Carbon nanopowders from the continuous-wave CO2 laser-induced pyrolysis of ethylene Original Research Article

Carbon nanopowders were obtained by the laser pyrolysis of ethylene. The high-temperature gradients and very rapid reaction times characteristic of the process lead to the formation of very fine powders. Carbon powders obtained in runs with different laser power values (400–900 W), pressures (250–950 mbar), and gas flows (100–300 sccm) were characterised by transmission electron microscopy (TEM), including high-resolution mode (HREM), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD) and Raman spectroscopy. The carbon particles were found to be approximately spherical in shape, with diameters around 45 nm, which may coalesce into larger agglomerates. The particles were found to be made up of layers forming a turbostratic structure. The experimental parameters influence the soot morphology and particle microstructure. Increasing the laser power and gas pressure leads to less coalescence and increased order. Structural parameters are presented for particles produced under different conditions.