Synthesis and Detailed Chemical Structure of Isotopically Enriched Graphite Oxide, Reduce Graphene Oxides, and Chemically Modified Graphenes

技术总结开发了一种从甲烷在电阻加热的金属箔上生长合成石墨的新技术。这种方法可以控制石墨的厚度，更重要的是，可以控制石墨的同位素组成。在这项由固体和材料化学计划资助的计划中，将探索三条研究道路。还原石墨烯氧化物和其他化学修饰石墨烯(CMGs)的形成机理和结构：以13C/12C为变量，合成石墨将转化为氧化石墨(GO)。无论是生产的GO还是剥离的GO，都将经过化学、物理或生物还原或功能化等各种修饰，以获得CMG材料。这种富含13C的GO将是一个迷人的碳源，用于研究我们实验室最近发现的新型碳(KOH活化的微波剥离氧化石墨，称为a-MEGO)的详细分子结构和形成机理(Science 2011)。利用~(13)C标记的碳源，从实验和理论上研究了外来原子(如N、B等)对CMG局域或全局电子结构和态密度(DOS)的影响。这种a-MAGO材料将通过固体核磁共振(SS-核磁共振)、成像微拉曼光谱、傅立叶变换红外光谱(FT-IR)和其他技术进行广泛的表征，以确定这些CMG的分子结构。将对CMGs进行表征，以确定其化学结构和在其生产过程中发挥作用的分子水平的机制。这些信息将被用于优化CMG生产的化学成分，用于重要用途，例如合成电能存储的导电材料。富13C材料生长的改进：我们将继续研究我们的生长方法，以进一步提高我们可以生产的富13C碳的质量、数量和形式。例如，已经建造了一种新型的生长系统(射频加热/特高压组件)，与我们现有的设置相比，应该会提供显著的优势。这个新的系统应该会产生额外的材料，我们可以提供给潜在的合作者。作为石墨烯薄膜来源的石墨的生长：可以生产只有几张纸厚的石墨层，横向尺寸为许多微米。将开发从衬底中去除石墨以生产高质量石墨烯的改进方法，这些石墨烯也可以富含13C用于基础物理研究。非技术总结这项拟议的研究的目标是更好地了解从石墨的化学修饰中获得的材料的结构。要做到这一点，这些材料必须由富含碳的13C同位素的合成石墨制成。为生产富13C石墨而建立的方法将意味着这种新材料类型将广泛用于其他科学家的研究。更好地了解氧化石墨及其衍生物的化学组成，对于开发以化学修饰石墨为基础的材料将是重要的。这些材料可应用于各种领域，如：储能材料和结构材料。该提案包括一项重要的外展计划，例如：面向研究生和博士后研究员的研究计划；为高中生和本科生(包括少数族裔)和高中教师提供的持续和暑期研究培训；增加课程材料；通过德克萨斯大学奥斯汀分校的UTeach计划进行教师培训，为7-12年级开发课程。与橡树岭国家实验室和伊利诺伊大学芝加哥分校的同事们正在进行合作(SS-核磁共振)。

TECHNICAL SUMMARYA novel technique for growing synthetic graphite from methane on resistively-heated metal foils has been developed. This method allows the control of the thickness and, crucially, the isotopic composition of the graphite. Three research paths will be pursued in this program funded by the Solid State and Materials Chemistry Program. Formation mechanisms and structures of reduced graphene oxides and other chemically modified graphenes (CMGs): With the ratio of 13C/12C as a variable, synthetic graphite will be converted to graphite oxide (GO). Both as-produced and exfoliated GO will be subjected to various modifications such as chemical, physical, or biological reduction, or functionalization, to give CMG materials. This 13C-enriched GO will be a fascinating carbon source to study the detailed molecular structure and the formation mechanism of the new type of carbon that has been recently discovered in our lab (KOH activated microwaved exfoliated graphite oxide called 'a-MEGO') (Science 2011). The fundamental study on the change of the local or global electronic structure and the Density of States (DOS) of CMG by foreign atoms (such as N, B, etc) is made both experimentally and theoretically possible with the aid of 13C-labeled carbon sources. This a-MEGO material will be extensively characterized by solid-state NMR (SS-NMR), imaging micro-Raman, Fourier transform infra-red (FT-IR) spectroscopy, and other techniques to determine the molecular structure of these CMGs. The CMGs will be characterized to determine their chemical structures and the molecular-level mechanisms at work during their production. This information will be used to optimize the chemistry of CMG production for important uses, e.g., the synthesis of conductive material for electrical energy storage. Improved growth of 13C-enriched material: We will continue to study our growth methods to further the quality, quantity, and forms of 13C-enriched carbons that we can produce. For example, a new type of growth system (RF heating/UHV components) has been built, that should offer significant advantages compared to our existing setup. This new system should result in extra material that we can supply to potential collaborators. Growth of graphite as a source of thin graphene films: It is possible to produce layers of graphite only a few sheets thick, with lateral dimensions of many microns. Improved methods of removing the graphite from the substrate to produce high-quality graphene that can also be 13C-enriched for fundamental physical studies will be developed.NON-TECHNICAL SUMMARYThe goal of this proposed research is to better understand the structure of materials derived from the chemical modification of graphite. To do this, the materials must be made from synthetic graphite enriched in the 13C isotope of carbon. The methods that are established for 13C-enriched graphite production will mean that this new material type will be broadly available for studies by other scientists. Improved understanding of the chemistries of graphite oxide and derivatives will be important for the development of materials based on chemically modified graphite. These materials may find application in diverse areas such as: energy storage materials and in structural materials. The proposal includes a significant program in outreach, such as: research programs for graduate students and postdoctoral fellows; continuous and summer research training for high school and undergraduate (including minority) students and high school teachers; additions to course materials; and curriculum development for grades 7-12 by teacher training through the UTeach program at the University of Texas at Austin. There are ongoing collaborations with Oak Ridge National Laboratory and with colleagues at the University of Illinois-Chicago (SS-NMR).