CAS: Developing Homogeneous Mn Catalyst Systems for the Oxygen Reduction Reaction

在化学系化学催化项目的支持下，弗吉尼亚大学的查尔斯·W·马坎博士正在研究分子锰化合物对二氧化氧的催化还原。氧的还原对于从化学键产生能量是很重要的。例如，燃料电池经常使用将氧气还原为水来产生清洁能源。目前该反应最好的催化剂是以铂金属为基础的，这种金属稀有且昂贵。在寻找地球上丰富的替代品的过程中，人们对含有铁和钴的体系进行了广泛的研究，然而，人们对这些体系的锰版本了解较少。通常，锰与氧气有很强的相互作用，有可能与铁或钴的催化活性相匹敌或超过。这些研究将通过制定锰络合物还原氧气的设计原则来实现这一点，从而使优化系统具有更好的性能。纳入这些努力的是一个以研究为重点的教育推广计划，该计划将制定科学交流培训计划和以研究为基础的实验室经验。综合研究和教育部分将解决该领域的根本挑战和当前NSF战略计划的优先事项，目标是最大化可再生能源技术的健康、环境和经济效益。在化学系化学催化计划的支持下，弗吉尼亚大学的查尔斯·W·马坎博士正在研究分子锰化合物对二氧化氧的催化还原。当与富含能量的分子的氧化结合在一起时，氧气还原是一种推动氧化反应或将化学能转换为电能的便捷方法。虽然锰金属中心作为分子催化剂活性中心的比例很低，但它与二氧化氧有很强的相互作用，可能会显示出与更多了解的铁和钴物种的催化活性相媲美或超过的催化活性。一种基于配位化学的方法将被用来通过调节锰中心的电子性质来增强二氧化氧的结合和活化，最终目标是改善催化性能。在初步研究中，已经开发了选择性产生过氧化氢或水作为反应产物的条件：过氧化氢是一种有价值的化学氧化剂，水是燃料电池理想的半反应。了解如何实现这些产品的高选择性和高活性对可再生能源的利用具有重要意义。为了满足对锰络合物还原氧气的基本了解的持续需要，将量化轴向配体在氧气结合和激活中的作用，将通过综合修改配体框架来改善催化响应，并将使用氧化还原介质寻求选择性过氧化氢和水生产的条件。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。

With the support of the Chemical Catalysis program in the Division of Chemistry, Dr. Charles W. Machan of the University of Virginia is studying the catalytic reduction of dioxygen by molecular manganese compounds. The reduction of dioxygen is important for producing energy from chemical bonds. Fuel cells, for example, often employ the reduction of dioxygen to water to generate clean energy. The current best catalysts for this reaction are based on platinum metal, which is rare and expensive. In the search for earth-abundant alternatives, systems containing iron and cobalt have been studied extensively, however, manganese versions of these systems are more poorly understood. Manganese generally interacts strongly with dioxygen and has the potential to rival or exceed the catalytic activity of iron or cobalt. These studies will achieve this by developing design principles for dioxygen reduction by manganese complexes, thus enabling optimized systems with improved performance. Integrated into these efforts is a research-focused educational outreach program, which will develop a scientific communication training program and a research-based lab experience. The integrated research and educational components will address fundamental challenges for the field and priorities of the current NSF Strategic Plan, with the goal of maximizing the health, environmental and economic benefits of renewable energy technologies.With the support of the Chemical Catalysis program in the Division of Chemistry, Dr. Charles W. Machan of the University of Virginia is studying the catalytic reduction of dioxygen by molecular manganese compounds. When paired with the oxidation of energy rich molecules, dioxygen reduction is a convenient way to drive oxidation reactions or to convert chemical energy to electrical energy. Manganese metal centers, while underrepresented as molecular catalyst active sites, have strong interactions with dioxygen and could demonstrate catalytic activity that rivals or exceeds the activity of more well-understood iron and cobalt species. A coordination chemistry-based approach will be used to enhance the binding and activation of dioxygen by tuning electronic properties at the Mn center, with the ultimate goal of improving catalytic performance. In initial studies, conditions for the selective generation of hydrogen peroxide or water as the reaction product have been developed: hydrogen peroxide is a valuable chemical oxidant and water is the desired half-reaction for fuel cells. Understanding how to achieve high selectivity and activity for each of these products has implications for renewable energy utilization. To address the ongoing need for fundamental understanding of the reduction of dioxygen by manganese complexes, the role of axial ligands in dioxygen binding and activation will be quantified, the catalytic response will be improved by synthetically modifying the ligand framework, and conditions for selective hydrogen peroxide and water production will be sought using redox mediators.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.