Synthesis and characterization of mesoporous carbon nano-dendrites with graphitic ultra-thin walls and their application to supercapacitor electrodes

Mesoporous carbon nano-dendrites (MCNDs) with ultra-thin graphitic walls are synthesized by controlling the highly exothermic segregation reaction of silver acetylide into a carbon skeleton and silver vapor. The dendroid acetylides were quickly warmed to 150 degrees C emitting a brilliant flash of reddish orange light with a thunderous sound indicative of the sudden jump of the local temperature to higher than 2000 degrees C. This sudden heating boils off the silver from the main body, leaving carbon skeletons, the MCNDs. Raman spectra clearly indicate that the skeletons consist of mainly single-layer graphene walls. SEM and TEM images as well as EELS spectra show that the main bodies with similar to 50 nm radii branches every 100-150 nm and is composed of cells with graphene walls. The MCNDs showed a BET surface area of 1610 m(2)/g. Cyclic voltammetry of a supercapacitor with MCND electrodes showed good rectangular curves, even at a scanning rate of 400 mV/s and a peak current density higher than 40 A/g, suggesting applicability for high current and high-speed charge-discharge capacitors for motor vehicles. These properties are attributed to the dendroid branching structure of the main body that allows fast and massive ion transport through the open channels between branches. (C) 2008 Elsevier Ltd. All rights reserved.