Functional Modification Of Graphene Oxide

As a new emerging carbon materials, graphene possessed distinctmechanical, optical, thermal and electrical properties, such as anomalousquantum Hall effect, high young modulus, high thermal conductivity andhigh specific surface area. Because of these excellent properties,graphene is widely applied for the preparation of various functionalnanocomposites and which obtained applications in the field ofelectronics, optics, catalysis and so on. However, there are manyobstacles in the industrial application of graphene and large-scaleproduction of graphene is one of the main challenges. Graphene oxide(GO) is usually treated as a precursor to graphene for its structuralsimilarity with graphene. By thermal or chemical way, GO can beconverted to graphene. Especially, the routes for the modification of GOin chemical way are numberous and worthy to be investigated. The mainwork in this paper was fucosed on the surface modification of grapheneoxide and graphene (oxide) functionalized with small organic molecule orsilver nanoparticles were prepared. The main contents of the paperinclude:1) Modification of graphene oxide with small organic molecule.2-amino-4,6-didodecylamino-1,3,5-triazine (ADDT) was firstlysynthesized from cyanuric chloride. Characterized by means of FT-IR and1HNMR, the chemical structure of ADDT was confirmed. Compared tomelamine, the thermal stability of ADDT is improved and thedecomposition temperature of ADDT matched well with that of thermoplastics. In order to modify GO by covalent bond, GO was firstlytreated by thionyl chloride and then reaction with ADDT. The obtainedproduction GO-ADDT was investigated by FT-IR, XPS and HRTEM.The results indicate that ADDT is covalently grafted onto the surface ofGO sheets by amide linkage. The thermal stability and solubility ofGO-ADDT was then discussed. According the data of TGA, the thermalstability of GO-ADDT is improved. With the increasing temperature, themass loss rate of GO-ADDT is significantly lower than that of GO. Whiledispersed in CHCl3/H2O mixture, GO-ADDT was all dispersed in CHCl3,implying the hydrophilic GO has been converted to hydrophobicGO-ADDT. And the shift will lay foundations for the application ofGO-ADDT in some nonpolar polymer-based composites.2) Under mild conditions, graphene/silver composites was preparedby simultaneous reduction of graphene oxide and silver ions in a rapidand one-step way. In the experiment, FAG was prepared by usingformaldehyde as the reducing agent and PVP as the protect agent; WhilePAG was prepared by using PVP as reducing agent individually. The twocomposites were investigated by HRTEM, SEM and XPS. The datas fromXPS spectra show different substrates between PAG and FAG. Theimages of SEM and HRTEM indicate that the oxygen-containing groupshave an effect on the growth of silver nanocrystal. Low-temperature andshort reaction time make the approach a promising alternative for thepreparation of silver–graphene nanocomposites.3) In order to prepared graphene (oxide)/silver composites withvarious degrees of reduction in a more convenient way, an improvingmethod is developed. By the addition of glucose,PVP and silver-ammoniasolution, GSG-25(25oC),GSG-40(40oC) and GSG-60(60oC) areprepared under different reaction temperatures. The investigation was mainly focused on GSG-25and GSG-60. The XPS spectra confirm thecontent of oxygen-containing groups between GSG-25and GSG-60isdifferent. The distribution of silver nanoparticles on the substrates wasexhibited in HRTEM images. It is clear that there are many more silvernanoparticles on GSG-25including some particles in relatively large size.The composites under different reaction times were investigated byUV-vis spectra； The interaction between silver nanoparticles andsubstrates was investigated, and the results confirmed it is nonconvalentway; In addtion, the redox components for the preparation of GSG-60were discussed; At last, the surface enhanced raman scattering (SERS)between GSG-25and GSG-60was investigated.