Preparation And Photocatalytic Properties Of Graphene/Manganese Phthalocyanine And Graphene/Titanium Dioxide Composites

In recent years, metal phthalocyanine and titanium dioxide have been used as photocatalysts because of their excellent photocatalytic activity, however, the catalytic efficiency is not high enough due to their easy agglomeration when used alone. If the metal phthalocyanine and titanium dioxide was loaded onto graphene oxide?GO? and benzoic acid functionalized graphene?BFG?, not only their dispersion in solution but also their catalytic activity could be improved. In this paper,a series of MnTAPc-GO,MnTAPc-BFG and TiO₂-BFG composites were synthesized and characterized,and their photocatalytic properties were studied.The composites MnTAPc-GO were synthesized by using manganese phthalocyanine ?MnTAPc? and GO via an amidation reaction. The structures of samples were characterized by transmission electron microscopy ?TEM?, transform infrared spectrograph ?FT-IR?, X-ray photoelectron spectroscopy ?XPS?. The results indicate MnTAPc is covalently bound to GO. The photocatalytic activity of MnTAPc-GO composites was investigated by using rhodamine B as a model pollutant under visible light irradiation. For MnTAPc-10%GO, the decolorization removal ratio of rhodamine B is up to 96% under the conditions of 55 ?, pH6 and 0.01 mol/L hydrogen peroxide in visible light for 70 minutes. The catalytic performance of the composites was not inhibited in the presence of IPA and NaCl, and the catalytic rate was also increased to a certain extent.The composites MnTAPc-BFG were synthesized by using MnTAPc and BFG via an amidation reaction, which were characterized by TEM, FT-IR, Raman and XPS.The results indicate MnTAPc is covalently bound to BFG. The MnTAPc-BFG composites are firstly used for degradation of rhodamine B under ultraviolet light.The results demonstrate that the photocatalytic activities of the composites are strongly enhanced compared to pure MnTAPc, and the composites with 10% doping ratio exhibit the highest photocatalytic efficiency. The degradation rate of MnTAPc-10%BFG reached 90% in 3.5h under ultraviolet light. On the one hand, the appropriate addition of 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 BFG nanosheets in composites might obstruct the light absorption of MnTAPc and prevent MnTAPc from reaching the reactants in solution. Thus the ultraviolet light catalytic efficiency is decreased.The TiO₂-BFG composites were prepared by using tetra-n-butyl titanate ?Ti?OBu?₄?and BFG via solvothermal method, which were characterized by XRD and XPS. The results indicate TiO₂ is covalently bound to BFG. The TiO₂-BFG composites were used for degradation of tetranitrophenol under ultraviolet light. The results show that the photocatalytic activities of the composites were strongly enhanced compared to pure TiO₂. For the TiO₂-BFG composite synthesized by controlling the reaction time of 4 h and the addition amount of BFG of 10 mg, the decolorization removal ratio of tetranitrophenol was up to 89% in ultraviolet light for 1 h, indicating that the addition of BFG can effectively improve the catalytic performance of TiO₂.