Preparation And NO₂ Gas Sensing Performance Study On Flower-like Molybdenum Selenide Composite Materiats

Nitrogen dioxide?NO₂?is one of the most common toxic gases causing air pollution,which is mainly released from fossil fuel combustion,automobile exhausts,and so on.It can cause acid rain and photochemical smog.Long-term exposure to NO₂ at even parts per million?ppm?levels will increase respiratory-disease risk and may cause lung malfunction.Therefore,developing high-performance gas sensors capable of detecting low concentrations of NO₂ for human health protection and air-quality monitoring is highly desirable.Two-dimensional?2-D?layered nanomaterials have attracted intensive attention in gas sensing applications due to their fascinating physicochemical properties,such as large surface-tovolume ratios,high surface activities,and good compatibility with device design.However,most two-dimensional materials cannot fully recover at room temperature due to their inherent properties,which limits their further application in the field of gas sensing.So far,modification of second phase particles on two-dimensional materials has been shown to improve their disadvantages.However,these sensing materials still have shortcomings such as low response and slow response.Based on the background,this paper firstly prepared the flower-like MoSe₂material by wet chemical method and modified it by two different methods:chemical precipitation method and heat treatment to prepare a graded MoSe₂ matrix composite with heterojunction:MoSe₂/PbS composite and MoSe₂/MoO₂ composite.The modified graded MoSe₂-based composites exhibited excellent gas-sensitive response to NO₂ at room temperature.Among them,the MoSe₂/MoO₂ composite has a response of 121%at 1 ppm NO₂ and 14 times that of pure MoSe₂.The sensor also has excellent selectivity and repeatability.Therefore,this study provides a facile method for preparing a MoSe₂-based sensor with a high sensing performance at room temperature.This study demonstrates that designing nanoheterojunctions based on hierarchical MoSe₂ is an efficient route to develop next-generation chemiresistive gas sensors with improved sensing performance.