Study On The Photoelectric Properties Of Porphyrin Composites

The two global problems of fossil energy depletion and environmental pollution have been accompanied by economy development,and solar energy is a kind of renewable green energy.Photodegradation technology can convert low-density solar energy into storable green hydrogen energy,which is of great significance to solve the energy and environmental problems.At present,using semiconductor photodegradation water to produce hydrogen is one of the most potential ways to sustainable energy development.However,it is still challenging to obtain a highly active catalyst which can capture wide solar spectrum in photocatalysis.Porphyrin is generally regarded as an organic n-type semiconductor material with moderate band gap,excellent photoelectric activity,fast electronic transmission efficiency and weak charge recombination ability.It is widely used in photoelectric sensors and energy catalytic.Because of the low quantum yield and high photogenerated charge recombination rate of porphyrin monomers,the modified porphyrin and loaded with other precious metals to improve the whole catalytic performance of the materials by the researchers.In this paper,light-sensitive materials porphyrins are acted as the core,and the properties of the prepared materials are comprehensively evaluated by multi angle performance analysis.Based on scanning electrochemical microscope,the catalytic properties of light-sensitive materials are explored from the perspective of micro dynamics.The following work is divided into three parts:Part I:Study on the Enhancement of Photoelectric Performance of MoS₂ by Porphyrin CocatalystsCompared with porphyrin monomers,porphyrin assemblies have more excellent catalytic performance and visible spectral response,Therefore,the porphyrin assemblies were prepared by acid-base neutralization and micelle confinement.The introduction of molybdenum disulfide can accelerate the electron transfer and inhibit the recombination ability of photocarriers.Based on this,SA-THPP/MoS₂ composite was prepared.In this experiment,p-n heterojunction structure was formed to reduce the recombination rate of photocharge and produce better catalytic performance.SEM,XRD,UV-vis and PL were used to show that the target material was successfully prepared.At the same time,through the electrochemical tests of CV,EIS and i-t curve,it was found that the composite SA-THPP/MoS₂ exhibited a strong photocurrent response(1.25μA·cm^-2)and a low carrier recombination rate.The micro interface activity and charge transfer kinetic parameters of the catalyst system were characterized by UV-Vis/SECM.In the whole catalytic system,porphyrin and molybdenum disulfide have synergistic effect.The experimental results show that the system can be used as a photoelectric sensor,and the strong oxidation holes generated can realize the catalytic oxidation of plasticizer n-butyl phthalate（DBP）under the light stimulation.PartⅡ:Study on the Photoelectric Performance of Porphyrin Based AuNPsMetal porphyrin（CuTPP）is an organic macromolecule closely related to the life process,in which metal ions have a significant impact on the physical and chemical properties of CuTPP,such as light,electricity,etc.the improvement of catalytic system ability and the mechanism of action of metal ions were investigated.In this work,the porphyrin assembly（SA-CuTPP）was prepared by the co-solvent method,and then the composite material AuNPs/SA-CuTPP was obtained by the reduction of chloroauric acid with sodium borohydride.The successful preparation of the material was confirmed by optical and electrochemical characterization.Under the optimal condition,the photocurrent response intensity is 2.7μA·cm^-2.The active sites and their properties are further characterized by UV-Vis/SECM testing from the micro point of view.The results show that the composite has excellent photocatalytic performance,and the detection limit of 4-NP can reach 1.67nM.PartⅢ:Study on Photoelectric Performance of PCN-224 Loaded CdSThe organic ligands TCPP and Zr-MOFs were synthesized successively.CdS/PCN-224 composite was prepared by hydrothermal loading of CdS on the surface of PCN-224.CdS/PCN-224 has a good photoelectric response(6μA·cm^-2)measured by i-t curve and EIS.The charge transfer behavior on the surface of the composite was studied by using SECM technology.It was found that the composite exhibited a fast electron transfer rate(0.07072 cm·s^-1)under light irradiation,which was mainly because the presence of CdS inhibited the recombination probability of PCN-224 carriers.