Synthesis of Carbon Onions Including Fe₃C by Chemical Vapor Deposition Using an Iron Catalyst Supported on Sodium Chloride

Abstract

Carbon onions including Fe3C were synthesized by the catalytic decomposition of acetylene at 400 °C using iron supported on sodium chloride as catalyst. The samples were examined by high resolution transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The results show that carbon onions including Fe3C core with a structure of stacked graphitic fragments and diameters in the range 15-50 nm were obtained. When the product was further heat-treated under vacuum at 1100 °C, carbon onions with a clear concentric graphitic layer structure were obtained.

Ethyne-Reducing Metal–Organic Frameworks to Control Fabrications of Core/shell Nanoparticles as Catalysts

“…At a temperature lower than 600 °C, the ethyne deposition facilitates the formation of porous carbon shells varying from amorphous to graphene with different degrees of graphitization. The resulted structure distinctly differs from the metal@carbon-onions where the graphitized carbon materials are in focus. − The defects formed in graphitization create transport channels to the active metal nanoparticles encapsulated. The higher the C 2 H 2 treatment temperature, the higher the resistance of the carbon shell to the acid leaching.…”

“…The resulted structure distinctly differs from the metal@carbon-onions where the graphitized carbon materials are in focus. [23][24][25][26][27][28] The defects formed in graphitization create transport channels to the active metal nanoparticles encapsulated. The higher the C2H2 treatment temperature, the higher the resistance of the carbon shell to the acid leaching.…”

“…Such core/shell structures were achieved by chemical vapor deposition of ethyne over MOFs. Ethyne deposition has been well studied for the preparation of carbon nanotubes or the carbon-encapsulated metal particles, which are also called metal@carbon-onions. − The previous studies focused on the graphitization of carbon materials. The metal nanoparticles in metal@carbon-onions have a broad size distribution varying from ten to hundreds of nanometers and a low metal concentration.…”