Syntheses And Properties Of Functional Materials Based On Transition Metals

Transition metal elements have electronic configurations different from those of the main group elements,which providing the transition metal compounds with some special optical,electrical and magnetic properties.Transition metal coordination polymers and transition metal oxides are widely used in photocatalysis,electrocatalysis,adsorption and other fields.The syntheses of new transition metal compounds,as well as the study of their properties and applications are of great significance for the design and development of new materials.The main work and findings of this thesis are listed below:(i)Three 3D coordination polymers,[Cu(cca)(4,4'-bipy)]n(1),[Co3(pda)3(1,10'-phen)2]n(2)and[Co(pda)(1,10'-phen)]n(3)have been synthesized from 4-carboxycinnamic acid(cca),1,4'-phenylenediacrylic acid(pda),4,4'-bipyridine(4,4'-bipy),1,10'-phenanthroline(1,10'-phen)and Cu2+/Co2+under different conditions.The structures of these three complexes were characterized by single crystal X-ray diffraction.Complex 1 exhibits a threefold 3D ?-Po interpenetration network.Complex 2 displays a 3D framework with six-connected single ?-Po framework constructed from Co3 unit.Complex 3 shows a 3D framework with bcu topology composed of 1D rod-shaped secondary building units(SBUs).Complex 2 exhibits good photocatalytic activity after excited by UV light,71%of Rhodamine B(RhB)can be decomposed in 300 min.(ii)Three rhodium complexes Rh(vpy)2(1-nqo)Cl2(4),Rh(vpy)(1-nqo)2Cl(5)and Rh(1-nqo)3(6)have been obtained through reactions of RhCl3 and 1,2-naphthoquinone-1-oxime(1-nqo)using 4-vinylpridine(4-vpy)as co-ligand.The structures of the complexes were analyzed by single crystal X-ray diffraction,FAB mass spectrometry and 1H-1H COSY NMR.(iii)A polyoxometalate based composite material(NiPW12NP/FrGO)has been synthesized,in which nanoparticles of polyoxometalate compound(NiPW12NP)distributes on carboxylate group functionalized reduced graphene oxide(FrGO)homogenously.The stability of this composite material is guaranteed through chemical bondings between NiPW12NP and FrGO.The NiPWi2NP/FrGO composite material shows excellent tetracycline adsorption ability with a capacity of 288.28 mg/g.(iv)A nitrogen doped mesoporous carbon matrix supported oxygen vacancy rich tungsten oxide composite material,WO3-x@NC(0<x<1),has been fabricated successfully with chitosan and H3PW12O40 as precursors through calcination.In this composite material,WO3-x particles with the size about 10 to 15 nm disperse evenly in nitrogen doped mesoporous carbon matrix.WO3-x@NC presents low overpotentials of 61 and 306 mV to reach a current density of 10 mA/cm2 for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in 1.0 mol/L KOH,respectively.With WO3-x@NC as both cathode and anode at the same time,an electrolyzer,WO3-x@NC/WO3-x@NC was constructed for overall water splitting,which only needs a cell voltage of 1.60 V to achieve a current of 10 mA/cm2.Moreover,WO3-x@NC also shows striking catalytic activity for reductive conversion of 4-nitrophenol to 4-aminophenol.(v)CeO2/PANI composite has been prepared by potentiostatic electrocodeposition of CeO2 and polyaniline(PANI)on graphite foil at 1.1 V(vs.SCE).The morphology of the CeO2/PANI composite were characterized by scanning electron microscope(SEM)and transmission electron microscope(TEM).The results indicate that the CeO2/PANI composite has "horn-like" morphology.Characteristic vibrations of PANI were observed on the Fourier transform infrared spectrum(FT-IR)of CeO2/PANI composite.Influences of electrochemical deposition conditions on the morphology of the composite were investigated.The results show that potential is the key factor for the formation of "horn-like".The wedge spaces with broad bottom and narrow top are helpful for the guest components to tansport into the composite to get fully contact with the active materials.