| In nature, porphyrin molecules, known as “Life dye”, are key componentinchlorophyll, hemoglobin and other biological macromolecules. Due to theirmacrocyclic π conjugate structure and strong absorption in the visible region，prophyrins provide primary electron to participate multi-step reaction process in thephotosynthesis in plant chloroplasts. Therefore, porphyrin and its derivatives areimportant compounds for the investigation of biomimetic chemistry, catalysis, solarsensitization, medicine, analytical chemistry and so on. Through photosynthesis,plants convert solar energy into chemical energy. It is proved that the photon captureand electron transfer in photoreaction center is the crucial factor of this process. Therecent research focuses on constructing the compounds being capable of harvestingphotons and studying on intramolecular light harvesting electron transfer and chargeseparation. In this paper, by combination of porphyrin and carbon nano-materials, aunique bionic model of light harvesting antenna was successfully constructed and itsinternal electron transfer process was investigated carefully. Futhermore, it isnoteworthy to point out that in this work we provide ideas and methods to mimicphotosynthesis and fabricate photoelectric devices. Our work mainly includes thefollowing three chapters:Chapter One: we prepared a novel Au@THPP (the core-shellgold-4-hydroxyphenyl porphyrin) hybrid composite structure and functionalizedcarbon nanotubes. Through the diazo-reaction, we assembled Au@THPP andmodified CNTs on the surface of the indium tin oxide (ITO). Depending on thecomplexity of the spatial structure and its dynamics of the optical system inphotosynthesis, we established a simple analog light harvesting bionic model, whichwere characterized by SEM, TEM, UV-vis, IR, XPS and AFM. These informationscan provide the platform for a practical strategy for rational design of the electrontransfer of photosystem.Chapter Two: we have prepared the novel functional the core shell gold-4-hydroxyphenyl porphyrin/CNTs hybrid nanocomposites, which have threedimensional space structures and a fantastic photoelectric property. According to thespatial elaborate architecture and the characteristics kinetics of the photosystem, anew bionic model of mimicking light harvesting was established. Furthermore, weanalyzed the model in detail and described the single contribution hierarchically viaUV-vis/scanning electrochemical microscopy (SECM), which provides a fast andquantitative method to measure with light harvesting electron transfer between themodel and electron mediator (benzoquinone). In the region of560nm the lightharvesting ET rate constant of this model is maximum, which was consistent with thatthe predominant chromophore matched with the optimal excited wavelength toachieve maximum absorption of light energy in PS, And this work can offer feasibilitythe ideas and methodologies to photoelectric device and the artificial photosystem.Chapter Three: A novel light “on-off” photoelectrochemical sensing for thesensitive determination of GSH (glutathione) with visible light was developed basedon the Au@THPP core-shell hybrid nanocomposites on vertically aligned carbonnanotube. At first, using reduction of tetra-hydroxyphenyl porphyrin (THPP),Au@THPP core-shell nanoparticles was preparated in the mixed solvents by one-potmethods. And then the core-shell of (Au@THPP) nanopaticles was assembled on theCNTs by electrostatic interaction. Because of carbon nanotubes and Au@THPPsynergistic effect, they react with GSH to produce strong photocurrent response,surveyed the influence of the wavelength and the bias with light response. Thismaterial has a prominent photocurrent response at-0.2V to detect the GSH under alight illumination at560nm. The high sensitivity and good stability at such a modifiedelectrode led us to construct a practical sensor successfully. Such Au@THPPcore-shell nanocomposites to detect content of GSH may hold great promise forapplications in photoelectrochemical sensing. |
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