基于金属有机骨架的复合体系中电子态行为的理论模拟研究

There is an important trend towards material design and utilization based on composite system. Metal-organic framework structure, owing to its advantages of high degree of diversity and tunability, is widely used to form composite materials with semiconductor, metal, molecule, and so on. MOF-based composite systems have been extensively investigated, exhibiting a great range of chemical and physical properties useful for important applications such as gas storage, catalysis and luminescence. However, the complexity of MOF structures, and the difficulty to control the complicated surfaces and interfaces in MOF-based composite systems, have impeded people from fully understanding the structure-property relationship as well as the synergetic effect of multiple processes. This has become the bottleneck for their realistic utilizations. The proposed project aims at developing and applying first-principles based multiscale modeling methods, to study the formation, coupling and evolution of electronic state in MOF-based composite system. This will convert the complicated modeling of various functions in complex systems, to the same type of simulation of electronic state behavior. We will focus on several typical MOF structures, in combining with some widely used semiconductors or metal nanocrystals, to investigate their photocatalysis and luminescence mechanisms. Theoretical methods including quantum chemistry, solid state physics, molecular mechanics, and classical electrodynamics will be combined to study the semi-periodical and large scale complex systems, to reveal the formation of electronic states, coupling of quantum states, and physical and chemical conversions. These information could lead to a clear understanding of the property dependence on key material parameters such as composition, crystal phase, morphology, impurity, defect, which will eventually help us to design practically efficient MOF-based composite systems for important applications.

金属有机骨架（metal-organic framework: MOF）材料具有多样性和易功能化等优点，其复合体系可实现许多重要应用。但MOF的非严格周期结构和局域量子态等复杂性，及材料复合的复杂表界面问题，导致构效关系和微观过程协同原理不清晰，造成其在光催化等领域的应用瓶颈。 项目基于微观角度，将MOF复合体系复杂的工作过程，归结为在独特空间与电子结构下电子态的形成、耦合和演化行为这一单一主线。聚焦于几个典型MOF与重要半导体、金属的复合结构的光催化应用，发展和应用计算化学的多尺度模拟方法，结合量子化学、固体物理、分子力学和经典电动力学模型，以第一性原理精度描述MOF这类具有非严格周期性的大尺度复杂体系，揭示其关键电子态形成、量子态耦合、物理与化学变化等行为，模拟其性质对材料组成、形貌、晶相、杂质和缺陷等因素的依赖关系，寻找适用于高效光催化和光电材料等的构效关系，设计实用复合体系。

我们以光催化等应用为导向，开发并使用适合于处理MOF复合体系的基于第一性原理的多尺度理论模拟方法，探索并研究金属有机骨架（MOF）材料表界面微观结构与宏观性能之间的构效关系。利用第一性原理的计算模拟，理解并揭示复合体系中电子态的形成、耦合、传输、复合或分离对结构、尺寸，化学组成等宏观参数的依赖性原理和调控机制。通过挖掘MOF复合材料电子态演化行为和协同调控机制，我们较好的完成了项目研究计划。