title: Copper induced hollow carbon nanospheres by arc discharge method: controlled synthesis and formation mechanism.
abstract: Hollow carbon nanospheres with controlled morphologies were synthesized via the copper-carbon direct current arc discharge method by alternating the concentrations of methane in the reactant gas mixture. A self-healing process to keep the structural integrity of encapsulated graphitic shells was evolved gradually by adding methane gas from 0% to 20%. The outer part of the coated layers expanded and hollow nanospheres grew to be large fluffy ones with high methane concentrations from 30% to 50%. A self-repairing function by the reattachment of broken graphitic layers initiated from near-electrode space to distance was also distinctly exhibited. By comparing several comparable metals (e.g. copper, silver, gold, zinc, iron and nickel)-carbon arc discharge products, a catalytic carbon-encapsulation mechanism combined with a core-escaping process has been proposed. Specifically, on the basis of the experimental results, copper could be applied as a unique model for both the catalysis of graphitic encapsulation and as an adequate template for the formation of hollow nanostructures.
authors.affiliation: Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561, Japan. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Hu
authors.forename: Mihai Alexandru
authors.initials: MA
authors.lastname: Ciolan
authors.forename: Xiangke
authors.initials: X
authors.lastname: Wang
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nagatsu