Search

We report direct printing and photo-thermal reduction of graphite oxide (GO) to obtain a highly porous pattern of interdigitated electrodes, leading to a supercapacitor on a flexible substrate. Key parameters optimized include the amount of GO delivered, the suitable photo-thermal energy level for effective flash reduction, and the substrate properties for appropriate adhesion after reduction. Tests with supercapacitors based on the printed-reduced GO showed performance comparable with commercial supercapacitors: the energy densities were 1.06 and 0.87 mWh/cm³ in ionic and organic electrolytes, respectively. The versatility in the architecture and choice of substrate makes this material promising for smart power applications. [ABSTRACT FROM AUTHOR]

We demonstrate a simple and reproducible technique to synthesize crystalline and superconducting In-Sn intermetallic nanowires sheathed in carbon nanotubes (CNTs). The method is based on the catalytic reaction of C2H2over a mixture of both SnO2 and In2O3 particles. Importantly, tetragonal &bgr;-In3Sn and hexagonal &ggr; -InSn4 nanowires with diameters of less than 100 nm are selectively synthesized at different SnO2 to In2O3weight ratios. CNTs may serve as cylindrical nanocontainers for continuous growth of liquid-phased In1-xSnx nanowires during growth process as well as for their solidification into In-Sn intermetallic nanowires during the cooling process. Microscopic and spectroscopic analyses clearly reveal evidence of a core-shell structure of the CNT-sheathed In-Sn intermetallic nanowires. Magnetization measurements show that the superconducting In-Sn nanowires have a critical magnetic field higher than the value of their bulk intermetallic compounds. Our method can be adopted to the nanofabrication of analogous binary and ternary alloys. [ABSTRACT FROM AUTHOR]

Cellular-type carbon fibers, prepared by heat-treatment of cellulose fibers that ranged from 500 to 2300 °C, were used as catalytic support for the growth of carbon nano-filaments. A comparison of the Raman spectra of products prepared at different heat-treatment temperatures showed significant variation in the carbon structure of the surfaces of the as-prepared carbon fibers. TEM observation clearly revealed that the products heat-treated below 1000 °C had an amorphous phase, and at 1500 °C they were similar to glassy carbon-an example of non-graphitizing carbon. Surface graphitization of the carbon fibers derived by pre-treatment at 1500 °C was accomplished at above 2000 °C. Multi-walled carbon nanotubes (MWCNTs), approximately 15 nm and 8 μm in diameter and length, were synthesized on the surface of the prepared carbon fibers via a tip growth mechanism. TEM images and Raman spectra confirmed that the higher synthesis temperature could lead to the formation of MWCNTs with better crystalline carbon shells. [ABSTRACT FROM AUTHOR]