SGER - Probing Oxygen Reduction Reaction Kinetics Using Heterostructured Thin-Film Microelectrodes

CBET-0844526 Shao-Horn本研究的目的是对氧还原动力学进行研究，以加深我们对钙钛矿表面氧还原的基本了解，包括动力学与表面特定结构和组成的关系，并利用这一理解来提高和稳定氧化物表面的电催化活性。在这个项目中，我们致力于探索氧还原动力学，通过将(La，Sr)x(Mn，Fe，Ni，Cu)YOZ钙钛矿微电极的氧表面交换与过渡金属和氧的键强度关联起来，我们的研究集中在两个假设上：(1)表面交换速率主要受氧化物的电子结构而不是结构中的氧空位影响；(2)钙钛矿型ABO3和A2BO4型氧化物之间的界面，这种界面可以增强氧表面交换，如川田最近的工作所表明的那样。这些假设将使用以下概念来检验：(I)对于给定的过渡金属价态，从锰到铜，随着过渡金属和氧键强度的降低，表面交换率将提高；(Ii)ABO3和A2BO4氧化物界面的成分变化可以改变过渡金属和氧键的键强度，因为氧空位可能会降低金属和氧键的离子活性，从而降低键强度，这可能被用来提高氧表面交换率。这项研究利用模型薄膜微电极来构建定义明确的体系，从而能够对混合离子和电子导电钙钛矿电催化剂上的氧还原反应限速步骤进行基础研究，并发现控制氧表面交换速率的基本原理。这些信息将使研究人员能够在基本原理的指导下创造具有快速氧表面交换的材料，并在纳米尺度上设计电极微结构，以便在中温下有效地进行氧还原。拟议的研究工作将产生对电化学能源技术具有重要意义的广泛知识产权，并创造出对整个催化领域感兴趣的知识。拟议的综合研究和教育活动培训未来的能源领导者，掌握电化学能量转换和材料方面的跨学科知识。该外展计划将向高中教师和学生传授能源基础知识，并将通过研讨会、课堂课程开发和服务学习项目帮助K-12支持能源研究和节约能源。

CBET-0844526Shao-HornThis objective of this research is to conduct a study of oxygen reduction kinetics to improve our fundamental understanding of oxygen reduction on perovskites, including the relationship of kinetics to surface-specific structure and composition, and exploit this understanding to enhance and stabilize oxide surface electrocatalytic activity. In this project, we focus on our efforts in probing oxygen reduction kinetics by correlating oxygen surface exchange of (La, Sr)x(Mn, Fe, Ni, Cu)yOz perovskite microelectrodes to the bond strength of transition metal and oxygen, where our research is centered around two hypothesis: (1) the surface exchange rate is influenced largely by the electronic structure of oxides rather than oxygen vacancy in the structure; and (2) interface between perovskite ABO3 and A2BO4 type oxides, where such interfaces may enhance oxygen surface exchange as shown by Kawada's recent work. These hypotheses will be examined using the following concepts: (i) for a given transition metal valence state, going from Mn to Cu, the surface exchange rate would be enhanced as the transition metal and oxygen bond strength is reduced; (ii) compositional changes at the ABO3 and A2BO4 oxide interfaces can modify bond strength of transition metal and oxygen as oxygen vacancy may decrease the ionic activity of metal and oxygen bonds and thus lower the bond strength, which might be exploited to enhance oxygen surface exchange rates. The proposed research employs model thin-film microelectrodes to fabricate well-defined systems that allow fundamental investigation of oxygen reduction reaction rate-limiting steps on mixed ionic and electronic conducting perovskite electrocatalysts, and discover the fundamental principles that governs oxygen surface exchange rate. The information would allow researchers to create materials with fast oxygen surface exchange guided by the fundamental principles, and design electrode microstructures at the nanometer-scale for efficient oxygen reduction at intermediate temperatures. The proposed research efforts will generate broad intellectual properties significant to electrochemical energy technologies and create knowledge of interest to the field of catalysis at large. The proposed integrated research and education activities train future energy leaders with interdisciplinary knowledge in electrochemical energy conversion and materials. The outreach program will teach high school teachers and students about energy basics, and will serve to engage K-12 to support energy research and conserve energy through workshop, classroom curriculum development and Service Learning projects.