Synthesis,Characterization And Catalytic Properties Of Water-soluble Cobalt Phthalocyanine/Graphene Oxide Composites

Graphene oxide(GO)as a novel carbon material has attracted more attention owing to its excellent optical and electrical properties,especially its unique surface structure.The oxygen-containing functional groups on its surface make it easy to be modified through introducing different kinds of functional molecules onto its surface by covalent or non-covalent method.Functionalized graphene oxide has potential applications in many fields such as photochemistry,photocatalyst,electrical chemistry etc.In this work,a novel water-soluble cobalt phthalocyanine/GO nano-composite was synthesized through non-covalent method aiming to develope a new kind of photocatalyst for degradation of organic pollutions in water under visible light irradiation.Firstly,a cationic phthalocyanine ImPcCo was synthesized through introducing four imidazole cationic substituents to the phthalocyanine ring.This complex can be well dissolved in water,but mainly as aggregation state.In order to reduce its aggregation,four kinds of imidazole ligands with different carbon train group including imidazole,methylimidazole,butylimidazole and hexadecylimidazole as the axial ligands were introduced to the metal center and four axially substituted phthalocyanines ImPcCo-Im,ImPcCo-MeIm,ImPcCo-BuIm and ImPcCo-HexIm were synthesized respectively.Comparing their UV-Vis absorption spectra,we can conclude that these four axially substituted cobalt phthalocyanines were dissolved in water mainly as monomer.That means the introduction of axial ligands can effectively reduce the aggregation state of the phthalocyanine ring,while the effect of hexadecylimidazole as the axial ligand is the weakest among them attributing to its long hydrophobic carbon train.In addition,the absorption peaks of Q-band of the axially substituted cobalt phthalocyanines were redshifted comparing to that of the non-axially substituted cobalt phthalocyanine with maximum of 10 nm.The above four cobalt phthalocyanines ImPcCo,ImPcCo-Im,ImPcCo-Melm and ImPcCo-BuIm were used to modify graphene oxide respectively and four nano-composites ImPcCo/GO,ImPcCo-Im/GO,ImPcCo-MeIm/GO and ImPcCo-BuIm/GO were synthesized successfully through utilizing two kinds of adsorption interactions:?-? interaction and electrostatic adsorption between phthalocyanine molecules and the surface of graphene oxide.They were characterized by FI-IR,UV-Vis,XRD and TG.A redshifted and broadened Q-band of phthalocyanines was found after being adsorbed on the surface of graphene oxide in the UV-Vis absorption spectra of these composites,which can be attributed to the strong ?-? interaction between phthalocyanine molecules and the surface of graphene oxide.The introduction of a suitable axial ligand does not destroy the ?-? interaction between phthalocyanine molecules and graphene oxide.Additionaly,the maximum adsorption quantities in composites ImPcCo/GO,ImPcCo-Im/GO,ImPcCo-Melm/GO and ImPcCo-BuIm/GO were determined as 1.33×10-4 mmoi/mgGO,9.64 × 10-5 mmol/mgGO,1.04× 10-4 mmol/mgGO and 1.04 × 10-4 mmol/mgGO by UV-Vis absorption spectrum method.Finally,the photocatalytic activity of composite ImPcCo/GO for degradation of RhB under visible light irradiation was studied.Under the same experimental conditions,independent complex ImPcCo and GO all had no activity for photocatalytic degradation of RhB,while the nano-composite ImPcCo/GO showed a certain photocatalytic activity.After reaching adsorption equilibrium,the degradation rate of RhB can reach 30%at 3 h under visible light irradiation.This results means that composite ImPcCo/GO can be used as a potential photocatalyst for degradation of organic pollutions.