金属组分可调的多级结构MOFs的设计合成、形成机制及构效关系研究

Nanoscale Metal–organic frameworks (MOFs) with well-defined 3-D hierarchical (e.g. porous, hollow) nanostructures have demonstrated great potentials in fields of catalysis, adsorption, hydrogen storage, and so on. The conventional synthetic methods (e.g. the templates-assisted method) of hierarchical MOFs-based nanostructures frequently have intrinsic drawbacks, ranging from high cost, low efficiency, to limited kinds of active metals in as-developed MOFs. The present work aims at the rational design and synthesis of hierarchical MOFs nanostructures by metals doping. We will focus on investigating the influences of experimental parameters (e.g. the species, valence state and concentration of doping metal ions; the solvent and pH of solution) on the size, shape and assembly behavior of MOFs. Following, the synthetic routes will be optimized for obtaining hierarchical MOFs nanostructures with well-defined structures and outstanding properties. To achieve a fine control over the materials synthesis, the growth mechanism, kinetics and assembly process of building blocks, and the key factors associated with the hierarchical MOFs formation will be revealed. Following this strategy, people can explore the new method and principle for synthesizing hierarchical (e.g. porous, hollow) MOFs nanostructure, and also collect MOFs-based samples with outstanding properties arising from metal doping. Finally, the relationship between the structures of MOFs (e.g. the metal doping and assembled structures) and their properties (catalytic or adsorption properties for environmental remediation) will be investigated, the results of which in response provides guidelines for material design and controlling. The finds in this work could pave the ways to the rational design and synthesis of hierarchical MOFs with outstanding properties, and also contribute to the in-depth understanding of the growth mechanism of MOFs.

以MOFs纳米颗粒为组装单元构建介孔、中空等多级结构MOFs，对拓展MOFs在催化、吸附、储氢等方面的应用具有重要意义。目前，这类MOFs的合成法 (如模板法)存在成本高、效率低、金属组分单一等缺点。本项目以开发具有优异性能MOFs为导向，发展利用金属离子掺杂获得多级结构MOFs的新方法和原理。掺杂离子在诱导形成多级结构MOFs同时，还为其引入源于外来离子特殊的物理化学性质。重点研究利用金属离子的种类\价态\浓度，及溶剂等外部因素的协同精细调控，优化不同类型多级结构MOFs合成技术路线。拟解决的关键科学问题在于：分析不同金属离子掺杂的MOFs的微观结构差异，揭示形成多级结构MOFs的生长机制和组装过程，以及不同因素调控生长和组装的机制。结合MOFs结构(金属组分、组装结构等)与性能(对水中污染物的催化或吸附去除)的关系研究，优化材料合成和调控策略，为制备新型MOFs提供实验基础和理论依据。

多孔金属有机框架材料（MOFs）具有大的比表面积、丰富的孔道结构和可调的金属催化中心，是理想的催化材料。然而，MOFs的孔道尺寸多在于微孔尺寸（< 2 nm），极大限制了反应底物到活性催化位点的传输。本项目选取系列MOFs催化材料（UiO-66、普鲁士蓝衍生物、ZIF-67等），提出异价金属离子调控生长法、高价态金属离子刻蚀法、自牺牲模板法等方法，发展制备具有可调金属中心和孔道尺寸的中空、介孔和大孔MOFs材料的新方法和原理，探讨调控相关MOFs金属离子、孔道尺寸的关键因素及机制，揭示多级孔MOFs结构差异及其在催化有机污染物降解、CO2还原等方面的应用，阐明孔道尺寸、多金属中心协同效应等关键控制因素与催化性能增效机制的内在关系，相关研究结果以第一通讯作者发表在Cell Reports Physical Science、Small、JMCA、Science China Materials等期刊上，为启发设计其他新型高效多级MOFs催化材料提供新思路，并为MOFs基催化材料及MOFs衍生物催化材料的构效关系研究提供实验和理论基础。