基于蒽和卟啉的分子笼状化合物设计合成与光电分解水性质及机理研究

Design and synthesis of highly effective, stable and cheap photocatalyst is the key to photocatalytic water splitting into hydrogen. This study is based on the idea of molecular design and plans to build stable polyhedral cages with fantastic photoelectric catalytic functions through the assembly of aza-ligands containing anthracene and porphyrin and metal ions, with suitable coordination configuration. To improve the catalytic efficiency and the stability of the catalyst during the photocatalytic water splitting into hydrogen is highly desirable. With uniform size, good containment, and easily controlled of the discrete polyhedral cages, the project intends to provide a new method for photocatalytic water splitting into H2 in the discrete polyhedral cages. The catalytic efficiency will be improved by adjusting the following parameter of photocatalytic process: such as the conjugated degree, ligands length, catalyst absorption bandwidth, and electron transfer rate. The catalytic efficiency will also be improved by means of encapsulating co-catalyst in cages. Based on the results of modern analysis and tests, it aims at investigating the bonding character, the rule of assemble, structure and charge transfer mechanism in photoreaction process, to find out the effect of photocatalytic water splitting, and conclude the relationship of structures and properties. This study will not only provide a new method for the designing of noble photocatalyst, but also open up new approaches for the synthesis study of highly-efficient novel photoelectrocatalysis materials.

设计合成高效、稳定、廉价的光催化剂是光催化分解水制取氢气的关键。本项目基于分子设计的思想，拟利用蒽和金属卟啉作为催化活性基团，探索合成含蒽和卟啉的氮氧杂配体，与廉价金属离子进行组装，构筑具有高效、稳定的多面体笼状配合物光催化材料。针对光催化分解水制氢过程中面临的如何提高催化剂的催化效率、稳定性、重复利用率、比表面积等科学问题，发挥分子笼包容性好、尺寸均匀且可调控等优势，本项目拟利用离散型多面体分子笼进行光解水制氢，通过调控蒽和卟啉的共轭程度和长度，拓展催化剂吸收谱带的宽度，加速电子转移速率，增大比表面积，从而提高催化效率；并通过在分子笼内包合共催化剂，进行协同光催化的方法，提高光解水制氢效率。运用多种现代检测手段，研究笼状配合物的结构规律、光催化过程中电荷传输机理、影响因素等基本科学问题，本项目将为新型光催化剂的设计合成提供新思路，为合成开发高效廉价的新型光(电)解水催化材料开辟新途径。

将太阳能有效转化为化学能是开发新能源的重要途径之一，设计合成高效、稳定、廉价的光催化剂是实现这一目标的关键。本项目构筑了有机分子（笼）催化剂和负载杂多酸或光敏剂的有机-金属催化剂，主要取得如下三点进展：（1）构筑了一系列含蒽的有机纳米分子笼催化剂，研究了该类催化剂光催化分解水的反应，考察了均相溶液中水的浓度、溶液的pH值、牺牲还原剂的浓度对催化反应速率的影响，提出合理的反应机理，并利用EPR捕获到反应过程中形成的单电子，证实了反应机理；（2）尝试了利用二维金属有机层与无机杂多酸分子或离子组装，构筑三维金属有机框架催化材料，进行H2O2的催化还原和NO2-的催化氧化反应。（3）利用氮杂类羧酸配体与Co(II)构筑具有较大孔道，且稳定性（化学稳定性和热稳定性）较好的金属有机骨架材料（MOFs），在孔道中负载光敏剂进行光电催化分解水。尤其重要的是项目负责人基于开发新能源材料的思想，利用上述合成的具有合适孔道尺寸且稳定的Co-MOF材料，逆向高效选择性吸附C2H2、C2H4、C2H6等三种气体，实现了分离纯化乙烯气体。本项目为太阳能的高效转化利用提供了一定的科学依据和材料基础，也为低碳高效纯化乙烯气体提供了材料支撑。