Study On The Properties Of Polyoxotitanate Clusters And Metal Coordination Polymer Composites

With the increasing demand of human beings for energy,the energy consumption worldwide has also been increasing.The photocatalytic reaction is of great significance in the aspects of sewage treatment,hydrogen production from solar energy decomposition,and the like.Polyoxotitanates(POTs)materials have many potential applications in the field of photocatalysis,such as structural diversity,property tunability,and so on.The main problems existing in titanium oxo-clusters are the poor chemical stability and narrow light absorption range,which limits the practical application of POTs in the field of photocatalysis.Therefore,how to improve the stability of titanium oxo-clusters and increase photocatalytic activity is an important research topic and a major challenge.Based on the knowledge background and research experience,we propose to improve the stability of titanium oxo-clusters and extend the light absorption range to visible-near-infrared light by preparing metal/non-metal doped and dye-sensitized POTs on the basis of full literature research.Area.This topic is devoted to systematically studying the synthesis,functionalization and structure-activity relationship of POTs.Through the study of this topic,general synthesis rules have been summarized,the relationship between structural properties has been studied,and economically efficient photocatalytic applications have been achieved.The results of this work may lead to widespread interest in POTs,especially in the field of photocatalysis.Porous liquid materials have unlimited prospects,and the preparation of synthetic porous liquids for gas adsorption and other research will be an important topic.Through the choice of the frame material and the ionic liquid,a highly stable,fluid,porous porous liquid is obtained.Provide more reference examples for the preparation of porous liquids.The main research results are summarized as follows:1.We present a novel strategy to improve the stability and optical absorption of polyoxotitanates(POTs)via concurrently fully carboxylate-coordinating and hetero-metal-doping and illustrate the strategy by an indium doped hetero-polyoxotitanate(h－POT)ofa[Ti12In6O18(OOCC6H5)30](POTi12In6)nanocluster,which possesses ultrahigh stability in both acid and base aqueous solutions.The nanocluster structurally features a core-shell double wheel structure and a polar cavity.Both experiments and theoretical calculations confirm the semi-conductive properties of the nanocluster.Under visible irradiation the POTi2In6 nanocluster can produce pronounced photocurrent,and reactive oxygen species for pollutant degradation.Without using any co-catalyst,POTi12In6 exhibits important visible-light-driven photocatalytic activity for H2 evolution in an aqueous system.This work could render a polyoxotitanate as a new type of visible photoactive photocatalyst.2.We report a new Cu-doped[Ti5Cu4O6(OOCC6H5)16](denoted as POTisCu4)nanocluster,which exhibits strong near-infrared(NIR)absorption and a pronounced photothermal effect and photocurrent under NIR irradiation.This work could open a new window to metal doped polyoxotitanate for NIR light utilization.3.Synthetic bimetallic doped titanium oxo-clusters were prepared by solvothermal methods:Ti12In4Zn4O22(OOCC6H5)24,Ti12In14Co4O22(OOCC6H5)24,and Ti12Zn4Mn4O22(OOCC6H5)24,which are all isostructural.Titanium oxide clusters with different light absorption are obtained by doping with different metal ions,and the properties of the titanium oxide clusters are adjusted according to different metal ions.They were used for the cycloaddition experiments of carbon dioxide and propylene oxide,and it was found that the activity of Mn-doped titanium oxide cluster was higher.4.MOF-based porous liquid by dispersing ZIF-8({Zn(mim)2},mim =2-methylimidazole)nanocrystallites in ionic liquid(IL)of[Bpy][NTf2].Preventing ZIF-8 nanocrystals from aggregation before dispersing is vital to form stable ZIF-8 colloid in IL via enhancing the interaction between ZIF-8 and IL.The resultant ZIF-8-[Bpy][NTf2]colloid is able to be stable over months without precipitating.[Bpy][NTf2]with larger ion sizes cannot occupy pores in ZIF-8,leaving ZIF-8 cage empty for guest molecules accessing.The porosity of this porous liquid system was verified by positron(e+)annihilation lifetime spectroscopy(PALS)and I2 adsorption in ZIF-8 in the colloid.MOF-based porous liquids could provide a new material platform for liquid-bed based gas separations.