Fabrication, Properties And The Electron Transfer Mechanism Of The Porphyrin-Based Composites With Novel Structure

Due to special structure and excellent physichemical performance, porphyrin and its derivatives can be easily modified and show potential applications in the fields of photocatalysis, sensors, optical devices and dye-sensitized solar cells. In this thesis, with the porphyrin as functional molecules, a variety of porphyrin-based functional composites with controllable morphology and excellent performance were rapidly constructed by non-covalent interaction. Furthermore, the photocatalytic activity of hydrogen evolution, stability and interfacial photoinduced electron transfer of the porphyrin-based composites were further studied. The main contents are summarized as the followed:Three kinds of graphene oxide (GO)-porphyrin composites were facilely assembled by means of non-covalent interaction. It was found that the functional groups linked on the peripheries of the porphyrins had an important influence on the combination mode of porphyrin and GO, and also the properties of GO-porphyrin composites.5,10,15, 20-Tetrakis(4-hydroxyphenyl)porphyrin (THPP) was easy to react with GO and flat on the GO due to the strong hydrogen bond and n-n interaction between THPP and GO. It was reasonable to conclude that the distance between THPP and GO was reduced owing to the flattening of THPP on the surface of GO, which further strengthened the interactions. Therefore, the photoelectric activity of the GO-THPP composite was higher than those of the other two porphyrins-GO composite. These results provided some hints for how to adjust the properties of the GO-porphyrin composites by modifying the combination mode between porphyrins and GO.By implanting metal ions as interfacial linkers of the graphene oxide (GO) and 5, 15-diphenyl-10,20-di(4-pyridyl)porphyrin(DPyP), a serial of novel GO-DPyP nanocomposites were achieved. In these composites, GO and DPyP were bridged by the metal ions by means of electrostatic interaction and coordination interaction. It was shown that the metal ions can modify the morphology and structure of the GO/DPyP nanocomposite, and facilitate electron transfer between GO and DPyP. Furthermore, the photocatalytic hydrogen evolution activity and electron transfer mechanism were investigated. The results demonstrated that the strong interaction and efficient electron transfer between the metal ions and DPyP/GO were the important reasons for the improvement of the photocatalytic hydrogen evolution performance. Implanting metal ions in the interface of GO and porphyrin is a simple and efficient approach to optimize the transfer pathway of photogenerated electrons and improve catalytic performance of nanocomposites.With 5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrin(THPP) and hexagonal Cu2O nanoparticle as the main reactants, a kind of the THPP/Cu2O complex with novel structure was facilely prepared. Combination mode between THPP and Cu2O were investigated in detail by UV-vis spectra and fluorescence spectra. The synergistic interaction caused by the coordination interaction between THPP and Cu+, and the interaction between the hydroxyl groups at the peripheries of the THPP and those on the surface of Cu2O should be the key to improve the physical and chemical performance of the THPP/Cu2O composite, as investigated by electrochemical impedance spectroscopy, photoelectric performance and photocatalytic hydrogen evolution.Carrying out the research contents in this paper, it will provide some new ideas for designing porphyrin assemblies with novel structure and excellent performance by a facile method. It will also provide theoretical guides for investigating photogenerated electron transfer in conversions of solar energy to hydrogen energy and to electric energy.