Synthesis of chemically bonded graphene/carbon nanotube composites and their application in large volumetric capacitance supercapacitors.

Chemically bonded graphene/carbon nanotube composites as flexible supercapacitor electrode materials are synthesized by amide bonding. Carbon nanotubes attached along the edges and onto the surface of graphene act as spacers to increase the electrolyte-accessible surface area. Our lamellar structure electrodes demonstrate the largest volumetric capacitance (165 F cm(-3) ) ever shown by carbon-based electrodes.

Strong charge-transfer doping of 1 to 10 layer graphene by NO₂.

We use resonance Raman and optical reflection contrast methods to study charge transfer in 1-10 layer (1L-10L) thick graphene samples on which NO(2) has adsorbed. Electrons transfer from the graphene to NO(2), leaving the graphene layers doped with mobile delocalized holes. Doping follows a Langmuir-type isotherm as a function of NO(2) pressure.

Optical reflectivity and Raman scattering in few-layer-thick graphene highly doped by K and Rb.

We report the optical reflectivity and Raman scattering of few layer (L) graphene exposed to K and Rb vapors. Samples many tens of layers thick show the reflectivity and Raman spectra of the stage 1 bulk alkali intercalation compounds (GICs) KC(8) and RbC(8). However, these bulk optical and Raman properties only begin to appear in samples more than about 15 graphene layers thick.

Synthesis and electrical characterization of magnetic bilayer graphene intercalate.

We report synthesis and transport properties of the minimal graphite intercalation compound, a ferric chloride (FeCl(3))(n) island monolayer inside bilayer graphene. Chemical doping by the intercalant is simultaneously probed by micro-Raman spectroscopy and Hall measurements. Quantum oscillations of conductivity originate from microscopic domains of intercalated and unintercalated regions.

Raman enhancement on graphene: adsorbed and intercalated molecular species.

Strong Raman scattering is observed from iodine anions adsorbed at ca. 3% coverage on single layer graphene. In addition, the Raman signal from just one bromine intercalation layer inside three and four layer thick graphenes is observed.

Charge transfer chemical doping of few layer graphenes: charge distribution and band gap formation.

The properties of few layer (one layer (1 L) to four layer (4 L)) graphenes doped by adsorption and intercalation of Br(2) and I(2) vapors are investigated. The Raman spectra of the graphene G vibrations are observed as a function of the number of layers. There is no evidence for chemical reaction disrupting the basal plane pi electron conjugation.

Graphene oxidation: thickness-dependent etching and strong chemical doping.

Patterned graphene shows substantial potential for applications in future molecular-scale integrated electronics. Environmental effects are a critical issue in a single-layer material where every atom is on the surface. Especially intriguing is the variety of rich chemical interactions shown by molecular oxygen with aromatic molecules.