Zr-MoFs Load ZnS:Mn Nanoparticles And Chemical Modification

Metal-organic frameworks?MOFs?constitute a class of materials with molecular scale porous structure,consisting of inorganic metal centers connected by organic linkers,the ligand usually contain oxygen,nitrogen and other carboxylic acid salt or imidazole ring.Because MOFs have high surface areas,adjustable structures and pore volumes,it has attracted the attentions and expectations of researchers in gas separation/storage,catalysis and drug delivery.Further,because of the channel and inner surface of the holes can be chemically tailoring,MOFs,as a host,have become a hot topic in research and application of loading functional guest molecules.However,there are still many difficulties in loading,such as the load condition is harsh,the hole of host is not easy to open and the size of guest is required,thus it is important to carry out the research on these fields.Recently,UiO materials?UiO=University of Oslo?consisted of Zr₆O₄?OH?₄ octahedron as a series of MOFs have attracted much attention because of their exceptional thermal and chemical stabilities.In this thesis,the effect of the load methods on the fluorescence properties of the guest are studied,with UiO-66?UiO-66=[Zr₆O₄?OH?₄?bdc?₆]_n;bdc=1,4-terephthalic acid?as the host frame,and ZnS particles doped by a little amount of Mn?ZnS:Mn?as the guest.Moreover,the structure modification and methods of UiO-66 are studied and application in the loading metal cations are discussed.The main conclusions are as follows:1.Preparation and the study of luminescence properties of ZnS:Mn@UiO-66The effects of monocarboxylic acid?methacrylic acid,MAA?on crystal morphology of UiO-66,as modifier,were investigated and the UiO-66 crystals with regular shape and uniform size?approx 0.40?m?were obtained.Compared with reflux method and hydrothermal method,ZnS:Mn nanoparticles,about 1.90nm?matching with the pore size of host?with the fluorescence properties,could obtained by hemical precipitation method.In comparison with thephysicalmethod?ultrasonic,hydrothermal,reflux?,“bottle-around-ship”and“ship-in-a-bottle”,the loading rate of“ship-in-a-bottle”was the highest,up to 45.90%.Photoluminescence?PL?analysis indicated that the ultrasonic method could load ZnS:Mn in the UiO-66 holes,thereby reducing the surface defect level of quantum dot and improving the luminous efficiency;PL characteristic peaks of“bottle-around-ship”were red shifted,which indicated that nanoparticles embedded in the holes of UiO-66 happened“Secondary absorption-emission effect”,resulting in the emission energy of ZnS:Mn lower and red shift of peaks;In“ship-in-a-bottle”,the Zn²⁺and S^2-fully reacted in the reflow conditions,which resulted in the reducing of electron-hole pairs transition of surface defect state and fluorescence intensity.2.Modification and metal ion absorption/desorption properties of UiO-66-SO₃^-UiO-66 was modified by sodium 3-sulfobenzoate?SSBA?and 5-sulfosalicylic?SSA?acid to obtain UiO-66-SO₃^-?SSBA?and UiO-66-SO₃^-?SSA?.XRD,FT-IR and SEM characterizations showed that the product maintains the original structure of UiO-66.The experiments of Cu²⁺adsorption/desorption showed that,compared with UiO-66,the removal rates of the modified products increased from 2.23%to 34.20%and 19.89%respectively,and the desorption rate both reduced by 15.50%to 1.10%.It indicated that the structure of modified products had some negative charge,and there was electrostatic interactions between UiO-66-SO₃^-and Cu²⁺.3.Modification and the loading of rare earth ions on UiO-66-PO₄^3-UiO-66 was modified by phosphoric acid?H₃PO₄?and foscarnet?PFA?to obtain UiO-66-PO₄^3-?H₃PO₄?and UiO-66-PO₄^3-?PFA?,and the research of loading rare earth ion was carried out.XRD,FT-IR and SEM characterizations showed that both of UiO-66-PO₄^3-kept the octahedral structure of UiO-66 and appeared fluorescence peaks of LaPO₄:Eu after loading the rare earth ion.It indicated that the rare earth ions were successfully loaded on UiO-66-PO₄^3-.