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

已经开发了一种用于在连续加热的金属箔上从甲烷生长合成石墨的新技术。该方法允许控制石墨的厚度，并且关键地控制石墨的同位素组成。三个研究路径将在由固态和材料化学计划资助的该计划中进行。还原氧化石墨烯和其他化学改性石墨烯（CMG）的形成机理和结构：以13 C/12 C的比例为变量，合成石墨将转化为氧化石墨（GO）。所产生的和剥离的GO都将进行各种改性，例如化学、物理或生物还原或官能化，以得到CMG材料。这种富含13 C的GO将是一种迷人的碳源，用于研究我们实验室最近发现的新型碳的详细分子结构和形成机制（KOH活化的微波剥离氧化石墨，称为“a-MEGO”）（Science 2011）。利用~（13）C标记的碳源，从实验和理论上为研究杂质原子（如N、B等）对CMG的局域或全局电子结构和态密度（DOS）的影响提供了可能。该a-MEGO材料将通过固态NMR（SS-NMR）、成像显微拉曼、傅里叶变换红外（FT-IR）光谱和其他技术来广泛表征以确定这些CMG的分子结构。CMG将被表征以确定其化学结构和在其生产过程中工作的分子水平机制。这些信息将用于优化CMG生产的化学成分，以用于重要用途，例如，用于电能存储的导电材料的合成。 改进13 C富集材料的生长：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13 C富集碳的质量、数量和形式。例如，一种新型的生长系统（RF加热/UHV组件）已经建成，与我们现有的设置相比，它应该提供显着的优势。这个新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。 石墨的生长作为石墨烯薄膜的来源：有可能产生仅几片厚的石墨层，其横向尺寸为许多微米。将开发改进的方法，从衬底上去除石墨，以生产高质量的石墨烯，这些石墨烯也可以富集13 C，用于基础物理研究。非技术总结这项拟议研究的目标是更好地了解石墨化学改性后的材料结构。要做到这一点，材料必须由富含碳的13 C同位素的合成石墨制成。为13 C富集石墨生产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。提高对氧化石墨及其衍生物化学性质的理解对于开发基于化学改性石墨的材料将是重要的。这些材料可以应用于不同的领域，例如：储能材料和结构材料。该提案包括一个重要的推广计划，如：研究生和博士后研究员的研究计划;高中和本科（包括少数民族）学生和高中教师的持续和夏季研究培训;课程材料的补充;以及通过德克萨斯大学奥斯汀分校的UTeach计划进行教师培训的7-12年级课程开发。目前正在与橡树岭国家实验室和伊利诺伊大学芝加哥分校的同事进行合作（SS-NMR）。

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).