Investigation of Heterogeneous Photocatalysts based on TiO2-Graphene Composites in Selective Synthetic Transformations

异构网络是一项激动人心的技术。开发允许利用维斯范围内的光源的催化剂，例如，太阳光对于许多应用是特别令人感兴趣的。在这里，我们建议开发，合成和表征高效的光催化二氧化钛-碳纳米材料为基础的复合材料，并合理化其活性。该复合材料将通过简单混合不同的市售的、众所周知的和表征的TiO 2纳米颗粒和市售的石墨烯物种来专门地非原位制备。每种组分都是多相光催化剂中的重要成分。除了探索所制备的复合材料的行为之外，还将探索后续水热方法或烧结的影响。新材料的结构和电子行为将与Guido Grundmeier教授和Jörg Lindner教授合作进行分析。该复合材料将在选择性有机光氧化还原催化合成碳-碳键形成转化中进行实验和理论研究。除了量子效率和催化活性，还将确定反应是否发生在TiO 2或石墨烯物质的表面上，以及这是否影响产物选择性。深入了解复合材料的光催化性能将是我们工作的一个特别重点：将进行基于密度泛函理论的第一性原理总能量和电子结构计算，以探索与合成材料相对应的模型系统的结构和催化性能。透射电子显微镜和X射线衍射数据用于确保模拟模型与合成结构中出现的结构图案紧密匹配。超越基态DFT的计算，即，约束DFT，含时DFT和多体微扰理论将被用来解决激发态相关的电子自旋。这些计算不仅将用于使实验结果合理化，而且将有助于设计有效的新催化剂。

Heterogeneous photocatalysis is an exciting technology. The development of catalysts that allow for exploiting light sources in the VIS range, e.g., sunlight, is of particular interest for numerous applications. Here we propose to develop, synthesize and characterize efficient photocatalytic TiO2-carbon nanomaterial-based composites and to rationalize their activity. The composites will be prepared exclusively ex situ via simple mixing of different commercially available, well-known and characterized TiO2 nanoparticles and commercially available graphene species. Each component is known as an important ingredient in heterogeneous photocatalysts. Next to exploring the behavior of the as prepared composites, the influence of subsequent hydrothermal methods or sintering will be explored. Structural and electronic behavior of the new materials will be analyzed in cooperation with Prof. Guido Grundmeier and Prof. Jörg Lindner. The composites will be investigated experimentally and theoretically in selective organic photoredox catalytic synthetic carbon-carbon bond forming transformations. Next to quantum efficiency and catalytic activity it will be also determined whether a reaction occurs on the surface of TiO2 or the graphene species and if this is influencing product selectivities. The in-depth understanding of the photocatalytic properties of the composite materials will be a particular focus of our work: First-principles total-energy and electronic-structure calculations based on density-functional theory will be performed in order to explore the structure and catalytic properties of model systems selected in correspondence to the synthesized material. Transmission electron microscopy and X-ray diffraction data are used to ensure that the simulated models match closely the structural motifs that occur in the synthesized structures. Calculations beyond ground-state DFT, i.e., constrained DFT, time-dependent DFT, and many-body perturbation theory will be used to address the excited states relevant for the photocatalysis. The calculations will not only be used to rationalize the experimental findings but will assist the design of efficient new catalysts.