Understanding electrochemical hydrogenation reactions over post-transition metal electrodes: the role of incidental mediators and metastable phases

电化学是利用电能来驱动化学反应。由于与可再生电力基础设施的兼容性，这些类型的反应越来越有趣。反应是通过分子与电极材料的相互作用而发生的，电极被保持在施加的电压下，当分子接触其表面时可以表现出催化特性。该项目将研究一种现象，即电极材料不是静态的，而是产生腐蚀产物，介导催化反应。在许多情况下，腐蚀被视为一个有害的过程；然而，在这个项目中，研究人员的目标是有目的地和有效地使用腐蚀产物。这种机制还没有被很好地理解，获得控制和利用它的能力可能会对广泛的化学生产的电化学系统的设计产生影响。本项目研究的具体反应涉及将生物质衍生分子转化为绿色燃料和将化学前体转化为可生物降解的塑料。除了博士培训对劳动力发展的预期好处之外，pi还将为本科生提供研究机会，并为更多的学生、科学家和非专业社区成员提供教育材料。该项目将为当地社区大学的教师提供一个新的研究体验机会，帮助他们制定未来的课程，并指导学生继续从两年制到四年制的学位课程。该项目的目标是了解由阴极腐蚀过程（如溶解金属氢化物或阴离子的形成）产生的还原金属在多大程度上可能介导分子的还原。虽然传统上被认为是有害的副反应，但该项目探索了这些阴极腐蚀产物可以介导均匀还原的假设，甚至在某些情况下作为主要机制。这一假设将根据可能的机制进行评估，这些机制包括来自天然电极材料或来自亚稳原位相（如固体金属氢化物或碱合金）的异质电荷转移。具体的反应性研究将涉及还原乙酰丙酸（LA）作为测试平台。这种分子来源于可再生生物质，可以电还原成几种有价值的产品。pi已经获得了初步证据，表明腐蚀产物中介可能涉及到从LA生产羟基戊酸（生物降解塑料的单体）和γ -戊内酯（绿色溶剂和生物燃料）的高度选择性材料。该计划是结合严格的动力学测量工具，量子化学计算，原位振动和电子光谱，以及一套其他先进的材料表征技术，以了解并最终利用更广泛的现象，更好地控制电解系统。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。

Electrochemistry enables the use of electrical energy to drive chemical reactions. These types of reactions are increasingly interesting due to their compatibility with renewable electricity infrastructure. The reactions occur by interaction of molecules with materials known as electrodes, which are held at an applied voltage and can exhibit catalytic properties when the molecules contact their surfaces. This project will investigate a phenomenon where the electrode material is not static, but instead generates corrosion products that mediate the catalytic reactions. In many cases, corrosion is seen as a detrimental process; however, in this project the investigators aim to use corrosion products purposefully and productively. The mechanism is not yet well understood, and gaining the ability to control and exploit it could have consequences for the design of electrochemical systems for a wide array of chemical production. Specific reactions to be studied in this project relate to the conversion of biomass-derived molecules to make green fuels and chemical precursors to biodegradable plastics. In addition to the expected benefits of Ph.D. training for workforce development, the PIs will establish research opportunities for undergraduates as well as educational materials for larger groups of students, scientists, and non-expert community members. Several of the initiatives to be supported are ongoing, while the project will add a new research experience opportunity for local community college instructors to help in shaping future curriculum and guiding students in continuing from two-year to four-year degree programs.The goal of this project is to understand the extent to which reduced metal species, generated by cathodic corrosion processes such as the formation of dissolved metal hydrides or anions, may mediate reduction of molecules. While traditionally viewed as detrimental side reactions, the project explores the hypothesis that these cathodic corrosion products can mediate homogeneous reduction, even as the primary mechanism in some cases. This hypothesis will be evaluated against possible mechanisms with heterogeneous charge transfer from either the native electrode material or from metastable in-situ phases such as solid metal hydrides or alkali alloys. Specific reactivity studies will involve reduction of levulinic acid (LA) as a testbed. This molecule is derived from renewable biomass and can be electro-reduced to several valuable products. The PIs have obtained preliminary evidence that corrosion-product mediation may be involved on materials that are highly selective to making hydroxyvaleric acid (a monomer for biodegradable plastics) and gamma-valerolactone (a green solvent and biofuel) from LA. The plan is to combine rigorous kinetic measurement tools, quantum chemical calculations, in-situ vibrational and electronic spectroscopy, and a suite of other advanced materials characterization techniques to understand and ultimately leverage the phenomena more broadly into better-controlled electrolysis systems.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.