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-A（CSDM-A）计划资助的项目中，路易斯安那州立大学的Revati Kumar教授正在研究液体如何与称为氧化石墨烯或“GO”的材料相互作用。在分子尺度上，GO可以被描述为连接在一起的碳原子片，其中氧原子在几个地方连接到碳原子。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“光滑性”来自于碳材料的微小薄片相互滑动。Kumar教授对GO的兴趣并不在于它的润滑能力，而是因为它可以用于吸附其他分子和离子（例如水中的杂质），或用于电池，燃料电池和催化剂等其他技术。GO的一个有趣的特征是它的化学性质是“可调的”。“也就是说，通过改变附着在碳片上的氧原子的数量，会产生不同的反应性。Kumar教授和她的学生正在开发计算机模型来模拟各种GO的性质和行为，以及它们与不同分子和液体的相互作用。 从事该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。Kumar教授开发了分子模拟模块，作为她所在大学本科物理化学课程的一部分。本课程为她针对研究生和博士后学生的计算方法国际课程提供了基础，以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。日倡议。她开发了“分子的乐趣”，这是一系列针对高中和初中学生的演示和动手学习模块，将代表性不足的少数民族学生介绍给STEM职业。该项目侧重于固液界面的化学反应性和动力学。氧化石墨烯（GO）是一种典型的表面体系，因为它同时含有疏水和亲水结构域。这种纳米尺度的异质性导致不对称的溶剂化环境，以及化学吸附和反应性从一个界面位置到下一个界面位置不同的一般条件。GO的氧含量可以在宽范围内变化，使GO成为“可调”材料。本计画利用计算分子动力学工具探讨氧含量对界面结构与动力学不均匀性的影响。三个具体的主题，是关键的GO为基础的技术正在探索，即，在溶剂化环境和动力学，在这些接口的反应性，并在电极-电解质界面结构的疏水和亲水域之间的竞争。准确而有效的多体，所有原子力场的发展以及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方法的反应力场也正在开发中，以模拟GO膜的酸碱反应性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.