基于金属有机框架结构的光催化制氢研究

Photo driven hydrogen production has attracted increasing attention, because hydrogen is a clean energy for the future to reduce dependence on fossil fuels and emissions of greenhouse gases in the long term. Research in the area involves heterogeneous materials based on inorganic semiconductor oxides photocatalyst and homogeneous artificial hydrogenase mimicking systems by using organic or metal-organic dyes as photosensitizers. The former one has the considerable convenience in application as functional devices, but the efficiency is limited by their poor ability of solar light harvesting; while the latter one exhibits attractive high activity in hydrogen production driven by light. It is highly desirable to develop new materials for photo driven hydrogen production which could typically display the combined advantages of the heterogenous and homogenous systems, such as high catalytic activity on one hand, easy to make functional devices on the other hand. Metal-organic frameworks (MOFs), which have recently emerged as an interesting class of porous solids built from organic bridging ligands and inorganic connecting nodes, is a promising artificial system for the integration of individual functional components in a structurally controlled manner. In this project, we will utilize MOFs as a platform to immobilize the functional components of the homogeneous artificial hydrogenase systems in a heterogeneous way. The dye derivate molecules will be acted as the bridged ligands and the photosensitizers. And special transition metal ions which were popularly used with mimicking hydrogenase(Fe, Co and Ni) complexes will be incorporated as the nodes and catalytic centers into suitable coordination environment. By carefully matching the redox potential between the metal catalytic centre and the dye-based ligands, highly efficient photo driven hydrogen production systems in the heterogenous type will be obtained. In addition, such MOFs based materials could be functionalized as photo active electrodes by inorganic membrane technology, which could open a new door for the possible application of photo driven hydrogen production in the future

光催化制氢技术在清洁能源制备上的巨大应用前景受到世界各国政府和科学家们的高度重视。在这一研究领域内，以无机氧化物半导体为代表的非均相催化体系在器件化应用上具有天然的优势，但材料本身在太阳光谱利用率方面的困难成为其实现高效率光能转化一个巨大的挑战，以人工模拟氢化酶为核心的均相体系利用染料分子为光敏剂，能够高效率的催化放氢，将这两类体系的优势有机结合将是光催化制氢走向实际应用的关键。本项目拟以金属有机框架结构这一由金属离子和有机配体通过配位键组装而成的高度有序的具有孔道结构的类分子筛材料为载体平台，通过有机配体部分将染料分子的高效光转化功能，以及通过金属离子节点将氢化酶活性中心的高活性催化功能引入结构明确，具有高反应接触面的多孔非均相体系中，达到在非均相条件下高效高活性光催化制备氢。进一步利用无机膜技术完成该体系的器件化，为实现高太阳光能利用率、高活性光催化制氢技术的实际应用拓展新的研究思路。

针对项目申请书所提出的将基于分子催化剂的均相光催化制氢体系与非均相催化体系的优势结合在一起，开发高效清洁可材料化的光催化分解水制氢技术的设计目标。两年期间在基金资助下逐步完成了以下研究目标：1. 以金属有机框架结构（MOFs）为目标载体，通过高吸收效率和高光激发量子产率染料的引入，构建光敏中心，并实现了光-金属中心协同催化的高效碳碳偶联反应；2. 以变价过渡金属为构成核心，通过合理设计配体，调控金属中心的氧化还原电位和质子传输路径，组装催化中心，实现了高效率的光催化放氢（催化剂摩尔转化率8000以上）； 3. 在上述研究基础上，通过以含光化学基团的金属有机框架结构（MOFs）为光敏剂，过渡金属配合物为催化中心，成功的构筑了申请书所提出的“基于金属有机框架结构的光催化制氢”非均相催化体系,进一步利用近年来发展起来的无机膜制备技术，将MOFs在系列基底材料上成膜，保证了其器件化应用能力,为拓宽高效率清洁可实用化的太阳能光催化分解水制氢技术提供新的思路。两年期间发表基金标注论文3篇，（Chem. Sci.; New. J. Chem. and Inorg. Chem. Commun.）, 另一篇（J.Mater. Chem.）已经基本接受。