| Recently, as a novel class of crystalline porous material, Metal-organic frameworks(MOFs) have attracted great concern of researchers. Due to large surface area, adjustable pore size and diverse pore structures, MOFs have bright application prospect in the fields of catalysis, gas storage and separation, sensors, especially membranes. Previous researches focused on the design of novel structures, compared to large single crystals, nano-sized MOFs have great research value for the clarification of crystal growth mechanism and the preparation of hierarchical architectures and membrane-typed metal-organic frameworks. Besides, hierarchical architectures, especially membrane-typed metal-organic frameworks have outstanding applications in catalysis, sensors and gas separation. Based on the above background, in this paper, rare earth metal-organic framework Tb(BTC)(H2O) and Eu(BTC)(H2O)6 and imidazole zeolite framework ZIF-67 was selected as research objects. First, green coordination modulation method was developed for the fabrication of ordered superstructures Tb(BTC)(H2O) and Eu(BTC)(H2O)6, and hydrothermal method and coordination modulation method was adopted to prepare nano- and micro-sized ZIF-67. Based on this, ITO glass-supported Tb(BTC)(H2O) film was prepared by dip-coating method, and porous SiO2-supported ZIF-67 membrane was prepared by in-situ hydrothermal method and seeded growth method.Green coordination modulation method was developed using eco-friendly ethanol and sodium acetate to fabricate hierarchical architectures Tb(BTC)(H2O), including rod-like crystals, dual-core shelled peanut-like crystals and double-head dandelion-like crystals. The working mechanism of sodium acetate is attributed to both alkine property and modulating effect of carboxylate groups, and the growth of dual-core shelled peanut-like crystals and double-head dandelion-like crystals follows the process of nucleation, aggregation, fusion growth, and annealing for double-head dandelion-like crystals. Double-head dandelion-like crystals with strongest photoluminescence intensity were used to detect heavy metal ions in aqueous solution. Followed, three types of modulators, including sodium acetate, sodium formate and glycine were used to fabricate various fascinating morphologies Eu(BTC)(H2O)6, involving cross-flower, wheat, cauliflower, et al. The role of glycine in tailoring morphologies is alkali property of-NH2 group and modulating effect of carboxylate group, and the formation mechanism of cauliflower-like crystals was deduced, involving nucleation-accumulation-fusion growth-annealing. Furthermore, large-scale and continuous Tb(BTC)(H2O) film was prepared by dip-coating method for the sensing of small molecule organic solvents.ZIF-67 with different sizes and morphologies was synthesized through hydrothermal method and coordination modulation method. Crystals possessing the size distribution of 70nm-2.47μm were obtained by manipulating reagent molar ratio, reagent concentration, reaction time and the quantities of modulator triethylamine. Triethylamine is a type of mono-function modulator, which reduces crystal size by increasing the pH value of solution, accelerating the deprotonation of ligand and then leading to the fast nucleation. In-situ hydrothermal method and seeded growth method were applied to prepare porous SiO2-supported ZIF-67 membrane. It shows that the optimum reaction condition of in-situ hydrothermal method is organic ligand/metal molar ratio 10, reactant concentration 1:1000, reaction temperature 100 oC and reaction time 3h. In the case of seeded growth method, the optimal reaction condition is seed suspension concentration 40g/L, organic ligand/metal molar ratio 10, reactant concentration 1:750, reaction temperature 80 oC, and reaction time 1h。Compared with in-situ hydrothermal method, seeded growth method not only decreases reaction temperature and shortens reaction time, but also improves the quality of ZIF-67 membrane。... |
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