Morphology-Controlled Syntheses Of Ti-based Metal-organic Frameworks And Their Catalytic Properties

The morphology-controlled syntheses of metal-organic frameworks?MOFs?,including size,shape and hierarchical structure,have attracted growing interests.These morphology-controlled micro/nanosized MOFs have shown significant size and shape effects and promising potential applications in catalysis,biomedicine,sensors,and energy storage and conversion.In this thesis,the morphology-controlled syntheses of the classical Ti-MOFs MIL-125 were studied by the coordination modulation method.The catalytic performance of the morphology-controlled MIL-125 crystals towards oxidative desulfurizaion were investigated.Ti-based metal-organic coordination capsule was synthesized and the crystal structure,photoelectrochemical and photocatalytic properties were studied.The main results in this thesis are summarized as follows:1.Truncated octahedral MIL-125 crystals were synthesized by using hexanoic acid as the coordination modulator.Compared to the typical circular plate shaped MIL-125crystals with dominant{001}facets,the truncated octahedral crystals exhibit high ratio of{101}facets,with sized reduced to 200–400 nm.The truncated octahedral MIL-125crystals exhibit remarkably enhanced catalytic performance towards oxidative desulfurizaion of DBT and 4,6-DMDBT.2.The micro-macro porous MIL-125 crystals with rich structure defects were synthesized by using 3-phenylpropionic acid as the coordination modulator.The crystals exhibit open hollow cube-like morphology with size significant reduced to 100 nm,which possess high external surface area.Compared to traditional micro-sized MIL-125crystal,the nanosized MIL-125 crystals show much enhanced catalytic performance towards oxidative desulfurization of DBT and 4,6-DMDBT.3.The metal-organic coordination capsule Ti₁₆DHB₄ was synthesized and structurally characterized by single-crystal X-ray diffraction analysis.Ti₁₆DHB₄ was constructed by the{Ti₈O₈H}cluster units and 2,5-dihydroxybenzoate?DHB?linkers.Due to the low-energy ligand-to-cluster charge-transfer transition?LCCT?,Ti₁₆DHB₄exhibits wide visible-light absorption band and narrow band gap of 2.1 eV.The unique structure of metal-organic coordination capsule forms an integrated dye-sensitized photoactive system which greatly promote the photocatalytic performance of Ti₁₆DHB₄.