Fabrication,Characterization And Performance Research Of Porphyrin Covalently Functionalized Graphene Materials

Graphene was firstly fabricated by A. K. Geimand and K. S. Novoselvo in 2004, with a simple method named mechanical exfoliation. And in the next 10 years, the novel two dimentional carbon material has drawn global attention because of its outstanding physicochemical properties. It is found to be the hardest material in the world with the best thermal and electrical conductivity. However, the solubility and processability of graphene are very bad which limit its large-scale preparation and application. Chemical functionalization of grapheme is one of the most efficient method focused on improving its solubility and processability in both water and organic solvents using different soluble groups. In addition, multi-functional composites can be obtained when introducing functional molecule into gaphene. Porphyrins are called the "pigments of life" which play very important roles in the metabolism of living organisms. For example heme(a kind of ferriporphyrins) can transfer oxygen and chlorophyll(a kind of magnesium porphyrins) is essential for photosynthesis. The porphyrins are a class of naturally occurring macrocyclic compounds which consist of for pyrrole ring by methyne. The conjugate system endows porphyrin great photoelectrochemical properties and can form "donor-acceptor" structure with grapheme. Electron and/or energy transfer between acceptor graphene and donor porphyrin are very fast in the composite which endow itself outstanding photoelectrochemical properties. This porphyrin/grapheme hybrid material has potential application in nonlinear optics, photocatalysts, sensing and other fields.Therefore, we hope to fabricate porphyrin/graphene hybrid material by a simple method and then study its photoelectrochemical properties. There are two methods to fabricate porphyrin/graphene hybrid material. One is noncovalent binding and the other is covalent binding. The former is mainly in two forms of π-π conjugate and electrostatic interaction, and the later is mainly in forms of ester bonds, amide bonds and C-C bonds. We focused on the covalent binding method because the stability of the noncovalent method is hard to satisfy practical applications. The detail works are as follow:(1)Design and fabricate two axial-covalently connected porphyrin/graphene composites. When tin porphyrin(SnP) is introduced onto both edge and basal plane of graphene we get GOSnP; while SnP is only introduced to the edge of graphene for GO’SnP. The two composites are characterized by spectroscopy, TGA and electron microscopy. Then we study the formation mechanism of morphology difference between GOSnP and GO’SnP. At last light limited properties and photocurrent response properties of two hybrids are compared by photoelectrochemical experiments.(2) Design and fabricate two unaxial-covalently connected porphyrin/graphene composites(GOTAPP and GO’TAPP). For GOTAPP, amino porphyrin is introduced onto both edge and basal plane of graphene, while for GO’TAPP amino porphyrin is only introduced into the edge of gaphene. GO’TAPP. The two composites are characterized by spectroscopy, TGA and electron microscopy. And the methylene blue(MB) is chosen as target sample in photo degradation experiments to study their photo catalytic performance.(3) Graphene/porphyrin/fullerene(GOTAPP-C60) with a structure of "acceptor-donor-acceptor" is fabricated in this part. Spectroscopy, TGA and electron microscopy detectation are carried out to characterize this hybrid material. Photo catalytic performance between GOTAPP-C60 and GOTAPP is compared in the experiments of photo degradation of MB.