Study On Preparation,Photoelectric Properties Of The Composites Based On TiO₂/Porphyrin Nanocomposites

Energy shortage is one of the three major problems in the 21st century.The total global energy consumption is up to 1.39×10¹3 J/s,while the solar energy on the earth's surface is up to 1.7×10¹7 J/s.Therefore,the conversion of solar energy into renewable resources through artificial photosynthesis is an important innovative technology.So how to achieve effective optical absorption?The photogenerated carriers efficiently separation and transfer is one of the key problems to the process of solar energy conversion.Developing new and efficient organic or inorganic semiconductor composite photocatalysts is one of the effective methods to solve these problems.Porphyrins,widely existing in nature,play the certain role in life of animals and plants.Porphyrin is considered to be a valuable photosensitizer.Because of the electron transition from HOMO to LUMO.porphyrin compounds exhibit strong optical absorption?B?soret?band at 350-450 nm and Q band at 500-700 nm?in the UV-visible region.Porphyrin compounds has good photochemical stability,high ¹O₂yield and good electronic donor performance.Porphyrin is an n-type semiconductor with fast electron injection efficiency,and its band gap can also match most other inorganic metal semiconductors.Therefore,porphyrin derivatives or porphyrin-based nanocomposites emerge in endlessly.It is widely used in solar cells and various optoelectronic devices.Hence,we constructed a TiO₂/porphyrin-based photocatalyst by introducing noble metals,element doping and morphology controlling strategies,and explored its photoelectrochemical properties through a variety of electrochemical techniques and applied to photoelectrochemical sensors.It includes the following three parts:1.Enhanced Photoelectrochemical Performance by plasmonic Gold Nanoparticle Integrated TiO₂/Molecular Zinc Porphyrin Photoanode.In this work,we mainly investigated the effect of Au nanoparticles?Au NPs?surface plasmon effect?LSPR?on the electron transfer of metal porphyrin ZnTPPS₄ and non-metal porphyrin TPPS₄.We found that the ZnTPPS₄ system exhibited better photoelectric properties than TPPS₄ in the plasma resonance field of Au NPs.Au NPs also act as photoelectron acceptors to accelerate electron transfer.The growth of 1D TiO₂ on FTO substrates by hydrothermal method provides a direct transmission channel for photogenerated charges.Then,the nanocomposites of TiO₂/Au/ZnTPPS₄ were successfully prepared by immersing Au NPs and ZnTPPS₄.The same method was used to prepare TiO₂/Au/TPPS₄.The photoelectric properties of the composites were tested by It-curve,EIS and SECM.This work provides a new perspective for the design of plasma metal-porphyrin based photoelectric nanocomposites.2.Preparation reduced TiO₂/Porphyrin nanocomposites and photoelectric properties researching.The solar light absorption of reduced TiO₂ is increased because that introduced the oxygen vacancies and Ti³⁺or disordered layer to the surface of high crystalline TiO₂.Therefore the charges recombination rate decreases and the catalytic performance improves.Reduction of TiO₂ is one of the effective ways to promote the photocatalytic activity of TiO₂ nanomaterials.In this work,black TiO₂was prepared by thermal reducting TiO₂ with NaBH₄.Then Au NPs were loaded by reduction of AuCl₄H₃O.Au NPs acted as relay to accelerate electron transport.Finally,ZnTPPS₄ was compounded by impregnation method,the b-TiO₂/Au/ZnTPPS₄nanocomposites were successfully prepared.The electrochemical techniques such as It-curve,EIS and IMPS were used to prove excellent photoelectric properties of the composites.The photoelectrochemical sensing of L-cysteine was constructed,and the detection limit of 0.06 uM was obtained.3.Preparation 2D composite material TiO₂/WS₂/TPPS₄ and photoelectric properties researching.2D nanostructured TiO₂ has large surface area and large volume at atomic scale,which has aroused great interest of its photocatalytic activity.In this work,firstly,2D nano-sheet composite of TiO₂/WS₂ was prepared by hydrothermal method,and then TPPS₄ was loaded by impregnation method.The material was characterized by SEM,XRD,XPS and other characterization methods.By electrochemical characterization such as It-curve,IMPS,EIS,it was found that the composite had excellent photoelectric properties.The photoelectrochemical sensing of glucose was constructed,and the detection limit of 1.9 mM was obtained.