Tuning Surface Chemistry through Polarization

在这个由化学学部大分子、超分子和纳米化学项目资助的项目中，耶鲁大学的Eric I. Altman教授将研究如何利用氧化物的极化来操纵表面化学和催化性质的基本原理。整个项目的目标是了解如何利用极性界面来诱导新的表面化学，并通过切换铁电载体的极化方向来创造表面化学可以显著改变的材料。这种理解对于开发新方法来调整苛刻反应的催化活性，创造允许开启和关闭表面反应的新型材料，以及创造表面性质可以可逆改变和图案化的材料至关重要。该目标是通过三个互补的推力来实现的，这些推力都利用了ZnO的戏剧性的极化方向依赖特性（0001）。第一个重点是在催化重要的非极性氧化物中诱导极化依赖性质的能力；Cr2O3/ZnO（0001）体系将作为一个原型系统进行研究，预计将提供最大的极化依赖性。第二个目标是在材料中诱导可切换的表面特性，这种材料的整体形式是极性的，但不是铁电的。在这种情况下，Altman教授和他的学生的目标是通过将氧化锌作为超薄层支撑在铁电支架上来诱导氧化锌的铁电性。第三个重点是新的铁电材料，其中组成氧化物具有相似的还原性并且化学活性都很高；ZnSnO3将作为这类新材料的模型进行研究。所提出的工作依赖于原子精确的制造工具和表征方法来确定定义良好的表面的内在表面化学性质，并与第一性原理理论合作来理解负责观察到的行为的机制。该项目将对新兴科学和技术领域的教育和培训作出贡献，从而产生广泛的影响。从事这个项目的研究生和本科生将获得一个独特的机会来开发调整反应性的新策略。为了实现这些目标，学生将在一个整合实验、理论和国际经验的协作环境中发展表面科学、材料科学、动力学和动力学以及光谱学等领域的专业知识。此外，国际合作伙伴关系将允许海外学生为该项目做出贡献，并为耶鲁学生出国旅行；由于研究现在是一项国际性的努力，这些合作伙伴关系提供了宝贵的国际联系和接触国际文化的机会，这对学生未来的职业生涯大有裨益。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Prof. Eric I. Altman of Yale University will investigate the fundamentals of how polarization in oxides can be used to manipulate surface chemical and catalytic properties. The overall program objective is to understand how polar interfaces can be exploited to induce new surface chemistry, and to create materials whose surface chemistry can be dramatically altered by switching the polarization direction of a ferroelectric support. This understanding is essential to developing new methods to tune catalytic activity for demanding reactions, to create new classes of materials that allow surface reactions to be turned on and off, and to create materials whose surface properties can be reversibly altered and patterned. The objective is met through three complementary thrusts that all exploit the dramatic polarization-direction dependent properties of ZnO(0001). The first thrust focuses on the ability to induce polarization-dependent properties in catalytically important oxides that are non-polar; the Cr2O3/ZnO (0001) system will be studied as a prototypical system anticipated to give the largest polarization dependence possible. The second thrust is directed towards inducing switchable surface properties in a material that in bulk form is polar but not ferroelectric. In this case Professor Altman and his students aim to induce ferroelectricity in ZnO by supporting it as an ultra-thin layer on a ferroelectric support. The third thrust focuses on new ferroelectric materials in which the constituent oxides have similar reducibilities and are both chemically active; ZnSnO3 will be studied as a model for this new class of materials. The proposed work relies on atomically precise fabrication tools and characterization methods to determine the intrinsic surface chemical properties of well-defined surfaces, and collaboration with first principles theory to understand the mechanisms responsible for the observed behavior. The project will have a broad impact through its contributions to education and training in emerging areas of science and technology. The graduate and undergraduate students working on this project will get a unique opportunity to develop new strategies for tuning reactivity. To meet these objectives the students will develop expertise in fields spanning surface science, materials science, kinetics and dynamics and spectroscopy in a collaborative environment integrating experiment and theory and international experiences. In addition, international partnerships will allow students from overseas to contribute to the project and for Yale students to travel abroad; as research is now an international endeavor, these partnerships provide valuable international connections and exposure to international cultures that greatly benefit the students' future careers.