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

电化学能够利用电能来驱动化学反应。由于它们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。这些反应是通过分子与被称为电极的材料相互作用而发生的，电极保持在施加的电压下，当分子接触其表面时，可以显示出催化特性。这个项目将研究一种现象，即电极材料不是静态的，而是产生促进催化反应的腐蚀产物。在许多情况下，腐蚀被视为一种有害的过程；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。这种机制目前还不清楚，获得控制和利用它的能力可能会对广泛化学生产的电化学系统的设计产生影响。本项目要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化学前体，使其成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外，个人投资促进机构还将为本科生提供研究机会，并为更多的学生、科学家和非专家社区成员提供教育材料。其中几项计划正在进行中，而该项目将为当地社区大学教师增加一个新的研究经验机会，以帮助制定未来的课程，并指导学生继续两年至四年的学位课程。该项目的目标是了解由阴极腐蚀过程(如形成溶解的金属氢化物或阴离子)产生的还原金属物种可能在多大程度上调节分子的还原。虽然传统上被视为有害的副反应，但该项目探索了这样的假设，即这些阴极腐蚀产物可以调解均匀还原，甚至在某些情况下作为主要机制。这一假说将根据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)的异质电荷转移的可能机制进行评估。特定的反应性研究将涉及作为试验床的乙酰丙酸(LA)的还原。这种分子是从可再生的生物质中提取出来的，可以电还原成几种有价值的产品。PIS已获得初步证据，表明腐蚀产物中介可能涉及对从LA制造羟基戊酸(可生物降解塑料的单体)和伽马-戊内酯(一种绿色溶剂和生物燃料)具有高度选择性的材料。该计划将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，以了解并最终更广泛地利用这些现象进入更好地控制的电解系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.