnitude, from hundreds of seconds to less than ten seconds. The enhanced response value and fast response time are mainly benefited from the modulation effect of NO2 to PbS@MoS2 heterostructure and the mechanically exfoliated MoS2 surface with few defects. This work can be expected to provide useful guidance for designing composite materials with excellent gas sensing properties.