Preparation And Properties Of Graphene/Metal Phthalocyanine Composites

Graphene as a new carbon material is a flat monolayer of carbon atoms packed tightly into a two-dimensional honeycomb lattice. Because of its specific structure, graphene has shown several outstanding optical, electrical, magnetism and mechanical properties. However, the poor solubility in solvents and poor compatibility seriously limits the exertion of its great potentials. Recently, graphene has been modified with different kinds of functional groups and compounds through covalent method. Functionalized graphene has attracted more attention because of their good dispersion in solvent and easy modifiability. Phthalocyanines possess excellent optical properties and have been widely used in the field of photovoltaic conversion materials, photocatalyst and nonlinear optical materials. In this work, a series of graphene/phthalocyanine composites have been synthesized and characterized. Their photocatalytic and nonlinear optical properties were studied in detail. The main contents are as follows:1. In this dissertation, three composites ZnTAPc-GO, ZnTAPc-BFG and CoTAPc-BFG were synthesized by using amino phthalocyanine (ZnTAPc, CoTAPc) and self-made functionalized graphene (graphene oxide GO, benzoic acid-functionalized graphene BFG) via an amidation reaction. The structures of samples were characterized by transform infrared spectrograph (FT-IR), Raman spectra (Raman), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The results indicate tetraamino-zinc phthalocyanine is covalently bound to benzoic acid-functionalized graphene.2. The ZnTAPc-GO and ZnTAPc-BFG composites are firstly used for degradation of rhodamine B under visible light irradiation. The results demonstrate that the photocatalytic activities of the composites are strongly enhanced compared to pure ZnTAPc, and the composites with 10% doping ratio exhibit the highest photocatalytic efficiency. The degradation rate of ZnTAPc-10%GO and ZnTAPc-10%BFG reached 82.32% and 90.47% in 3.5h under visible light, respectively. The appropriate addition of GO or BFG can improve the acceptance and transfer of photogenerated electrons to promote the separation of electron-hole pairs under irradiation. On the other hand, the excessive graphene nanosheets in composites not only obstruct the light absorption of ZnTAPc, but also prevent ZnTAPc from reaching the reactants in solution, thus the efficiency of the visible light catalytic efficiency is decreased.3. The third-order nonlinear optical properties of the CoTAPc, BFG and CoTAPc-BFG composite were studied by Z-scan technique. Nonlinear absorption coefficient p were measured to be 1.4×10-11,2.1×10-10 and 6.0×10-10m·W-1. On the other hand, the third-order nonlinear properties of the composite can be improved obviously compared to CoTAPc and BFG.