Catalytic activity of nitrogen-containing functional groups supported on carbon structures for cathodic oxygen reduction reaction for PEM fuel cells

使用铂（Pt）催化剂的高成本，加上聚合物电解质膜（PEM）燃料电池中最大的潜在损失是由于阴极氧还原反应（ORR）的动力学引起的，这使得一些研究将重点放在了新型ORR催化剂的开发上。其中一些研究是基于使用血红蛋白类型分子来执行氧还原功能的自然启发概念。据报道，含有铁（Fe）或钴（Co）中心的大型有机大环在高表面积碳上支撑时对ORR具有活性。虽然这些复杂的化合物在燃料电池环境中不能长时间稳定，但当它们受到热处理时，剩余的含氮碳结构具有金属中心，显示出活性和稳定。虽然文献中有大量证据表明碳负载氮官能团（带或不带金属中心）作为PEM燃料电池的潜在阴极电催化剂可能具有氧还原活性，但对活性位点的性质和氧还原反应的机理还没有明确的认识。本提案的重点是研究含氮碳纳米结构中氧还原活性位点的性质，作为PEM燃料电池的潜在阴极催化剂。主要目标是(a)对活性位点的性质、金属中心的作用和碳支撑结构有一个基本的了解，(b)开发这些催化剂的纳米级合成技术，(c)建立一个知识库，从而设计出用于燃料电池电极的新型非贵金属催化材料。虽然该研究的最终目标是开发新型无铂PEM燃料电池电极，但目前的研究将重点放在含氮碳电极材料的合成上，以专门研究和评估影响氧还原活性的因素、金属/氮官能团/碳纳米结构/氧还原活性之间的相互关系、负责活性的活性位点、形成活性位点所需的前驱体材料的形式，以及这些材料在实际条件下的性能和稳定性。广泛的影响向氢经济的转变是一个国家的目标——因此，促进燃料电池广泛应用的技术的发展变得越来越重要。这项工作的结果可能使燃料电池的应用更接近现实。其他影响包括课程开发（“催化和燃料电池”的新课程，OSU-IGERT项目的系列研讨会），为研究生和本科生研究人员提供培训场地，并创建示范工具，用于“女性工程新生指导”项目，这将激发她们的想象力，并使她们对从事工程职业感到兴奋。该项目还将加强P.I.与法国cnrs催化研究所之间现有的国际合作。

ABSTRACTPI: Umit OzkanInstitution: Ohio State UniversityProposal Number: 0437451ResearchThe high costs associated with the use of platinum (Pt) catalysts coupled with the fact that the most significant potential loss in polymer electrolyte membrane (PEM) fuel cells is due to the kinetics of the oxygen reduction reaction (ORR) in the cathode have led several studies to focus on the development of novel ORR catalysts. Some of these studies are based on the nature-inspired concept of using hemoglobin-type molecules to perform the oxygen reduction function. Large organic macrocycles containing iron (Fe) or cobalt (Co) centers are reported to be active for ORR when supported on high-surface area carbon. Although these complex compounds are not stable for long periods of time in the fuel cell environment, when they are subjected to a heat treatment, the remaining nitrogen-containing carbon structures with metal centers are shown to be active and stable.Although there is ample evidence in the literature about the possible oxygen reduction activity of carbon-supported nitrogen functional groups (with and without metal centers) as potential cathode electrocatalysts for PEM fuel cells, there is no clear understanding about the nature of active sites and the mechanism of oxygen reduction reaction. The focus of this proposal is investigation of the nature of oxygen reduction active sites in nitrogen containing carbon nano-structures as potential cathode catalysts for PEM fuel cells. The main objectives are (a) acquiring a fundamental understanding of the nature of active sites, the role of the metal centers and the carbon support structure, (b) developing techniques for nano-scale synthesis of these catalysts and (c) building a knowledge base that would lead to the nano-scale design of novel, non-precious metal catalytic materials to be used as fuel cell electrodes. While the ultimate goal of the proposed research is the development of novel, platinum-free PEM fuel cell electrodes, the present study will focus on the synthesis of nitrogen-containing carbon electrode materials to specifically study and assess the factors contributing to oxygen reduction activity, the inter-relation between metal/nitrogen functional groups/carbon nano-structure/oxygen reduction activity, the active site(s) responsible for activity, the forms of precursor material necessary for active site formation, and the performance and stability of these materials under real conditions.Broad ImpactThe move to a hydrogen economy is a national target - consequently the development of technologies that facilitate wide application of fuel cells are becoming increasingly important. The results of this work could bring the application of fuel cells closer to reality. Other impacts include curriculum development (new course in "Catalysis and Fuel Cells", seminar series in OSU-IGERT program), providing a training ground for graduate and undergraduate researchers, and creating demonstration tools to be used in the "Orientation for Women Engineering Freshmen" program that would capture the imagination and that would get them excited about a career in engineering. The project will also strengthen an existing international collaboration between the P.I. and the French CNRS-Catalysis Research Institute.