金属-有机框架二维纳米材料的可控合成及电催化性质研究

Two-dimensional (2D) metal-organic framework nanosheets can combine the advantages of both 2D inorganic materials and metal-organic frameworks (MOFs), being beneficial for searching high-activity electrocatalysts and helpful for studying the structure-property relationships. However, the instability of the coordination bonds in these materials renders great difficulties for their preparation and characterization. This project will take advantage of the anisotropy of coordination bond in three-dimensional (3D) pillared-layer MOFs and selectively remove the “pillar” ligands through the synergistic action of host-guest interactions and external forces, thus leading to the 2D metal-organic nanosheets which retain the characteristics of the “layer” in the original pillared-layer MOFs. Combining multiple characterization technologies and computational simulation, the accurate structural informations of these 2D materials could be obtained. The new developing strategy for the controllable synthesis of 2D metal-organic nanosheets is based on crystal engineering, and expands the preparation methodology for these materials. Furthermore, some reasonable means, such as structural design, element doping, changing the pendant group of ligands and orientied growth etc, could be employed to precisely regulate the structure and function of the 2D nanosheets. The performances of the as-synthesized metal-organic nanosheets acting as catalyst for hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction and carbon dioxide reduction reaction will be systematically optimized, and some of the catalysts should be selected as electrode materials and incorporated into electrolytic cell and rechargeable metal-air batteries. The structure-property relationships of these materials will be clarified by accurate structural information, in-situ characterization of reactions and density functional calculation, which supplies a new pathway for the construction of energy storage and conversion devices with high efficiency.

金属-有机框架(MOF)二维纳米材料结合了MOF和无机二维纳米材料的优点，在获取高效电催化性能的同时还有助于研究构效关系，但受限于配位键的不稳定，还难于制备和表征。本项目拟利用三维柱层式MOF中配位键的各向异性，通过主-客体作用以及外界作用力的协同选择性地移除柱层式结构中的“柱子”配体从而定向形成只保留“层”的MOF二维纳米材料，结合各类表征技术和计算机理论模拟确定二维纳米材料的精确结构信息，实现基于晶体工程的MOF二维纳米材料的定向可控合成，拓展MOF二维材料的制备手段。此外，通过结构设计、元素掺杂、配体侧基调控以及取向生长等精确调控催化剂的结构与性能，并系统地优化基于电催化产氢、产氧、氧还原和二氧化碳还原的电解池和可充放电金属-空气电池的性能和实现材料的器件化。结合催化剂的精确结构、反应的原位表征和密度泛函理论计算阐明材料的构效关系，为构建高效的能源储存和转化器件提供新颖的策略。

由于化石能源的消耗和环境污染日益严峻，全球对可再生清洁能源的需求急剧增加，开发高性能的电催化剂提高能源储存和转换至关重要。金属-有机框架(MOFs)二维纳米材料结合了MOFs和二维无机纳米材料的优点，使它在电催化领域具有得天独厚的优势。本项目组利用MOF结构中配位键的各向异性，通过原位电化学氧化剥离、主-客体和外界作用力协同剥离、离子诱导插层剥离、原位电场刻蚀等方法制备MOF二维纳米材料，实现基于晶体工程的MOF二维纳米材料的定向可控合成。此外，基于MOF二维材料的精确结构，系统地优化MOF二维材料作为电催化剂的各种催化性能指标(例如，Onset电压、过电位、Tafel斜率、法拉第效率和电化学稳定性等)，并通过反应的原位表征和密度泛函理论计算阐明构效关系。本项目的研究在相关领域取得了一定的学术研究成果。