Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons.

Published versio

Graphene nanoribbons prepared from carbon nanotubes via alkali metal exposure

In various embodiments, the present disclosure describes processes for preparing functionalized graphene nanoribbons from carbon nanotubes. In general, the processes include exposing a plurality of carbon nanotubes to an alkali metal source in the absence of a solvent and thereafter adding an electrophile to form functionalized graphene nanoribbons. Exposing the carbon nanotubes to an alkali metal source in the absence of a solvent, generally while being heated, results in opening of the carbon nanotubes substantially parallel to their longitudinal axis, which may occur in a spiralwise manner in an embodiment. The graphene nanoribbons of the present disclosure are functionalized on at least their edges and are substantially defect free. As a result, the functionalized graphene nanoribbons described herein display a very high electrical conductivity that is comparable to that of mechanically exfoliated graphene

Layer-by-layer removal of graphene

The present invention provides methods of selectively removing one or more graphene layers from a graphene material by: (1) applying a metal to a surface of the graphene material; and (2) applying a hydrogen containing solution to the surface of the graphene material that is associated with the metal. The hydrogen containing solution dissolves the metal along with one or more layers of graphene associated with the metal, thereby removing the layer(s) of graphene from the graphene material. In some embodiments, the hydrogen containing solution is an acidic solution, such as hydrochloric acid. In some embodiments, the metal is zinc. In some embodiments, the methods of the present invention are utilized to selectively remove one or more layers of graphene from one or more targeted sites on the surface of a graphene material

Graphene compositions and drilling fluids derived therefrom

Drilling fluids comprising graphenes and nanoplatelet additives and methods for production thereof are disclosed. Graphene includes graphite oxide, graphene oxide, chemically-converted graphene, and functionalized chemically-converted graphene. Derivatized graphenes and methods for production thereof are disclosed. The derivatized graphenes are prepared from a chemically-converted graphene through derivatization with a plurality of functional groups. Derivatization can be accomplished, for example, by reaction of a chemically-converted graphene with a diazonium species. Methods for preparation of graphite oxide are also disclosed

Pristine Graphite Oxide

Graphite oxide (GO) is a lamellar substance with an ambiguous structure due to material complexity. Recently published GO-related studies employ only one out of several existing models to interpret the experimental data. Because the models are different, this leads to confusion in understanding the nature of the observed phenomena. Lessening the structural ambiguity would lead to further developments in functionalization and use of GO. Here, we show that the structure and properties of GO depend significantly on the quenching and purification procedures, rather than, as is commonly thought, on the type of graphite used or oxidation protocol. We introduce a new purification protocol that produces a product that we refer to as pristine GO (pGO) in contrast to the commonly known material that we will refer to as conventional GO (cGO). We explain the differences between pGO and cGO by transformations caused by reaction with water. We produce ultraviolet–visible spectroscopic, Fourier transform infrared spectroscopic, solid-state nuclear magnetic resonance spectroscopic, thermogravimetric, and scanning electron microscopic analytical evidence for the structure of pGO. This work provides a new explanation for the acidity of GO solutions and allows us to add critical details to existing GO models

Supporting Information for Tunable hybridized morphologies obtained through flash Joule heating of carbon nanotubes

Characterization of temperature during the FJH of SWCNT; Raman analyses; TEM images; SEM images; UV–vis characterization; and resistivity of composites made with additives.Peer reviewe

Spin Dynamics and Relaxation in Graphene Nanoribbons: Electron Spin Resonance Probing

Here we report the results of a multifrequency (∼9, 20, 34, 239.2, and 336 GHz) variable-temperature continuous wave (cw) and X-band (∼9 GHz) pulse electron spin resonance (ESR) measurement performed at cryogenic temperatures on potassium split graphene nanoribbons (GNRs). Important experimental findings include the following: (a) The multifrequency cw ESR data infer the presence of only carbon-related paramagnetic nonbonding states, at any measured temperature, with the <i>g</i> value independent of microwave frequency and temperature. (b) A linear broadening of the ESR signal as a function of microwave frequency is noticed. The observed linear frequency dependence of ESR signal width points to a distribution of <i>g</i> factors causing the non-Lorentzian line shape, and the <i>g</i> broadening contribution is found to be very small. (c) The ESR process is found to be characterized by slow and fast components, whose temperature dependences could be well described by a tunneling level state model. This work not only could help in advancing the present fundamental understanding on the edge spin (or magnetic)-based properties of GNRs but also pave the way to GNR-based spin devices

Laser-Induced Conversion of Teflon into Fluorinated Nanodiamonds or Fluorinated Graphene

Laser-assisted materials fabrication is an advanced technique that has propelled recent carbon synthesis approaches. Direct laser writing on polyimide or lignocellulose materials by a CO₂ laser has successfully transformed the substrates into hierarchical graphene. However, formation of other carbon allotropes such as diamond and fullerene remains challenging. Here, we report the direct synthesis of fluorinated nanodiamonds or fluorinated graphene by treating polytetrafluoroethylene (Teflon, or PTFE) with a 9.3 μm pulsed CO₂ laser under argon; no exogenous fluorine source is needed. The laser is part of a commercial laser cutting/scribing system that is found in most machine shops. Therefore, it is a readily accessible tool. This discovery could inspire future development for the laser-assisted synthesis of functionalized carbon allotropes