Product Code: ICA10_N305

Growth of Carbon Nano-Onions in Open Air Through Laser Resonant Excitation of Ethylene Molecules
Authors:
Y. Gao, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
J.B. Park, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
Y.S. Zhou, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
X.N. He, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
Z.Q. Xie, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
Y.F. Lu, Department of Electrical Engineering, University of Nebraska-Lincoln; Lincoln NE USA
Presented at ICALEO 2010

Carbon nano-onions (CNOs) containing multi-shell structures exhibited potential applications in extensive fields, such as gas storage media, catalyst support, supercapacitor electrode, and electromagnetic shielding/absorbing material. A handful of methods have been developed for growing CNOs. However, these methods require either high temperature processing (thermal annealing of diamond nanoparticles), or further purification process to remove amorphous carbon and metallic catalysts (arc discharge, laser ablation, carbon ion implantation, and CVD). A convenient, scalable, efficient synthetic strategy is required for preparing high quality CNOs in large scale at a low cost. In this study, we developed a multi-energy synthetic strategy to achieve highly efficient growth of CNOs in open air through laser resonant excitations of precursor molecules in combustion flame. A wavelength-tunable CO2 laser (spectrum range from 9.2 to 10.9 μm) was used for resonant excitations. A pre-mixed ethylene/oxygenB gaseous mixture was used as precursor for growing CNOs. Laser beams of the matching wavelength, 10.532 µm, were coupled into the combustion process to resonantly excite the CHB2B wagging mode of ethylene molecules. CNOs with highly ordered lattices were obtained through the laser resonant excitations. Significant decreases were observed for the full width at half maximum (FWHM) values of D- and G-bands without and with laser resonant excitation. An obviously increased G/D ratio was observed, indicating improved crystalline structures. Improvement in the CNO crystalline structures were ascribed to the increase of C2 radicals in the combustion flame which is believed to play a critical role in forming more ordered grapheme layers.