Researches On High Performance Graphene-based Gas Sensing Materials

Graphene is a two-dimensional crystal with a single atomic thickness.It has large specific surface area,outstanding electrical conductivity and excellent mechanical properties,therefore,it is considered to be one of the most promising materials for gas sensors.Although there have been a lot of research and reports on graphene-based sensors,most of them still have shortcomings such as low sensitivity,high limit of detection,and poor reversible desorption performance.Herein,we greatly improved the sensing performance of graphene-based sensors through chemical etching,chemical modifying,and optimizing the structure of the graphene sensing layer.The effects of etching defects,modified functional groups and sensing layer structure on the sensing performance of graphene-based sensors were systematically investigated by characterizing the microstructure and testing the sensing properties of graphene-based sensors.The main research contents and results were as follows:(1)Porous reduction graphene oxide(PRGO)with abundant in-plane defects was prepared through a mild solution-etching reaction.The concentration of defects and conductivity of graphene could be controlled through adjusting etching time and the degree of reduction.The introduced edge defects can serve as active adsorption sites for target molecules.Consequently,the sensitivity towards nitrogen dioxide was greatly improved.Compared with reduced graphene oxide(RGO),the PRGO-based sensor exhibited higher sensitivity(88.76%),lower limit of detection(LOD of 20 ppb),faster response(10 min)and recovery(15 min)to nitrogen dioxide.Furtheremore,the sensor can be performed at room temperature without any thermal or UV/IR illumination assistance,demonstrating great potential for practical applications.(2)Agnanoparticles(Ag NP)anchoredtwo-dimensional aminoanthroquinone-functionalized reduced graphene oxide(AQRGO)sheets were prepared through one-step wet chemical method.Then,a multilevel-structured flexible three-dimensional reduced graphene oxide fiber scaffold(Ag NP-3D-AQRGO)was prepared by electrospinning and self-assembly techniques.The sensing performance of the Ag NP-3D-AQRGO-based sensor is remarkably improved by increasing the active adsorption sites for target molecules and optimizing the microstructure of the sensing layer.The obtained multilevel structured Ag NP-3D-AQRGO-based gas sensor can be performed at room temperature and exhibited outstanding sensing performance including ultra-high sensitivity(10.3 ppm^-1),extremely low LOD(0.6 ppb),fast response(5 min)and recovery(10 min)and excellent selectivity for nitrogen dioxide among various interfering gases.In addition,the sensor has excellent mechanical flexibility,the sensing result remains stable under multiple bending conditions,and it is expected to integrate into wearable electronics for nitrogen dioxide sensing.