CAREER: Promoting Selective Electrochemical CO2 Reduction by Controlling a Catalyst's Primary, Secondary, and Outer Coordination Spheres

将二氧化碳（CO2）转化为增值产品是储存太阳能和风能等间歇性能源作为化学燃料的重要手段。 CO2转化的挑战之一是，用于该反应的最活性的催化剂倾向于同时产生许多不同的产物，例如一氧化碳、甲醇、甲烷、乙烯和副产物氢气（H2）。 虽然期望将CO2还原成这些化学品中的任一种，但是由于产物分离和隔离中的问题，非选择性地产生多种产物是不理想的。McCrory博士以天然酶为灵感，正在创建合成系统，其中催化剂嵌入聚合物中，控制活性位点环境和反应物输送，以促进选择性CO2还原为单一产品。拟议的研究具有更广泛的社会影响，因为它为开发用于CO2回收和储能的新催化剂系统提供了框架。 同时，McCrory博士专注于通过三步教育计划提高密歇根州的能源素养，包括1）研究生科学传播培训，2）通过公共活动中的互动演示进行社区推广，以及3）在密歇根大学自然历史博物馆开发和实施一个专注于可再生能源存储的展览。 通过这种方法，McCrory博士正在努力使更广泛的社区能够更好地参与能源政策和使用决策。 在化学部化学催化计划的资助下，查尔斯·C·L.密歇根大学安阿伯分校的McCrory正在合成新的电催化材料，通过控制催化剂活性部位周围的初级、次级和外部配位球来选择性地减少二氧化碳。 该建议的中心假设是，分子电催化剂的多电子转换，如CO2还原的反应性和选择性可以调制不仅通过修改周围的金属中心的配体框架，但也通过修改催化剂？的化学环境，以控制H+和基板交付的金属活性位点。 为了验证这一假设，McCrory博士将平面过渡金属配合物与大环配体封装在配位聚合物中。 使用各种光谱和电分析技术的配位环境，电子结构和所得的聚合物催化剂系统的催化活性进行了研究。 通过对配体、聚合物和反应条件的系统性修改，McCrory博士独立控制金属中心周围的初级、次级和外部配位球，并确定每个配位球对整体催化活性和产物选择性的影响。 从这项研究中获得的知识对于开发用于选择性CO2还原的新型催化剂-聚合物复合材料系统至关重要，并且在设计用于可再生能源储存和CO2减排的新型电催化系统方面具有更广泛的社会影响。 此外，McCrory博士还致力于通过为公众设计与可再生能源储存相关的互动演示，以及在密歇根大学自然历史博物馆举办展览，突出可再生能源储存的进展和挑战，来提高密歇根州的能源素养。该奖项的研究和综合教育部分共同强调了克服能源储存和二氧化碳转化挑战的新方法，并将影响这些重要问题在科学和社会层面的解决方式。该奖项反映了NSF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。

The conversion of carbon dioxide (CO2) into value-added products is of fundamental importance as a means of storing intermittent energy sources like solar and wind as chemical fuels. One of the challenges in CO2 conversion is that the most active catalysts for this reaction tend to simultaneously produce a number of different products such as carbon monoxide, methanol, methane, ethylene, and the side product hydrogen gas (H2). While the reduction of CO2 to any one of these chemicals is desired, the non-selective generation of multiple products is non-ideal due to problems in product separation and isolation. Using natural enzymes as inspiration, Dr. McCrory is creating synthetic systems in which catalysts are embedded within polymers that control the active site environment and reactant delivery to facilitate selective CO2 reduction to single products. The proposed research has significant broader societal impact in that it provides a framework for the development of new catalyst systems for CO2 recycling and energy storage. Concurrently, Dr. McCrory is focused on increasing energy literacy in Michigan using a 3-step education plan involving 1) graduate student training in scientific communication, 2) community outreach through interactive demonstrations at public events, and 3) the development and implementation of an exhibit at the University of Michigan Natural History Museum focused on renewable energy storage. Through this approach, Dr. McCrory is working to enable the broader community to better engage in energy policy and usage decisions. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Charles C. L. McCrory of the University of Michigan, Ann Arbor is synthesizing new electrocatalytic materials for selective carbon dioxide reduction by controlling the primary, secondary, and outer coordination spheres surrounding the catalyst's active site. The central hypothesis for this proposal is that the reactivity and selectivity of molecular electrocatalysts for multi-electron transformations such as CO2 reduction can be modulated not only by modifying the ligand framework surrounding the metal center, but also by modifying the catalyst?s chemical environment to control H+ and substrate delivery to the metal active site. To test this hypothesis, Dr. McCrory is encapsulating planar transition metal complexes with macrocyclic ligands inside of coordinating polymers. The coordination environment, electronic structure and catalytic activity of the resulting polymer-catalyst systems are studied using a variety of spectroscopic and electroanalytical techniques. Through systematic modifications of the ligand, polymer, and reaction conditions, Dr. McCrory is independently controlling the primary, secondary, and outer coordination spheres surrounding the metal center and determining the effect of each coordination sphere on the overall catalytic activity and product selectivity. The knowledge gained from this study is crucial for the development of new catalyst-polymer composite systems for selective CO2 reduction and has significant broader societal impact in the design of new electrocatalytic systems for renewable energy storage and CO2 mitigation. In addition, Dr. McCrory is working to increase energy literacy in Michigan through the design of interactive demonstrations relevant to renewable energy storage for the general public and the development of an exhibit at the University of Michigan Natural History Museum highlighting progress and challenges in renewable energy storage. Together, the research and integrated education components of this proposal highlight a new approach to overcoming challenges in energy storage and carbon dioxide conversion and will impact the way these important issues are addressed, both at the scientific and societal level.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.