Photoelectrocatalysis with Porous Coordination Polymers - Architectural Design, Morphology Control and Transport Properties

该项目的总体目标是建立一个集成的金属有机框架（MOF）平台，用于光电催化水分解，以克服颗粒系统中普遍存在的牺牲供体/受体方案的需要。因此，我们的方法通过阐明和控制基于卟啉连接剂的生物启发MOF-co-催化剂混合结构中驱动电荷传输和氧化还原催化的基本原理，解决了MOF光催化和电催化之间未知的界面。设计高效光电化学电池的先决条件将是：(1)具有光收集和电子通信亚基的高多孔MOF系统的发展，以及(2)高质量均匀定向MOF薄膜电极的合成策略。我们的方法将通过固体核磁共振波谱和阻抗波谱对MOF薄膜的结构、动力学、光学特性、电子和离子传输特性的深入了解，以及光诱导氧化还原过程的（光）电化学分析，反馈到设计回路中，以创建具有高活性的氢和氧析，降低过电位和长期稳定性的MOF光电极。为了完成这项高度跨学科的任务，b.v. Lotsch、m.t. Elm和J. Senker的研究小组在结构和输运性质的合成和表征方面增加了他们的互补技能。Lotsch集团在MOF纳米材料的合成、MOF薄膜的生长和MOF的合成后改性方面有着长期的专业知识。Lotsch团队将开发基于卟啉和芘的光活性MOF系统，该系统将与分子和异相共催化剂相结合，以协调光诱导的多电子氧化还原过程，并将其投射到高质量的薄膜结构中。对于MOF结构的结构阐明，Senker团队将提供大量最先进的核磁共振晶体学策略。他的团队将开发一种薄膜核磁共振探针，用于分析MOF薄膜的结构完整性和孔隙度，表征约束对催化转化的影响，研究光诱导载流子产生的机制，跟踪它们的迁移率，探测激子/极化子的局域化。补充实验由M. T. Elm进行，他是在各种环境下基于（照片）电化学技术（包括阻抗谱）表征电子和离子传输特性的专家。通过这种方式，将探索电荷载流子的性质，它们的浓度和远程传输，以及缺陷对催化转化的传输和效率的影响。

The overall goal of this project is to establish an integrated metal-organic framework (MOF) platform for photoelectrocatalytic water splitting to overcome the need for sacrificial donor/acceptor schemes prevailing in particulate systems. Our approach thus addresses the uncharted interface between MOF photocatalysis and electrocatalysis by elucidating and controlling the very fundamentals of light-driven charge transport and redox catalysis in bio-inspired MOF-co-catalyst hybrid architectures based on porphyrin linkers. A prerequisite for the design of efficient photoelectrochemical cells will be the development of (i) highly porous MOF systems with light harvesting and electronically communicating subunits, and of (ii) synthesis strategies for high quality homogeneous, oriented MOF thin film electrodes. Our approach will be guided by insights into structure, dynamics, optical characteristics and electronic as well as ionic transport properties of the MOF films by solid-state NMR spectroscopy and impedance spectroscopy, as well as (photo)electrochemical analysis of the light-induced redox processes, feeding back into the design loop to create MOF photoelectrodes with high activity for hydrogen and oxygen evolution, reduced overpotentials and long-term stability. To accomplish this highly interdisciplinary task the research groups of B. V. Lotsch, M. T. Elm and J. Senker add their complementary skills in the synthesis and characterization of structural and transport properties. The Lotsch group has long standing expertise on the synthesis of MOF nanomaterials, the growth of MOF thin films and their post-synthetic modification of MOFs. The Lotsch group will develop photoactive porphyrin- and pyrene-based MOF systems, which will be interfaced with molecular and heterogeneous co-catalysts to orchestrate the light-induced multi-electron redox processes, and cast into high quality thin film architectures. For the structure elucidation of the MOF architectures the Senker group will provide a large repertoire of state-of-the art NMR crystallographic strategies. A thin film NMR probe will be developed in his group to analyze the structural integrity and porosity of the MOF films, to characterize the impact of confinement on the catalytic conversion, and to study the mechanism of light-induced charge carrier generation, to follow their mobility, and to probe the localization of excitons/polarons. Complementary experiments are carried out by M. T. Elm who is an expert on characterizing the electronic and ionic transport properties based on (photo)electrochemical techniques including impedance spectroscopy in various environments. In this way the nature of charge carriers, their concentrations and long-range transport, as well as the influence of defects on the transport and efficiency of the catalytic conversion will be probed.