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.
