非贵金属钴配合物作为均相催化剂应用于太阳能制氢研究

The discovery and application of homogeneous catalysts (mainly coordination complexes) in solar driven hydrogen production from water is currently a hot field in solar energy conversion. In nature, hydrogenases serve as the function of proton reduction for hydrogen production, in which the pendant amine group (-NR) plays an important role as proton relay and help proton reduction. Inspired by nature, we propose to synthesize and characterize novel cobalt coordination complexes as robust homogeneous catalysts for hydrogen production. We previously discovered that cobalt dimethylglyoxime complexes could be used as homogeneous catalysts in photocatalytic reactions for hydrogen production from water. However, the stability and efficiency of these complexes need to be improved. In this project, tetradentate ligand will be used to improve the stability of cobalt coordination complexes and the proton relay group will be coupled to tetradentate metal binding ligand in order to improve the rate of proton reduction. We will subsequently investigate the photophysical and electrochemical properties of these cobalt based complexes, and apply the complexes as homogeneous catalysts for solar driven hydrogen production from water. On the other hand, another target will be design and assembly molecular photochemical devices for hydrogen production by covalently linking the photosensitizer and catalysts. The mechanism and process of photoinduced electron transfer will be studied. Based above research, our goals are (1) to find the relationship between the stability and the coordination ligands; (2) to discover the role of the proton relay group during catalysis for hydrogen production and (3) to build efficient molecular photochemical devices for solar driven hydrogen production from water. We wish our research could help and strength the field of solar energy conversion in China.

功能配合物可用于催化太阳能分解水制氢，是当前国际上基础研究的热点之一。自然界中氢化酶活性中心可通过邻位的胺基作为质子传输体帮助质子的传递，并证实可以提高产氢的效率。申请人在前期的科研工作中发现钴的二乙肟配合物可作为氢化酶功能模型化合物引入太阳能光催化体系分解水制氢，但是稳定性和光催化效率都还有待提高。本研究项目着重于设计并合成一系列新颖的含有邻位质子传输体的多齿配体，来制备非贵金属钴配合物催化剂，并将催化剂通过共价键或者自组装的方式连接到光敏剂上制备太阳能驱动的产氢分子器件。通过以上研究内容进一步探索：（1）多齿配体对配合物在催化过程中稳定性的影响；（2）邻位质子传输体在钴基金属配合物催化太阳能制氢中的作用；（3）研究太阳能驱动产氢分子器件的反应过程和机理，发现光吸收基团和催化中心之间距离对于产氢效率的影响。本研究项目将从新的视角出发模拟人工光合作用，为我国的太阳能利用研究提供理论依据。

近年来，利用功能配合物和纳米材料模拟自然界中氢化酶活性中心用于催化太阳能分解水制氢，吸引了人们极大的关注。本研究项目设计合成一系列非贵金属配合物和纳米催化剂材料，用于太阳能光催化制氢，探索了影响配合物催化剂稳定性的因素，优化了反应条件，获得了一些有意义的成果。项目基本按计划完成，发表了52篇SCI论文, 达到了以下目标：1）探索了非贵金属均相和异相催化剂材料，包括基于钴的金属配合物，也研究了镍和铁元素作为金属催化中心的光催化体系，实现了加速水的分解和氢气的产生。催化剂避免了使用价格昂贵的贵金属材；2）稳定性上，我们找到了稳定性可达一个星期以上的催化剂材料，比如镍配合物和异相磷化镍、磷化钴等催化剂；3）产氢速率和产氢效率方面，发展了产氢速率达到1000 h-1 以上的催化剂材料，产氢转化率达到10000以上；4）实现光吸收材料和催化剂之间的快速光诱导电子转移，构建了高效的可见光驱动的光催化产氢体系。