Application Of Gas Adsorption, Lithium-air Battery Cathode And Fluorescent Materials Over Several Novel MOFs

Compared to traditional materials, Metal-Organic Frameworks show incomparable advantages in the application of adsorption separation, membrane separation, fluorescence and so on. Thus, this thesis focuses on the increasingly serious problem of environmental pollution and energy issues and develop efficient environmental purification materials and energy storage materials. Several novel metal-organic framework materials were prepared and their application in gas adsorption, lithium-air battery electrode and fluorescent properties were studied.We studied the adsorption and desorption of toluene on the HKUST-1 and MIL-101. Results showed that the maximum amount adsorbed of toluene on MIL-101 was 15.1 mmol/g, which was the largest adsorption capacity reported. However, the isotherm of toluene in the range of P/P0 < 0.09 on the HKUST-1 was much higher than that on the MIL-101. It suggested that the HKUST-1 had better adsorption performance than the MIL-101 at low concentration of VOCs. Thermal desorption experiments showed that the desorption efficiency of toluene from the HKUST-1 and MIL-101 can separately reach above 93 % and nearly 100 % at 393 K.We studied the preparation of ZIF-8 membrane on α-Al2O3 by the secondary seeded growth method. The results showed that: the low concentration of the seed suspension and three-subsequent dip-coating method help to obtain a perfect ZIF-8 seeds layer of support; in the process of secondary growth, a series of experimental conditions were optimized, and thus a continuous ZIF-8 film with thickness of 8.8 μm was successfully fabricated.We studied the permeance diffusion behaviors of a series of single gas molecules and CO2/N2 mixed gas separation performance through the ZIF-8 membrane. The results showed that: the permeation of single-component gas was increasing with the decrease of the gas dynamics diameter; the gas diffusion of H2 was governed by Knudsen diffusion. CO2 diffusion was controlled by activated diffusion whereas the larger molecules of O2、N2、CH4 exhibited molecular sieving effect. The separation factor of CO2/N2 through a ZIF-8 membrane could reach 6 at 298 K,406 kPa and the CO2 content of 90 %.We studied the electrochemical properties of Pt@UIO-66 material as cathode material. The Pt@UIO-66 showed an excellent discharge capacity and sustained repeated cycling for 8 cycles with discharge capacity of 2000 mAh/g. When the mass amount of Pt in Pt@UIO-66 becomes 5 wt%, the discharge capacity reached 13315 mAh/g, close to the highest capacity ever reported. The result showed that MOFs hold wide potential in being an excellent cathode material for Li-air batteries.We studied the optical properties of two new 3D coordination networks Ca(cca)·H2O(1) and Mg(cca)·2H2O(2)(H2cca = 4-carboxycinnamic acid). Results showed that both compounds 1 and 2 had high thermal stability and remained intact in aqueous solutions of a broad range of pH values ranging from 3 to 11. Both compounds also showed significantly enhanced luminescence with respect to the free ligand, giving rise to an increase in qauntum yield by as much as 4-fold.We developed an ultrafast synthesis method for the preparation of GrO@HKUST-1 composites at room temperature. The reactions were completed within 1 min. The adsorption capacity of 2GrO@HKUST-1 for CO2 at 1 bar and 273 K is up to 9.02 mmol/g, which is significantly higher than that of HKUST-1(6.85 mmol/g), with an increase of 32%. At 1 bar, the CO2/N2 adsorption selectivity of 2GrO@HKUST-1 is up to 186, which is almost 1.8 times that of HKUST-1(103). This ultrafast room temperature strategy is promising for the synthesis of new MOF-based composites, which may become suitable for the sample production at industrial scale.