Technical: This project is on "foliated graphene" or thin carbon sheets grown on the sidewall of multiwall carbon nanotubes. Studying this materials system from the nucleation and growth to the atomic level surface chemistry and structure to the electronic properties will enable a rigorous intellectual assessment of this unique material and the development of phenomenological models of nucleation and growth. An iterative nucleation, growth, materials analysis, and properties measurements feedback loop is expected to be established through this research project to insure the most rapid and effective knowledge creation and implementation. A combined kinetic-thermodynamic approach is used to evaluate foliated graphene nucleation thresholds as well as measure growth rates as a function of critical parameters such as carbon nanotube diameter, catalyst nanoparticle size and temperature to understand rate determining steps and activation energies for the model development. Electron microscopy, Raman scattering and photoemission spectroscopy measurements are used to examine the structure, chemistry and graphene-nanotube interfaces as a function of these nucleation and growth parameters.
The project addresses basic research issues in a topical area of materials science and engineering with potential technological relevance. High charge densities of the graphene edges will be exploited via supercapacitance (for energy storage), charge injection (for neural stimulation electrodes), and field emission (for vacuum microelectronic devices). The research is expected to provide insight into the growth mechanisms of nanostructured carbon materials. Graduate and undergraduate students are trained in an interdisciplinary environment for materials growth, characterization, and modeling.