One-Dimensional Functional Nanocrystals with Non-Precious-Metal Cores and Precious-Metal Shells

非技术摘要：开发高效和绿色能源转换技术对美国能源和环境可持续性具有战略重要性。与传统的化石燃料燃烧装置相比，质子交换膜燃料电池（PEMFC）在运输和固定电网应用中具有巨大的潜力，因为它们更清洁，更便宜，更可靠;它们使用可再生氢燃料;它们表现出高效率，最小化碳排放。本项目旨在开发一类具有一维结构和核/壳结构的新兴纳米结构材料，以最大限度地发挥PEMFC的优势。这种纳米材料的合理设计和精确制备可以显着提高对高效和具有成本效益的PEMFC和许多其他应用（包括电池，电解槽和电化学传感器）的材料设计和合成的理解。该项目的成果可以加速PEMFC的大规模应用，潜在地改变美国的能源组合，并建立一个生态良性的能源社会。一项教育计划旨在与研究活动相结合，以促进包括K-12、本科生和研究生在内的各级教育的教学、培训和学习。部分活动包括涉及代表人数不足的少数群体的教育外联活动。该项目可以在催化、能源技术和其他科学、技术、工程和数学（STEM）领域吸引、培养和留住高素质的下一代劳动力。技术摘要： 质子交换膜燃料电池（PEMFC），基于可再生氢源，在建立可持续和清洁的氢能源经济，以减少我们的社会对传统化石燃料和相关燃烧技术的依赖方面发挥着关键作用。适用于大规模运输和固定电网电力的先进PEMFC需要纳米结构材料，该纳米结构材料可用于在足够长的时间段内以高活性加速阴极氧还原反应（ORR），并且使用最小化的铂族金属。本项目的目标是设计和合成具有非贵金属核的一维核-壳纳米晶体，通过精确控制其核-壳材料组成和物理参数（例如一维纳米棒的长度，核-壳界面和壳轮廓），从根本上了解原子级结构与有利的电催化性能的相关性。主要研究者利用在纳米材料合成、结构表征、电化学和理论计算方面的专业知识，主要专注于四项任务：（1）合理设计和合成具有可控长度和壳轮廓的磷化钴-铂核壳纳米棒;（2）调整核壳界面和结构排列;（3）优化纳米棒的结构和尺寸。（3）通过使用过渡金属掺杂的磷化钴纳米棒核来优化纳米晶体的效率;以及（4）通过电化学、光谱和计算方法的组合来理解优化ORR转化的设计规则。所产生的知识通过利用原子水平的合成机制控制来加速新型纳米材料的开发，并揭示了如何关联和控制其功能活性和结构稳定性。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。

Non-Technical Abstract:Developing efficient and green energy conversion technologies is of strategic importance for the United States energy and environmental sustainability. Compared with conventional fossil fuel combustion devices, proton exchange membrane fuel cells (PEMFCs) hold great potentials for both transportation and stationary grid applications since they are cleaner, more affordable, and more reliable; they run with renewable hydrogen fuel; and they demonstrate high efficiency with minimized carbon emission. This project aims to develop an emerging class of nanostructured materials with one-dimensional architecture and core/shell structure which can maximize the benefit of PEMFCs. The rational design and precise preparation of such nanomaterials can significantly advance the understanding of both materials design and synthesis for efficient and cost-effective PEMFCs and many other applications, including batteries, electrolyzers, and electrochemical sensors. The outcome of this project can accelerate the large-scale application of PEMFCs, potentially transform the United States energy portfolio, and establish an eco-benign energy society. An education plan is designed to be integrated with research activities to promote teaching, training and learning at several levels, covering K-12, undergraduate and graduate students. Parts of the activities include educational outreach involving underrepresented minorities. The project can attract, build and retain a high-quality next-generation workforce in catalysis, energy technology and other science, technology, engineering, and math (STEM) fields.Technical Abstract: Proton exchange membrane fuel cells (PEMFCs), based on renewable hydrogen sources, play a critical role in establishing a sustainable and clean hydrogen energy economy to reduce our society's dependency on conventional fossil fuels and the related combustion technologies. Advanced PEMFCs suitable for large-scale transportation and stationary grid powers demand a nanostructured material that can be used to accelerate the cathodic oxygen reduction reaction (ORR) with a high activity over a sufficiently long period of time and with minimized platinum group metal usage. The objective of this project is to design and synthesize one-dimensional core-shell nanocrystals with non-precious-metal cores, by precisely controlling their core-shell material compositions and physical parameters (e.g. lengths of one-dimensional nanorods, core-shell interfaces, and shell profiles), to fundamentally understand the correlation of atomic level nanocrystal architecture to the favorable electrocatalytic properties. The Principle Investigator leverages the expertise in nanomaterials synthesis, structural characterization, electrochemistry and theoretical calculation, to primarily focus on four tasks: (1) Rationally designing and synthesizing cobalt phosphide-platinum core-shell nanorods with controlled lengths and shell profiles; (2) Tuning the core-shell interface and structural arrangements; (3) Optimizing the efficiency of nanocrystals by using transition metal doped cobalt phosphide nanorod cores; and (4) Understanding the design rules for optimized ORR conversion through a combination of electrochemical, spectroscopic, and computational approaches. The generated knowledge accelerates the development of new forms of nanomaterials by exploiting the mechanism controls of synthesis at the atomic level and uncovers how to correlate and control their functional activity and structural stability.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.