Hybrid Supramolecular Water Oxidation Catalysts for Massive Electrochemical Response

太阳能在化学键中的再生储存是由自然界在光合作用中进行了数千年。人工光合装置的发展可以在将能源生产从化石燃料转向可再生能源方面发挥巨大作用。能量以化学键的形式储存，能量密度高，易于传输。因此，化学能量载体可以容易地通过已建立的技术分散地存储和使用，这是相对于例如来自太阳能电池的发电能量的关键优势。人工光合系统发展的瓶颈是水氧化成分子氧。过去几年，水氧化分子催化剂的合成取得了巨大的优势，反应速率现已与自然界中的反应速率相当。该项目旨在进一步提高分子水氧化催化剂的反应速率和稳定性，以应用于水裂解装置。随着对水氧化催化反应机理的深入了解，Llobet教授及其同事在西班牙ICIQ开发出了迄今为止最好的分子水氧化催化剂[Ru（tda）（py）2]。双氧键是由这种催化剂通过极性反转的氧原子对水分子的亲电攻击而建立的。在自然界中，这种亲电攻击的活化能通过蛋白质环境对水分子的预组织而降低。在该项目的第一部分中，这种预组织应该通过Ru-tda催化剂的大环排列来引入。因此，我想将Ru-tda催化剂与不同的联吡啶配体结合联合收割机，以产生具有不同空腔尺寸的超分子催化剂。然后将得到的配位低聚物进行强烈的结构和电化学研究，以确定空腔尺寸对催化性能的影响。我想使用第一部分的结果来设计1D，2D和3D配位聚合物，这些聚合物具有确定的，最佳的孔径，基于由多吡啶配体连接的Ru-tda催化剂。这种多孔金属有机框架将理想地适合于在其空腔中预组织水分子，这将提高催化剂的反应速率，同时提供提高的稳定性。因此，聚合物水氧化催化剂可以为人工光合装置的发展做出巨大贡献。

The regenerative storage of solar energy in chemical bonds is performed by nature for millennia in photosynthesis. The development of artificial photosynthetic devices can have a huge share in changing the energy production from fossil fuels towards renewable energy sources. Energy stored in chemical bond has a high energy density and is easy to transport. Thus, chemical energy carriers can be easily stored and used decentralized by established techniques, which is a crucial advantage over electric generated energy, e.g. from solar cells. The bottle neck in the development of artificial photosynthetic systems is the oxidation of water to dioxygen. The synthesis of molecular catalysts for water oxidation has made huge advantages over the last years and reaction rates are now comparable to those in nature. The project intents to further increase the reaction rates and the stability of molecular water oxidation catalysts for application in water splitting devices. Increased understanding of the reaction mechanisms in water oxidation catalysis led to the development of the, up to now, best molecular water oxidation catalyst [Ru(tda)(py)2] by Prof. Llobet and his coworkers at the ICIQ in Spain. The dioxygen bond is built by this catalyst via an electrophilic attack of a polarity inversed Oxygen atom on a water molecule. In nature, the activation energy for this electrophilic attack is reduced by the pre-organization of water molecules by a protein environment. In the first part of the project this pre-organization should be introduced by a macrocyclic arrangement of Ru-tda catalysts. Therefore, I want to combine the Ru-tda catalyst with different bipyridyl ligands, to create supramolecular catalysts with varying cavity sizes. The obtained coordination oligomers will then be subject to intense structural and electrochemical investigation to determine the influence of the cavity size on the catalytic properties. I want to use the results from this first part to design 1D, 2D, and 3D coordination polymers with defined, optimal pore sizes based on the Ru-tda catalyst linked by polypyridyl ligands. Such porous metal organic frameworks will be ideally fit to pre-organize water molecules in their cavities, which should enhance the reaction rate of the catalyst while providing elevated stability. Thus, polymeric water oxidation catalysts can make a huge contribution to the development of artificial photosynthetic devices.