CAREER: Enhancing Atomic Mobility and Desorption Kinetics in Metal Hydrides

非技术描述：该项目旨在通过实施研究和教育推广活动，帮助发展氢经济，并激发公众对燃料电池和电动机车载氢储存主题的讨论。这些研究项目将研究限制氢作为一种实际可行的燃料来源的实施的重要未解问题。具体来说，催化剂在金属氢化物中的作用将使用位于美国和国外同步加速器x射线和中子设施的最先进的仪器进行研究。调查将围绕以下问题展开：？催化剂如何促进金属氢化物粉末（如NaAlH4或LiBH4）中H2气体的去除和吸收？然后呢?同样的催化剂是否会增强或减少氢化物粉末中的长距离原子运动？由该基金设立的其他项目将包括每年由一组学生设立的高中设计挑战项目。这个高中项目将被称为“能源项目”（探索与Y世代相关的新能源替代方案）（参见projectEnerG.com了解最新情况）。技术细节：本提案的目的是了解催化添加剂在提高金属氢化物（特别是NaAlH4和LiBH4）的原子迁移率和解吸率方面的影响。将研究烧结模型对一类新材料的适应性，同时结合x射线和中子散射研究来了解这些氢化物在解吸过程中的局部晶格变化。之前了解催化剂作用的实验研究仅限于单一实验，如x射线吸收光谱、核磁共振或直接成像，以了解催化剂周围的局部结构。另外，建议的项目通过应用整个范例来解决这个问题。为了建立理解过渡金属在氢化物中的作用的概念，思想取自一个发达的研究领域（即陶瓷烧结和致密化），其中了解掺杂剂如何影响扩散和质量输运。研究将探讨过渡金属催化剂添加剂对H2脱附过程中不同阶段原子迁移率的影响。同步加速器x射线散射数据有助于理解质量传递和H2解吸在微观结构修复中的相对作用。由于催化添加而形成的点缺陷的浓度和类型将通过正电子湮灭研究来确定。此外，原位同步加速器x射线衍射、中子扩散散射研究与原子对分布函数分析以及x射线吸收光谱将能够检查氢解吸和吸收时的局部晶格应变、晶格非晶化和催化剂局部结构。PI有指导同步加速器x射线研究的学生研究人员的历史？通过她在历史悠久的黑人大学——格兰布林州立大学和路易斯安那理工大学的联合教职，许多人来自代表性不足的群体。该项目将同时支持本科生和研究生。教育活动包括同步加速器x射线研究和替代能源的新课程，以及一个高中外展计划。

NON-TECHNICAL DESCRIPTION: The project is designed to aid in the development of the hydrogen economy and to stimulate public discourse on the topic of on-board vehicular hydrogen storage for fuel cells and electric motors by implementing research and educational outreach activities. The research projects will study important unanswered questions which limit the implementation of hydrogen as a practical and viable fuel source. Specifically, the role of catalysts in metal hydrides will be studied using state-of-the-art instrumentation located at synchrotron x-ray and neutron facilities within the U.S. and abroad. Investigations will surround the questions: ?How do catalysts facilitate the removal and uptake of H2 gas in metal hydride powders (e.g. NaAlH4 or LiBH4)?? and ?Do the same catalysts act to enhance or decrease long range atomic movement in the hydride powders?? Other projects instituted by this funding will include a high school design challenge project to be instituted annually with a team of students. The high school program will be called Project ENERGY (Exploring New Energy-alternatives Relevant to Generation Y) (see projectEnerG.com for updates).TECHNICAL DETAILS: The objective of this proposal is to understand the influence of catalytic additives in enhancing atomic mobility and desorption rates in metal hydrides (specifically, NaAlH4 and LiBH4). The adaptation of sintering models to a new class of materials will be investigated, while incorporating x-ray and neutron scattering studies to understand local lattice changes in these hydrides during desorption. Prior experimental investigations to understand the role of catalysts have been limited to single-experiments such as x-ray absorption spectroscopy, nuclear magnetic resonance, or direct imaging to understand the local structure around the catalysts. Alternatively, the proposed project approaches this problem by applying an entire paradigm. In order to build concepts in understanding the role of the transition metals in hydrides, ideas are taken from a well-developed field of study (i.e., ceramic sintering and densification) wherein it is understood how dopants effect diffusion and mass transport. Studies will investigate the effect of transition metal catalytic additives on atomic mobility at various stages of the H2 desorption process. Synchrotron x-ray scattering data aid in understanding the relative roles of mass transport and H2 desorption on microstructure remediation. Concentration and type of point defects formed as a result of catalytic additions will be determined using positron annihilation studies. As well, in situ synchrotron x-ray diffraction, neutron diffuse scattering studies with atomic pair distribution function analysis, and x-ray absorption spectroscopy will enable examination of local lattice strains, lattice amorphization and catalyst local structure upon hydrogen desorption and uptake. The PI has a history of mentoring student researchers at synchrotron x-ray studies ? many from underrepresented groups, through her joint faculty position between Grambling State University, a historically Black university, and Louisiana Tech University. This program will support both undergraduate and graduate students. Educational activities include new courses on synchrotron x-ray studies and alternative energy, and a high school outreach program.