Collaborative Research: Structure Sensitive Surface Chemistry - Small Molecule Activation and Spillover

在这个由美国国家科学基金会化学分部化学结构动力学和机理（CSDM-A）项目资助的合作研究项目中，安德鲁·格尔曼教授（卡内基梅隆大学）和查尔斯·赛克斯教授（塔夫茨大学）正在研究金属表面的原子结构对催化相关表面反应速率的影响。众所周知，在金属表面发生的化学反应的速率和选择性是由催化剂的表面结构决定的。理想情况下，催化剂的设计将确定表面结构，以优化所需产品的产量。然而，在实验上，在金属表面的许多可能的结构上全面地绘制反应性是具有挑战性的。Gellman和Sykes开发了一套互补的工具来测量表面反应动力学，并同时在数百个不同的表面方向上对原子表面结构进行成像。这些方法将用于生成数据集，催化剂开发人员将使用这些数据集来设计新的和改进的催化材料。参与该项目的学生将获得表面化学、x射线光谱学和扫描探针显微镜等领域的宝贵技能。Gellman和Sykes使用球形弯曲的Cu和Ag单晶，暴露出数百种不同的Cu（hkl）和Ag（hkl）表面作为样品库，用于研究表面结构和反应性。Gellman正在使用空间分辨x射线光谱学来测量小分子（如O2， CO2和CH3CH2OH）在数百种不同的Cu（hkl）和Ag（hkl）表面上的等温吸附和活化速率，以确定最活跃的表面取向以及与表面结构相关的反应性趋势。Sykes正在用扫描隧道显微镜研究这些表面吸附前后的结构。此外，Gellman和Sykes正在对由Ni、Pd和Pt等金属的孤立原子修饰的表面进行类似的测量，以创建具有明确表面结构的单原子合金催化剂。这项工作将为开发理解结构敏感催化表面化学的预测理论模型提供信息。这个项目也检验了我们目前对催化溢出机制的理解。最终，这个项目有望促进我们对催化科学的集体理解，以及我们设计新的或改进催化材料的能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this collaborative research project funded by the Chemical Structure Dynamics and Mechanisms (CSDM-A) program of the National Science Foundation’s Chemistry Division, Professors Andrew Gellman (Carnegie Mellon University) and Charles Sykes (Tufts University) are studying the influence of the atomistic structure of metal surfaces on the rates of catalytically relevant surface reactions. It is well known that the rates and selectivities of chemical reactions occurring on metal surfaces are determined by catalyst surface structure. Ideally, the design of catalysts would identify surface structures that optimize the yield of desired products. However, it is experimentally challenging to map reactivity comprehensively across the many possible structures of a metal surface. Gellman and Sykes have developed a complementary set of tools to measure surface reaction kinetics and to image atomistic surface structure across hundreds of different surface orientations concurrently. These methods will be used to generate datasets that will be used by catalyst developers to design new and improved catalytic materials. Students working on this project are gaining valuable skills in the fields of surface chemistry, x-ray spectroscopy and scanning probe microscopy.Gellman and Sykes are using spherically curved Cu and Ag single crystals that expose hundreds of different Cu(hkl) and Ag(hkl) surfaces as sample libraries for the study of surface structure and reactivity. Gellman is using spatially resolved x-ray photoemission spectroscopy to measure the rates of isothermal adsorption and activation of small molecules such as O2, CO2 and CH3CH2OH on hundreds of different Cu(hkl) and Ag(hkl) surfaces in order to identify the most active surface orientations and the trends correlating reactivity with surface structure. Sykes is studying the structures of these surfaces before and after adsorption using scanning tunneling microscopy. In addition, Gellman and Sykes are conducting similar measurements on surfaces modified by isolated atoms of metals such as Ni, Pd, and Pt to create single atom alloy catalysts with well-defined surface structures. This work will inform efforts to develop predictive theoretical models for understanding structure sensitive catalytic surface chemistry. This project also tests our current understanding of the mechanism of spillover in catalysis. Ultimately, this project is expected to advance our collective understanding of catalysis science and our ability to design new or improve catalytic materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.