Design, Preparation And Performance Study Of Porphyrin-graphene Oxide Nano-hybrid Optical Limiting Functional Material

Graphene has attracted tremendous research attention in the past years owing to its unique mechanical performance,excellent optoelectronic properties and chemical properties.Meanwhile,people also pay attention to the new excellent properties about graphene derivatives.Graphene oxide?GO?is from the oxidation of graphene by strong oxidant under strong acid conditions,so the surface has many oxygen-containing groups?such as carboxyl and hydroxyl?that make GO better dispersibility than graphene,which greatly expands the use of graphene.Porphyrin,a large?conjugated electron system,which can be modified in various ways.For example,it can be substituted by various groups,central metal and the size of the ring can be changed.Therefore,porphyrins and their derivatives have been recognized as a potential nonlinear optical material.The covalently functionalized GO with porphyrin can not only effectively improve the solubility of GO,but also combine the unique advantages of both porphyrin and GO.In this thesis,three aspects of the nonlinear optical properties of porphyrin covalently modified graphene oxide hybrid materials were studied.In chapter 2,we prepared carboxylation GO by nucleophilic substitution reaction.GO-TPP and GO-CH₂COOTPP nanohybrids were prepared through a chemical covalentlybondedmethodbyreactingGO-CH₂COOTPP/GOwith monohydroxyporphyrin.The composites were characterized by Fourier-transform infrared,Raman spectroscopy,thermogravimetric analysis,scanning electron microscopy,X-ray photoelectron spectroscopy,ultraviolet-visible spectroscopy and fluorescence spectroscopy.The results show that these composites have strong fluorescence quenching.The extinction effect indicates that there is a strong electron-energy interaction between porphyrin and GO.Finally,the nonlinear optical?including optical limiting?of the hybrid materials were carried out by Z-scan technique.The results show that the two composite materials have obvious enhanced nonlinear optical response with respect to the monomer,and the GO-CH₂COOTPP has better nonlinear optical effect than the GO-TPP.In chapter 3,we prepared two kinds of porphyrin covalent organic polymers COP-1 and COP-2 by Schiff base reaction,and using these two organic polymers to covalent functionalize GO.The hybrid materials GO-COP-1 and GO-COP-2 were prepared through a chemical covalently bonded method.The successful covalent attachment of porphyrin covalent organic polymers onto GO were confirmed by Fourier-transform infrared,Raman spectroscopy,X-ray photoelectron spectroscopy,ultraviolet-visible spectroscopy.The fluorescence spectra of the nano-hybrid materials showed different degrees of fluorescence quenching effect,indicating that there is a photoinduced electron/energy transfer effect between the porphyrin polymer molecules and GO.At the same time,the results of the Z-scan technology test indicate that the two synthesized hybrid materials have an enhanced nonlinear optical response compared to those of porphyrin organic polymer monomers and GO.In chapter 4,three hybrid materials GO-LaTPP,GO-EuTPP,GO-NdTPP were prepared through a chemical covalently bonded method,and characterized by infrared spectroscopy,thermogravimetricanalysis,Raman spectroscopy,andX-ray photoelectron spectroscopy.Moreover,the fluorescence spectra of these three hybrid materials also show fluorescence quenching,indicating that there is a photoinduced electron/energy transfer effect between the precursors,which is attributed to the synergistic effect of metalloporphyrin and graphene oxide.