Electron Irradiation of Graphene in Air at Atmospheric Pressure: a Method for Hydrogenating Graphene for Hydrogen Storage Applications

非技术概述氢储存是当前发展基于氢的绿色和可再生能源经济的重要课题。经过数十年的研究，氢尚未在汽车燃料电池等领域获得广泛的商业应用，主要是因为安全，经济和有效地储存氢的问题。通过这个项目，由材料研究部的固态和材料化学计划支持，Jose Perez教授和他在北德克萨斯大学（UNT）的研究小组将研究一种简单，安全和商业上可行的储氢方法，在大气压下使用石墨烯的电子辐照。大气压下的石墨烯具有吸附在其表面上的大量水，并且吸附的水的电子照射可以将水解离成氢，然后氢被吸附在石墨烯上;当石墨烯的温度增加到约200摄氏度的相对低的温度时，吸附的氢解吸。主要目的是确定吸附的物种是否是氢，并研究这种材料的存储，电学和光学性质。如果被吸附的物质是氢，则这可以为氢存储带来显著的益处。该项目将从代表性不足的群体中招募和培训本科生和研究生，并在当地高中组织展览和演示，并在UNT举办关于气候变化和可再生能源的科学博览会。目的是研究石墨烯在近大气压空气中用1-30 keV电子辐照后的性质。在这种条件下照射的机械剥离的悬浮石墨烯的初步实验显示出拉曼D峰强度与拉曼G峰强度的极高比率为5.3，表明高缺陷密度。先前关于在真空中对支撑的剥离的石墨烯进行电子辐照的报道显示了产生的缺陷是氢吸附物的证据。假设在近大气压下照射的石墨烯中产生的缺陷也是氢吸附物，在这种情况下观察到的高缺陷密度可能意味着高氢覆盖率，其将满足或超过4.5wt%氢存储的能源部目标。这种材料可以具有独特且有价值的储氢、机械、电和光学性质。主要目标是确定辐照石墨烯中缺陷的身份和性质。在这个项目中使用的表征技术是从单个石墨烯样品的热脱附，标记质谱，扫描隧道显微镜，拉曼光谱，原子力显微镜和X射线光电子能谱。该项目的推广活动包括在当地高中举办展览和演示，并为大都会地区的高中生组织关于气候变化和绿色能源的年度科学博览会。该奖项反映了NSF的法定使命，并通过使用基金会的智力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 SUMMARYHydrogen storage is a topic of significant interest in the current development of a hydrogen-based energy economy that is green and renewable. After decades of research, hydrogen has not yet reached widespread commercial applications in areas such as vehicle fuel cells, mainly because of the problem of storing hydrogen safely, economically, and efficiently. With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor Jose Perez and his research group at the University of North Texas (UNT) will investigate a method for storing hydrogen that is simple, safe, and commercially viable using electron irradiation of graphene at atmospheric pressure. Graphene at atmospheric pressure has a lot of water adsorbed on its surface, and electron irradiation of the adsorbed water may dissociate the water into hydrogen that then becomes adsorbed on the graphene; the adsorbed hydrogen desorbs when the temperature of the graphene increases to a relatively low temperature of about 200 degrees Celsius. The main objectives are to determine if the adsorbed species is hydrogen and investigate the storage, electrical and optical properties of this material. If the adsorbed species is hydrogen, this may bring significant benefits to hydrogen storage. The project will recruit and train undergraduate and graduate students from underrepresented groups and organize exhibits and demonstrations at local high schools and a science fair at UNT on climate change and renewable energy resources.TECHNICAL SUMMARYThis project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, aims to investigate the properties of graphene after irradiation with 1-30 keV electrons in air at near-atmospheric pressure. Preliminary experiments on mechanically exfoliated suspended graphene irradiated under such conditions show an extremely high ratio of the Raman D peak intensity to the Raman G peak intensity of 5.3, indicating a high defect density. Previous reports on electron irradiation of supported exfoliated graphene in a vacuum showed evidence that the defects produced are hydrogen adsorbates. Assuming the defects produced in graphene irradiated at near-atmospheric pressure are also hydrogen adsorbates, the high defect densities observed in this case may imply high hydrogen coverages that would meet or exceed the Department of Energy target of 4.5 wt % hydrogen storage. Such material may have unique and valuable hydrogen storage, mechanical, electrical, and optical properties. The primary objectives are to determine the identity and properties of the defects in the irradiated graphene. The characterization techniques used in this project are thermal desorption from individual graphene samples, labeled mass spectroscopy, scanning tunneling microscopy, Raman spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. The outreach activities for this project include presenting exhibits and demonstrations at local high schools and organizing a yearly science fair for high school students in the Metroplex area on climate change and green energy.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.