Towards Photoactive Membranes for Artificial Photosynthesis

该项目的目标是将分子化合物，即光催化剂和氧化还原活性天线染料，整合到最近开发的碳纳米膜中，用于光催化电池等。这种用于人工光合作用的新型光活性膜的研究将包括材料和物理化学方面的不同任务：(i)开发具有基准电子给体、受体和光敏剂功能化的新型碳纳米膜；（ii）开发具有新功能的碳纳米膜的新合成方法，即光敏剂和集成在膜平面内的电子给体/受体；（iii）发展对新型碳纳米膜内光诱导基本过程的机理理解，以及用钴胺素质子还原催化剂功能化碳纳米膜的光催化析氢的概念验证。该项目旨在为设计用于人工光合作用的新型光活性膜奠定概念基础。所研究的超分子体系是基于分子薄碳膜的，可以在膜的任何一侧进行特异性功能化。在这个项目中，重点将不是设备集成，而是建立基本的设计原则，并对系统在光催化水分解中的潜在应用的基本反应步骤进行必要的机理研究。碳纳米膜将被Ru(II)-聚吡啶衍生物系统功能化，该系统既充当发色团，即光吸收单元，又充当主要的电子给体。在设想的光活性碳纳米膜的设计中，电子给体将被接枝到分子薄膜的一侧，而膜的另一侧将被相应的受体单元正交功能化。因此，预计在辐照后会形成电荷分离态，而光氧化和光还原的物质在空间上被纳米膜分离。为了提高电荷分离状态的寿命，从而提高光分离电荷的“可用性”，我们将采用分子三联体（即受体-发色团-供体）和设计系统的概念，其中膜的发色团一侧额外配备了电子供体单元。

The project targets the integration of molecular compounds, i.e. photocatalysts and redox-active antenna dyes, into recently developed carbon nanomembranes for applications in, e.g., photocatalytic cells. This research on novel photoactive membranes for artificial photosynthesis will comprise different tasks from materials and physical chemistry: (i) development of novel carbon nanomembranes functionalized with benchmark electron donors, acceptors and photosensitizers; (ii) development of novel synthetic procedures for the fabrication of carbon nanomembranes with new functionalities, i.e. photosensitizers and electron donors/acceptors integrated within the membrane plane; (iii) developing a mechanistic understanding of light-induced elementary processes within the novel carbon nanomembranes and proof-of-concept photocatalytic hydrogen evolution from carbon nanomembranes functionalized with cobaloxime proton-reduction catalysts. The project aims at establishing the conceptual basis for the design of novel photoactive membranes for artificial photosynthesis. The supramolecular systems to be researched are based on molecularly thin carbon membranes, which can be specifically functionalized on either side of the membrane. In this project the focus will not (yet) be on device integration but on establishing the basic design principles and performing essential mechanistic studies on the elementary reaction steps underlying a potential use of the systems in photocatalytic water splitting. The carbon nanomembranes will be functionalized with Ru(II)-polypyridine-derived systems, which act both as the chromophores, i.e. the light-absorbing units, and the primary electron donors. In the envisioned design of the photoactive carbon nanomembranes the electron donors will be grafted onto one side of the molecularly thin membranes, while the opposite side of the membrane will be functionalized orthogonally by the corresponding acceptor units. Thereby, the formation of charge separated states is expected upon irradiation, whereas the photooxidized and photoreduced species are spatially separated by the nanomembrane. In order to enhance the lifetime of the charge separated state, and hence the 'usability' the photoseparated charges, we will adopt concepts from the design of molecular triads (i.e. acceptor-chromophore-donor) and design systems, in which the chromophore-side of the membrane is additionally equipped with electron donor units.