Well-Defined Nanographene-Metal Complexes for Selective Electrocatalytic CO2 Reduction

将如此多的社会活动产生的过量二氧化碳(CO2)转化为燃料和其他有用的材料需要能量的投入。目前，减少完成这一任务所需的能量被认为是一项极具挑战性的任务。在这个项目中，印第安纳大学的李良石博士和克里希南·拉加瓦查里博士正在研究如何将有序的碳结构纳米颗粒与过渡金属原子相结合，以制造一种新的催化剂家族。它们催化二氧化碳的减少，也就是说，它们提高了转换的能源效率。这是通过LI小组的实验努力和Raghavachari小组的计算模型的协同组合来完成的。该研究试图对碳材料的结构如何决定过渡金属的催化性能有一个基本的了解。更广泛地说，这项工作旨在为基于含金属碳材料的改进催化剂提供设计指导，从而导致碳材料在环境和能源相关应用中的可再生利用，同时为研究生和本科生提供各种教育机会。针对代表性不足的群体，包括与Prairie View A&Amp；M大学合作的夏季研究体验项目，目标是来自这所历史悠久的黑人大学的本科生。在化学系化学催化项目的资助下，印第安纳大学的李良诗博士和Krishnan Raghavachari博士正在开发定义明确的纳米金属络合物(NMC)，并研究它们的电催化活性，以选择性地减少二氧化碳。特别是，定义良好的纳米茂金属配体与Re或Mn形成络合物，分析和优化其选择性电催化CO2还原为CO的性能。由于它们的大共轭尺寸，纳米管可以很容易地进行多次还原，有效地存储了化学转化所需的电子，在初步工作中，纳米管(含Re)已经被证明产生了迄今为止报道的最低的二氧化碳还原潜力。在协同实验和理论研究的基础上，研究了活化NMC催化CO2还原的必要条件。对于不同尺寸和官能化的纳米茂金属配体，为了设计高效、稳定、富含稀土金属的电催化剂，需要对纳米金属化合物的催化机理有详细的了解。在更广泛的背景下，该项目旨在建立纳米分子作为一种新的氧化还原非无辜配体，潜在地应用于许多类型的多电子反应的过渡金属催化剂的开发。这一奖项反映了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。

Converting the excess carbon dioxide (CO2) produced by so many of society's activities to fuels and other useful materials requires an input of energy. Currently, decreasing the energy needed to accomplish this is recognized to be a highly challenging task. In this project, Drs. Liang-shi Li and Krishnan Raghavachari at Indiana University are investigating how to combine ordered carbonstructures known as nanographenes with transition metal atoms to make a new family of catalysts. These catalyze CO2 reduction, that is, they improve the energy efficiency of the conversion. This is being accomplished by a synergistic combination of the experimental efforts from the Li group and the computational modeling from the Raghavachari group. The study seeks a basic understanding of how the structures of the carbon materials determine the catalytic performance of the transition metal. More broadly, the work aims to provide design guidance for improved catalysts based on metal-containing carbon materials, thereby leading to renewable uses of carbon materials for environment- and energy-related applications, while providing a diverse range of educational opportunities for graduate and undergraduate students. Outreach to underrepresented groups include a summer research experience program with Prairie View A&M University targeting undergraduate students from that historically black university.With funding from the Chemical Catalysis Program of the Chemistry Division, Drs. Liang-shi Li and Krishnan Raghavachari at Indiana University are developing well-defined nanographene-metal complexes (NMCs) and investigating their electrocatalytic activities for selective CO2 reduction. Specially, well-defined nanographene ligands form complexes with Re or Mn to analyze and optimize their performance for selective electrocatalytic CO2 reduction to CO. Because of their large conjugation size, the nanographenes can readily undergo multiple reductions, effectively storing the electrons for chemical transformations, and in preliminary work, NMCs (containing Re) have already been demonstrated to yield an onset CO2 reduction potential that is the lowest reported so far. With synergistic experimental and theoretical efforts, the necessary conditions for the NMCs to be activated to catalyze the CO2 reduction are investigated. With nanographene ligands of various sizes and functionalizations, a detailed understanding on catalytic mechanisms of the NMCs is sought for the design of energy efficient and stable electrocatalysts that contain earth abundant metals and can be made with simple methods. In a broader context, the project aims to establish the nanographenes as a new class of redox non-innocent ligands, for potential application to the development of transition metal catalysts for many classes of multi-electron reactions.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.