Carbon Encapsulated Magnetic Nanoparticles Produced by a Catalytic Disproportionation of Carbon Monoxide
- PDF / 164,133 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 73 Downloads / 196 Views
S5.10.1
Carbon Encapsulated Magnetic Nanoparticles Produced by a Catalytic Disproportionation of Carbon Monoxide Oleg Prilutskiy, Eugene A. Katz,1 Alexander I. Shames,2 D. Mogilyanski,3 Emma Mogilko4 and Ishai Bruckental4 CMC Ltd., POB 633, Ofakim 80300 Israel 1 Department of Solar Energy & Environmental Physics, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel 2 Department of Physics, Ben-Gurion University of the Negev, P.O.Box 653, 84105 Be’er-Sheva, Israel 3 Institutes of Applied Research, Ben-Gurion University of the Negev, P. O. Box 653, 84105 Be’er-Sheva, Israel 4 Department of Physics, Bar-Ilan University, Ramat Gan 51900, Israel
ABSTRACT Carbon nanocapsules with a ferromagnetic core of single-crystalline Fe3O4 are demonstrated to be effectively synthesized and collected separately from the other nano-carbon products of the low-temperature reaction of catalytic disproportionation of carbon monoxide. HRTEM demonstrated a defect-free crystalline structure of the Fe3O4 nanoparticles. The encapsulating carbon shells of the Fe3O4 nanoparticles are stable in air at room temperature, but do not prevent them at high temperatures. Accordingly, these nanoparticles may also act as catalysts for the corresponding production of carbon nanomaterials via carbon monoxide disproportionation. In particular, we demonstrate the corresponding transformation of a Fe3O4 core to an iron carbide nanoparticle with simultaneous formation of additional encapsulating carbon layers. Characterization of the synthesized materials by DC magnetization represents clearly resolved hysteresis loops. However characteristic S-shape of the loops (magnetization is still not saturated at 16 kOe) points out some superparamagnetic effects driven by the nano-size origin of the samples. Analysis of the sample’s EPR spectra provides an additional insight to the coexistence of several magnetic phases in the synthesized nanomaterials.
INTRODUCTION Carbon nanotubes produced by various catalytic methods, and in particular by a catalytic disproportionation of carbon monoxide, are known to be decorated by catalyst metal particles and quasi-spherical carbon nanocapsules with a catalyst metal core [1]. Carbon particles of all shapes (tubular and spherical) and sizes are collected all together and their separation constitutes a serious technological challenge and certainly will increase final prices of carbon nanotubes and nanopsheres. Here we report the serendipitous discovery of the fact that, using low-temperature reaction of catalytic disproportionation of carbon monoxide [2-3], quasi-spherical highly crystalline magnetic nanoparticles can be effectively synthesized as a side-product of carbon
S5.10.2
nanotube synthesis and collected separately from the other products of the reaction (carbon nanotubes, large carbon onions, amorphous carbon). Nanoparticles were analyzed by Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spe
Data Loading...
