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

这项研究计划专注于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。出于几个原因，他们的研究是具有挑战性的领域。首先，表面是一个二维系统，几乎所有重要的化学事件都只有在分子与表面直接接触时才会发生。因此，研究表面化学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，如果表面将反应序列中的任何参与者结合得太强，它将堵塞，反应将停止翻转。在这项研究计划中，我们将主要使用扫描隧道显微镜(STM)来研究单个反应物分子或分子对，在精确定义的反应表面上的单个位置。STM技术可以直接成像原子或亚分子分辨率的导电表面。有三个子项目：(1)单原子合金(SAA)的研究，由隔离在相对惰性金属表面的非常活跃的金属原子组成。这些类型的曲面可以实现两个目标。它们可能会限制催化反应所需的贵金属数量。此外，它们可能会阻止表面与反应物或中间体结合得太强；(2)表面对映体选择性化学的研究。这是我们小组目前正在进行领导工作的一个领域。在上一次授予期间(2011-2016)，我们开展了与铂对映选择性氢化有关的表面现象的最终工作。我们现在建议转到金属表面上的对映选择性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。主要地，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，这项研究为利用分子间弱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的专家。近年来，二维碳化物的合成和应用引起了人们极大的兴趣。然而，除了表面端接对材料性能有深远影响之外，人们对它们的表面化学几乎一无所知。我们正在对2D碳化物的表面化学进行系统的研究。HQP将直接执行所有项目中的所有实验表面科学测量。他们将在毕业时掌握完全熟练使用复杂仪器的技能，以及在各种表面和界面应用方面的基本专业知识。

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.