CAS-SC: Elucidating the Electrocatalytic Coupling of Nitrate and Carbon Dioxide: Toward Electron Efficient C-N Coupling

在化学系化学催化计划的支持下，密歇根大学的Nirala Singh、Bryan Goldsmith和Suljo Linic正在研究利用废水中的可再生电力、二氧化碳和硝酸盐生产尿素这一重要肥料。尿素目前是用氨水制造的。用于尿素合成的氨生产会排放大量二氧化碳，因为氨是通过首先将天然气转化为氢和二氧化碳，然后在高温下将氢和氮结合而产生的。相反，拟议的工艺将使用由可再生电力提供动力的低温电化学方法，将二氧化碳和硝酸盐结合起来，直接生产二氧化碳排放量少得多的尿素。这项研究有可能改变尿素生产的模式，同时减轻两种有害的空气和水污染物。该项目将通过灰熊学者计划让小学生了解STEM(科学、技术、工程和数学)，并通过暑期高中学徒研究计划为高中生提供研究经验。这些教育项目旨在促进下一代STEM学生的发展。在该项目下，密歇根大学的Nirala Singh、Bryan Goldsmith和Suljo Linic团队正在研究使用二氧化碳和硝酸盐的电催化C-N偶联。通过联合计算和实验方法，他们将研究二氧化碳和硝酸盐在金属合金上的反应机理，目标是提高对尿素的选择性。他们将测量二氧化碳分压和硝酸盐浓度的影响，以确定潜在的反应机理，并与原子模拟研究进行比较，以确定速率决定步骤和选择性决定步骤。他们将使用拉曼光谱和X射线吸收光谱来表征反应条件下的电催化剂，以更好地了解反应机理。他们还将调查线性吸附比例关系在限制尿素选择性方面的作用，以及使用新的合金成分如何避免这些限制。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, Nirala Singh, Bryan Goldsmith, and Suljo Linic of the University of Michigan are studying the production of urea, an important fertilizer, using renewable electricity, carbon dioxide, and nitrate from wastewater. Urea is currently manufactured using ammonia. Ammonia production for urea synthesis emits large quantities of carbon dioxide because ammonia is produced by first converting natural gas to hydrogen and carbon dioxide, then combining hydrogen and nitrogen at high temperatures. The proposed process will instead use low-temperature electrochemical methods powered by renewable electricity to couple carbon dioxide and nitrate to directly produce urea with much less carbon dioxide emissions. This research has the potential for a paradigm shift in the production of urea while mitigating two harmful air and water pollutants. The project will engage elementary schoolers about STEM (science, technology, engineering and mathematics) through the Grizzly Scholar program and provide high school students with research experience each summer through a Summer High School Apprentice Researchers Program. These educational programs aim to foster development of the next generation of STEM students. Under this project the team of Nirala Singh, Bryan Goldsmith, and Suljo Linic of the University of Michigan is studying electrocatalytic C-N coupling using carbon dioxide and nitrate. Through a joint computational and experimental approach, they will study the reaction mechanism of carbon dioxide and nitrate coupling on metal alloys with a target of increasing selectivity to urea. They will measure the effects of partial pressure of carbon dioxide and concentration of nitrate to identify potential reaction mechanisms and compare with atomistic modeling studies to identify rate-determining and selectivity-determining steps. They will use Raman and X-ray absorption spectroscopies to characterize the electrocatalysts under reaction conditions to better understand the reaction mechanism. They will also investigate the role that linear adsorbate scaling relations have on limiting the urea selectivity, and how the use of novel alloy compositions can avoid these limitations.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.