Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp(2)-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

The effects of residues introduced during the transfer of chemical vapor deposited graphene from a Cu substrate to an insulating (SiO 2) substrate on the physical and electrical of the transferred graphene are studied. X-ray photoelectron spectroscopy and atomic force microscopy show that this residue can be substantially reduced by annealing in vacuum. The impact of the removal of poly(methyl methacrylate) residue on the electrical properties of graphene field effect devices is demonstrated, including a nearly 2 Â increase in average mobility from 1400 to 2700 cm 2 /Vs. The electrical results are compared with graphene doping measurements by Raman spectroscopy. V

A novel nanomaterial which consists of graphene sheets decorated with silsesquioxane molecoles has been developed. Indeed, aminopropyl-silsesquioxane (POSS-NH 2 ) has been employed to functionalize graphene oxide sheets (GOs). The surface grafting of GOs with POSS-NH 2 has been established by infrared spectroscopy and X-ray photoelectron spectroscopy, while the morphology has been investigated by field emission electron microscopy as well as by atomic force microscopy. The combination of the amino functionalized POSS molecules with GO sheets produces a hybrid silicon/graphite-based nanomaterial, named GRAPOSS, for which the electrical conductivity of reduced GO was restored, thus allowing promising exploitations in several fields such as polymer nanocomposites.Supporting Information. Experimental procedures, AFM and XPS characterization of the prepared samples. This material is available free of charge via the Internet at

Field-effect transistors fabricated on graphene grown by chemical vapor deposition (CVD) often exhibit large hysteresis accompanied by low mobility, high positive backgate voltage corresponding to the minimum conductivity point (V(min)), and high intrinsic carrier concentration (n(0)). In this report, we show that the mobility reported to date for CVD graphene devices on SiO(2) is limited by trapped water between the graphene and SiO(2) substrate, impurities introduced during the transfer process and adsorbates acquired from the ambient. We systematically study the origin of the scattering impurities and report on a process which achieves the highest mobility (μ) reported to date on large-area devices for CVD graphene on SiO(2): maximum mobility (μ(max)) of 7800 cm(2)/(V·s) measured at room temperature and 12,700 cm(2)/(V·s) at 77 K. These mobility values are close to those reported for exfoliated graphene on SiO(2) and can be obtained through the careful control of device fabrication steps including minimizing resist residue and non-aqueous transfer combined with annealing. It is also observed that CVD graphene is prone to adsorption of atmospheric species, and annealing at elevated temperature in vacuum helps remove these species.

We present a study of the nucleation of atomic layer deposition of Al2O3 on highly oriented pyrolytic graphite (HOPG) using trimethlyaluminum (TMA) with ozone as the oxidant (TMA/O3). In situ x-ray photoelectron spectroscopy (XPS) is used to study TMA/O3 depositions on HOPG. We examine the dependence of TMA/O3 nucleation on deposition temperature and characterize the morphology and uniformity of deposited films by ex situ atomic force microscopy. The impact of several predeposition surface treatments of the graphite surface condition is discussed, particularly with regard to the presence of adsorbed atmospheric contamination.

Deposition of Al2O3 and HfO2 dielectrics on graphite is studied as a route to the formation of a high-κ dielectric on graphene. Electron beam evaporation of metal Al and Hf is followed by a separate oxidation step. Reactive e-beam deposition of HfO2 by introduction of O2 to the deposition chamber is also demonstrated as an alternative to the two-step metal deposition and oxidation approach. We employ in situ x-ray photoelectron spectroscopy to study reactions between the substrate and deposited film and ex situ atomic force microscopy to examine the dielectric film morphology.

A study of the chemical interactions between the atomic layer deposition (ALD) Al2O3 precursors trimethlyaluminum (TMA) and ozone (TMA/O3) and sp2 carbon surfaces is presented. In-situ x-ray photoelectron spectroscopy is used to study these interactions, while ex-situ atomic force microscopy (AFM) is used to monitor the surface morphology. Ozone functionalization of the sp2 carbon surface is discussed and the dependence of TMA/O3 reactions over a range of ALD process conditions is examined. The utilization of a 6-cycle room temperature TMA/O3 ALD seed layer to nucleate the conformal growth of Al2O3 by TMA/H2O at 200 °C as well as the quality of such films is discussed. Two stages of ozone reactions are observed: first the ozone appears to remove adsorbed species from the graphite surface before reacting with the surface. The deposition of Al2O3 is found to be strongly dependant on the N2 purge time as well as the precursor pulse sequence. It is shown that the quality of these low temperature deposited films can easily be improved by removal of carbon containing species through an 300 °C anneal.

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