Single-Complex, Single-Molecule, Single-Atom and Single-Site Studies of Chemical Events on Reactive Surfaces

这个研究项目的重点是研究用于加速化学过程的表面。这些表面被称为多相催化剂。由于几个原因，他们的研究是一个具有挑战性的领域。首先，表面是一个二维系统，几乎所有重要的化学事件只有在分子与表面直接接触时才会发生。因此，对表面化学的研究需要非常灵敏的仪器。其次，化学过程通常只在表面的某些部位加速，即所谓的活性部位。第三，如果表面对反应序列中任何参与者的结合过于强烈，它就会堵塞，反应就会停止。在这个研究项目中，我们将主要使用扫描隧道显微镜（STM）在精确定义的反应表面的单个位点上研究单个反应物分子或分子对。STM技术可以直接对导电表面进行原子或亚分子分辨率成像。有三个子项目：(1)单原子合金（SAA）的研究，由一个非常活跃的金属原子隔离在相对惰性的金属表面组成。这些类型的表面可以达到两个目的。它们可能会限制催化反应所需的贵金属数量。此外，它们还可以防止表面与反应物或中间体的结合过于强烈；(2)表面对映选择化学的研究。这是我们小组目前正在做的主导工作。在上一次拨款期间（2011-2016年），我们开展了与铂对映选择性加氢相关的表面现象的权威研究。我们现在建议转向金属表面上对映选择性CC偶联反应的研究。手性产物的合成是这一领域的重要进展，原因有很多。基本上，化学物质（例如药物）与我们身体的相互作用敏感地取决于化学物质的手性。从催化基础研究的角度来看，该研究对利用弱分子间相互作用实现反应选择性提供了显著的见解。(3)二维金属碳化物的研究。我们是传统金属碳化物表面研究方面的专家。近年来，人们对二维碳化物的合成和应用产生了浓厚的兴趣。然而，人们对它们的表面化学几乎一无所知——除了知道表面终止对材料的性质有深远的影响。我们正在开展二维碳化物表面化学的系统研究。HQP将直接执行所有项目中的所有表面科学实验测量。他们毕业时将掌握完全轻松地使用复杂仪器的技能，并掌握无数表面和界面应用的基本专业知识。

This research program is focused on the study of surfaces that are used to accelerate chemical processes. These surfaces are called heterogeneous catalysts. Their study is challenging area for several reasons. First, a surface is a two-dimensional system where almost all of the important chemical events occur only when the molecules make direct contact with the surface. As a result, the study of chemistry on surfaces requires very sensitive instruments. Second, chemical processes are often only accelerated at certain sites on the surface, so-called active sites. Third, if the surface binds any of the participants in the reaction sequence too strongly, it will clog up and the reaction will stop turning over. In this research program, we will primarily use scanning tunneling microscopy (STM) to study individual reactant molecules, or couples of molecules, at individual sites on precisely defined reactive surfaces. The STM technique can directly image conducting surfaces with atomic or sub-molecular resolution. There are three sub-projects: (1) A study of single-atom alloys (SAA), composed of atoms of a very reactive metal isolated on a relatively inert metal surface. These types of surfaces may achieve two objectives. They might limit the amount of precious metals needed to catalyze reactions. Also, they may prevent the surface from binding reactants or intermediates too strongly; (2) The study of enantioselective chemistry on surfaces. This in an area in which our group a currently doing leading work. During the last granting period (2011-2016), we carried out the definitive body of work on surface phenomena related to enantioselective hydrogenation on platinum. We are now proposing to move to the study of enantioselective CC coupling reactions on metal surfaces. Progress in this area, the synthesis of chiral products, is important for many reasons. Principally, the interaction of chemicals (for example, medicines) with our bodies depends sensitively on the chirality of the chemical. From the perspective of fundamental research in catalysis, the study provides remarkable insight on the use of weak intermolecular interactions to achieve reaction selectivity. (3) The study of two-dimensional metal carbides. We are experts in the surface study of conventional metal carbides. Recently, there has been an explosion of interest in the synthesis and application of 2D carbides. However, almost nothing is known about their surface chemistry-apart from the understanding that the surface termination has a profound affect on the material’s properties. We are launching a systematic study of the surface chemistry of 2D carbides. HQP will directly perform all of the experimental surface science measurements in all of the projects. They will graduate with the skill of being completely at ease with complex instrumentation, and with fundamental expertise in the myriad applications of surfaces and interfaces.