Growth Kinetics Of Graphene Based On Ethanol Pyrolysis Products And Its Surface Enhanced Raman Study

Chemical vapor deposition is an important method for graphene growth.Largearea and high-quality graphene films can be prepared on catalytically active transition metal substrate copper foils and copper-nickel alloys.However,the transfer of graphene is required in application and the commonly used wet etching method will have residues of chemicals,which will cause a large number of defects in graphene and affect the application effect.Therefore,the direct preparation of graphene on silicon dioxide substrate(SiO2/Si)is an important development direction.In this paper,we successfully prepared graphene on copper foil,copper-nickel alloy and SiO2/Si by atmospheric pressure chemical vapor deposition(APCVD),and discussed the growth mechanism by innovatively using gas chromatography.Surface enhanced Raman scattering(SERS)substrates were prepared by combining the as-prepared graphene with nano-silver,and its enhanced properties were investigated.The main research contents are as follows:1.Through APCVD,using ethanol as carbon precursor and only argon as carrier and protective gas,different quality of graphene films were rapidly fabricated on copper foil,copper-nickel alloy and silicon dioxide dielectric substrates by adjusting the growth time parameters.The different graphene indicate that the three substrates have different catalytic activities.Gas chromatography was used to analyze the whereabouts of carbon atoms in ethanol pyrolysis during the growth of graphene.It was found that the whereabouts of carbon atoms in ethanol pyrolysis were deposited carbon and escaped carbon.The concentrations of CO and CO2 of escaped carbon from different substrates were compared and analyzed to explain the catalytic activity of different substrates and the kinetic differences of graphene growth.2.SERS substrates were prepared by composite of graphene and nano-silver on three substrates,the Raman characteristic peaks of R6G molecular probe were characterized.The enhancement effect of Transfer-G(Cu)/Ag/SiO2 SERS substrate is remarkable,and the enhancement factor is up to 9.93 × 105.Transfer-G(Cu-Ni)/Ag/SiO2 SERS substrate prepared by double and multi-layer graphene grown on copper-nickel alloy had weaker enhancement effect compared with single-layer graphene,and with the increase of layers,the enhancement effect became weaker.The enhancement factor of Transfer-G(Cu-Ni)/Ag/SiO2 is 2.09×105.For graphene on SiO2/Si substrate,without transfer,it can be directly compounded with nano-silver to prepare Ag/G/SiO2 SERS substrate in one step,which improves the efficiency and has a great impact on industrialization.The enhanced factor of the optimal Ag/G/SiO2 SERS substrate is 9.23 × 105 which is comparable to the SERS substrate prepared by single layer graphene,and has good uniformity and thermal stability.This brings great convenience for the simple and rapid preparation of SERS substrate,which is a feasible and rapid preparation method for detection substrate with future application prospect.