CAREER: Multi-Electron Nickel Redox Cycles for Solar Energy Conversion and Storage

太阳能作为一种可再生能源的成功实施必须克服提高光能到电能转换效率的关键挑战以及电网规模储能技术的发展。染料敏化太阳能电池和氧化还原液流电池是两种很有前途的技术，可以应对这些挑战。重要的是，这两种设备都利用小分子来促进能量转换和能量存储。在这个项目中，奥本大学的法纳姆博士正在开发从廉价、富含地球的金属中提取的化合物，这些金属能够在每个分子中存储两个电子。一次存储一个以上电子的能力导致了更高的能量存储密度(更小的电池寿命更长)。此外，分子被设计成能够产生高电压，这可以带来更高的功率。法纳姆博士通过积极接触当地社区，提高了学生对可再生能源转换和储存的兴趣。他的活动包括向中学生进行科学演示，与高中生进行电池实验，以及与当地学院和大学的本科生合作进行暑期研究项目。奥本大学的Farnum博士在化学系化学结构、动力学和机制-B项目的资助下，正在从机理上理解单金属镍基配位化合物的多电子氧化还原反应。他的工作主要集中在四配位镍(Ni(II))络合物上，这些络合物经过两电子氧化还原化学生成六配位镍(IV)。这些研究的灵感来自于对提高异质结太阳能电池效率的需求，以及对电化学储能技术日益增长的兴趣，这将使可再生能源的进一步实施成为可能。镍配合物利用了d8Ni(II)和d6Ni(IV)金属中心之间的电子转移引起的配位环境的明显变化。使用电化学、光谱和计算方法对这个氧化还原循环进行详细的机理分析，可能会彻底理解Ni(II)和Ni(IV)氧化态之间的相互转化机理。对这些氧化还原对的进一步了解可能会提高染料敏化太阳能电池的太阳能转换能力和Flow电池的储能能力，以及利用类似氧化还原循环的新的分子氧化还原对。Farnum博士还积极参与旨在提高阿拉巴马州和佐治亚州当地地区对太阳能转换和储存必要性的认识的外展项目。具体地说，Farnum博士与奥本大学的目标STEM活动和暑期科学研究所合作，通过侧重于电化学储能和能源可持续概念的互动学习模块，让初中生和高中生参与进来。Farnum博士还邀请规模较小的地区性学院和大学的本科生在他的实验室进行暑期研究项目，让这些学生接触并有机会参与太阳能转换和储存方面的尖端研究。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。

The successful implementation of solar energy as a renewable energy resource must overcome the critical challenge of improving light to electric energy conversion efficiency as well as the development of grid-scale energy storage technologies. Dye-sensitized solar cells and redox flow batteries are two promising technologies which could meet these challenges. Importantly, both devices make use of small molecules to facilitate energy conversion and energy storage. In this project, Dr. Farnum of Auburn University is developing chemical compounds derived from inexpensive, earth-abundant metals capable of storing two electrons per molecule. The ability to store more than one electron at a time, results in increased energy storage density (smaller batteries with longer life). Furthermore, the molecules are designed to enable large voltages to be produced, which can lead to improved power. Dr. Farnum's increases student interest in renewable energy conversion and storage through active outreach efforts to the local community. His activities include science demonstrations to middle-schoolers, battery experimentation with high-schoolers, and collaborative summer research projects with undergraduates from local colleges and universities. With funding from the Chemical Structure, Dynamics, and Mechanisms-B Program of the Chemistry Division, Dr. Farnum of Auburn University is developing mechanistic understanding of multi-electron redox reactions at mono-metallic, nickel-based coordination compounds. His work specifically focuses on 4-coodinate nickel (Ni(II)) complexes which undergo two-electron redox chemistry to generate 6-coordinate Ni(IV). These studies are inspired by the demand for higher efficiencies in heterojunction solar cells as well as growing interests in electrochemical energy storage technologies that will allow further implementation of renewable energy resources. The nickel complexes take advantage of distinct changes in coordination environment induced upon electron transfer between d8 Ni(II) and d6 Ni(IV) metal centers. Detailed mechanistic analysis of this redox cycle using electrochemical, spectroscopic, and computational methods may result in a thorough understanding of mechanisms for interconversion between Ni(II) and Ni(IV) oxidation states. Further understanding of these redox couples could lead to increased solar energy conversion in dye-sensitized solar cells and energy storage capacities in redox flow batteries, as well as to new molecular redox couples that take advantage of similar redox cycles. Dr. Farnum is also actively engaged in outreach programs designed to raise awareness of the need for solar energy conversion and storage to the local regions of Alabama and Georgia. Specifically, Dr. Farnum works with Auburn University’s Destination STEM event and Summer Science Institute to engage middle and high school students with interactive learning modules focused on concepts of electrochemical energy storage and energy sustainability. Dr. Farnum also invites undergraduate students from smaller, regional colleges and universities to perform summer research projects in his lab, giving theses students exposure and opportunities to participate in cutting edge research in the conversion and storage of solar energy.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.