Carbon nanotube sheet electrodes have been prepared from catalytically grown carbon nanotubes of high purity and narrow diameter distribution, centered around 80 Å. Our study shows that the electrodes are free-standing mats of entangled nanotubes with an open porous structure almost impossible to obtain with activated carbon or carbon fiber. These properties are highly desirable for high power and long cycle life electrochemical capacitors. Specific capacitances of 102 and 49 F/g were measured at 1 and 100 Hz, respectively, on a single cell device with 38 wt % H2SO4 as the electrolyte. The same cell had a power density of >8000 W/kg.

Thin-film transistors (TFTs) are the fundamental building blocks for the rapidly growing field of macroelectronics. The use of plastic substrates is also increasing in importance owing to their light weight, flexibility, shock resistance and low cost. Current polycrystalline-Si TFT technology is difficult to implement on plastics because of the high process temperatures required. Amorphous-Si and organic semiconductor TFTs, which can be processed at lower temperatures, but are limited by poor carrier mobility. As a result, applications that require even modest computation, control or communication functions on plastics cannot be addressed by existing TFT technology. Alternative semiconductor materials that could form TFTs with performance comparable to or better than polycrystalline or single-crystal Si, and which can be processed at low temperatures over large-area plastic substrates, should not only improve the existing technologies, but also enable new applications in flexible, wearable and disposable electronics. Here we report the fabrication of TFTs using oriented Si nanowire thin films or CdS nanoribbons as semiconducting channels. We show that high-performance TFTs can be produced on various substrates, including plastics, using a low-temperature assembly process. Our approach is general to a broad range of materials including high-mobility materials (such as InAs or InP).

Pulsed laser ablation of graphite targets combined with an intense, atomic nitrogen source has been used to prepare C-N thin film materials. The average nitrogen content in the films was systematically varied by controlling atomic nitrogen flux. Rutherford backscattering measurements show that up to 40 percent nitrogen can be incorporated on average into these solids under the present reaction conditions. Photoelectron spectroscopy further indicates that carbon and nitrogen form an unpolarized covalent bond in these C-N materials. Qualitative tests indicate that the C-N solids are thermally robust and hard. In addition, strong electron diffraction is observed from crystallites within the films. Notably, analysis of these diffraction data show that the only viable structure for the C-N crystallites is that of beta-C(3)N(4), a material predicted theoretically to exhibit superhardness. The experimental synthesis of this new C-N material offers exciting prospects for both basic research and engineering applications.

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Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10(-3) S cm(-1) at room temperature, among the highest reported values to date. In this work, we investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using ab initio density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.