Research Of The Synthesis And Photoelectric Properties Of Titanium-Oxo Clusters Modified With Redox Ligands

Titanium oxide clusters(TOCs)have attracted much attention because of their precise structure information,which lay a theoretical foundation for studying the structure-property relationship of titanium oxide materials as model compounds.In addition,TOCs have great potential applications in catalysis,photocatalysis and photoelectric conversion.With the efforts of researchers around the world,the research of TOC materials has achieved great development.Although many functional ligand-modified TOCs have been reported,little research has been done on the modification of TOCs with redox ligands.The redox ligands have reversible redox electrochemical properties and excellent electron donor-acceptor properties,which contribute to the rapid and effective separation and transfer of electrons and holes,thus improving the photoelectric properties of devices.In this thesis,we focus on the construction of various redox ligand-modified TOCs as electrode-modified hybrid materials to further study their electrochemical properties and photoelectric response properties.The main contents of the thesis are as follows:(1)In introduction,the properties and current research of TOCs were summarized,and the applications of TOCs such as photoelectric conversion,perovskite solar cells,potassium ion batteries,capacitors,catalysts,multi-functional coating layers,and drug identification were further elaborated.(2)In order to synthesize new TOCs,two TOCs,Ti13O10(o-BDC)4(SAL)4(OiPr)16(1)and Ti13O10(o-BDC)4(SAL-Cl)4(OiPr)16(2)co-coordinated by phthalic acid(BDC)and salicylic acid salt(SAL)were successfully prepared by solvothermal method.X-Ray single crystal analysis showed that compounds 1 and 2 adopt the S4 symmetry "paddle"arrangement,and the non-compact structures were further stabilized by the common coordination of BDC and SAL ligands.The film photoelectrodes of the compounds were prepared by solution spin coating method,and the photoelectric response properties of the film electrodes were studied.(3)In order to study the properties of TOCs modified by classical redox ligands,in this section,the redox ligand ferrocenecarboxylic acid(HOOCFc)modified TOC[[Ti6O6(OiPr)6(OOCFc)6](3)was synthesized.As a comparison,the analogue[Ti6O6(O'Pr)6(OOCiPr)6](4)modified by HOOC'Pr(isobutyric acid)was also synthesized.Compound 3 displayed redox properties contributed by the presence of the ferrocenecarboxylic acid ligand,whereas compound 4 has no redox property.Charge transfer from the ferrocene groups to the TOC core was confirmed by electronic spectra and theoretical calculation in compound 3.The ferrocene group promotes effective electron excitation and charge separation.The photoelectric response of compound 3 modified electrode was better than that of compound 4.In addition,the photoelectric responses of compound 3 to four sugars(glucose,fructose,maltose,and sucrose)were measured.The results showed that the electrode only responded to reducing sugar.(4)In order to study the effect of multiple sensitizers on the photoelectric properties of TOCs,in chapter 4,two dye ligands,ferrocenecarboxylic acid(HO2CFc)and catechol(Cat),co-modified TOCs[Ti30(OiPr)6(Cat)(FcCO2)2](5)and[Ti7O4(OiPr)8(Cat)5(FcCO2)2](6)were synthesized.As a comparison,phthalic acid(BDC)modified analogue[Ti7O3(OiPr)12(Cat)4(BDC)](7)was synthesized.Electronic spectroscopy and theoretical calculations showed that both of the FcC02 and Cat ligands were involved in charge transfer in compounds 5 and 6.Among them,redox ligand FcC02 contributes more than Cat.Dye-sensitized TiO working electrodes were prepared using the TOCs as precursors of TiO dye system and their photoelectric response properties were tested.The photoelectric response properties of the working electrodes were better than that of the single dye system,which verified that the synergistic effect between dye ligands can enhance the photoelectric performance.(5)In order to study the effect of redox functional ligand tetrathiafulvalene(TTF)on the photoelectric properties of TOCs,in chapter 5,a thiophene(Th)derivative and a TTF derivative were selected as ligands,and four TOCs were successfully synthesized:[Ti30(OiPr)8(LTh)2](8),[Ti4O2(OiPr)10(LTTF)2](9),[Ti6O4(OiPr)10(LTh)2(O3PPh)2](10),and[Ti6O4(OiPr)10(LTTF)2(O3PPh)2](11).The electronic spectra and theoretical calculations showed that charge transfer is from Th or TTF electron donors to TOC core.Dye-sensitized solar cell devices were fabricated using the TOCs as the precursors of TiO dye system,and the photoelectric properties of the devices were tested.The experimental results showed that the photoelectric performance of TTF TOC modified device is better than that of Th TOC,which is mainly due to the fact that TTF is a sulfur-rich conjugate system.This work is the first example to systematically study TOCs modified with different conjugated sulfur heterocyclic ligands and their photoelectric properties at the molecular level.