The Preparation And Photoelectrocatalytic Properties Of Graphene-like Two-dimensional Porphyrin Nanocomposites

The graphene-like material is a kind of new nanomaterial like typical graphene with atomic thickness and ultra-thin two-dimensional layered structure,which possess excellent electron transfer ability and large specific surface area.Porphyrin,a unique molecular structure,implies great photosensitive properties and excellent electron donating ability.Based on their unique performance,there are a lot of studies about the combination between porphyrins and graphene-like materials to achieve efficient electron transfer between them,which can be applied in photoelectric converter,analytical sensor and photocatalyst.The main contents of research are as follows:1.The reduced graphene oxide(rGO)with increasing degree of reduction was prepared by chemical reduction method from graphene oxide(GO),which was charged with a decreasing negative charge.The cationic porphyrin(5,10,15,20-tetra(4-propyl pyridinio)porphyrin,TPPyP)was self-assembled onto the surface of rGO to obtaine the rGO/TPPyP composite.It was further found that Zn2+ could be effectively embedded into the porphyrin ring to form rGO/TPPyP-Zn complex at room temperature and the embedding velocity was directly related to the surface charge of rGO.The experimental results showed that the assembly of TPPyP onto rGO and the embedding process of Zn2+ lead to red shift of the porphyrin characteristic absorption in the UV-visible absorption spectra,the thickness change of the two-dimensional nanosheet under the atomic force microscope(AFM)and the quenching effect of the fluorescence spectrum.Therefore,a new method for the preparation of water-soluble zinc-porphyrin-graphene nanocomposites was developed at room temperature,and it was found the prepared rGO/TPPyP-Zn nanocomposites show enhanced photoelectrocatalytic activity for CO2 reduction.2.By liquid phase exfoliation of graphite under ultrasonic condition,the water-dispersed graphene(wG)with increasing surface negative charge were prepared.which were further combined with the metal cationic porphyrin(copper porphyrin and zinc porphyrin)to form the graphene-metal porphyrin composite And the UV-visible absorption spectra,AFM,Zeta potential and other results showed that the photoelectrochemical properties of the composites were directly affected by the surface charge of wG.The complex could be applied to the catalytic reduction of CO2.3.The graphite-like carbon nitride(g-C3N4)was synthesized by thermal polymerization of melamine precursor,which was further treated by acidification and ultrasonic treatment to get the ultra-thin g-C3N4 nanosheets.The surface positve and negative charge properties of thenanosheets were changed with the pH values of the solution.It was found that the nanosheets possess pH-regulated photodegradability towards different dyes,rhodamine B(RhB)and chromotropic acid 2R(Ch2R).Besides,by the interaction of g-C3N4 nanosheets with cationic porphyrin(tetrakis [4-sulfopropylbenzene pyridine] porphyrin,THPPyP)and anionic porphyrin(meso-tetra(4-sulfophosphate)porphyrin,TPPS4)under suitable conditions,the g-C3N4/THPPyP and g-C3N4/TPPS4 nanocomposites were obtained.The composite were characterized by UV-visible absorption spectra,fluorescence spectra and electrochemical methods.The thin film modified electrode was fabricated through charge-induced layer-by-layer assembly of g-C3N4/THPPyP composite onto FTO.Furthermore,the photocurrent response of the modified electrode was gradually increased with the number of layers and the composite film had enhanced photoelectrocatalytic ability for CO2 reduction.