耐水性异质MOF复合材料的制备及其VOCs的高效吸附

金属有机骨架（MOFs）材料在挥发性有机物（VOCs）的吸附中展现出优异的性能，然而水分子与不饱和金属位点的结合会造成MOFs的坍塌和性能下降。本项目拟利用高吸附性MOFs和高疏水性MOFs各自特点，通过异质复合在低耐水性和高吸附性MOF颗粒表面合成一层具有超疏水孔道的超薄MOF壳层，增强所合成复合材料的稳定性；同时利用异质壳层减少水分子和VOCs对内部MOFs的不饱和位点的竞争性吸附，提升吸附性能，提出一种异质MOF材料复合理念。发展并开发直接晶化、层层组装和凝胶涂覆转化等异质生长方法，研究不同异质生长方法、合成条件以及活化过程对复合材料的亲疏水性、异质比例、结构、界面结合方式和金属节点状态的影响，开发出高效的异质生长方法。研究复合材料结构形态、异质组合方式、不饱和金属位点结合状态和水的竞争性吸附对吸附性能的影响，阐明吸附机理。为实现高性能MOF吸附剂的制备和应用提供实验和理论基础。

Metal-organic frameworks (MOFs) show great potential and excellent capability in adsorption of volatile organic compounds (VOCs). However, the competitive adsorption of water molecules on open metal sites of MOFs will lead to the collapse of frameworks and reduction of adsorption performance. In this project, we will take the advantages of the special physicochemical properties of different MOFs to fabricate a series of heterogeneous MOF composite materials, which contain the ultrathin shell MOFs with super-hydrophobic pores and the core MOFs with excellent adsorption capability. In the concept of heterogeneous MOF composites, the super-hydrophobic shells can prevent water from entering inside core MOFs, therefore, the water-resistance can be great enhanced and the competitive adsorption of water can be reduced predictably. Meanwhile, because the core MOFs can maintain the intact framework structure and the shell MOFs are VOC permeable, the MOF composites will exhibit excellent adsorption selectivity and performance. We will develop the heterogeneous growth methods, such as direct crystallization, layer-by-layer assembly and gel-coating/transformation, to obtain the uniform heterogeneous MOF composite materials, and investigate the effect of growth method, synthesis condition and activation process on the hydrophobicity, heterogeneous proportion, construction, pore structure, interfacial structure, and metal node of composite materials. Moreover, we will explore the effect of composite structure, heterogeneous combination state, bonding condition of open metal site, water competitive adsorption on VOC removal performance, to elucidate the adsorption mechanism of heterogeneous MOF composite materials. This research will provide the experimental and theoretical guidance for fabrication and application of high-performance MOF adsorbents.