Research On Preparation And Sensing Properties Of Graphene Composites

Human health and environmental safety are seriously threatened by pollutions caused by industrial development.As one of the critical equipment for monitoring these pollutants,sensors play an essential role in health monitoring and environmental monitoring.Due to its large surface-to-volume ratio,adjustable physical and chemical properties,and environmentally sensitive surface properties,two-dimensional materials have become a research hotspot in various sensing applications in recent years.In this paper,nitrogen-doped graphene(NG)composite materials and reduced graphene oxide/molybdenum disulfide(r GO/Mo S2)composite materials were prepared based on graphene oxide(GO).Furthermore,their application in electrochemical sensing and humidity sensing were discussed.The main content and conclusions of this study are as follows:(1)GO was mixed with urea,cyanamine and melamine,respectively.NG was prepared by heat treatment,and used as an electrode modification material for electrochemical sensing.The ability of NG to detect Cd²⁺,Pb²⁺,Cu²⁺,and Hg²⁺in water was studied,and the detection mechanism was aslo analyzed.The experimental results showed that the presence of N and defects in NG significantly enhanced the detection capability of heavy metal ions(HMI).Among them,the dissolution peak current of the NG10-C modified electrode had a good linear relationship with the concentration of each HMI.The limit of detection(LOD)of Cd²⁺,Pb²⁺,Cu²⁺,and Hg²⁺were 7.0 n M,0.9 n M,9.5 n M,and 7.5 n M.In addition,the sensing platform also had good selectivity,repeatability and stability,and can be used for actual water sample detection.(2)The rGO was prepared by thermal treatment,and the r GO/Mo S2 composites were synthesized by the ultrasonic method.The humidity response of r GO/Mo S2 composites in the flexible humidity sensor was tested,and the humidity sensing mechanism was analyzed.The study found that when the mass ratio of r GO to Mo S2 is 1:20,the r GO/Mo S2 composite has excellent humidity sensing properties,the hydrophilic oxygen-containing functional groups on r GO,the edge position defects of Mo S2,and the synergistic effect of the combination of the two,enhance the material's ability to adsorb water molecules.The humidity response of the device to water molecules was up to120,000%when non-contact closing and up to 1500%when breathing,and the sensitivity was very high.Besides,the humidity sensor has a short response/recovery time good stability.(3)As an electrode modification material,r GO/Mo S2 composites were applied to electrochemical sensing platform,and its ability to detect Hg²⁺in water was studied.The detection mechanism was also analyzed.The results showed that when the mass ratio of r GO to Mo S2 was 1:1,the r GO/Mo S2 composite modified electrode had the best performance in detecting Hg²⁺.The peak dissolution current of r GO/Mo S2 modified electrode had a good linear relationship with Hg²⁺concentration,and the LOD of Hg²⁺was 1.0 n M.The electrochemical sensing platform also had high sensitivity,strong selectivity,and good repeatability and stability.