Study On Synthesis And Gas Sensing Properties Of Novel Substituted Corrole And MetalloCorrole

As one of the main environmental problems,air pollution will cause great harm to human health and industrial production.Therefore,if these air pollutants can be detected and treated in time,the degree of air pollution can be reduced to a large extent.This makes gas sensors play an important role in the detection of toxic and harmful gases.However,the development of gas sensors is restricted by the high detection requirements of gas-sensing materials,so it is imperative to develop gas-sensing materials.Corrole compounds with 18-?electronic structure and their metal complexes show potential applications in the field of sensors.In this paper,the preparation of graphene oxide,A₃ corrole,A₃ metallocorrole,A₂B corroles and A2B metallocorroles are introduced.Moreover,their sensitivity to NO2 are studyed.At the same time,the preparation of corrole/graphene oxide and metallocorrole/graphene oxide functional composites by physical composite and chemical grafting are also proposed,and their sensitivity to NO₂ is investigated.The details are as follows:1.Graphene oxide with oxygen groups on the surface of single or several layers was prepared by improved Hummers method.The structure and surface groups of graphene oxide aer characterized to determine its structure.Graphene oxide is used as a gas sensing material to test its sensitivity to different concentrations of NO₂ at room temperature.Graphene oxide shows excellent sensitivity to NO2 at concentrations of 5 ppm and 50 ppm?resistance decreased from 49386?to 47944?and from 48040?to 44920??.What's more,the Graphene oxide also shows excellent performance when high concentration of NO₂ was withdrawn.However,it does not show recovery to the low concentration gas.2.The?4-methylphenyl?₃Cor,?4-NO₂Ph??4-CH₃Ph?₂Cor and?4-ClPh??4-CH₃Ph?₂Cor were synthesized by improved Lindsey method,the?4-NO₂Ph??4-CH₃Ph?₂Cor was reduced to the?4-NH₂Ph??4-CH₃Ph?₂Cor.At the same time,the corrole compounds were coordinatedwithCo?andtriphenylphosphinetopreparethe?4-methylphenyl?3CorCoPPh3,?4-NO2Ph??4-CH3Ph?2CorCoPPh3,?4-ClPh??4-CH₃Ph?₂CorCoPPh₃ and?4-NH₂Ph??4-CH₃Ph?₂CorCoPPh₃.3.The sensitivity of the corrole compounds and metallocorrole to NO₂ was characterized.It was found that the A₂B metallocorrole complexes have better conductivity and sensitivity to NO₂ because of their stronge polarity.What's more,the stronger the electron absorption ability of substituents,the better the sensitivity of materials to NO₂.The resistance of?4-ClPh??4-CH₃Ph?₂CorCoPPh₃ decreases from 6.5 M?to 3.5 M?after contacting with NO₂ with concentration of 50 ppm,When the NO₂ is removed,The resistance rebounded slowly and showed a certain degree of recovery.4.Corrole/graphene oxide and metallocorrole/graphene oxide functional composite:A₃Cor+GO?A₃Cor-Co+GO?Cl-Cor+GO?Cl-Cor-Co+GO?NO₂-Cor+GO?NO₂-Cor-Co+GO?NH₂-Cor+GO?NH₂-Cor-Co+GO?NH₂-Cor-GO and NH₂-Cor-Co-GO are prepared by physical composite and chemical grafting of corrole and metallocorrole with graphene oxide.The gas sensing properties of the functional composites were investigated.Cl-Cor-Co+GO has the best sensitivity to NO₂ because of its strong electron-absorbing ability of substituents.When NO₂ gas with a concentration of 5 ppm is introduced,the resistance decreases rapidly from 600614?to 581830?.After removing the NO₂,the resistance recovers.When NO₂ with a concentration of 50 ppm is introduced,the resistance decreases from 590983?.When the resistance is reduced to 551693?,the resistance recovers greatly after the removal of the NO₂.This indicates that a gas sensitive material which can repeatedly detect the low concentration of NO₂ at room temperature has been successfully prepared in this paper.