Nanocrystalline Al-Mg Alloys for Hydrogen Storage

技术支持：在运输车辆中储存和使用氢气所涉及的危险导致了对用于储氢的金属氧化物的研究。要求该催化剂具有高的重量和体积储存容量、在相对低的温度下的快速氢化/脱氢动力学和在环境条件下的稳定结构。最近已经表明，镁铝矾土Mg（AlH 4）2具有存储容量和脱氢性能的最佳组合，并且在环境条件下相对稳定。然而，其加氢特性尚不清楚。预计几个因素可以增强氢化动力学，包括将晶粒尺寸减小到纳米范围，增加表面积和掺入催化剂。另一方面，合成过程中的污染是阻碍氢吸收的主要问题。在这个项目中，将开发一种新的合成技术，将生产纳米晶多孔粉末的铝镁合金与控制成分和高纯度。在这些合金中的氢化物形成的基本过程将阐明与定制的组合物和纳米结构的优化储氢特性的目标。采用电沉积技术制备Mg含量在25 ~ 60wt%范围内的纳米晶Al-Mg合金。将研究亚稳态沉积合金的热稳定性和相演变，并对选定的微观结构进行加氢特性测试。基于在纳米级的结构的详细表征和氢化数据的分析，合金的组成和结构对吸氢动力学的影响的机械理解将被开发。如有必要，将加入催化剂如石墨和Pd以增强氢化动力学。将研究具有优化的氢化性能的合金的氢脱附特性。本研究结果将提供一种新的合成技术，并阐明加氢/脱氢过程的机理。非技术性：能源消耗的快速增长，化石燃料的急剧减少以及对高效清洁燃料替代品的需求导致了对需要氢气作为燃料的燃料电池的深入研究和开发。这是佛罗里达大学材料科学与工程系和中央佛罗里达大学佛罗里达太阳能中心之间的合作项目。这项工作将通过在同行评审的期刊上发表和在国家和国际会议，大学，国家实验室等上发表的结果传播来影响科学界。这些研究的结果将有助于开发一种潜在的储氢材料，这将对燃料电池驱动的汽车的发展产生重大影响。这项研究的技术影响将是重要的，因为电沉积是一个成熟的行业，技术转让将是非常容易的。该计划的教育部分包括在大一和高年级的研究生和本科生的培训。由于材料科学与工程在高中和初中学生中并不广为人知，因此将努力通过参加MSE教学研讨会和在实验室接待高中学生来教育教师。将通过为国际学生提供实习来促进国际教育。

TECHNICAL: The hazards involved in storing and using hydrogen gas in transportation vehicles has led to the investigation of metal hydrides for hydrogen storage. The hydrides are required to have high gravimetric and volumetric storage capacities, fast hydrogenation/dehydrogenation kinetics at relatively low temperatures and stable structures in ambient conditions. Recently it has been shown that magnesium alanate, Mg(AlH4)2, has the best combination of storage capacity and dehydrogenation properties and is relatively stable under ambient conditions. However, its hydrogenation characteristics are not known. Several factors are expected to enhance the hydrogenation kinetics including reducing grain size to nano-regime, increasing the surface area and incorporating catalysts. On the other hand contamination during synthesis is a major issue that impedes the hydrogen uptake. In this program, a new synthesis technique will be developed that will produce nanocrystalline porous powders of Al-Mg alloys with controlled composition and high purity. Fundamental process of hydride formation in these alloys will be elucidated with the objective of tailoring the composition and nanostructure for optimized hydrogen storage characteristics. Electrodeposition techniques will be employed for fabricating the nanocrystalline Al-Mg alloys within 25 to 60wt% Mg composition range. Thermal stability and the phase evolution of the metastable as-deposited alloys will be investigated and selected microstructures will be tested for hydrogenation characteristics. Based on the detailed characterization of the structure at nanoscale and analysis of the hydrogenation data, a mechanistic understanding of the effects of alloy composition and structure on the hydrogen uptake kinetics will be developed. Catalysts such as graphite and Pd will be incorporated to enhance the hydrogenation kinetics, if necessary. The alloys with optimized hydrogenation properties will be investigated for their hydrogen desorption characteristics. The results of this research will provide a new technique for synthesis and shed light on the mechanisms of hydrogenation/dehydrogenation processes. NON-TECHNICAL: The fast increase in energy consumption, the drastic decrease in fossil fuels, and the demand for an efficient and clean fuel alternative have resulted to the intensive research and development of fuel cells, which require hydrogen as fuel. This is a collaborative program between the Materials Science and Engineering Department at the University of Florida and the Florida Solar Energy Center at the University of Central Florida. This work will impact the scientific community through the dissemination of the results by publishing in peer-assessed journals and presentation at national and international conferences, universities, national labs, etc. Results from these studies will help to develop a potential material for hydrogen storage which will have significant impact on the development of fuel cell driven cars. The technological impact of this research will be important because electrodeposition is a well-established industry and the transfer of technology will be very easy. The educational component of this program includes training of graduate and undergraduate students at freshman as well senior level. Since Materials Science and Engineering is not well known among the high school and middle school students, efforts will be placed on educating the teachers through participation in the MSE-teach workshop and hosting high school students in labs. Education at an international level will be promoted by providing internship for international students.