NO₂ Gas Sensing Properties Of Monolayer Graphene And Bilayer Graphene Composites Fabricated Material

In recent years,air pollution(NO2 and other toxic gases)became an important factor that influenced human health in China.Using gas sensors to detect toxic gases was an effective method.The high working temperature was the main shortcoming of the gas sensors in the present market.Therefore,research on new material based gas sensing was very important.Graphene has broad prospects and academic value in the field of gas sensing,due to it's unique electrical properties and large specific surface area.Previous studies have shown that monolayer graphene has low responsivity,high detection limit and long adsorption time.Using doped graphene and graphene composites materimal can effectively improve graphene properties.This paper introduced the basic properties of graphene,the development status and the modification method of graphene.The energy structure and NO2 gas sensitivity of graphene were calculated and analyzed by the first principle principle in quantum mechanics.Monolayer graphene prepared by chemical vapor deposition(CVD)methpd was used as to fabricate monolayer,nitrogen-doped monolayer,bilayer graphene based gas sensor by wet transfer method.The as prepared graphene samples were charactered by optical microscope and Raman spectrum,the result showed that the graphene samples had many advantages,such as large area,high quality and no impurity.In the aspect of graphene composite material,we employed the transition metal sulfide Sn Se2 which was also a kind of two-dimensional material.The Sn Se2 quantum dot as a nanomaterial of composite graphene material was prepared by liquid phase ultrasonic stripping method.The gas sensing properties of several materials were tested in our experiments.The responsiveness,lower detection limit and desorption time of the modified graphene were compared with monolayer graphene.In this paper,the method of irradiating bilayer graphene with ultraviolet light is also used to shorten the desorption time.The results showed that nitrogen-doped monographene and bilayer graphene under ultraviolet light irradiation were shortened by two orders of magnitude in the adsorption time characteristics.The detection limit was extended from the ppm level to the ppb level.The bilayer graphene and Sn Se2 quantum dot/graphene composite material were4-10 times more responsive than monolayer graphene.In this paper,the graphene gas sensing material prepared by chemical vapor deposition method had opened up new ideas and methods in the direction.It provided a new experimental basis for improving the gas sensing properties of graphene,especially the desorption characteristics.I wish our works in this paper could have some contributions to the development of gas sensors.