CAREER: Exploring Chemistry at Graphene Oxide Liquid Interfaces

在这个由化学系化学结构、动力学和机制(CSDM-A)项目资助的项目中，路易斯安那州立大学的Revati Kumar教授正在研究液体如何与一种名为石墨烯氧化物或GO的材料相互作用。在分子尺度上，GO可以被描述为一张连接在一起的碳原子，氧原子在几个地方附着在碳原子上。GO的片状结构类似于石墨，石墨是另一种用于润滑剂和铅笔芯的碳材料。石墨的“滑性”来自于碳材料的细小薄片相互滑动。库马尔教授对围棋的兴趣不是因为它的润滑能力，而是因为它可以用来吸附其他分子和离子(例如水中的杂质)，或者用于电池、燃料电池和催化剂等其他技术。围棋的一个有趣的特点是它的化学性质是“可调的”。也就是说，通过改变附着在碳片上的氧原子的数量，产生不同的反应性。库马尔教授和她的学生正在开发计算机模型，以模拟各种围棋的性质和行为，以及它们与不同分子和液体的相互作用。从事这一项目的研究生和本科生正在接受理论和计算化学方面的培训，范围从统计力学和量子力学的基本概念到计算算法和建模。作为大学本科生物理化学课程的一部分，库马尔教授开发了分子模拟模块。这门课程为她针对研究生和博士后的计算方法国际课程提供了基础，帮助他们了解该领域使用的最先进的计算方法。库马尔教授还参与了K-12科学活动，如超级科学星期六和马丁·路德·金。一天的活动。她开发了一系列面向高中生和中学生的演讲和实践学习模块，向未被充分代表的少数族裔学生介绍STEM职业。该项目主要研究固-液界面的化学反应和动力学。氧化石墨烯(GO)既含有疏水结构域，又含有亲水结构域，是一种模拟表面体系。这种纳米尺度的异质性导致了不对称的溶剂化环境，以及化学吸附和反应活性从一个界面位置到另一个界面位置不同的一般条件。GO的含氧量可以在很大范围内变化，使GO成为一种“可调”的材料。这个项目使用计算分子动力学工具来探索氧含量对界面结构和动力学非均质性的影响。对GO技术至关重要的三个特定主题进行了探索，即疏水和亲水结构域之间对溶剂化环境和动力学的竞争，这些界面上的反应活性，以及电极-电解液界面上的结构。发展精确而高效的多体、全原子力场以及对实验数据的分子解释是该项目的关键方面。基于化学直观的经验价键法模拟GO膜的酸碱反应性的反应力场也在开发中。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program of the Chemistry Division, Professor Revati Kumar from Louisiana State University is investigating how liquids interact with a material called graphene oxide or "GO". At the molecular scale, GO can be described as a sheet of carbon atoms linked together, with oxygen atoms attached to carbon atoms in a few places. The sheet-like structure of GO is similar to graphite, another carbon material which is used in lubricants and pencil leads. The "slipperiness" of graphite derives from the tiny sheets of carbon material sliding past each other. Professor Kumar's interest in GO is not for its lubrication abilities, but because it can be used to adsorb other molecules and ions (for example impurities in water), or be used in other technologies like batteries, fuel cells and catalysts. An interesting feature of GO is that its chemical properties are "tunable." That is, by varying the number of oxygen atoms attached to the carbon sheet, different reactivities result. Professor Kumar and her students are developing computer models to simulate the properties and behavior of various kinds of GO, and their interactions with different molecules and liquids. Graduate and undergraduate students working on this project are being trained in theoretical and computational chemistry ranging from fundamental concepts in statistical mechanics and quantum mechanics to computational algorithms and modeling. Professor Kumar develops molecular simulation modules as part of the undergraduate physical chemistry curriculum at her university. This course provides a basis for her international course on computational methods targeting graduate students and postdoctoral students to help them understand the state-of-the-art computational methods used in the field. Professor Kumar is also involved in K-12 science activities such as Super Science Saturday and Martin Luther King, Jr. Day initiatives. She develops "Fun with molecules", a series of presentations and hands-on learning modules for high school and middle school students that introduce underrepresented minority students to STEM careers. This project focuses on chemical reactivity and dynamics at solid-liquid interfaces. Graphene oxide (GO) is model surface system because it contains both hydrophobic and hydrophilic domains. This nano-scale heterogeneity leads to asymmetrical solvation environments, and a general condition where chemical adsorption and reactivity differ from one interfacial site to the next. The oxygen content of GO can be varied over a wide range, making GO a "tunable" material. This project uses computational molecular dynamics tools to explore the effect of oxygen content on interfacial structural and dynamical heterogeneity. Three specific themes that are critical for GO-based technologies are being explored, namely, the competition between hydrophobic and hydrophilic domains on solvation environment and dynamics, reactivity at these interfaces, and structuring at the electrode-electrolyte interface. The development of accurate yet efficient many-body, all atom force-fields as well as molecular interpretations of experimental data are key aspects of this project. Reactive force-fields based on the chemically intuitive empirical valence bond approach to model acid-base reactivity of GO membranes are also being developed.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.