Interfacial engineering of semiconductors for highly selective light-driven chemical transformations

由于界面能量学和光激发电荷在被照射半导体上的反应性的不同方面，光驱动的非均相光（电）催化反应对于发展在传统的热催化或电催化中可能不容易实现的高选择性化学转化具有特殊的前景。然而，迄今为止开发的多相选择性光催化系统的总体性能仍然相当低，并且对多相选择性光催化系统中的选择性的影响因素仍然知之甚少。基于我们在各种光驱动选择性转化方面的初步工作，该项目的主要目标是开发用于各种高度吸引人的转化（即，醇和二苯硫醚的选择性氧化，氧还原为过氧化氢，二氧化碳还原），并获得对与产物选择性直接相关的电荷分离、电荷重组和催化转换的动力学因素的基本机理理解。具体而言，该项目的目标是：i）研究将具有最佳表面催化性能的材料与作为光收集器的良好钝化的低带隙半导体相结合的复合材料，ii）研究各种类型的附加金属催化位点的影响（单原子/离子vs.纳米团簇vs.颗粒），iii）开发颗粒光催化剂的串联催化配置，其中在一种组分中选择性形成的产物用于-原位通过另一种组分进行进一步的光驱动选择性转化。这些目标将通过合成（例如，ALD）、光电化学、光谱（例如，瞬态吸收/荧光光谱、光谱电化学、强度调制光电流/光电压光谱）和理论（特别是密度泛函理论（DFT）和反应力场）研究。该项目的结果预计将提供独特的设计规则的发展，高活性和选择性的光（电）催化架构，并推进我们的理解，这种系统的基本优势和瓶颈的选择性催化转化。

Due to the distinct aspects of interfacial energetics and reactivity of photoexcited charges at illuminated semiconductors, light-driven heterogeneous photo(electro)catalytic reactions hold special promise for the development of highly selective chemical transformations that might not be easily achieved in conventional thermal catalysis or electrocatalysis. However, the overall performance of heterogeneous selective photocatalytic systems developed so far is still rather low, and the factors governing the selectivity in heterogeneous photocatalysis are still poorly understood. Based on our preliminary work on various light-driven selective conversions, the major thrust of this project is to develop novel and more efficient photo(electro)catalytic systems for various highly attractive conversions (i.e., selective oxidations of alcohols and diphenyl sulfides, reduction of oxygen to hydrogen peroxide, reduction of carbon dioxide) and to gain fundamental mechanistic understanding of the factors governing the kinetics of charge separation, charge recombination and catalytic turnover in direct relation to product selectivity. Specifically, the project aims are: i) to investigate composites combining materials with optimum surface catalytic properties with well-passivated low-gap semiconductors as light harvesters, ii) to study the influence of various types of additional metal catalytic sites (single atoms/ions vs. nanoclusters vs. particles), iii) to develop tandem catalytic configurations of particulate photocatalysts in which the products formed selectively at one component are utilized in-situ by another component for further light-driven selective transformation. These objectives will be addressed by a combination of synthetic (e.g., ALD), photoelectrochemical, spectroscopic (e.g., transient absorption/fluorescence spectroscopy, spectroelectrochemistry, intensity-modulated photocurrent/photovoltage spectroscopy), and theoretical (in particular density functional theory (DFT) and reactive forcefields) studies. The project results are expected to provide unique design rules for the development of highly active and selective photo(electro)catalytic architectures, and to advance our understanding of the fundamental advantages and bottlenecks of such systems for selective catalytic transformations.